s390/smp: enable DAT before CPU restart callback is called
The restart interrupt is triggered whenever a secondary CPU is
brought online, a remote function call dispatched from another
CPU or a manual PSW restart is initiated and causes the system
to kdump. The handling routine is always called with DAT turned
off. It then initializes the stack frame and invokes a callback.
The existing callbacks handle DAT as follows:
* __do_restart() and __machine_kexec() turn in on upon entry;
* __ipl_run(), __reipl_run() and __dump_run() do not turn it
right away, but all of them call diag308() - which turns DAT
on, but only if kasan is enabled;
In addition to the described complexity all callbacks (and the
functions they call) should avoid kasan instrumentation while
DAT is off.
This update enables DAT in the assembler restart handler and
relieves any callbacks (which are mostly C functions) from
dealing with DAT altogether.
There are four types of CPU restart that initialize control
registers in different ways:
1. Start of secondary CPU on boot - control registers are
inherited from the IPL CPU;
2. Restart of online CPU - control registers of the CPU being
restarted are kept;
3. Hotplug of offline CPU - control registers are inherited
from the starting CPU;
4. Start of offline CPU triggered by manual PSW restart -
the control registers are read from the absolute lowcore
and contain the boot time IPL CPU values updated with all
follow-up calls of smp_ctl_set_bit() and smp_ctl_clear_bit()
routines;
In first three cases contents of the control registers is the
most recent. In the latter case control registers are good
enough to facilitate successful completion of kdump operation.
s390/ap: fix state machine hang after failure to enable irq
If for any reason the interrupt enable for an ap queue fails the
state machine run for the queue returned wrong return codes to the
caller. So the caller assumed interrupt support for this queue in
enabled and thus did not re-establish the high resolution timer used
for polling. In the end this let to a hang for the user space process
waiting "forever" for the reply.
This patch reworks these return codes to return correct indications
for the caller to re-establish the timer when a queue runs without
interrupt support.
Please note that this is fixing a wrong behavior after a first
failure (enable interrupt support for the queue) failed. However,
looks like this occasionally happens on KVM systems.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Generate kvm hypercall functions with a macro instead of duplicating
the more or less identical code seven times. This also reduces number
of lines of code.
However the main purpose is to get rid of as many as possible open
coded error prone register asm constructs in s390 architecture code.
For the only user of kvm_hypercall identical code is created
before/after this patch (drivers/s390/virtio/virtio_ccw.c).
* Other (not traced at default level):
- SYN1: Synchronous wait start
- SYN2: Synchronous wait end
Since the SCLP interface is used by console drivers this patch also
moves s390dbf printks outside the critical section protected by debug
area locks to prevent a potential deadlock that would otherwise be
introduced between console_owner --> sclp_lock --> sclp_debug.lock.
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Debug areas can currently only be used after s390dbf initialization
which occurs as a postcore_initcall. This is too late for tracing
earlier code such as that related to console_init().
This patch introduces a macro for defining a statically initialized
debug area that can be used to trace very early code. The macro is made
available for built-in code only because modules are never running
during early boot.
Note: The debug area is automatically registered in debugfs during boot.
A driver must not call any of the debug_register()/_unregister()
functions on a static debug_info_t!
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Currently allocation and registration of s390dbf debug areas are tied
together. As a result, a debug area cannot be unregistered and
re-registered while any process has an associated debugfs file open.
Fix this by splitting alloc/release from register/unregister.
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Any previously recorded s390dbf debug data is reset when a debug area
is resized using the 'pages' sysfs attribute. This can make
live-debugging unnecessarily complex.
Fix this by copying existing debug data to the newly allocated debug
area when resizing.
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Heiko Carstens [Tue, 24 Aug 2021 13:21:44 +0000 (15:21 +0200)]
s390/mm,pageattr: fix walk_pte_level() early exit
In case of splitting to 4k mapping the early exit in walk_pte_level()
must only be taken iff flags is equal to SET_MEMORY_4K.
Currently the early exit is taken if the flag is set, and also others
might be set. This may lead to the situation that a mapping is split
but other changes are not done, like e.g. setting pages to R/W.
There is currently no such caller, but there might be in the future.
Randy Dunlap [Fri, 6 Aug 2021 05:01:49 +0000 (22:01 -0700)]
s390/crypto: fix all kernel-doc warnings in vfio_ap_ops.c
The 0day bot reported some kernel-doc warnings in this file so clean up
all of the kernel-doc and use proper kernel-doc formatting.
There are no more kernel-doc errors or warnings reported in this file.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: kernel test robot <lkp@intel.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Tony Krowiak <akrowiak@linux.ibm.com> Cc: Halil Pasic <pasic@linux.ibm.com> Cc: Jason Herne <jjherne@linux.ibm.com> Cc: Harald Freudenberger <freude@linux.ibm.com> Cc: linux-s390@vger.kernel.org Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com> Link: https://lore.kernel.org/r/20210806050149.9614-1-rdunlap@infradead.org Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Currently zpci_dma_init_device()/zpci_dma_exit_device() is called as
part of zpci_enable_device()/zpci_disable_device() and errors for
zpci_dma_exit_device() are always ignored even if we could abort.
Improve upon this by moving zpci_dma_exit_device() out of
zpci_disable_device() and check for errors whenever we have a way to
abort the current operation. Note that for example in
zpci_event_hard_deconfigured() the device is expected to be gone so we
really can't abort and proceed even in case of error.
Similarly move the cc == 3 special case out of zpci_unregister_ioat()
and into the callers allowing to abort when finding an already disabled
devices precludes proceeding with the operation.
While we are at it log IOAT register/unregister errors in the s390
debugfs log,
Currently clp_get_state() and clp_refresh_fh() awkwardly use the
clp_list_pci() callback mechanism to find the entry for a specific FID
and update its zdev, respectively return its state.
This is both needlessly complex and means we are always going through
the entire PCI function list even if the FID has already been found.
Instead lets introduce a clp_find_pci() function to find a specific
entry and share the CLP List PCI request handling code with
clp_list_pci().
With that in place we can also easily make the function handle a simple
out parameter instead of directly altering the zdev allowing easier
access to the updated function handle by the caller.
s390/pci: handle FH state mismatch only on disable
Instead of always treating CLP_RC_SETPCIFN_ALRDY as success and blindly
updating the function handle restrict this special handling to the
disable case by moving it into zpci_disable_device() and still treating
it as an error while also updating the function handle such that
a subsequent zpci_disable_device() succeeds or the caller can ignore the
error when aborting is not an option such as for zPCI event 0x304.
Also print this occurrence to the log such that an admin can tell why
a disable operation returned an error.
A mismatch between the state of the underlying device and our view of it
can naturally happen when the device suddenly enters the error state but
we haven't gotten the error notification yet, it must not happen on
enable though.
Currently clp_set_pci_fn() always returns 0 as long as the CLP request
itself succeeds even if the operation itself returns a response code
other than CLP_RC_OK or CLP_RC_SETPCIFN_ALRDY. This is highly misleading
because calling code assumes that a zero rc means that the operation was
successful.
Fix this by returning the response code or cc on failure with the
exception of the special handling for CLP_RC_SETPCIFN_ALRDY. Also let's
not assume that the returned function handle for CLP_RC_SETPCIFN_ALRDY
is 0, we don't need it anyway.
Julian Wiedmann [Mon, 7 Jun 2021 09:18:44 +0000 (11:18 +0200)]
s390/ap: use the common driver-data pointer
The device struct provides a pointer for driver-private data. Use this
in the zcrypt drivers (as vfio_ap already does), and then remove the
custom pointer from the AP device structs.
As really_probe() will always clear the drvdata pointer on error, we
no longer have to do so ourselves.
Niklas Schnelle [Fri, 6 Aug 2021 10:12:11 +0000 (12:12 +0200)]
s390/pci: reset zdev->zbus on registration failure
On failure to register a struct zpci_dev with a struct zpci_bus we left
a dangling pointer in zdev->zbus. As zpci_create_device() bails if
zpci_bus_device_register() fails this is of no consequence but still bad
practice.
Niklas Schnelle [Fri, 6 Aug 2021 08:28:40 +0000 (10:28 +0200)]
s390/pci: cleanup resources only if necessary
It's currently safe to call zpci_cleanup_bus_resources() even if the
resources were never created but it makes no sense so check
zdev->has_resources before we call zpci_cleanup_bus_resources() in
zpci_release_device().
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> Acked-by: Pierre Morel <pmorel@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
s390/sclp: reserve memory occupied by sclp early buffer
The memory block occupied by the SCLP early buffer that is allocated
by the decompressor and then handed over to the decompressed kernel,
must be reserved to prevent it from being reused for other purposes.
This is necessary because the SCLP early buffer is still in use
during kernel initialization.
Fixes: 95335b44233e ("s390/boot: move sclp early buffer from fixed address in asm to C") Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com> Reported-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
s390/zcrypt: fix wrong offset index for APKA master key valid state
Tests showed a mismatch between what the CCA tool reports about
the APKA master key state and what's displayed by the zcrypt dd
in sysfs. After some investigation, we found out that the
documentation which was the source for the zcrypt dd implementation
lacks the listing of 3 fields. So this patch now moves the
evaluation of the APKA master key state to the correct offset.
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
The last user of arch_set_page_states(), arch_set_page_nodat() and
arch_test_page_nodat() was removed in commit 21d625e1bf8b
("s390: remove broken hibernate / power management support"),
let's remove these functions.
Move all QIB-related code into qdio_setup_qib(), and slightly re-order
it according to the order of the struct's fields. This makes it easier
to understand what the QIB actually looks like before we send it to HW.
Also get rid of the qebsm_possible() helper - as 31-bit support is long
gone, the comment doesn't make any sense. And while removing some stale
QIB-related comment, also move the clearing of the QDR into its proper
place.
Push the sync check from qdio_inspect_queue() down into the two
get_*_buffer_frontier() code paths, where we actually need the sync to
look at the current queue state. This lets us avoid the check when we
know that there is no work on the queue (ie. when q->nr_buf_used is 0).
While at it introduce the qdio_sync_*_queue() helpers, so that we can
avoid the branch on q->is_input_q when we already know the queue type.
Don't bother with translating the SIGA-related capability bits into
our own internal format, just cache the full qdioac1 field instead.
Also adjust the helper macros so that they take a qdio_irq argument
and can be used everywhere, instead of taking a qdio_q and then
internally dereferencing the parent pointer.
The queue processing is fully decoupled from any preceding interrupt,
so we're no longer making any use of the sync-after-IRQ HW capabilities.
And as SIGA-sync is a legacy feature, there's also not much point in
re-designing the driver & qdio-layer code just so that we can
potentially avoid a few syncs. So just remove all the leftover code.
s390/cio: add dev_busid sysfs entry for each subchannel
Introduce dev_busid, which exports the device-id associated with the
io-subchannel (and message-subchannel). The dev_busid indicates that of
the device which may be physically installed on the corrosponding
subchannel. The dev_busid value "none" indicates that the subchannel
is not valid, there is no I/O device currently associated with the
subchannel.
The dev_busid information would be helpful to write device-specific
udev-rules associated with the subchannel. The dev_busid interface would
be available even when the sch is not bound to any driver or if there is
no operational device connected on it. Hence this attribute can be used to
write udev-rules which are specific to the device associated with the
subchannel.
s390/cio: add rescan functionality on channel subsystem
This patch introduces a new rescan sys-interface for channel-subsystem.
The rescan interface allows the user to invoke an evaluation of all
subchannels defined in the I/O configuration.
The new rescan interface can be found at /sys/devices/css0/rescan
and can be triggered by,
echo > /sys/devices/css0/rescan
Writing to this interface triggers subchannel evaluation. The write
request completes only after scan-related work has completed
This user-invoked subchannel evaluation allows manual recovery in error
situations such as:
- restart of device discovery after resolution of temporary device
error
- inconsistent OS view of subchannel state due to missing state-change
interrupts (CRWs)
Heiko Carstens [Wed, 4 Aug 2021 11:40:31 +0000 (13:40 +0200)]
s390: rename dma section to amode31
The dma section name is confusing, since the code which resides within
that section has nothing to do with direct memory access. Instead the
limitation is that the code has to run in 31 bit addressing mode, and
therefore has to reside below 2GB. So the name was chosen since
ZONE_DMA is the same region.
To reduce confusion rename the section to amode31, which hopefully
describes better what this is about.
Note: this will also change vmcoreinfo strings
- SDMA=... gets renamed to SAMODE31=...
- EDMA=... gets renamed to EAMODE31=...
The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().
Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.
The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().
Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.
s390 allows hotpatching the mask of a conditional jump instruction.
Make use of this feature in order to avoid the expensive stop_machine()
call.
The new trampolines are split in 3 stages:
- A first stage is a 6-byte relative conditional long branch located at
each function's entry point. Its offset always points to the second
stage for the corresponding function, and its mask is either all 0s
(ftrace off) or all 1s (ftrace on). The code for flipping the mask is
borrowed from ftrace_{enable,disable}_ftrace_graph_caller. After
flipping, ftrace_arch_code_modify_post_process() syncs with all the
other CPUs by sending SIGPs.
- Second stages for vmlinux are stored in a separate part of the .text
section reserved by the linker script, and in dynamically allocated
memory for modules. This prevents the icache pollution. The total
size of second stages is about 1.5% of that of the kernel image.
Putting second stages in the .bss section is possible and decreases
the size of the non-compressed vmlinux, but splits the kernel 1:1
mapping, which is a bad tradeoff.
Each second stage contains a call to the third stage, a pointer to
the part of the intercepted function right after the first stage, and
a pointer to an interceptor function (e.g. ftrace_caller).
Second stages are 8-byte aligned for the future direct calls
implementation.
- There are only two copies of the third stage: in the .text section
for vmlinux and in dynamically allocated memory for modules. It can be
an expoline, which is relatively large, so inlining it into each
second stage is prohibitively expensive.
As a result of this organization, phoronix-test-suite with ftrace off
does not show any performance degradation.
Implementing live patching on s390 requires each function's prologue to
contain a very special kind of nop, which gcc and clang don't generate.
However, the current code assumes that if CC_USING_NOP_MCOUNT is
defined, then whatever the compiler generates is good enough.
Move the CC_USING_NOP_MCOUNT check into the new ftrace_need_init_nop()
macro, that the architectures can override.
An alternative solution is to disable using -mnop-mcount in the
Makefile, however, this makes the build logic (even) more complicated
and forces the arch-specific code to deal with the useless __fentry__
symbol.
Currently, the install target in arch/s390/Makefile descends into
arch/s390/boot/Makefile to invoke the shell script, but there is no
good reason to do so.
arch/s390/Makefile can run the shell script directly.
cycles_t has a different type across architectures: unsigned int,
unsinged long, or unsigned long long. Depending on architecture this
will generate this warning:
kernel/kcsan/debugfs.c: In function ‘microbenchmark’:
./include/linux/kern_levels.h:5:25: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘cycles_t’ {aka ‘long unsigned int’} [-Wformat=]
To avoid this simply change the type of cycle to u64 in microbenchmark(),
since u64 is of type unsigned long long for all architectures.
Sven Schnelle [Wed, 28 Jul 2021 19:02:52 +0000 (21:02 +0200)]
kfence: add function to mask address bits
s390 only reports the page address during a translation fault.
To make the kfence unit tests pass, add a function that might
be implemented by architectures to mask out address bits.
Marco Elver [Wed, 28 Jul 2021 19:57:41 +0000 (21:57 +0200)]
kfence, x86: only define helpers if !MODULE
x86's <asm/tlbflush.h> only declares non-module accessible functions
(such as flush_tlb_one_kernel) if !MODULE.
In preparation of including <asm/kfence.h> from the KFENCE test module,
only define the helpers if !MODULE to avoid breaking the build with
CONFIG_KFENCE_KUNIT_TEST=m.
Commit 3ab560395087 ("s390: show virtualization support in /proc/cpuinfo")
introduced special handling for sie capability, saying this should not be
exposed via hwcaps, without giving a reason.
However this leads to an inconsistent /proc/cpuinfo features line
where all features except the sie capability are also present in
hwcaps. I really don't see a reason to not add that to hwcaps - it
might be quite pointless, but at least this way it is possible to get
rid of some special handling.
Remove the not so obvious "(elf_hwcap & (1UL << 2)" which only checks
if stfle is available. This used to be required for old code before
test_facility() was introduced. test_facility() will do the right
thing, regardless if stfle is available or not.
s390/hwcaps: open code initialization of first six hwcap bits
The first six hwcap bits are initialized in a rather odd way: an array
contains the stfl(e) bits which need to be set, so that the
corresponding bit position (= array index) within hwcaps are set.
Better open code it like it is done for all other bits, making it
obvious which bit is set when.
Introduce HWCAP bit numbers, making it easier to tell at which bit
number we currently are. Also use these bits with the BIT macro to
define the real HWCAP masks.
Remove s390 part of all HWCAP defines, just to make them shorter and
easier to handle. The namespace is anyway per architecture.
This is similar to what arm64 has.
In order to support the use of enhanced PCI instructions in both kernel-
and userspace we need both hardware support and proper setup in the
kernel. The latter can be toggled off with the pci=nomio command line
option.
Thus availability of this feature in userspace depends on all of kernel
configuration (CONFIG_PCI), hardware support and the current kernel
command line and can thus not rely solely on a facility bit. Instead
let's introduce a new ELF hardware capability bit HWCAP_S390_PCI_MIO to
tell userspace whether these PCI instructions can be used.
Kernel support for the newer PCI mio instructions can be toggled off
with the pci=nomio command line option which needs to integrate with
common code PCI option parsing. However this option then toggles static
branches which can't be toggled yet in an early_param() call.
Thus commit 2adb29b98ee5 ("s390: fix setting of mio addressing control")
moved toggling the static branches to the PCI init routine.
With this setup however we can't check for mio support outside the PCI
code during early boot, i.e. before switching the static branches, which
we need to be able to export this as an ELF HWCAP.
Improve on this by turning mio availability into a machine flag that
gets initially set based on CONFIG_PCI and the facility bit and gets
toggled off if pci=nomio is found during PCI option parsing allowing
simple access to this machine flag after early init.
s390/qdio: clarify reporting of errors to the drivers
Now that all drivers use qdio_inspect_queue() and qdio's internal
queue tasklets are gone, the driver-specified queue handlers are
only called for async error reporting (eg. for an error condition in
the QEBSM code).
So take a moment to clean up the Output Queue handlers (they are
_always_ called with qdio_error != 0), and clarify which error types
can be reported through what interface. As Benjamin already suggested
a while ago, we should turn these into distinct enums at some point.
Julian Wiedmann [Tue, 1 Jun 2021 06:20:09 +0000 (08:20 +0200)]
s390/qdio: propagate error when cancelling a ccw fails
If qdio_cancel_ccw() times out (or is interrupted) before the interrupt
for the {halt,clear} action arrives, report this back to the caller as
an error.
Julian Wiedmann [Mon, 31 May 2021 15:38:04 +0000 (18:38 +0300)]
s390/qdio: improve roll-back after error on ESTABLISH ccw
If the ESTABLISH ccw fails (ie. the qdio_irq is set to
QDIO_IRQ_STATE_ERR), we don't need to call qdio_shutdown() for rolling
back our earlier actions. All the needed logic is already available in
qdio_establish()'s error chain, and using it means we don't have to
temporarily drop the setup_mutex either.
This makes qdio_shutdown() a purely external function, that should only
be called by the driver if an earlier qdio_establish() succeeded.
Julian Wiedmann [Mon, 31 May 2021 15:33:02 +0000 (18:33 +0300)]
s390/qdio: cancel the ESTABLISH ccw after timeout
When the ESTABLISH ccw does not complete within the specified timeout,
try our best to cancel the ccw program that is still active on the
device. Otherwise the IO subsystem might be accessing it even after
the driver eg. called qdio_free().
Julian Wiedmann [Mon, 31 May 2021 15:40:06 +0000 (18:40 +0300)]
s390/qdio: fix roll-back after timeout on ESTABLISH ccw
When qdio_establish() times out while waiting for the ESTABLISH ccw to
complete, it calls qdio_shutdown() to roll back all of its previous
actions. But at this point the qdio_irq's state is still
QDIO_IRQ_STATE_INACTIVE, so qdio_shutdown() will exit immediately
without doing any actual work.
Which means that eg. the qdio_irq's thinint-indicator stays registered,
and cdev->handler isn't restored to its old value. And since
commit 9890df027122 ("s390/qdio: make thinint registration symmetric")
the qdio_irq also stays on the tiq_list, so on the next qdio_establish()
we might get a helpful BUG from the list-debugging code:
Fix this by extracting a goto-chain from the existing error exits in
qdio_establish(), and check the return value of the wait_event_...()
to detect the timeout condition.
Fixes: 1086a79cead2 ("[S390] qdio: new qdio driver.") Root-caused-by: Benjamin Block <bblock@linux.ibm.com> Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> Reviewed-by: Benjamin Block <bblock@linux.ibm.com> Cc: <stable@vger.kernel.org> # 2.6.27 Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
s390/setup: don't reserve memory that occupied decompressor's head
There is no useful information within [STARTUP_NORMAL_OFFSET, HEAD_END] now.
But the memory region [0, STARTUP_NORMAL_OFFSET] is used by:
* lowcore
* kdump for swapping memory
* stand-alone zipl dumpers for code, data, stack and heap
s390/boot: move dma sections from decompressor to decompressed kernel
This change simplifies the task of making the decompressor relocatable.
The decompressor's image contains special DMA sections between _sdma and
_edma. This DMA segment is loaded at boot as part of the decompressor and
then simply handed over to the decompressed kernel. The decompressor itself
never uses it in any way. The primary reason for this is the need to keep
the aforementioned DMA segment below 2GB which is required by architecture,
and because the decompressor is always loaded at a fixed low physical
address, it is guaranteed that the DMA region will not cross the 2GB
memory limit. If the DMA region had been placed in the decompressed kernel,
then KASLR would make this guarantee impossible to fulfill or it would
be restricted to the first 2GB of memory address space.
This commit moves all DMA sections between _sdma and _edma from
the decompressor's image to the decompressed kernel's image. The complete
DMA region is placed in the init section of the decompressed kernel and
immediately relocated below 2GB at start-up before it is needed by other
parts of the decompressed kernel. The relocation of the DMA region happens
even if the decompressed kernel is already located below 2GB in order
to keep the first implementation simple. The relocation should not have
any noticeable impact on boot time because the DMA segment is only a couple
of pages.
After relocating the DMA sections, the kernel has to fix all references
which point into it. In order to automate this, place all variables
pointing into the DMA sections in a special .dma.refs section. All such
variables must be defined using the new __dma_ref macro. Only variables
containing addresses within the DMA sections must be placed in the new
.dma.refs section.
Furthermore, move the initialization of control registers from
the decompressor to the decompressed kernel because some control registers
reference tables that must be placed in the DMA data section to
guarantee that their addresses are below 2G. Because the decompressed
kernel relocates the DMA sections at startup, the content of control
registers CR2, CR5 and CR15 must be updated with new addresses after
the relocation. The decompressed kernel initializes all control registers
early at boot and then updates the content of CR2, CR5 and CR15
as soon as the DMA relocation has occurred. This practically reverts
the commit efad8fcfb29f ("s390/kernel: introduce .dma sections").
s390/boot: make _diag308_reset_dma() position-independent
As a preparation for moving the .dma.data section from the decompressor to
the decompressed kernel, the .dma.data section must be made relocatable
by replacing absolute memory addressing with relative one. This is required
in order to be able to relocate the DMA section to a memory address <= 2G
as required by the hardware architecture. The DMA section must be
relocated in case the decompressed kernel was loaded to an address >= 2G
which can occur if KASAN is enabled. By making the whole DMA section
position-independent we avoid applying relocations to it whenever it is
moved to a different address, which becomes possible as soon as it becomes
a part of the decompressed kernel.
The macros
* IPL_DEVICE_OFFSET
* INITRD_START_OFFSET
* INITRD_SIZE_OFFSET
* OLDMEM_BASE_OFFSET
* OLDMEM_SIZE_OFFSET
* KERNEL_VERSION_OFFSET
* COMMAND_LINE_OFFSET
are no longer necessary and used only to define another set of macros
with the same names but w/o the suffix _OFFSET. Therefore, drop this
unnecessary indirection.
Drop the macro KERNEL_VERSION_OFFSET w/o renaming it to KERNEL_VERSION
because it is used nowhere.
The new boot data struct shall replace global variables OLDMEM_BASE and
OLDMEM_SIZE. It is initialized in the decompressor and passed
to the decompressed kernel. In comparison to the old solution, this one
doesn't access data at fixed physical addresses which will become important
when the decompressor becomes relocatable.
The new boot data struct shall replace global variables INITRD_START and
INITRD_SIZE. It is initialized in the decompressor and passed
to the decompressed kernel. In comparison to the old solution, this one
doesn't access data at fixed physical addresses which will become important
when the decompressor becomes relocatable.
s390/boot: move sclp early buffer from fixed address in asm to C
To make the decompressor relocatable, the early SCLP buffer with a fixed
address must be replaced with a relocatable C buffer of the according size
and alignment as required by SCLP.
Introduce a new function sclp_early_set_buffer() into the SCLP driver
which enables the decompressor to change the SCLP early buffer at any time.
This will be useful when the decompressor becomes fully relocatable and
might need to change the SCLP early buffer to one with an address < 2G
as required by SCLP because it was loaded at an address >= 2G.
Use system call functions instead of open-coding svc inline
assemblies. This is mostly to get rid of even more register asm
constructs.
Besides that, it makes the code also a bit easier to understand.
The generated code is identical to what is was before.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
s390/syscall: provide generic system call functions
Provide generic system call functions which should be used whenever a
system call needs to be done from user space. The only in-kernel code
is vdso, which will be converted with a follow on patch.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Heiko Carstens [Fri, 25 Jun 2021 14:42:55 +0000 (16:42 +0200)]
s390/cpacf: get rid of register asm
Using register asm statements has been proven to be very error prone,
especially when using code instrumentation where gcc may add function
calls, which clobbers register contents in an unexpected way.
Therefore get rid of register asm statements in cpacf code, and make
sure this bug class cannot happen.
Reviewed-by: Patrick Steuer <patrick.steuer@de.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
s390/uv: de-duplicate checks for Protected Host Virtualization
De-duplicate checks for Protected Host Virtualization in decompressor and
kernel.
Set prot_virt_host=0 in the decompressor in *any* of the following cases
and hand it over to the decompressed kernel:
* No explicit prot_virt=1 is given on the kernel command-line
* Protected Guest Virtualization is enabled
* Hardware support not present
* kdump or stand-alone dump
The decompressed kernel needs to use only is_prot_virt_host() instead of
performing again all checks done by the decompressor.
s390/boot: move uv function declarations to boot/uv.h
The functions adjust_to_uv_max() and uv_query_info() are used only
in the decompressor. Therefore, move the function declarations from
the global arch/s390/include/asm/uv.h to arch/s390/boot/uv.h.
s390/jump_label: print real address in a case of a jump label bug
In case of a jump label print the real address of the piece of code
where a mismatch was detected. This is right before the system panics,
so there is nothing revealed.
s390/mm: don't print hashed values for pte_ERROR() & friends
Print the real pte, pmd, etc. values instead of some hashed
value. Otherwise debugging would be even more difficult.
This also matches what most other architectures are doing.
s390/sclp: use only one sclp early buffer to send commands
A buffer that can be used for communication with SCLP is required
to lie below 2GB memory address. Therefore, both sclp_info_sccb
and sclp_early_sccb must fulfill this requirement if passed directly
to the sclp_early_cmd() function. Instead, use only sclp_early_sccb
for communication with SCLP. This allows the buffer sclp_info_sccb
to be placed anywhere in the memory address space and, therefore,
simplifies the process of making the decompressor relocatable later on,
one thing less to relocate. And make sure that the length of the new unified
early SCLP buffer is no less than the length of the removed sclp_info_sccb
buffer which might be larger than the length of the sclp_early_sccb buffer.
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