diff options
| -rw-r--r-- | arch/x86_64/kernel/time.c | 21 |
1 files changed, 8 insertions, 13 deletions
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 560ed944dc0e..ea00915d393a 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -189,20 +189,15 @@ unsigned long profile_pc(struct pt_regs *regs) { unsigned long pc = instruction_pointer(regs); - /* Assume the lock function has either no stack frame or only a single - word. This checks if the address on the stack looks like a kernel - text address. - There is a small window for false hits, but in that case the tick - is just accounted to the spinlock function. - Better would be to write these functions in assembler again - and check exactly. */ + /* Assume the lock function has either no stack frame or a copy + of eflags from PUSHF + Eflags always has bits 22 and up cleared unlike kernel addresses. */ if (!user_mode(regs) && in_lock_functions(pc)) { - char *v = *(char **)regs->rsp; - if ((v >= _stext && v <= _etext) || - (v >= _sinittext && v <= _einittext) || - (v >= (char *)MODULES_VADDR && v <= (char *)MODULES_END)) - return (unsigned long)v; - return ((unsigned long *)regs->rsp)[1]; + unsigned long *sp = (unsigned long *)regs->rsp; + if (sp[0] >> 22) + return sp[0]; + if (sp[1] >> 22) + return sp[1]; } return pc; } |