From: Andy Lutomirski <[email protected]> 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Link: https://lkml.kernel.org/r/be3179c0a38c392fa44ebeb7dd89391ff5c010c3.1511497875.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/include/asm/processor.h | 1 - arch/x86/kernel/dumpstack.c | 3 +-- arch/x86/kernel/process.c | 1 - arch/x86/kernel/traps.c | 7 ------- 4 files changed, 1 insertion(+), 11 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 2f6d5634da55..806011202733 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -342,7 +342,6 @@ struct tss_struct { * Space for the temporary SYSENTER stack, used for SYSENTER * and the entry trampoline as well. */ - unsigned long SYSENTER_stack_canary; unsigned long SYSENTER_stack[64]; /* diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 47ea8e0daf81..35876e94286d 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -48,8 +48,7 @@ bool in_sysenter_stack(unsigned long *stack, struct stack_info *info) int cpu = smp_processor_id(); 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_canary; + void *begin = &tss->SYSENTER_stack; void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack); if ((void *)stack < begin || (void *)stack >= end) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 2cf7e2aa1730..298be43d63de 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -81,7 +81,6 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = { */ .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 }, #endif - .SYSENTER_stack_canary = STACK_END_MAGIC, }; EXPORT_PER_CPU_SYMBOL(cpu_tss); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 450688c75b3b..de4e3c80cf34 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -819,13 +819,6 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code) debug_stack_usage_dec(); 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); } NOKPROBE_SYMBOL(do_debug); -- 2.14.1
