diff options
| -rw-r--r-- | arch/x86/include/asm/ptrace.h | 15 | ||||
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 28 |
2 files changed, 32 insertions, 11 deletions
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index dcfde52979c..19f16ebaf4f 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -205,21 +205,14 @@ static inline bool user_64bit_mode(struct pt_regs *regs) } #endif -/* - * X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode - * when it traps. The previous stack will be directly underneath the saved - * registers, and 'sp/ss' won't even have been saved. Thus the '®s->sp'. - * - * This is valid only for kernel mode traps. - */ -static inline unsigned long kernel_stack_pointer(struct pt_regs *regs) -{ #ifdef CONFIG_X86_32 - return (unsigned long)(®s->sp); +extern unsigned long kernel_stack_pointer(struct pt_regs *regs); #else +static inline unsigned long kernel_stack_pointer(struct pt_regs *regs) +{ return regs->sp; -#endif } +#endif #define GET_IP(regs) ((regs)->ip) #define GET_FP(regs) ((regs)->bp) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index cf1178332bc..d3e115297fe 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -165,6 +165,34 @@ static inline bool invalid_selector(u16 value) #define FLAG_MASK FLAG_MASK_32 +/* + * X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode + * when it traps. The previous stack will be directly underneath the saved + * registers, and 'sp/ss' won't even have been saved. Thus the '®s->sp'. + * + * Now, if the stack is empty, '®s->sp' is out of range. In this + * case we try to take the previous stack. To always return a non-null + * stack pointer we fall back to regs as stack if no previous stack + * exists. + * + * This is valid only for kernel mode traps. + */ +unsigned long kernel_stack_pointer(struct pt_regs *regs) +{ + unsigned long context = (unsigned long)regs & ~(THREAD_SIZE - 1); + unsigned long sp = (unsigned long)®s->sp; + struct thread_info *tinfo; + + if (context == (sp & ~(THREAD_SIZE - 1))) + return sp; + + tinfo = (struct thread_info *)context; + if (tinfo->previous_esp) + return tinfo->previous_esp; + + return (unsigned long)regs; +} + static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long regno) { BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0); |