Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
the default is off.
- kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode
- Valid arguments: 0, 1, 2
- kmemcheck=0 (disabled)
- kmemcheck=1 (enabled)
- kmemcheck=2 (one-shot mode)
- Default: 2 (one-shot mode)
-
kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
Default is 0 (don't ignore, but inject #GP)
kasan
ubsan
kmemleak
- kmemcheck
gdb-kernel-debugging
kgdb
kselftest
+++ /dev/null
-Getting started with kmemcheck
-==============================
-
-Vegard Nossum <vegardno@ifi.uio.no>
-
-
-Introduction
-------------
-
-kmemcheck is a debugging feature for the Linux Kernel. More specifically, it
-is a dynamic checker that detects and warns about some uses of uninitialized
-memory.
-
-Userspace programmers might be familiar with Valgrind's memcheck. The main
-difference between memcheck and kmemcheck is that memcheck works for userspace
-programs only, and kmemcheck works for the kernel only. The implementations
-are of course vastly different. Because of this, kmemcheck is not as accurate
-as memcheck, but it turns out to be good enough in practice to discover real
-programmer errors that the compiler is not able to find through static
-analysis.
-
-Enabling kmemcheck on a kernel will probably slow it down to the extent that
-the machine will not be usable for normal workloads such as e.g. an
-interactive desktop. kmemcheck will also cause the kernel to use about twice
-as much memory as normal. For this reason, kmemcheck is strictly a debugging
-feature.
-
-
-Downloading
------------
-
-As of version 2.6.31-rc1, kmemcheck is included in the mainline kernel.
-
-
-Configuring and compiling
--------------------------
-
-kmemcheck only works for the x86 (both 32- and 64-bit) platform. A number of
-configuration variables must have specific settings in order for the kmemcheck
-menu to even appear in "menuconfig". These are:
-
-- ``CONFIG_CC_OPTIMIZE_FOR_SIZE=n``
- This option is located under "General setup" / "Optimize for size".
-
- Without this, gcc will use certain optimizations that usually lead to
- false positive warnings from kmemcheck. An example of this is a 16-bit
- field in a struct, where gcc may load 32 bits, then discard the upper
- 16 bits. kmemcheck sees only the 32-bit load, and may trigger a
- warning for the upper 16 bits (if they're uninitialized).
-
-- ``CONFIG_SLAB=y`` or ``CONFIG_SLUB=y``
- This option is located under "General setup" / "Choose SLAB
- allocator".
-
-- ``CONFIG_FUNCTION_TRACER=n``
- This option is located under "Kernel hacking" / "Tracers" / "Kernel
- Function Tracer"
-
- When function tracing is compiled in, gcc emits a call to another
- function at the beginning of every function. This means that when the
- page fault handler is called, the ftrace framework will be called
- before kmemcheck has had a chance to handle the fault. If ftrace then
- modifies memory that was tracked by kmemcheck, the result is an
- endless recursive page fault.
-
-- ``CONFIG_DEBUG_PAGEALLOC=n``
- This option is located under "Kernel hacking" / "Memory Debugging"
- / "Debug page memory allocations".
-
-In addition, I highly recommend turning on ``CONFIG_DEBUG_INFO=y``. This is also
-located under "Kernel hacking". With this, you will be able to get line number
-information from the kmemcheck warnings, which is extremely valuable in
-debugging a problem. This option is not mandatory, however, because it slows
-down the compilation process and produces a much bigger kernel image.
-
-Now the kmemcheck menu should be visible (under "Kernel hacking" / "Memory
-Debugging" / "kmemcheck: trap use of uninitialized memory"). Here follows
-a description of the kmemcheck configuration variables:
-
-- ``CONFIG_KMEMCHECK``
- This must be enabled in order to use kmemcheck at all...
-
-- ``CONFIG_KMEMCHECK_``[``DISABLED`` | ``ENABLED`` | ``ONESHOT``]``_BY_DEFAULT``
- This option controls the status of kmemcheck at boot-time. "Enabled"
- will enable kmemcheck right from the start, "disabled" will boot the
- kernel as normal (but with the kmemcheck code compiled in, so it can
- be enabled at run-time after the kernel has booted), and "one-shot" is
- a special mode which will turn kmemcheck off automatically after
- detecting the first use of uninitialized memory.
-
- If you are using kmemcheck to actively debug a problem, then you
- probably want to choose "enabled" here.
-
- The one-shot mode is mostly useful in automated test setups because it
- can prevent floods of warnings and increase the chances of the machine
- surviving in case something is really wrong. In other cases, the one-
- shot mode could actually be counter-productive because it would turn
- itself off at the very first error -- in the case of a false positive
- too -- and this would come in the way of debugging the specific
- problem you were interested in.
-
- If you would like to use your kernel as normal, but with a chance to
- enable kmemcheck in case of some problem, it might be a good idea to
- choose "disabled" here. When kmemcheck is disabled, most of the run-
- time overhead is not incurred, and the kernel will be almost as fast
- as normal.
-
-- ``CONFIG_KMEMCHECK_QUEUE_SIZE``
- Select the maximum number of error reports to store in an internal
- (fixed-size) buffer. Since errors can occur virtually anywhere and in
- any context, we need a temporary storage area which is guaranteed not
- to generate any other page faults when accessed. The queue will be
- emptied as soon as a tasklet may be scheduled. If the queue is full,
- new error reports will be lost.
-
- The default value of 64 is probably fine. If some code produces more
- than 64 errors within an irqs-off section, then the code is likely to
- produce many, many more, too, and these additional reports seldom give
- any more information (the first report is usually the most valuable
- anyway).
-
- This number might have to be adjusted if you are not using serial
- console or similar to capture the kernel log. If you are using the
- "dmesg" command to save the log, then getting a lot of kmemcheck
- warnings might overflow the kernel log itself, and the earlier reports
- will get lost in that way instead. Try setting this to 10 or so on
- such a setup.
-
-- ``CONFIG_KMEMCHECK_SHADOW_COPY_SHIFT``
- Select the number of shadow bytes to save along with each entry of the
- error-report queue. These bytes indicate what parts of an allocation
- are initialized, uninitialized, etc. and will be displayed when an
- error is detected to help the debugging of a particular problem.
-
- The number entered here is actually the logarithm of the number of
- bytes that will be saved. So if you pick for example 5 here, kmemcheck
- will save 2^5 = 32 bytes.
-
- The default value should be fine for debugging most problems. It also
- fits nicely within 80 columns.
-
-- ``CONFIG_KMEMCHECK_PARTIAL_OK``
- This option (when enabled) works around certain GCC optimizations that
- produce 32-bit reads from 16-bit variables where the upper 16 bits are
- thrown away afterwards.
-
- The default value (enabled) is recommended. This may of course hide
- some real errors, but disabling it would probably produce a lot of
- false positives.
-
-- ``CONFIG_KMEMCHECK_BITOPS_OK``
- This option silences warnings that would be generated for bit-field
- accesses where not all the bits are initialized at the same time. This
- may also hide some real bugs.
-
- This option is probably obsolete, or it should be replaced with
- the kmemcheck-/bitfield-annotations for the code in question. The
- default value is therefore fine.
-
-Now compile the kernel as usual.
-
-
-How to use
-----------
-
-Booting
-~~~~~~~
-
-First some information about the command-line options. There is only one
-option specific to kmemcheck, and this is called "kmemcheck". It can be used
-to override the default mode as chosen by the ``CONFIG_KMEMCHECK_*_BY_DEFAULT``
-option. Its possible settings are:
-
-- ``kmemcheck=0`` (disabled)
-- ``kmemcheck=1`` (enabled)
-- ``kmemcheck=2`` (one-shot mode)
-
-If SLUB debugging has been enabled in the kernel, it may take precedence over
-kmemcheck in such a way that the slab caches which are under SLUB debugging
-will not be tracked by kmemcheck. In order to ensure that this doesn't happen
-(even though it shouldn't by default), use SLUB's boot option ``slub_debug``,
-like this: ``slub_debug=-``
-
-In fact, this option may also be used for fine-grained control over SLUB vs.
-kmemcheck. For example, if the command line includes
-``kmemcheck=1 slub_debug=,dentry``, then SLUB debugging will be used only
-for the "dentry" slab cache, and with kmemcheck tracking all the other
-caches. This is advanced usage, however, and is not generally recommended.
-
-
-Run-time enable/disable
-~~~~~~~~~~~~~~~~~~~~~~~
-
-When the kernel has booted, it is possible to enable or disable kmemcheck at
-run-time. WARNING: This feature is still experimental and may cause false
-positive warnings to appear. Therefore, try not to use this. If you find that
-it doesn't work properly (e.g. you see an unreasonable amount of warnings), I
-will be happy to take bug reports.
-
-Use the file ``/proc/sys/kernel/kmemcheck`` for this purpose, e.g.::
-
- $ echo 0 > /proc/sys/kernel/kmemcheck # disables kmemcheck
-
-The numbers are the same as for the ``kmemcheck=`` command-line option.
-
-
-Debugging
-~~~~~~~~~
-
-A typical report will look something like this::
-
- WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff88003e4a2024)
- 80000000000000000000000000000000000000000088ffff0000000000000000
- i i i i u u u u i i i i i i i i u u u u u u u u u u u u u u u u
- ^
-
- Pid: 1856, comm: ntpdate Not tainted 2.6.29-rc5 #264 945P-A
- RIP: 0010:[<ffffffff8104ede8>] [<ffffffff8104ede8>] __dequeue_signal+0xc8/0x190
- RSP: 0018:ffff88003cdf7d98 EFLAGS: 00210002
- RAX: 0000000000000030 RBX: ffff88003d4ea968 RCX: 0000000000000009
- RDX: ffff88003e5d6018 RSI: ffff88003e5d6024 RDI: ffff88003cdf7e84
- RBP: ffff88003cdf7db8 R08: ffff88003e5d6000 R09: 0000000000000000
- R10: 0000000000000080 R11: 0000000000000000 R12: 000000000000000e
- R13: ffff88003cdf7e78 R14: ffff88003d530710 R15: ffff88003d5a98c8
- FS: 0000000000000000(0000) GS:ffff880001982000(0063) knlGS:00000
- CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
- CR2: ffff88003f806ea0 CR3: 000000003c036000 CR4: 00000000000006a0
- DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
- DR3: 0000000000000000 DR6: 00000000ffff4ff0 DR7: 0000000000000400
- [<ffffffff8104f04e>] dequeue_signal+0x8e/0x170
- [<ffffffff81050bd8>] get_signal_to_deliver+0x98/0x390
- [<ffffffff8100b87d>] do_notify_resume+0xad/0x7d0
- [<ffffffff8100c7b5>] int_signal+0x12/0x17
- [<ffffffffffffffff>] 0xffffffffffffffff
-
-The single most valuable information in this report is the RIP (or EIP on 32-
-bit) value. This will help us pinpoint exactly which instruction that caused
-the warning.
-
-If your kernel was compiled with ``CONFIG_DEBUG_INFO=y``, then all we have to do
-is give this address to the addr2line program, like this::
-
- $ addr2line -e vmlinux -i ffffffff8104ede8
- arch/x86/include/asm/string_64.h:12
- include/asm-generic/siginfo.h:287
- kernel/signal.c:380
- kernel/signal.c:410
-
-The "``-e vmlinux``" tells addr2line which file to look in. **IMPORTANT:**
-This must be the vmlinux of the kernel that produced the warning in the
-first place! If not, the line number information will almost certainly be
-wrong.
-
-The "``-i``" tells addr2line to also print the line numbers of inlined
-functions. In this case, the flag was very important, because otherwise,
-it would only have printed the first line, which is just a call to
-``memcpy()``, which could be called from a thousand places in the kernel, and
-is therefore not very useful. These inlined functions would not show up in
-the stack trace above, simply because the kernel doesn't load the extra
-debugging information. This technique can of course be used with ordinary
-kernel oopses as well.
-
-In this case, it's the caller of ``memcpy()`` that is interesting, and it can be
-found in ``include/asm-generic/siginfo.h``, line 287::
-
- 281 static inline void copy_siginfo(struct siginfo *to, struct siginfo *from)
- 282 {
- 283 if (from->si_code < 0)
- 284 memcpy(to, from, sizeof(*to));
- 285 else
- 286 /* _sigchld is currently the largest know union member */
- 287 memcpy(to, from, __ARCH_SI_PREAMBLE_SIZE + sizeof(from->_sifields._sigchld));
- 288 }
-
-Since this was a read (kmemcheck usually warns about reads only, though it can
-warn about writes to unallocated or freed memory as well), it was probably the
-"from" argument which contained some uninitialized bytes. Following the chain
-of calls, we move upwards to see where "from" was allocated or initialized,
-``kernel/signal.c``, line 380::
-
- 359 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
- 360 {
- ...
- 367 list_for_each_entry(q, &list->list, list) {
- 368 if (q->info.si_signo == sig) {
- 369 if (first)
- 370 goto still_pending;
- 371 first = q;
- ...
- 377 if (first) {
- 378 still_pending:
- 379 list_del_init(&first->list);
- 380 copy_siginfo(info, &first->info);
- 381 __sigqueue_free(first);
- ...
- 392 }
- 393 }
-
-Here, it is ``&first->info`` that is being passed on to ``copy_siginfo()``. The
-variable ``first`` was found on a list -- passed in as the second argument to
-``collect_signal()``. We continue our journey through the stack, to figure out
-where the item on "list" was allocated or initialized. We move to line 410::
-
- 395 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
- 396 siginfo_t *info)
- 397 {
- ...
- 410 collect_signal(sig, pending, info);
- ...
- 414 }
-
-Now we need to follow the ``pending`` pointer, since that is being passed on to
-``collect_signal()`` as ``list``. At this point, we've run out of lines from the
-"addr2line" output. Not to worry, we just paste the next addresses from the
-kmemcheck stack dump, i.e.::
-
- [<ffffffff8104f04e>] dequeue_signal+0x8e/0x170
- [<ffffffff81050bd8>] get_signal_to_deliver+0x98/0x390
- [<ffffffff8100b87d>] do_notify_resume+0xad/0x7d0
- [<ffffffff8100c7b5>] int_signal+0x12/0x17
-
- $ addr2line -e vmlinux -i ffffffff8104f04e ffffffff81050bd8 \
- ffffffff8100b87d ffffffff8100c7b5
- kernel/signal.c:446
- kernel/signal.c:1806
- arch/x86/kernel/signal.c:805
- arch/x86/kernel/signal.c:871
- arch/x86/kernel/entry_64.S:694
-
-Remember that since these addresses were found on the stack and not as the
-RIP value, they actually point to the _next_ instruction (they are return
-addresses). This becomes obvious when we look at the code for line 446::
-
- 422 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
- 423 {
- ...
- 431 signr = __dequeue_signal(&tsk->signal->shared_pending,
- 432 mask, info);
- 433 /*
- 434 * itimer signal ?
- 435 *
- 436 * itimers are process shared and we restart periodic
- 437 * itimers in the signal delivery path to prevent DoS
- 438 * attacks in the high resolution timer case. This is
- 439 * compliant with the old way of self restarting
- 440 * itimers, as the SIGALRM is a legacy signal and only
- 441 * queued once. Changing the restart behaviour to
- 442 * restart the timer in the signal dequeue path is
- 443 * reducing the timer noise on heavy loaded !highres
- 444 * systems too.
- 445 */
- 446 if (unlikely(signr == SIGALRM)) {
- ...
- 489 }
-
-So instead of looking at 446, we should be looking at 431, which is the line
-that executes just before 446. Here we see that what we are looking for is
-``&tsk->signal->shared_pending``.
-
-Our next task is now to figure out which function that puts items on this
-``shared_pending`` list. A crude, but efficient tool, is ``git grep``::
-
- $ git grep -n 'shared_pending' kernel/
- ...
- kernel/signal.c:828: pending = group ? &t->signal->shared_pending : &t->pending;
- kernel/signal.c:1339: pending = group ? &t->signal->shared_pending : &t->pending;
- ...
-
-There were more results, but none of them were related to list operations,
-and these were the only assignments. We inspect the line numbers more closely
-and find that this is indeed where items are being added to the list::
-
- 816 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
- 817 int group)
- 818 {
- ...
- 828 pending = group ? &t->signal->shared_pending : &t->pending;
- ...
- 851 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
- 852 (is_si_special(info) ||
- 853 info->si_code >= 0)));
- 854 if (q) {
- 855 list_add_tail(&q->list, &pending->list);
- ...
- 890 }
-
-and::
-
- 1309 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
- 1310 {
- ....
- 1339 pending = group ? &t->signal->shared_pending : &t->pending;
- 1340 list_add_tail(&q->list, &pending->list);
- ....
- 1347 }
-
-In the first case, the list element we are looking for, ``q``, is being
-returned from the function ``__sigqueue_alloc()``, which looks like an
-allocation function. Let's take a look at it::
-
- 187 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
- 188 int override_rlimit)
- 189 {
- 190 struct sigqueue *q = NULL;
- 191 struct user_struct *user;
- 192
- 193 /*
- 194 * We won't get problems with the target's UID changing under us
- 195 * because changing it requires RCU be used, and if t != current, the
- 196 * caller must be holding the RCU readlock (by way of a spinlock) and
- 197 * we use RCU protection here
- 198 */
- 199 user = get_uid(__task_cred(t)->user);
- 200 atomic_inc(&user->sigpending);
- 201 if (override_rlimit ||
- 202 atomic_read(&user->sigpending) <=
- 203 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
- 204 q = kmem_cache_alloc(sigqueue_cachep, flags);
- 205 if (unlikely(q == NULL)) {
- 206 atomic_dec(&user->sigpending);
- 207 free_uid(user);
- 208 } else {
- 209 INIT_LIST_HEAD(&q->list);
- 210 q->flags = 0;
- 211 q->user = user;
- 212 }
- 213
- 214 return q;
- 215 }
-
-We see that this function initializes ``q->list``, ``q->flags``, and
-``q->user``. It seems that now is the time to look at the definition of
-``struct sigqueue``, e.g.::
-
- 14 struct sigqueue {
- 15 struct list_head list;
- 16 int flags;
- 17 siginfo_t info;
- 18 struct user_struct *user;
- 19 };
-
-And, you might remember, it was a ``memcpy()`` on ``&first->info`` that
-caused the warning, so this makes perfect sense. It also seems reasonable
-to assume that it is the caller of ``__sigqueue_alloc()`` that has the
-responsibility of filling out (initializing) this member.
-
-But just which fields of the struct were uninitialized? Let's look at
-kmemcheck's report again::
-
- WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff88003e4a2024)
- 80000000000000000000000000000000000000000088ffff0000000000000000
- i i i i u u u u i i i i i i i i u u u u u u u u u u u u u u u u
- ^
-
-These first two lines are the memory dump of the memory object itself, and
-the shadow bytemap, respectively. The memory object itself is in this case
-``&first->info``. Just beware that the start of this dump is NOT the start
-of the object itself! The position of the caret (^) corresponds with the
-address of the read (ffff88003e4a2024).
-
-The shadow bytemap dump legend is as follows:
-
-- i: initialized
-- u: uninitialized
-- a: unallocated (memory has been allocated by the slab layer, but has not
- yet been handed off to anybody)
-- f: freed (memory has been allocated by the slab layer, but has been freed
- by the previous owner)
-
-In order to figure out where (relative to the start of the object) the
-uninitialized memory was located, we have to look at the disassembly. For
-that, we'll need the RIP address again::
-
- RIP: 0010:[<ffffffff8104ede8>] [<ffffffff8104ede8>] __dequeue_signal+0xc8/0x190
-
- $ objdump -d --no-show-raw-insn vmlinux | grep -C 8 ffffffff8104ede8:
- ffffffff8104edc8: mov %r8,0x8(%r8)
- ffffffff8104edcc: test %r10d,%r10d
- ffffffff8104edcf: js ffffffff8104ee88 <__dequeue_signal+0x168>
- ffffffff8104edd5: mov %rax,%rdx
- ffffffff8104edd8: mov $0xc,%ecx
- ffffffff8104eddd: mov %r13,%rdi
- ffffffff8104ede0: mov $0x30,%eax
- ffffffff8104ede5: mov %rdx,%rsi
- ffffffff8104ede8: rep movsl %ds:(%rsi),%es:(%rdi)
- ffffffff8104edea: test $0x2,%al
- ffffffff8104edec: je ffffffff8104edf0 <__dequeue_signal+0xd0>
- ffffffff8104edee: movsw %ds:(%rsi),%es:(%rdi)
- ffffffff8104edf0: test $0x1,%al
- ffffffff8104edf2: je ffffffff8104edf5 <__dequeue_signal+0xd5>
- ffffffff8104edf4: movsb %ds:(%rsi),%es:(%rdi)
- ffffffff8104edf5: mov %r8,%rdi
- ffffffff8104edf8: callq ffffffff8104de60 <__sigqueue_free>
-
-As expected, it's the "``rep movsl``" instruction from the ``memcpy()``
-that causes the warning. We know about ``REP MOVSL`` that it uses the register
-``RCX`` to count the number of remaining iterations. By taking a look at the
-register dump again (from the kmemcheck report), we can figure out how many
-bytes were left to copy::
-
- RAX: 0000000000000030 RBX: ffff88003d4ea968 RCX: 0000000000000009
-
-By looking at the disassembly, we also see that ``%ecx`` is being loaded
-with the value ``$0xc`` just before (ffffffff8104edd8), so we are very
-lucky. Keep in mind that this is the number of iterations, not bytes. And
-since this is a "long" operation, we need to multiply by 4 to get the
-number of bytes. So this means that the uninitialized value was encountered
-at 4 * (0xc - 0x9) = 12 bytes from the start of the object.
-
-We can now try to figure out which field of the "``struct siginfo``" that
-was not initialized. This is the beginning of the struct::
-
- 40 typedef struct siginfo {
- 41 int si_signo;
- 42 int si_errno;
- 43 int si_code;
- 44
- 45 union {
- ..
- 92 } _sifields;
- 93 } siginfo_t;
-
-On 64-bit, the int is 4 bytes long, so it must the union member that has
-not been initialized. We can verify this using gdb::
-
- $ gdb vmlinux
- ...
- (gdb) p &((struct siginfo *) 0)->_sifields
- $1 = (union {...} *) 0x10
-
-Actually, it seems that the union member is located at offset 0x10 -- which
-means that gcc has inserted 4 bytes of padding between the members ``si_code``
-and ``_sifields``. We can now get a fuller picture of the memory dump::
-
- _----------------------------=> si_code
- / _--------------------=> (padding)
- | / _------------=> _sifields(._kill._pid)
- | | / _----=> _sifields(._kill._uid)
- | | | /
- -------|-------|-------|-------|
- 80000000000000000000000000000000000000000088ffff0000000000000000
- i i i i u u u u i i i i i i i i u u u u u u u u u u u u u u u u
-
-This allows us to realize another important fact: ``si_code`` contains the
-value 0x80. Remember that x86 is little endian, so the first 4 bytes
-"80000000" are really the number 0x00000080. With a bit of research, we
-find that this is actually the constant ``SI_KERNEL`` defined in
-``include/asm-generic/siginfo.h``::
-
- 144 #define SI_KERNEL 0x80 /* sent by the kernel from somewhere */
-
-This macro is used in exactly one place in the x86 kernel: In ``send_signal()``
-in ``kernel/signal.c``::
-
- 816 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
- 817 int group)
- 818 {
- ...
- 828 pending = group ? &t->signal->shared_pending : &t->pending;
- ...
- 851 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
- 852 (is_si_special(info) ||
- 853 info->si_code >= 0)));
- 854 if (q) {
- 855 list_add_tail(&q->list, &pending->list);
- 856 switch ((unsigned long) info) {
- ...
- 865 case (unsigned long) SEND_SIG_PRIV:
- 866 q->info.si_signo = sig;
- 867 q->info.si_errno = 0;
- 868 q->info.si_code = SI_KERNEL;
- 869 q->info.si_pid = 0;
- 870 q->info.si_uid = 0;
- 871 break;
- ...
- 890 }
-
-Not only does this match with the ``.si_code`` member, it also matches the place
-we found earlier when looking for where siginfo_t objects are enqueued on the
-``shared_pending`` list.
-
-So to sum up: It seems that it is the padding introduced by the compiler
-between two struct fields that is uninitialized, and this gets reported when
-we do a ``memcpy()`` on the struct. This means that we have identified a false
-positive warning.
-
-Normally, kmemcheck will not report uninitialized accesses in ``memcpy()`` calls
-when both the source and destination addresses are tracked. (Instead, we copy
-the shadow bytemap as well). In this case, the destination address clearly
-was not tracked. We can dig a little deeper into the stack trace from above::
-
- arch/x86/kernel/signal.c:805
- arch/x86/kernel/signal.c:871
- arch/x86/kernel/entry_64.S:694
-
-And we clearly see that the destination siginfo object is located on the
-stack::
-
- 782 static void do_signal(struct pt_regs *regs)
- 783 {
- 784 struct k_sigaction ka;
- 785 siginfo_t info;
- ...
- 804 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
- ...
- 854 }
-
-And this ``&info`` is what eventually gets passed to ``copy_siginfo()`` as the
-destination argument.
-
-Now, even though we didn't find an actual error here, the example is still a
-good one, because it shows how one would go about to find out what the report
-was all about.
-
-
-Annotating false positives
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-There are a few different ways to make annotations in the source code that
-will keep kmemcheck from checking and reporting certain allocations. Here
-they are:
-
-- ``__GFP_NOTRACK_FALSE_POSITIVE``
- This flag can be passed to ``kmalloc()`` or ``kmem_cache_alloc()``
- (therefore also to other functions that end up calling one of
- these) to indicate that the allocation should not be tracked
- because it would lead to a false positive report. This is a "big
- hammer" way of silencing kmemcheck; after all, even if the false
- positive pertains to particular field in a struct, for example, we
- will now lose the ability to find (real) errors in other parts of
- the same struct.
-
- Example::
-
- /* No warnings will ever trigger on accessing any part of x */
- x = kmalloc(sizeof *x, GFP_KERNEL | __GFP_NOTRACK_FALSE_POSITIVE);
-
-- ``kmemcheck_bitfield_begin(name)``/``kmemcheck_bitfield_end(name)`` and
- ``kmemcheck_annotate_bitfield(ptr, name)``
- The first two of these three macros can be used inside struct
- definitions to signal, respectively, the beginning and end of a
- bitfield. Additionally, this will assign the bitfield a name, which
- is given as an argument to the macros.
-
- Having used these markers, one can later use
- kmemcheck_annotate_bitfield() at the point of allocation, to indicate
- which parts of the allocation is part of a bitfield.
-
- Example::
-
- struct foo {
- int x;
-
- kmemcheck_bitfield_begin(flags);
- int flag_a:1;
- int flag_b:1;
- kmemcheck_bitfield_end(flags);
-
- int y;
- };
-
- struct foo *x = kmalloc(sizeof *x);
-
- /* No warnings will trigger on accessing the bitfield of x */
- kmemcheck_annotate_bitfield(x, flags);
-
- Note that ``kmemcheck_annotate_bitfield()`` can be used even before the
- return value of ``kmalloc()`` is checked -- in other words, passing NULL
- as the first argument is legal (and will do nothing).
-
-
-Reporting errors
-----------------
-
-As we have seen, kmemcheck will produce false positive reports. Therefore, it
-is not very wise to blindly post kmemcheck warnings to mailing lists and
-maintainers. Instead, I encourage maintainers and developers to find errors
-in their own code. If you get a warning, you can try to work around it, try
-to figure out if it's a real error or not, or simply ignore it. Most
-developers know their own code and will quickly and efficiently determine the
-root cause of a kmemcheck report. This is therefore also the most efficient
-way to work with kmemcheck.
-
-That said, we (the kmemcheck maintainers) will always be on the lookout for
-false positives that we can annotate and silence. So whatever you find,
-please drop us a note privately! Kernel configs and steps to reproduce (if
-available) are of course a great help too.
-
-Happy hacking!
-
-
-Technical description
----------------------
-
-kmemcheck works by marking memory pages non-present. This means that whenever
-somebody attempts to access the page, a page fault is generated. The page
-fault handler notices that the page was in fact only hidden, and so it calls
-on the kmemcheck code to make further investigations.
-
-When the investigations are completed, kmemcheck "shows" the page by marking
-it present (as it would be under normal circumstances). This way, the
-interrupted code can continue as usual.
-
-But after the instruction has been executed, we should hide the page again, so
-that we can catch the next access too! Now kmemcheck makes use of a debugging
-feature of the processor, namely single-stepping. When the processor has
-finished the one instruction that generated the memory access, a debug
-exception is raised. From here, we simply hide the page again and continue
-execution, this time with the single-stepping feature turned off.
-
-kmemcheck requires some assistance from the memory allocator in order to work.
-The memory allocator needs to
-
- 1. Tell kmemcheck about newly allocated pages and pages that are about to
- be freed. This allows kmemcheck to set up and tear down the shadow memory
- for the pages in question. The shadow memory stores the status of each
- byte in the allocation proper, e.g. whether it is initialized or
- uninitialized.
-
- 2. Tell kmemcheck which parts of memory should be marked uninitialized.
- There are actually a few more states, such as "not yet allocated" and
- "recently freed".
-
-If a slab cache is set up using the SLAB_NOTRACK flag, it will never return
-memory that can take page faults because of kmemcheck.
-
-If a slab cache is NOT set up using the SLAB_NOTRACK flag, callers can still
-request memory with the __GFP_NOTRACK or __GFP_NOTRACK_FALSE_POSITIVE flags.
-This does not prevent the page faults from occurring, however, but marks the
-object in question as being initialized so that no warnings will ever be
-produced for this object.
-
-Currently, the SLAB and SLUB allocators are supported by kmemcheck.
F: include/linux/kgdb.h
F: kernel/debug/
-KMEMCHECK
-M: Vegard Nossum <vegardno@ifi.uio.no>
-M: Pekka Enberg <penberg@kernel.org>
-S: Maintained
-F: Documentation/dev-tools/kmemcheck.rst
-F: arch/x86/include/asm/kmemcheck.h
-F: arch/x86/mm/kmemcheck/
-F: include/linux/kmemcheck.h
-F: mm/kmemcheck.c
-
KMEMLEAK
M: Catalin Marinas <catalin.marinas@arm.com>
S: Maintained
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
select HAVE_ARCH_KGDB
- select HAVE_ARCH_KMEMCHECK
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
config X86_DIRECT_GBPAGES
def_bool y
- depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK
+ depends on X86_64 && !DEBUG_PAGEALLOC
---help---
Certain kernel features effectively disable kernel
linear 1 GB mappings (even if the CPU otherwise
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ASM_X86_KMEMCHECK_H
-#define ASM_X86_KMEMCHECK_H
-
-#include <linux/types.h>
-#include <asm/ptrace.h>
-
-#ifdef CONFIG_KMEMCHECK
-bool kmemcheck_active(struct pt_regs *regs);
-
-void kmemcheck_show(struct pt_regs *regs);
-void kmemcheck_hide(struct pt_regs *regs);
-
-bool kmemcheck_fault(struct pt_regs *regs,
- unsigned long address, unsigned long error_code);
-bool kmemcheck_trap(struct pt_regs *regs);
-#else
-static inline bool kmemcheck_active(struct pt_regs *regs)
-{
- return false;
-}
-
-static inline void kmemcheck_show(struct pt_regs *regs)
-{
-}
-
-static inline void kmemcheck_hide(struct pt_regs *regs)
-{
-}
-
-static inline bool kmemcheck_fault(struct pt_regs *regs,
- unsigned long address, unsigned long error_code)
-{
- return false;
-}
-
-static inline bool kmemcheck_trap(struct pt_regs *regs)
-{
- return false;
-}
-#endif /* CONFIG_KMEMCHECK */
-
-#endif
* No 3D Now!
*/
-#ifndef CONFIG_KMEMCHECK
-
#if (__GNUC__ >= 4)
#define memcpy(t, f, n) __builtin_memcpy(t, f, n)
#else
? __constant_memcpy((t), (f), (n)) \
: __memcpy((t), (f), (n)))
#endif
-#else
-/*
- * kmemcheck becomes very happy if we use the REP instructions unconditionally,
- * because it means that we know both memory operands in advance.
- */
-#define memcpy(t, f, n) __memcpy((t), (f), (n))
-#endif
#endif
#endif /* !CONFIG_FORTIFY_SOURCE */
extern void *__memcpy(void *to, const void *from, size_t len);
#ifndef CONFIG_FORTIFY_SOURCE
-#ifndef CONFIG_KMEMCHECK
#if (__GNUC__ == 4 && __GNUC_MINOR__ < 3) || __GNUC__ < 4
#define memcpy(dst, src, len) \
({ \
__ret; \
})
#endif
-#else
-/*
- * kmemcheck becomes very happy if we use the REP instructions unconditionally,
- * because it means that we know both memory operands in advance.
- */
-#define memcpy(dst, src, len) __inline_memcpy((dst), (src), (len))
-#endif
#endif /* !CONFIG_FORTIFY_SOURCE */
#define __HAVE_ARCH_MEMSET
if (c->x86 == 6 && c->x86_model < 15)
clear_cpu_cap(c, X86_FEATURE_PAT);
-#ifdef CONFIG_KMEMCHECK
- /*
- * P4s have a "fast strings" feature which causes single-
- * stepping REP instructions to only generate a #DB on
- * cache-line boundaries.
- *
- * Ingo Molnar reported a Pentium D (model 6) and a Xeon
- * (model 2) with the same problem.
- */
- if (c->x86 == 15)
- if (msr_clear_bit(MSR_IA32_MISC_ENABLE,
- MSR_IA32_MISC_ENABLE_FAST_STRING_BIT) > 0)
- pr_info("kmemcheck: Disabling fast string operations\n");
-#endif
-
/*
* If fast string is not enabled in IA32_MISC_ENABLE for any reason,
* clear the fast string and enhanced fast string CPU capabilities.
obj-$(CONFIG_HIGHMEM) += highmem_32.o
-obj-$(CONFIG_KMEMCHECK) += kmemcheck/
-
KASAN_SANITIZE_kasan_init_$(BITS).o := n
obj-$(CONFIG_KASAN) += kasan_init_$(BITS).o
static void __init probe_page_size_mask(void)
{
/*
- * For CONFIG_KMEMCHECK or pagealloc debugging, identity mapping will
- * use small pages.
+ * For pagealloc debugging, identity mapping will use small pages.
* This will simplify cpa(), which otherwise needs to support splitting
* large pages into small in interrupt context, etc.
*/
- if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled() && !IS_ENABLED(CONFIG_KMEMCHECK))
+ if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled())
page_size_mask |= 1 << PG_LEVEL_2M;
else
direct_gbpages = 0;
+++ /dev/null
-obj-y := error.o kmemcheck.o opcode.o pte.o selftest.o shadow.o
// SPDX-License-Identifier: GPL-2.0
-#include <linux/interrupt.h>
-#include <linux/kdebug.h>
-#include <linux/kmemcheck.h>
-#include <linux/kernel.h>
-#include <linux/types.h>
-#include <linux/ptrace.h>
-#include <linux/stacktrace.h>
-#include <linux/string.h>
-
-#include "error.h"
-#include "shadow.h"
-
-enum kmemcheck_error_type {
- KMEMCHECK_ERROR_INVALID_ACCESS,
- KMEMCHECK_ERROR_BUG,
-};
-
-#define SHADOW_COPY_SIZE (1 << CONFIG_KMEMCHECK_SHADOW_COPY_SHIFT)
-
-struct kmemcheck_error {
- enum kmemcheck_error_type type;
-
- union {
- /* KMEMCHECK_ERROR_INVALID_ACCESS */
- struct {
- /* Kind of access that caused the error */
- enum kmemcheck_shadow state;
- /* Address and size of the erroneous read */
- unsigned long address;
- unsigned int size;
- };
- };
-
- struct pt_regs regs;
- struct stack_trace trace;
- unsigned long trace_entries[32];
-
- /* We compress it to a char. */
- unsigned char shadow_copy[SHADOW_COPY_SIZE];
- unsigned char memory_copy[SHADOW_COPY_SIZE];
-};
-
-/*
- * Create a ring queue of errors to output. We can't call printk() directly
- * from the kmemcheck traps, since this may call the console drivers and
- * result in a recursive fault.
- */
-static struct kmemcheck_error error_fifo[CONFIG_KMEMCHECK_QUEUE_SIZE];
-static unsigned int error_count;
-static unsigned int error_rd;
-static unsigned int error_wr;
-static unsigned int error_missed_count;
-
-static struct kmemcheck_error *error_next_wr(void)
-{
- struct kmemcheck_error *e;
-
- if (error_count == ARRAY_SIZE(error_fifo)) {
- ++error_missed_count;
- return NULL;
- }
-
- e = &error_fifo[error_wr];
- if (++error_wr == ARRAY_SIZE(error_fifo))
- error_wr = 0;
- ++error_count;
- return e;
-}
-
-static struct kmemcheck_error *error_next_rd(void)
-{
- struct kmemcheck_error *e;
-
- if (error_count == 0)
- return NULL;
-
- e = &error_fifo[error_rd];
- if (++error_rd == ARRAY_SIZE(error_fifo))
- error_rd = 0;
- --error_count;
- return e;
-}
-
-void kmemcheck_error_recall(void)
-{
- static const char *desc[] = {
- [KMEMCHECK_SHADOW_UNALLOCATED] = "unallocated",
- [KMEMCHECK_SHADOW_UNINITIALIZED] = "uninitialized",
- [KMEMCHECK_SHADOW_INITIALIZED] = "initialized",
- [KMEMCHECK_SHADOW_FREED] = "freed",
- };
-
- static const char short_desc[] = {
- [KMEMCHECK_SHADOW_UNALLOCATED] = 'a',
- [KMEMCHECK_SHADOW_UNINITIALIZED] = 'u',
- [KMEMCHECK_SHADOW_INITIALIZED] = 'i',
- [KMEMCHECK_SHADOW_FREED] = 'f',
- };
-
- struct kmemcheck_error *e;
- unsigned int i;
-
- e = error_next_rd();
- if (!e)
- return;
-
- switch (e->type) {
- case KMEMCHECK_ERROR_INVALID_ACCESS:
- printk(KERN_WARNING "WARNING: kmemcheck: Caught %d-bit read from %s memory (%p)\n",
- 8 * e->size, e->state < ARRAY_SIZE(desc) ?
- desc[e->state] : "(invalid shadow state)",
- (void *) e->address);
-
- printk(KERN_WARNING);
- for (i = 0; i < SHADOW_COPY_SIZE; ++i)
- printk(KERN_CONT "%02x", e->memory_copy[i]);
- printk(KERN_CONT "\n");
-
- printk(KERN_WARNING);
- for (i = 0; i < SHADOW_COPY_SIZE; ++i) {
- if (e->shadow_copy[i] < ARRAY_SIZE(short_desc))
- printk(KERN_CONT " %c", short_desc[e->shadow_copy[i]]);
- else
- printk(KERN_CONT " ?");
- }
- printk(KERN_CONT "\n");
- printk(KERN_WARNING "%*c\n", 2 + 2
- * (int) (e->address & (SHADOW_COPY_SIZE - 1)), '^');
- break;
- case KMEMCHECK_ERROR_BUG:
- printk(KERN_EMERG "ERROR: kmemcheck: Fatal error\n");
- break;
- }
-
- __show_regs(&e->regs, 1);
- print_stack_trace(&e->trace, 0);
-}
-
-static void do_wakeup(unsigned long data)
-{
- while (error_count > 0)
- kmemcheck_error_recall();
-
- if (error_missed_count > 0) {
- printk(KERN_WARNING "kmemcheck: Lost %d error reports because "
- "the queue was too small\n", error_missed_count);
- error_missed_count = 0;
- }
-}
-
-static DECLARE_TASKLET(kmemcheck_tasklet, &do_wakeup, 0);
-
-/*
- * Save the context of an error report.
- */
-void kmemcheck_error_save(enum kmemcheck_shadow state,
- unsigned long address, unsigned int size, struct pt_regs *regs)
-{
- static unsigned long prev_ip;
-
- struct kmemcheck_error *e;
- void *shadow_copy;
- void *memory_copy;
-
- /* Don't report several adjacent errors from the same EIP. */
- if (regs->ip == prev_ip)
- return;
- prev_ip = regs->ip;
-
- e = error_next_wr();
- if (!e)
- return;
-
- e->type = KMEMCHECK_ERROR_INVALID_ACCESS;
-
- e->state = state;
- e->address = address;
- e->size = size;
-
- /* Save regs */
- memcpy(&e->regs, regs, sizeof(*regs));
-
- /* Save stack trace */
- e->trace.nr_entries = 0;
- e->trace.entries = e->trace_entries;
- e->trace.max_entries = ARRAY_SIZE(e->trace_entries);
- e->trace.skip = 0;
- save_stack_trace_regs(regs, &e->trace);
-
- /* Round address down to nearest 16 bytes */
- shadow_copy = kmemcheck_shadow_lookup(address
- & ~(SHADOW_COPY_SIZE - 1));
- BUG_ON(!shadow_copy);
-
- memcpy(e->shadow_copy, shadow_copy, SHADOW_COPY_SIZE);
-
- kmemcheck_show_addr(address);
- memory_copy = (void *) (address & ~(SHADOW_COPY_SIZE - 1));
- memcpy(e->memory_copy, memory_copy, SHADOW_COPY_SIZE);
- kmemcheck_hide_addr(address);
-
- tasklet_hi_schedule_first(&kmemcheck_tasklet);
-}
-
-/*
- * Save the context of a kmemcheck bug.
- */
-void kmemcheck_error_save_bug(struct pt_regs *regs)
-{
- struct kmemcheck_error *e;
-
- e = error_next_wr();
- if (!e)
- return;
-
- e->type = KMEMCHECK_ERROR_BUG;
-
- memcpy(&e->regs, regs, sizeof(*regs));
-
- e->trace.nr_entries = 0;
- e->trace.entries = e->trace_entries;
- e->trace.max_entries = ARRAY_SIZE(e->trace_entries);
- e->trace.skip = 1;
- save_stack_trace(&e->trace);
-
- tasklet_hi_schedule_first(&kmemcheck_tasklet);
-}
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ARCH__X86__MM__KMEMCHECK__ERROR_H
-#define ARCH__X86__MM__KMEMCHECK__ERROR_H
-
-#include <linux/ptrace.h>
-
-#include "shadow.h"
-
-void kmemcheck_error_save(enum kmemcheck_shadow state,
- unsigned long address, unsigned int size, struct pt_regs *regs);
-
-void kmemcheck_error_save_bug(struct pt_regs *regs);
-
-void kmemcheck_error_recall(void);
-
-#endif
+++ /dev/null
-/**
- * kmemcheck - a heavyweight memory checker for the linux kernel
- * Copyright (C) 2007, 2008 Vegard Nossum <vegardno@ifi.uio.no>
- * (With a lot of help from Ingo Molnar and Pekka Enberg.)
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License (version 2) as
- * published by the Free Software Foundation.
- */
-
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/kallsyms.h>
-#include <linux/kernel.h>
-#include <linux/kmemcheck.h>
-#include <linux/mm.h>
-#include <linux/page-flags.h>
-#include <linux/percpu.h>
-#include <linux/ptrace.h>
-#include <linux/string.h>
-#include <linux/types.h>
-
-#include <asm/cacheflush.h>
-#include <asm/kmemcheck.h>
-#include <asm/pgtable.h>
-#include <asm/tlbflush.h>
-
-#include "error.h"
-#include "opcode.h"
-#include "pte.h"
-#include "selftest.h"
-#include "shadow.h"
-
-
-#ifdef CONFIG_KMEMCHECK_DISABLED_BY_DEFAULT
-# define KMEMCHECK_ENABLED 0
-#endif
-
-#ifdef CONFIG_KMEMCHECK_ENABLED_BY_DEFAULT
-# define KMEMCHECK_ENABLED 1
-#endif
-
-#ifdef CONFIG_KMEMCHECK_ONESHOT_BY_DEFAULT
-# define KMEMCHECK_ENABLED 2
-#endif
-
-int kmemcheck_enabled = KMEMCHECK_ENABLED;
-
-int __init kmemcheck_init(void)
-{
-#ifdef CONFIG_SMP
- /*
- * Limit SMP to use a single CPU. We rely on the fact that this code
- * runs before SMP is set up.
- */
- if (setup_max_cpus > 1) {
- printk(KERN_INFO
- "kmemcheck: Limiting number of CPUs to 1.\n");
- setup_max_cpus = 1;
- }
-#endif
-
- if (!kmemcheck_selftest()) {
- printk(KERN_INFO "kmemcheck: self-tests failed; disabling\n");
- kmemcheck_enabled = 0;
- return -EINVAL;
- }
-
- printk(KERN_INFO "kmemcheck: Initialized\n");
- return 0;
-}
-
-early_initcall(kmemcheck_init);
-
-/*
- * We need to parse the kmemcheck= option before any memory is allocated.
- */
-static int __init param_kmemcheck(char *str)
-{
- int val;
- int ret;
-
- if (!str)
- return -EINVAL;
-
- ret = kstrtoint(str, 0, &val);
- if (ret)
- return ret;
- kmemcheck_enabled = val;
- return 0;
-}
-
-early_param("kmemcheck", param_kmemcheck);
-
-int kmemcheck_show_addr(unsigned long address)
-{
- pte_t *pte;
-
- pte = kmemcheck_pte_lookup(address);
- if (!pte)
- return 0;
-
- set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT));
- __flush_tlb_one(address);
- return 1;
-}
-
-int kmemcheck_hide_addr(unsigned long address)
-{
- pte_t *pte;
-
- pte = kmemcheck_pte_lookup(address);
- if (!pte)
- return 0;
-
- set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_PRESENT));
- __flush_tlb_one(address);
- return 1;
-}
-
-struct kmemcheck_context {
- bool busy;
- int balance;
-
- /*
- * There can be at most two memory operands to an instruction, but
- * each address can cross a page boundary -- so we may need up to
- * four addresses that must be hidden/revealed for each fault.
- */
- unsigned long addr[4];
- unsigned long n_addrs;
- unsigned long flags;
-
- /* Data size of the instruction that caused a fault. */
- unsigned int size;
-};
-
-static DEFINE_PER_CPU(struct kmemcheck_context, kmemcheck_context);
-
-bool kmemcheck_active(struct pt_regs *regs)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
-
- return data->balance > 0;
-}
-
-/* Save an address that needs to be shown/hidden */
-static void kmemcheck_save_addr(unsigned long addr)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
-
- BUG_ON(data->n_addrs >= ARRAY_SIZE(data->addr));
- data->addr[data->n_addrs++] = addr;
-}
-
-static unsigned int kmemcheck_show_all(void)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
- unsigned int i;
- unsigned int n;
-
- n = 0;
- for (i = 0; i < data->n_addrs; ++i)
- n += kmemcheck_show_addr(data->addr[i]);
-
- return n;
-}
-
-static unsigned int kmemcheck_hide_all(void)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
- unsigned int i;
- unsigned int n;
-
- n = 0;
- for (i = 0; i < data->n_addrs; ++i)
- n += kmemcheck_hide_addr(data->addr[i]);
-
- return n;
-}
-
-/*
- * Called from the #PF handler.
- */
-void kmemcheck_show(struct pt_regs *regs)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
-
- BUG_ON(!irqs_disabled());
-
- if (unlikely(data->balance != 0)) {
- kmemcheck_show_all();
- kmemcheck_error_save_bug(regs);
- data->balance = 0;
- return;
- }
-
- /*
- * None of the addresses actually belonged to kmemcheck. Note that
- * this is not an error.
- */
- if (kmemcheck_show_all() == 0)
- return;
-
- ++data->balance;
-
- /*
- * The IF needs to be cleared as well, so that the faulting
- * instruction can run "uninterrupted". Otherwise, we might take
- * an interrupt and start executing that before we've had a chance
- * to hide the page again.
- *
- * NOTE: In the rare case of multiple faults, we must not override
- * the original flags:
- */
- if (!(regs->flags & X86_EFLAGS_TF))
- data->flags = regs->flags;
-
- regs->flags |= X86_EFLAGS_TF;
- regs->flags &= ~X86_EFLAGS_IF;
-}
-
-/*
- * Called from the #DB handler.
- */
-void kmemcheck_hide(struct pt_regs *regs)
-{
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
- int n;
-
- BUG_ON(!irqs_disabled());
-
- if (unlikely(data->balance != 1)) {
- kmemcheck_show_all();
- kmemcheck_error_save_bug(regs);
- data->n_addrs = 0;
- data->balance = 0;
-
- if (!(data->flags & X86_EFLAGS_TF))
- regs->flags &= ~X86_EFLAGS_TF;
- if (data->flags & X86_EFLAGS_IF)
- regs->flags |= X86_EFLAGS_IF;
- return;
- }
-
- if (kmemcheck_enabled)
- n = kmemcheck_hide_all();
- else
- n = kmemcheck_show_all();
-
- if (n == 0)
- return;
-
- --data->balance;
-
- data->n_addrs = 0;
-
- if (!(data->flags & X86_EFLAGS_TF))
- regs->flags &= ~X86_EFLAGS_TF;
- if (data->flags & X86_EFLAGS_IF)
- regs->flags |= X86_EFLAGS_IF;
-}
-
-void kmemcheck_show_pages(struct page *p, unsigned int n)
-{
- unsigned int i;
-
- for (i = 0; i < n; ++i) {
- unsigned long address;
- pte_t *pte;
- unsigned int level;
-
- address = (unsigned long) page_address(&p[i]);
- pte = lookup_address(address, &level);
- BUG_ON(!pte);
- BUG_ON(level != PG_LEVEL_4K);
-
- set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT));
- set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_HIDDEN));
- __flush_tlb_one(address);
- }
-}
-
-bool kmemcheck_page_is_tracked(struct page *p)
-{
- /* This will also check the "hidden" flag of the PTE. */
- return kmemcheck_pte_lookup((unsigned long) page_address(p));
-}
-
-void kmemcheck_hide_pages(struct page *p, unsigned int n)
-{
- unsigned int i;
-
- for (i = 0; i < n; ++i) {
- unsigned long address;
- pte_t *pte;
- unsigned int level;
-
- address = (unsigned long) page_address(&p[i]);
- pte = lookup_address(address, &level);
- BUG_ON(!pte);
- BUG_ON(level != PG_LEVEL_4K);
-
- set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_PRESENT));
- set_pte(pte, __pte(pte_val(*pte) | _PAGE_HIDDEN));
- __flush_tlb_one(address);
- }
-}
-
-/* Access may NOT cross page boundary */
-static void kmemcheck_read_strict(struct pt_regs *regs,
- unsigned long addr, unsigned int size)
-{
- void *shadow;
- enum kmemcheck_shadow status;
-
- shadow = kmemcheck_shadow_lookup(addr);
- if (!shadow)
- return;
-
- kmemcheck_save_addr(addr);
- status = kmemcheck_shadow_test(shadow, size);
- if (status == KMEMCHECK_SHADOW_INITIALIZED)
- return;
-
- if (kmemcheck_enabled)
- kmemcheck_error_save(status, addr, size, regs);
-
- if (kmemcheck_enabled == 2)
- kmemcheck_enabled = 0;
-
- /* Don't warn about it again. */
- kmemcheck_shadow_set(shadow, size);
-}
-
-bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size)
-{
- enum kmemcheck_shadow status;
- void *shadow;
-
- shadow = kmemcheck_shadow_lookup(addr);
- if (!shadow)
- return true;
-
- status = kmemcheck_shadow_test_all(shadow, size);
-
- return status == KMEMCHECK_SHADOW_INITIALIZED;
-}
-
-/* Access may cross page boundary */
-static void kmemcheck_read(struct pt_regs *regs,
- unsigned long addr, unsigned int size)
-{
- unsigned long page = addr & PAGE_MASK;
- unsigned long next_addr = addr + size - 1;
- unsigned long next_page = next_addr & PAGE_MASK;
-
- if (likely(page == next_page)) {
- kmemcheck_read_strict(regs, addr, size);
- return;
- }
-
- /*
- * What we do is basically to split the access across the
- * two pages and handle each part separately. Yes, this means
- * that we may now see reads that are 3 + 5 bytes, for
- * example (and if both are uninitialized, there will be two
- * reports), but it makes the code a lot simpler.
- */
- kmemcheck_read_strict(regs, addr, next_page - addr);
- kmemcheck_read_strict(regs, next_page, next_addr - next_page);
-}
-
-static void kmemcheck_write_strict(struct pt_regs *regs,
- unsigned long addr, unsigned int size)
-{
- void *shadow;
-
- shadow = kmemcheck_shadow_lookup(addr);
- if (!shadow)
- return;
-
- kmemcheck_save_addr(addr);
- kmemcheck_shadow_set(shadow, size);
-}
-
-static void kmemcheck_write(struct pt_regs *regs,
- unsigned long addr, unsigned int size)
-{
- unsigned long page = addr & PAGE_MASK;
- unsigned long next_addr = addr + size - 1;
- unsigned long next_page = next_addr & PAGE_MASK;
-
- if (likely(page == next_page)) {
- kmemcheck_write_strict(regs, addr, size);
- return;
- }
-
- /* See comment in kmemcheck_read(). */
- kmemcheck_write_strict(regs, addr, next_page - addr);
- kmemcheck_write_strict(regs, next_page, next_addr - next_page);
-}
-
-/*
- * Copying is hard. We have two addresses, each of which may be split across
- * a page (and each page will have different shadow addresses).
- */
-static void kmemcheck_copy(struct pt_regs *regs,
- unsigned long src_addr, unsigned long dst_addr, unsigned int size)
-{
- uint8_t shadow[8];
- enum kmemcheck_shadow status;
-
- unsigned long page;
- unsigned long next_addr;
- unsigned long next_page;
-
- uint8_t *x;
- unsigned int i;
- unsigned int n;
-
- BUG_ON(size > sizeof(shadow));
-
- page = src_addr & PAGE_MASK;
- next_addr = src_addr + size - 1;
- next_page = next_addr & PAGE_MASK;
-
- if (likely(page == next_page)) {
- /* Same page */
- x = kmemcheck_shadow_lookup(src_addr);
- if (x) {
- kmemcheck_save_addr(src_addr);
- for (i = 0; i < size; ++i)
- shadow[i] = x[i];
- } else {
- for (i = 0; i < size; ++i)
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
- } else {
- n = next_page - src_addr;
- BUG_ON(n > sizeof(shadow));
-
- /* First page */
- x = kmemcheck_shadow_lookup(src_addr);
- if (x) {
- kmemcheck_save_addr(src_addr);
- for (i = 0; i < n; ++i)
- shadow[i] = x[i];
- } else {
- /* Not tracked */
- for (i = 0; i < n; ++i)
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
-
- /* Second page */
- x = kmemcheck_shadow_lookup(next_page);
- if (x) {
- kmemcheck_save_addr(next_page);
- for (i = n; i < size; ++i)
- shadow[i] = x[i - n];
- } else {
- /* Not tracked */
- for (i = n; i < size; ++i)
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
- }
-
- page = dst_addr & PAGE_MASK;
- next_addr = dst_addr + size - 1;
- next_page = next_addr & PAGE_MASK;
-
- if (likely(page == next_page)) {
- /* Same page */
- x = kmemcheck_shadow_lookup(dst_addr);
- if (x) {
- kmemcheck_save_addr(dst_addr);
- for (i = 0; i < size; ++i) {
- x[i] = shadow[i];
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
- }
- } else {
- n = next_page - dst_addr;
- BUG_ON(n > sizeof(shadow));
-
- /* First page */
- x = kmemcheck_shadow_lookup(dst_addr);
- if (x) {
- kmemcheck_save_addr(dst_addr);
- for (i = 0; i < n; ++i) {
- x[i] = shadow[i];
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
- }
-
- /* Second page */
- x = kmemcheck_shadow_lookup(next_page);
- if (x) {
- kmemcheck_save_addr(next_page);
- for (i = n; i < size; ++i) {
- x[i - n] = shadow[i];
- shadow[i] = KMEMCHECK_SHADOW_INITIALIZED;
- }
- }
- }
-
- status = kmemcheck_shadow_test(shadow, size);
- if (status == KMEMCHECK_SHADOW_INITIALIZED)
- return;
-
- if (kmemcheck_enabled)
- kmemcheck_error_save(status, src_addr, size, regs);
-
- if (kmemcheck_enabled == 2)
- kmemcheck_enabled = 0;
-}
-
-enum kmemcheck_method {
- KMEMCHECK_READ,
- KMEMCHECK_WRITE,
-};
-
-static void kmemcheck_access(struct pt_regs *regs,
- unsigned long fallback_address, enum kmemcheck_method fallback_method)
-{
- const uint8_t *insn;
- const uint8_t *insn_primary;
- unsigned int size;
-
- struct kmemcheck_context *data = this_cpu_ptr(&kmemcheck_context);
-
- /* Recursive fault -- ouch. */
- if (data->busy) {
- kmemcheck_show_addr(fallback_address);
- kmemcheck_error_save_bug(regs);
- return;
- }
-
- data->busy = true;
-
- insn = (const uint8_t *) regs->ip;
- insn_primary = kmemcheck_opcode_get_primary(insn);
-
- kmemcheck_opcode_decode(insn, &size);
-
- switch (insn_primary[0]) {
-#ifdef CONFIG_KMEMCHECK_BITOPS_OK
- /* AND, OR, XOR */
- /*
- * Unfortunately, these instructions have to be excluded from
- * our regular checking since they access only some (and not
- * all) bits. This clears out "bogus" bitfield-access warnings.
- */
- case 0x80:
- case 0x81:
- case 0x82:
- case 0x83:
- switch ((insn_primary[1] >> 3) & 7) {
- /* OR */
- case 1:
- /* AND */
- case 4:
- /* XOR */
- case 6:
- kmemcheck_write(regs, fallback_address, size);
- goto out;
-
- /* ADD */
- case 0:
- /* ADC */
- case 2:
- /* SBB */
- case 3:
- /* SUB */
- case 5:
- /* CMP */
- case 7:
- break;
- }
- break;
-#endif
-
- /* MOVS, MOVSB, MOVSW, MOVSD */
- case 0xa4:
- case 0xa5:
- /*
- * These instructions are special because they take two
- * addresses, but we only get one page fault.
- */
- kmemcheck_copy(regs, regs->si, regs->di, size);
- goto out;
-
- /* CMPS, CMPSB, CMPSW, CMPSD */
- case 0xa6:
- case 0xa7:
- kmemcheck_read(regs, regs->si, size);
- kmemcheck_read(regs, regs->di, size);
- goto out;
- }
-
- /*
- * If the opcode isn't special in any way, we use the data from the
- * page fault handler to determine the address and type of memory
- * access.
- */
- switch (fallback_method) {
- case KMEMCHECK_READ:
- kmemcheck_read(regs, fallback_address, size);
- goto out;
- case KMEMCHECK_WRITE:
- kmemcheck_write(regs, fallback_address, size);
- goto out;
- }
-
-out:
- data->busy = false;
-}
-
-bool kmemcheck_fault(struct pt_regs *regs, unsigned long address,
- unsigned long error_code)
-{
- pte_t *pte;
-
- /*
- * XXX: Is it safe to assume that memory accesses from virtual 86
- * mode or non-kernel code segments will _never_ access kernel
- * memory (e.g. tracked pages)? For now, we need this to avoid
- * invoking kmemcheck for PnP BIOS calls.
- */
- if (regs->flags & X86_VM_MASK)
- return false;
- if (regs->cs != __KERNEL_CS)
- return false;
-
- pte = kmemcheck_pte_lookup(address);
- if (!pte)
- return false;
-
- WARN_ON_ONCE(in_nmi());
-
- if (error_code & 2)
- kmemcheck_access(regs, address, KMEMCHECK_WRITE);
- else
- kmemcheck_access(regs, address, KMEMCHECK_READ);
-
- kmemcheck_show(regs);
- return true;
-}
-
-bool kmemcheck_trap(struct pt_regs *regs)
-{
- if (!kmemcheck_active(regs))
- return false;
-
- /* We're done. */
- kmemcheck_hide(regs);
- return true;
-}
// SPDX-License-Identifier: GPL-2.0
-#include <linux/types.h>
-
-#include "opcode.h"
-
-static bool opcode_is_prefix(uint8_t b)
-{
- return
- /* Group 1 */
- b == 0xf0 || b == 0xf2 || b == 0xf3
- /* Group 2 */
- || b == 0x2e || b == 0x36 || b == 0x3e || b == 0x26
- || b == 0x64 || b == 0x65
- /* Group 3 */
- || b == 0x66
- /* Group 4 */
- || b == 0x67;
-}
-
-#ifdef CONFIG_X86_64
-static bool opcode_is_rex_prefix(uint8_t b)
-{
- return (b & 0xf0) == 0x40;
-}
-#else
-static bool opcode_is_rex_prefix(uint8_t b)
-{
- return false;
-}
-#endif
-
-#define REX_W (1 << 3)
-
-/*
- * This is a VERY crude opcode decoder. We only need to find the size of the
- * load/store that caused our #PF and this should work for all the opcodes
- * that we care about. Moreover, the ones who invented this instruction set
- * should be shot.
- */
-void kmemcheck_opcode_decode(const uint8_t *op, unsigned int *size)
-{
- /* Default operand size */
- int operand_size_override = 4;
-
- /* prefixes */
- for (; opcode_is_prefix(*op); ++op) {
- if (*op == 0x66)
- operand_size_override = 2;
- }
-
- /* REX prefix */
- if (opcode_is_rex_prefix(*op)) {
- uint8_t rex = *op;
-
- ++op;
- if (rex & REX_W) {
- switch (*op) {
- case 0x63:
- *size = 4;
- return;
- case 0x0f:
- ++op;
-
- switch (*op) {
- case 0xb6:
- case 0xbe:
- *size = 1;
- return;
- case 0xb7:
- case 0xbf:
- *size = 2;
- return;
- }
-
- break;
- }
-
- *size = 8;
- return;
- }
- }
-
- /* escape opcode */
- if (*op == 0x0f) {
- ++op;
-
- /*
- * This is move with zero-extend and sign-extend, respectively;
- * we don't have to think about 0xb6/0xbe, because this is
- * already handled in the conditional below.
- */
- if (*op == 0xb7 || *op == 0xbf)
- operand_size_override = 2;
- }
-
- *size = (*op & 1) ? operand_size_override : 1;
-}
-
-const uint8_t *kmemcheck_opcode_get_primary(const uint8_t *op)
-{
- /* skip prefixes */
- while (opcode_is_prefix(*op))
- ++op;
- if (opcode_is_rex_prefix(*op))
- ++op;
- return op;
-}
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ARCH__X86__MM__KMEMCHECK__OPCODE_H
-#define ARCH__X86__MM__KMEMCHECK__OPCODE_H
-
-#include <linux/types.h>
-
-void kmemcheck_opcode_decode(const uint8_t *op, unsigned int *size);
-const uint8_t *kmemcheck_opcode_get_primary(const uint8_t *op);
-
-#endif
// SPDX-License-Identifier: GPL-2.0
-#include <linux/mm.h>
-
-#include <asm/pgtable.h>
-
-#include "pte.h"
-
-pte_t *kmemcheck_pte_lookup(unsigned long address)
-{
- pte_t *pte;
- unsigned int level;
-
- pte = lookup_address(address, &level);
- if (!pte)
- return NULL;
- if (level != PG_LEVEL_4K)
- return NULL;
- if (!pte_hidden(*pte))
- return NULL;
-
- return pte;
-}
-
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ARCH__X86__MM__KMEMCHECK__PTE_H
-#define ARCH__X86__MM__KMEMCHECK__PTE_H
-
-#include <linux/mm.h>
-
-#include <asm/pgtable.h>
-
-pte_t *kmemcheck_pte_lookup(unsigned long address);
-
-#endif
// SPDX-License-Identifier: GPL-2.0
-#include <linux/bug.h>
-#include <linux/kernel.h>
-
-#include "opcode.h"
-#include "selftest.h"
-
-struct selftest_opcode {
- unsigned int expected_size;
- const uint8_t *insn;
- const char *desc;
-};
-
-static const struct selftest_opcode selftest_opcodes[] = {
- /* REP MOVS */
- {1, "\xf3\xa4", "rep movsb <mem8>, <mem8>"},
- {4, "\xf3\xa5", "rep movsl <mem32>, <mem32>"},
-
- /* MOVZX / MOVZXD */
- {1, "\x66\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg16>"},
- {1, "\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg32>"},
-
- /* MOVSX / MOVSXD */
- {1, "\x66\x0f\xbe\x51\xf8", "movswq <mem8>, <reg16>"},
- {1, "\x0f\xbe\x51\xf8", "movswq <mem8>, <reg32>"},
-
-#ifdef CONFIG_X86_64
- /* MOVZX / MOVZXD */
- {1, "\x49\x0f\xb6\x51\xf8", "movzbq <mem8>, <reg64>"},
- {2, "\x49\x0f\xb7\x51\xf8", "movzbq <mem16>, <reg64>"},
-
- /* MOVSX / MOVSXD */
- {1, "\x49\x0f\xbe\x51\xf8", "movsbq <mem8>, <reg64>"},
- {2, "\x49\x0f\xbf\x51\xf8", "movsbq <mem16>, <reg64>"},
- {4, "\x49\x63\x51\xf8", "movslq <mem32>, <reg64>"},
-#endif
-};
-
-static bool selftest_opcode_one(const struct selftest_opcode *op)
-{
- unsigned size;
-
- kmemcheck_opcode_decode(op->insn, &size);
-
- if (size == op->expected_size)
- return true;
-
- printk(KERN_WARNING "kmemcheck: opcode %s: expected size %d, got %d\n",
- op->desc, op->expected_size, size);
- return false;
-}
-
-static bool selftest_opcodes_all(void)
-{
- bool pass = true;
- unsigned int i;
-
- for (i = 0; i < ARRAY_SIZE(selftest_opcodes); ++i)
- pass = pass && selftest_opcode_one(&selftest_opcodes[i]);
-
- return pass;
-}
-
-bool kmemcheck_selftest(void)
-{
- bool pass = true;
-
- pass = pass && selftest_opcodes_all();
-
- return pass;
-}
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ARCH_X86_MM_KMEMCHECK_SELFTEST_H
-#define ARCH_X86_MM_KMEMCHECK_SELFTEST_H
-
-bool kmemcheck_selftest(void);
-
-#endif
+++ /dev/null
-#include <linux/kmemcheck.h>
-#include <linux/export.h>
-#include <linux/mm.h>
-
-#include <asm/page.h>
-#include <asm/pgtable.h>
-
-#include "pte.h"
-#include "shadow.h"
-
-/*
- * Return the shadow address for the given address. Returns NULL if the
- * address is not tracked.
- *
- * We need to be extremely careful not to follow any invalid pointers,
- * because this function can be called for *any* possible address.
- */
-void *kmemcheck_shadow_lookup(unsigned long address)
-{
- pte_t *pte;
- struct page *page;
-
- if (!virt_addr_valid(address))
- return NULL;
-
- pte = kmemcheck_pte_lookup(address);
- if (!pte)
- return NULL;
-
- page = virt_to_page(address);
- if (!page->shadow)
- return NULL;
- return page->shadow + (address & (PAGE_SIZE - 1));
-}
-
-static void mark_shadow(void *address, unsigned int n,
- enum kmemcheck_shadow status)
-{
- unsigned long addr = (unsigned long) address;
- unsigned long last_addr = addr + n - 1;
- unsigned long page = addr & PAGE_MASK;
- unsigned long last_page = last_addr & PAGE_MASK;
- unsigned int first_n;
- void *shadow;
-
- /* If the memory range crosses a page boundary, stop there. */
- if (page == last_page)
- first_n = n;
- else
- first_n = page + PAGE_SIZE - addr;
-
- shadow = kmemcheck_shadow_lookup(addr);
- if (shadow)
- memset(shadow, status, first_n);
-
- addr += first_n;
- n -= first_n;
-
- /* Do full-page memset()s. */
- while (n >= PAGE_SIZE) {
- shadow = kmemcheck_shadow_lookup(addr);
- if (shadow)
- memset(shadow, status, PAGE_SIZE);
-
- addr += PAGE_SIZE;
- n -= PAGE_SIZE;
- }
-
- /* Do the remaining page, if any. */
- if (n > 0) {
- shadow = kmemcheck_shadow_lookup(addr);
- if (shadow)
- memset(shadow, status, n);
- }
-}
-
-void kmemcheck_mark_unallocated(void *address, unsigned int n)
-{
- mark_shadow(address, n, KMEMCHECK_SHADOW_UNALLOCATED);
-}
-
-void kmemcheck_mark_uninitialized(void *address, unsigned int n)
-{
- mark_shadow(address, n, KMEMCHECK_SHADOW_UNINITIALIZED);
-}
-
-/*
- * Fill the shadow memory of the given address such that the memory at that
- * address is marked as being initialized.
- */
-void kmemcheck_mark_initialized(void *address, unsigned int n)
-{
- mark_shadow(address, n, KMEMCHECK_SHADOW_INITIALIZED);
-}
-EXPORT_SYMBOL_GPL(kmemcheck_mark_initialized);
-
-void kmemcheck_mark_freed(void *address, unsigned int n)
-{
- mark_shadow(address, n, KMEMCHECK_SHADOW_FREED);
-}
-
-void kmemcheck_mark_unallocated_pages(struct page *p, unsigned int n)
-{
- unsigned int i;
-
- for (i = 0; i < n; ++i)
- kmemcheck_mark_unallocated(page_address(&p[i]), PAGE_SIZE);
-}
-
-void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n)
-{
- unsigned int i;
-
- for (i = 0; i < n; ++i)
- kmemcheck_mark_uninitialized(page_address(&p[i]), PAGE_SIZE);
-}
-
-void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n)
-{
- unsigned int i;
-
- for (i = 0; i < n; ++i)
- kmemcheck_mark_initialized(page_address(&p[i]), PAGE_SIZE);
-}
-
-enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size)
-{
-#ifdef CONFIG_KMEMCHECK_PARTIAL_OK
- uint8_t *x;
- unsigned int i;
-
- x = shadow;
-
- /*
- * Make sure _some_ bytes are initialized. Gcc frequently generates
- * code to access neighboring bytes.
- */
- for (i = 0; i < size; ++i) {
- if (x[i] == KMEMCHECK_SHADOW_INITIALIZED)
- return x[i];
- }
-
- return x[0];
-#else
- return kmemcheck_shadow_test_all(shadow, size);
-#endif
-}
-
-enum kmemcheck_shadow kmemcheck_shadow_test_all(void *shadow, unsigned int size)
-{
- uint8_t *x;
- unsigned int i;
-
- x = shadow;
-
- /* All bytes must be initialized. */
- for (i = 0; i < size; ++i) {
- if (x[i] != KMEMCHECK_SHADOW_INITIALIZED)
- return x[i];
- }
-
- return x[0];
-}
-
-void kmemcheck_shadow_set(void *shadow, unsigned int size)
-{
- uint8_t *x;
- unsigned int i;
-
- x = shadow;
- for (i = 0; i < size; ++i)
- x[i] = KMEMCHECK_SHADOW_INITIALIZED;
-}
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef ARCH__X86__MM__KMEMCHECK__SHADOW_H
-#define ARCH__X86__MM__KMEMCHECK__SHADOW_H
-
-enum kmemcheck_shadow {
- KMEMCHECK_SHADOW_UNALLOCATED,
- KMEMCHECK_SHADOW_UNINITIALIZED,
- KMEMCHECK_SHADOW_INITIALIZED,
- KMEMCHECK_SHADOW_FREED,
-};
-
-void *kmemcheck_shadow_lookup(unsigned long address);
-
-enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size);
-enum kmemcheck_shadow kmemcheck_shadow_test_all(void *shadow,
- unsigned int size);
-void kmemcheck_shadow_set(void *shadow, unsigned int size);
-
-#endif
__tasklet_hi_schedule(t);
}
-extern void __tasklet_hi_schedule_first(struct tasklet_struct *t);
-
-/*
- * This version avoids touching any other tasklets. Needed for kmemcheck
- * in order not to take any page faults while enqueueing this tasklet;
- * consider VERY carefully whether you really need this or
- * tasklet_hi_schedule()...
- */
-static inline void tasklet_hi_schedule_first(struct tasklet_struct *t)
-{
- if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
- __tasklet_hi_schedule_first(t);
-}
-
-
static inline void tasklet_disable_nosync(struct tasklet_struct *t)
{
atomic_inc(&t->count);
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef LINUX_KMEMCHECK_H
-#define LINUX_KMEMCHECK_H
-
-#include <linux/mm_types.h>
-#include <linux/types.h>
-
-#ifdef CONFIG_KMEMCHECK
-extern int kmemcheck_enabled;
-
-/* The slab-related functions. */
-void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node);
-void kmemcheck_free_shadow(struct page *page, int order);
-void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
- size_t size);
-void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size);
-
-void kmemcheck_pagealloc_alloc(struct page *p, unsigned int order,
- gfp_t gfpflags);
-
-void kmemcheck_show_pages(struct page *p, unsigned int n);
-void kmemcheck_hide_pages(struct page *p, unsigned int n);
-
-bool kmemcheck_page_is_tracked(struct page *p);
-
-void kmemcheck_mark_unallocated(void *address, unsigned int n);
-void kmemcheck_mark_uninitialized(void *address, unsigned int n);
-void kmemcheck_mark_initialized(void *address, unsigned int n);
-void kmemcheck_mark_freed(void *address, unsigned int n);
-
-void kmemcheck_mark_unallocated_pages(struct page *p, unsigned int n);
-void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n);
-void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n);
-
-int kmemcheck_show_addr(unsigned long address);
-int kmemcheck_hide_addr(unsigned long address);
-
-bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size);
-
-/*
- * Bitfield annotations
- *
- * How to use: If you have a struct using bitfields, for example
- *
- * struct a {
- * int x:8, y:8;
- * };
- *
- * then this should be rewritten as
- *
- * struct a {
- * kmemcheck_bitfield_begin(flags);
- * int x:8, y:8;
- * kmemcheck_bitfield_end(flags);
- * };
- *
- * Now the "flags_begin" and "flags_end" members may be used to refer to the
- * beginning and end, respectively, of the bitfield (and things like
- * &x.flags_begin is allowed). As soon as the struct is allocated, the bit-
- * fields should be annotated:
- *
- * struct a *a = kmalloc(sizeof(struct a), GFP_KERNEL);
- * kmemcheck_annotate_bitfield(a, flags);
- */
-#define kmemcheck_bitfield_begin(name) \
- int name##_begin[0];
-
-#define kmemcheck_bitfield_end(name) \
- int name##_end[0];
-
-#define kmemcheck_annotate_bitfield(ptr, name) \
- do { \
- int _n; \
- \
- if (!ptr) \
- break; \
- \
- _n = (long) &((ptr)->name##_end) \
- - (long) &((ptr)->name##_begin); \
- BUILD_BUG_ON(_n < 0); \
- \
- kmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \
- } while (0)
-
-#define kmemcheck_annotate_variable(var) \
- do { \
- kmemcheck_mark_initialized(&(var), sizeof(var)); \
- } while (0) \
-
-#else
-#define kmemcheck_enabled 0
-
-static inline void
-kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
-{
-}
-
-static inline void
-kmemcheck_free_shadow(struct page *page, int order)
-{
-}
-
-static inline void
-kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
- size_t size)
-{
-}
-
-static inline void kmemcheck_slab_free(struct kmem_cache *s, void *object,
- size_t size)
-{
-}
-
-static inline void kmemcheck_pagealloc_alloc(struct page *p,
- unsigned int order, gfp_t gfpflags)
-{
-}
-
-static inline bool kmemcheck_page_is_tracked(struct page *p)
-{
- return false;
-}
-
-static inline void kmemcheck_mark_unallocated(void *address, unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_uninitialized(void *address, unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_initialized(void *address, unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_freed(void *address, unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_unallocated_pages(struct page *p,
- unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_uninitialized_pages(struct page *p,
- unsigned int n)
-{
-}
-
-static inline void kmemcheck_mark_initialized_pages(struct page *p,
- unsigned int n)
-{
-}
-
-static inline bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size)
-{
- return true;
-}
-
-#define kmemcheck_bitfield_begin(name)
-#define kmemcheck_bitfield_end(name)
-#define kmemcheck_annotate_bitfield(ptr, name) \
- do { \
- } while (0)
-
-#define kmemcheck_annotate_variable(var) \
- do { \
- } while (0)
-
-#endif /* CONFIG_KMEMCHECK */
-
-#endif /* LINUX_KMEMCHECK_H */
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
-void __tasklet_hi_schedule_first(struct tasklet_struct *t)
-{
- lockdep_assert_irqs_disabled();
-
- t->next = __this_cpu_read(tasklet_hi_vec.head);
- __this_cpu_write(tasklet_hi_vec.head, t);
- __raise_softirq_irqoff(HI_SOFTIRQ);
-}
-EXPORT_SYMBOL(__tasklet_hi_schedule_first);
-
static __latent_entropy void tasklet_action(struct softirq_action *a)
{
struct tasklet_struct *list;
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/ctype.h>
-#include <linux/kmemcheck.h>
#include <linux/kmemleak.h>
#include <linux/fs.h>
#include <linux/init.h>
.extra1 = &zero,
.extra2 = &one_thousand,
},
-#endif
-#ifdef CONFIG_KMEMCHECK
- {
- .procname = "kmemcheck",
- .data = &kmemcheck_enabled,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
#endif
{
.procname = "panic_on_warn",
config DEBUG_SLAB
bool "Debug slab memory allocations"
- depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
+ depends on DEBUG_KERNEL && SLAB
help
Say Y here to have the kernel do limited verification on memory
allocation as well as poisoning memory on free to catch use of freed
config SLUB_DEBUG_ON
bool "SLUB debugging on by default"
- depends on SLUB && SLUB_DEBUG && !KMEMCHECK
+ depends on SLUB && SLUB_DEBUG
default n
help
Boot with debugging on by default. SLUB boots by default with
If in doubt, say "N".
-source "lib/Kconfig.kmemcheck"
-
source "lib/Kconfig.kasan"
endmenu # "Memory Debugging"
+++ /dev/null
-config HAVE_ARCH_KMEMCHECK
- bool
-
-if HAVE_ARCH_KMEMCHECK
-
-menuconfig KMEMCHECK
- bool "kmemcheck: trap use of uninitialized memory"
- depends on DEBUG_KERNEL
- depends on !X86_USE_3DNOW
- depends on SLUB || SLAB
- depends on !CC_OPTIMIZE_FOR_SIZE
- depends on !FUNCTION_TRACER
- select FRAME_POINTER
- select STACKTRACE
- default n
- help
- This option enables tracing of dynamically allocated kernel memory
- to see if memory is used before it has been given an initial value.
- Be aware that this requires half of your memory for bookkeeping and
- will insert extra code at *every* read and write to tracked memory
- thus slow down the kernel code (but user code is unaffected).
-
- The kernel may be started with kmemcheck=0 or kmemcheck=1 to disable
- or enable kmemcheck at boot-time. If the kernel is started with
- kmemcheck=0, the large memory and CPU overhead is not incurred.
-
-choice
- prompt "kmemcheck: default mode at boot"
- depends on KMEMCHECK
- default KMEMCHECK_ONESHOT_BY_DEFAULT
- help
- This option controls the default behaviour of kmemcheck when the
- kernel boots and no kmemcheck= parameter is given.
-
-config KMEMCHECK_DISABLED_BY_DEFAULT
- bool "disabled"
- depends on KMEMCHECK
-
-config KMEMCHECK_ENABLED_BY_DEFAULT
- bool "enabled"
- depends on KMEMCHECK
-
-config KMEMCHECK_ONESHOT_BY_DEFAULT
- bool "one-shot"
- depends on KMEMCHECK
- help
- In one-shot mode, only the first error detected is reported before
- kmemcheck is disabled.
-
-endchoice
-
-config KMEMCHECK_QUEUE_SIZE
- int "kmemcheck: error queue size"
- depends on KMEMCHECK
- default 64
- help
- Select the maximum number of errors to store in the queue. Since
- errors can occur virtually anywhere and in any context, we need a
- temporary storage area which is guarantueed not to generate any
- other faults. The queue will be emptied as soon as a tasklet may
- be scheduled. If the queue is full, new error reports will be
- lost.
-
-config KMEMCHECK_SHADOW_COPY_SHIFT
- int "kmemcheck: shadow copy size (5 => 32 bytes, 6 => 64 bytes)"
- depends on KMEMCHECK
- range 2 8
- default 5
- help
- Select the number of shadow bytes to save along with each entry of
- the queue. These bytes indicate what parts of an allocation are
- initialized, uninitialized, etc. and will be displayed when an
- error is detected to help the debugging of a particular problem.
-
-config KMEMCHECK_PARTIAL_OK
- bool "kmemcheck: allow partially uninitialized memory"
- depends on KMEMCHECK
- default y
- help
- This option works around certain GCC optimizations that produce
- 32-bit reads from 16-bit variables where the upper 16 bits are
- thrown away afterwards. This may of course also hide some real
- bugs.
-
-config KMEMCHECK_BITOPS_OK
- bool "kmemcheck: allow bit-field manipulation"
- depends on KMEMCHECK
- default n
- help
- This option silences warnings that would be generated for bit-field
- accesses where not all the bits are initialized at the same time.
- This may also hide some real bugs.
-
-endif
bool "Debug page memory allocations"
depends on DEBUG_KERNEL
depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
- depends on !KMEMCHECK
select PAGE_EXTENSION
select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
---help---
KCOV_INSTRUMENT_page_alloc.o := n
KCOV_INSTRUMENT_debug-pagealloc.o := n
KCOV_INSTRUMENT_kmemleak.o := n
-KCOV_INSTRUMENT_kmemcheck.o := n
KCOV_INSTRUMENT_memcontrol.o := n
KCOV_INSTRUMENT_mmzone.o := n
KCOV_INSTRUMENT_vmstat.o := n
obj-$(CONFIG_PAGE_POISONING) += page_poison.o
obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_SLUB) += slub.o
-obj-$(CONFIG_KMEMCHECK) += kmemcheck.o
obj-$(CONFIG_KASAN) += kasan/
obj-$(CONFIG_FAILSLAB) += failslab.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
// SPDX-License-Identifier: GPL-2.0
-#include <linux/gfp.h>
-#include <linux/mm_types.h>
-#include <linux/mm.h>
-#include <linux/slab.h>
-#include "slab.h"
-#include <linux/kmemcheck.h>
-
-void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
-{
- struct page *shadow;
- int pages;
- int i;
-
- pages = 1 << order;
-
- /*
- * With kmemcheck enabled, we need to allocate a memory area for the
- * shadow bits as well.
- */
- shadow = alloc_pages_node(node, flags, order);
- if (!shadow) {
- if (printk_ratelimit())
- pr_err("kmemcheck: failed to allocate shadow bitmap\n");
- return;
- }
-
- for(i = 0; i < pages; ++i)
- page[i].shadow = page_address(&shadow[i]);
-
- /*
- * Mark it as non-present for the MMU so that our accesses to
- * this memory will trigger a page fault and let us analyze
- * the memory accesses.
- */
- kmemcheck_hide_pages(page, pages);
-}
-
-void kmemcheck_free_shadow(struct page *page, int order)
-{
- struct page *shadow;
- int pages;
- int i;
-
- if (!kmemcheck_page_is_tracked(page))
- return;
-
- pages = 1 << order;
-
- kmemcheck_show_pages(page, pages);
-
- shadow = virt_to_page(page[0].shadow);
-
- for(i = 0; i < pages; ++i)
- page[i].shadow = NULL;
-
- __free_pages(shadow, order);
-}
-
-void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
- size_t size)
-{
- if (unlikely(!object)) /* Skip object if allocation failed */
- return;
-
- /*
- * Has already been memset(), which initializes the shadow for us
- * as well.
- */
- if (gfpflags & __GFP_ZERO)
- return;
-
- /* No need to initialize the shadow of a non-tracked slab. */
- if (s->flags & SLAB_NOTRACK)
- return;
-
- if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
- /*
- * Allow notracked objects to be allocated from
- * tracked caches. Note however that these objects
- * will still get page faults on access, they just
- * won't ever be flagged as uninitialized. If page
- * faults are not acceptable, the slab cache itself
- * should be marked NOTRACK.
- */
- kmemcheck_mark_initialized(object, size);
- } else if (!s->ctor) {
- /*
- * New objects should be marked uninitialized before
- * they're returned to the called.
- */
- kmemcheck_mark_uninitialized(object, size);
- }
-}
-
-void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
-{
- /* TODO: RCU freeing is unsupported for now; hide false positives. */
- if (!s->ctor && !(s->flags & SLAB_TYPESAFE_BY_RCU))
- kmemcheck_mark_freed(object, size);
-}
-
-void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
- gfp_t gfpflags)
-{
- int pages;
-
- if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
- return;
-
- pages = 1 << order;
-
- /*
- * NOTE: We choose to track GFP_ZERO pages too; in fact, they
- * can become uninitialized by copying uninitialized memory
- * into them.
- */
-
- /* XXX: Can use zone->node for node? */
- kmemcheck_alloc_shadow(page, order, gfpflags, -1);
-
- if (gfpflags & __GFP_ZERO)
- kmemcheck_mark_initialized_pages(page, pages);
- else
- kmemcheck_mark_uninitialized_pages(page, pages);
-}
* So in order to make the debug calls that expect irqs to be
* disabled we need to disable interrupts temporarily.
*/
-#if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP)
+#ifdef CONFIG_LOCKDEP
{
unsigned long flags;
* Compiler cannot detect this function can be removed if slab_free_hook()
* evaluates to nothing. Thus, catch all relevant config debug options here.
*/
-#if defined(CONFIG_KMEMCHECK) || \
- defined(CONFIG_LOCKDEP) || \
+#if defined(CONFIG_LOCKDEP) || \
defined(CONFIG_DEBUG_KMEMLEAK) || \
defined(CONFIG_DEBUG_OBJECTS_FREE) || \
defined(CONFIG_KASAN)
# strip comments:
$members =~ s/\/\*.*?\*\///gos;
$nested =~ s/\/\*.*?\*\///gos;
- # strip kmemcheck_bitfield_{begin,end}.*;
- $members =~ s/kmemcheck_bitfield_.*?;//gos;
# strip attributes
$members =~ s/__attribute__\s*\(\([a-z,_\*\s\(\)]*\)\)//i;
$members =~ s/__aligned\s*\([^;]*\)//gos;
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _LIBLOCKDEP_LINUX_KMEMCHECK_H_
-#define _LIBLOCKDEP_LINUX_KMEMCHECK_H_
-
-static inline void kmemcheck_mark_initialized(void *address, unsigned int n)
-{
-}
-
-#endif
projects / kernel.git / commitdiff