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x86/entry/64: Remove the SYSENTER stack canary

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Now that the SYSENTER stack has a guard page, there's no need for a canary
to detect overflow after the fact.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-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/20171204150606.572577316@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-12-04 15:07:27 +01:00 • committed by Ingo Molnar
parent 40e7f949e0
commit 7fbbd5cbeb
4 changed files with 1 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/include/asm/processor.h
View file

@ -341,7 +341,6 @@ struct tss_struct {
* Space for the temporary SYSENTER stack, used for SYSENTER * Space for the temporary SYSENTER stack, used for SYSENTER
* and the entry trampoline as well. * and the entry trampoline as well.
*/ */
unsigned long SYSENTER_stack_canary;
unsigned long SYSENTER_stack[64]; unsigned long SYSENTER_stack[64];
/* /*

3
arch/x86/kernel/dumpstack.c
View file

@ -48,8 +48,7 @@ bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
int cpu = smp_processor_id(); int cpu = smp_processor_id();
struct tss_struct *tss = &get_cpu_entry_area(cpu)->tss; struct tss_struct *tss = &get_cpu_entry_area(cpu)->tss;
/* Treat the canary as part of the stack for unwinding purposes. */ void *begin = &tss->SYSENTER_stack;
void *begin = &tss->SYSENTER_stack_canary;
void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack); void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
if ((void *)stack < begin || (void *)stack >= end) if ((void *)stack < begin || (void *)stack >= end)

1
arch/x86/kernel/process.c
View file

@ -81,7 +81,6 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
*/ */
.io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 }, .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 },
#endif #endif
.SYSENTER_stack_canary = STACK_END_MAGIC,
}; };
EXPORT_PER_CPU_SYMBOL(cpu_tss); EXPORT_PER_CPU_SYMBOL(cpu_tss);

7
arch/x86/kernel/traps.c
View file

@ -814,13 +814,6 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_dec(); debug_stack_usage_dec();
exit: exit:
/*
* This is the most likely code path that involves non-trivial use
* of the SYSENTER stack. Check that we haven't overrun it.
*/
WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
"Overran or corrupted SYSENTER stack\n");
ist_exit(regs); ist_exit(regs);
} }
NOKPROBE_SYMBOL(do_debug); NOKPROBE_SYMBOL(do_debug);