mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-21 11:44:01 +08:00
bfe9a2cfe9
Li Zhong points out an issue with our current __get_SP() implementation. If ftrace function tracing is enabled (ie -pg profiling using _mcount) we spill a stack frame on 64bit all the time. If a function calls __get_SP() and later calls a function that is tail call optimised, we will pop the stack frame and the value returned by __get_SP() is no longer valid. An example from Li can be found in save_stack_trace -> save_context_stack: c0000000000432c0 <.save_stack_trace>: c0000000000432c0: mflr r0 c0000000000432c4: std r0,16(r1) c0000000000432c8: stdu r1,-128(r1) <-- stack frame for _mcount c0000000000432cc: std r3,112(r1) c0000000000432d0: bl <._mcount> c0000000000432d4: nop c0000000000432d8: mr r4,r1 <-- __get_SP() c0000000000432dc: ld r5,632(r13) c0000000000432e0: ld r3,112(r1) c0000000000432e4: li r6,1 c0000000000432e8: addi r1,r1,128 <-- pop stack frame c0000000000432ec: ld r0,16(r1) c0000000000432f0: mtlr r0 c0000000000432f4: b <.save_context_stack> <-- tail call optimized save_context_stack ends up with a stack pointer below the current one, and it is likely to be scribbled over. Fix this by making __get_SP() a function which returns the callers stack frame. Also replace inline assembly which grabs the stack pointer in save_stack_trace and show_stack with __get_SP(). This also fixes an issue with perf_arch_fetch_caller_regs(). It currently unwinds the stack once, which will skip a valid stack frame on a leaf function. With the __get_SP() fixes in this patch, we never need to unwind the stack frame to get to the first interesting frame. We have to export __get_SP() because perf_arch_fetch_caller_regs() (which is used in modules) calls it from a header file. Reported-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
64 lines
1.4 KiB
C
64 lines
1.4 KiB
C
/*
|
|
* Stack trace utility
|
|
*
|
|
* Copyright 2008 Christoph Hellwig, IBM Corp.
|
|
*
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/processor.h>
|
|
|
|
/*
|
|
* Save stack-backtrace addresses into a stack_trace buffer.
|
|
*/
|
|
static void save_context_stack(struct stack_trace *trace, unsigned long sp,
|
|
struct task_struct *tsk, int savesched)
|
|
{
|
|
for (;;) {
|
|
unsigned long *stack = (unsigned long *) sp;
|
|
unsigned long newsp, ip;
|
|
|
|
if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
|
|
return;
|
|
|
|
newsp = stack[0];
|
|
ip = stack[STACK_FRAME_LR_SAVE];
|
|
|
|
if (savesched || !in_sched_functions(ip)) {
|
|
if (!trace->skip)
|
|
trace->entries[trace->nr_entries++] = ip;
|
|
else
|
|
trace->skip--;
|
|
}
|
|
|
|
if (trace->nr_entries >= trace->max_entries)
|
|
return;
|
|
|
|
sp = newsp;
|
|
}
|
|
}
|
|
|
|
void save_stack_trace(struct stack_trace *trace)
|
|
{
|
|
unsigned long sp;
|
|
|
|
sp = __get_SP();
|
|
|
|
save_context_stack(trace, sp, current, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(save_stack_trace);
|
|
|
|
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
|
|
{
|
|
save_context_stack(trace, tsk->thread.ksp, tsk, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
|