diff options
Diffstat (limited to 'arch/x86/include/asm/thread_info.h')
-rw-r--r-- | arch/x86/include/asm/thread_info.h | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 9b028204685d..0c977fc124a7 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -166,6 +166,61 @@ static inline struct thread_info *current_thread_info(void) return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); } +static inline unsigned long current_stack_pointer(void) +{ + unsigned long sp; +#ifdef CONFIG_X86_64 + asm("mov %%rsp,%0" : "=g" (sp)); +#else + asm("mov %%esp,%0" : "=g" (sp)); +#endif + return sp; +} + +/* + * Walks up the stack frames to make sure that the specified object is + * entirely contained by a single stack frame. + * + * Returns: + * 1 if within a frame + * -1 if placed across a frame boundary (or outside stack) + * 0 unable to determine (no frame pointers, etc) + */ +static inline int arch_within_stack_frames(const void * const stack, + const void * const stackend, + const void *obj, unsigned long len) +{ +#if defined(CONFIG_FRAME_POINTER) + const void *frame = NULL; + const void *oldframe; + + oldframe = __builtin_frame_address(1); + if (oldframe) + frame = __builtin_frame_address(2); + /* + * low ----------------------------------------------> high + * [saved bp][saved ip][args][local vars][saved bp][saved ip] + * ^----------------^ + * allow copies only within here + */ + while (stack <= frame && frame < stackend) { + /* + * If obj + len extends past the last frame, this + * check won't pass and the next frame will be 0, + * causing us to bail out and correctly report + * the copy as invalid. + */ + if (obj + len <= frame) + return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; + oldframe = frame; + frame = *(const void * const *)frame; + } + return -1; +#else + return 0; +#endif +} + #else /* !__ASSEMBLY__ */ #ifdef CONFIG_X86_64 |