x86/dumpstack: Add get_stack_info() support for the SYSENTER stack

get_stack_info() doesn't currently know about the SYSENTER stack, so
unwinding will fail if we entered the kernel on the SYSENTER stack
and haven't fully switched off.  Teach get_stack_info() about the
SYSENTER stack.

With future patches applied that run part of the entry code on the
SYSENTER stack and introduce an intentional BUG(), I would get:

  PANIC: double fault, error_code: 0x0
  ...
  RIP: 0010:do_error_trap+0x33/0x1c0
  ...
  Call Trace:
  Code: ...

With this patch, I get:

  PANIC: double fault, error_code: 0x0
  ...
  Call Trace:
   <SYSENTER>
   ? async_page_fault+0x36/0x60
   ? invalid_op+0x22/0x40
   ? async_page_fault+0x36/0x60
   ? sync_regs+0x3c/0x40
   ? sync_regs+0x2e/0x40
   ? error_entry+0x6c/0xd0
   ? async_page_fault+0x36/0x60
   </SYSENTER>
  Code: ...

which is a lot more informative.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.392711508@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 8da111b3c342bbb61a9e630e101c8a83422a15ea..f8062bfd43a072dc950b23f242893b6ca3310652 100644 (file)
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -16,6 +16,7 @@ enum stack_type {
        STACK_TYPE_TASK,
        STACK_TYPE_IRQ,
        STACK_TYPE_SOFTIRQ,
+       STACK_TYPE_SYSENTER,
        STACK_TYPE_EXCEPTION,
        STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1,
 };
@@ -28,6 +29,8 @@ struct stack_info {
 bool in_task_stack(unsigned long *stack, struct task_struct *task,
                   struct stack_info *info);
 
+bool in_sysenter_stack(unsigned long *stack, struct stack_info *info);
+
 int get_stack_info(unsigned long *stack, struct task_struct *task,
                   struct stack_info *info, unsigned long *visit_mask);
 

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 0bc95be5c6385c11ad2e3d3013dd0fb9d7c0f08a..a33a1373a2522fbfe4fcfba9afe6c38f585c7d58 100644 (file)
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -43,6 +43,25 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task,
        return true;
 }
 
+bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
+{
+       struct tss_struct *tss = this_cpu_ptr(&cpu_tss);
+
+       /* Treat the canary as part of the stack for unwinding purposes. */
+       void *begin = &tss->SYSENTER_stack_canary;
+       void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
+
+       if ((void *)stack < begin || (void *)stack >= end)
+               return false;
+
+       info->type      = STACK_TYPE_SYSENTER;
+       info->begin     = begin;
+       info->end       = end;
+       info->next_sp   = NULL;
+
+       return true;
+}
+
 static void printk_stack_address(unsigned long address, int reliable,
                                 char *log_lvl)
 {

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index daefae83a3aa86c59602b75bd3e6734c6e3b1030..5ff13a6b368069f68505099ce94267b8bf0f45b9 100644 (file)
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -26,6 +26,9 @@ const char *stack_type_name(enum stack_type type)
        if (type == STACK_TYPE_SOFTIRQ)
                return "SOFTIRQ";
 
+       if (type == STACK_TYPE_SYSENTER)
+               return "SYSENTER";
+
        return NULL;
 }
 
@@ -93,6 +96,9 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
        if (task != current)
                goto unknown;
 
+       if (in_sysenter_stack(stack, info))
+               goto recursion_check;
+
        if (in_hardirq_stack(stack, info))
                goto recursion_check;
 

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 88ce2ffdb110303502ad33e64d357d8af5afd8c6..abc828f8c29785b4fae8398ec19775015447ee22 100644 (file)
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -37,6 +37,9 @@ const char *stack_type_name(enum stack_type type)
        if (type == STACK_TYPE_IRQ)
                return "IRQ";
 
+       if (type == STACK_TYPE_SYSENTER)
+               return "SYSENTER";
+
        if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
                return exception_stack_names[type - STACK_TYPE_EXCEPTION];
 
@@ -115,6 +118,9 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
        if (in_irq_stack(stack, info))
                goto recursion_check;
 
+       if (in_sysenter_stack(stack, info))
+               goto recursion_check;
+
        goto unknown;
 
 recursion_check: