diff options
Diffstat (limited to 'include/asm-i386')
| -rw-r--r-- | include/asm-i386/processor.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 13ecf66b098c..29ad87e9123f 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -561,10 +561,20 @@ unsigned long get_wchan(struct task_struct *p); (unsigned long)(&__ptr[THREAD_SIZE_LONGS]); \ }) +/* + * The below -8 is to reserve 8 bytes on top of the ring0 stack. + * This is necessary to guarantee that the entire "struct pt_regs" + * is accessable even if the CPU haven't stored the SS/ESP registers + * on the stack (interrupt gate does not save these registers + * when switching to the same priv ring). + * Therefore beware: accessing the xss/esp fields of the + * "struct pt_regs" is possible, but they may contain the + * completely wrong values. + */ #define task_pt_regs(task) \ ({ \ struct pt_regs *__regs__; \ - __regs__ = (struct pt_regs *)KSTK_TOP((task)->thread_info); \ + __regs__ = (struct pt_regs *)(KSTK_TOP((task)->thread_info)-8); \ __regs__ - 1; \ }) |