From: Zhaoyang Huang <zhaoyang.hu...@unisoc.com>
In some cases, the instruction of "bl foo1" will be the last one of the
foo2[1], which will cause the lr be the first instruction of the adjacent
foo3[2]. Hence, the backtrace will show the weird result as bellow[3].
The patch will fix it by miner 4 of the lr when dump_backtrace
[1]
0xffffff80081e6b04 <handle_mm_fault+3996>: adrp x0, 0xffffff8008ca8000
0xffffff80081e6b08 <handle_mm_fault+4000>: add x0, x0, #0x5a8
0xffffff80081e6b0c <handle_mm_fault+4004>: bl 0xffffff80081b0ca0
<panic>
0xffffff80081e6b10 <access_remote_vm>: stp x29, x30, [sp,#-64]!
0xffffff80081e6b14 <access_remote_vm+4>: mov x29, sp
[2]
crash_arm64> rd ffffffc02eec3bd0 2
ffffffc02eec3bd0: ffffffc02eec3cb0 ffffff80081e6b10
[3]
wrong:
[<ffffff80081b0d90>] panic+0xf0/0x24c
[<ffffff80081e6b10>] access_remote_vm+0x0/0x5c
[<ffffff800809d7b0>] do_page_fault+0x290/0x3b8
[<ffffff8008081570>] do_mem_abort+0x64/0xdc
correct:
[ffffffc02eec3bd0] panic at ffffff80081b0da4
[ffffffc02eec3cb0] handle_mm_fault at ffffff80081e6b0c
[ffffffc02eec3d80] do_page_fault at ffffff800809d7ac
[ffffffc02eec3df0] do_mem_abort at ffffff800808156c
Signed-off-by: Zhaoyang Huang <zhaoyang.hu...@unisoc.com>
---
arch/arm64/kernel/traps.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index d399d45..7a097cc 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -113,7 +113,7 @@ void dump_backtrace(struct pt_regs *regs, struct
task_struct *tsk)
if (tsk == current) {
frame.fp = (unsigned long)__builtin_frame_address(0);
- frame.pc = (unsigned long)dump_backtrace;
+ frame.pc = (unsigned long)dump_backtrace + 4;
} else {
/*
* task blocked in __switch_to
@@ -130,7 +130,7 @@ void dump_backtrace(struct pt_regs *regs, struct
task_struct *tsk)
do {
/* skip until specified stack frame */
if (!skip) {
- dump_backtrace_entry(frame.pc);
+ dump_backtrace_entry(frame.pc - 4);
} else if (frame.fp == regs->regs[29]) {
skip = 0;
/*
--
1.9.1
