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Commit 33a2f1a6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

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: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent 1a79797b

arch/x86/include/asm/stacktrace.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/dumpstack.c

+19 −0
Original line number Diff line number Diff line
@@ -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)

{

arch/x86/kernel/dumpstack_32.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/dumpstack_64.c

+6 −0
Original line number Diff line number Diff line
@@ -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: