linux/arch/loongarch/kernel/stacktrace.c
Qing Zhang 4d7bf939df LoongArch: Add USER_STACKTRACE support
To get the best stacktrace output, you can compile your userspace
programs with frame pointers (at least glibc + the app you are tracing).

1, export "CC = gcc -fno-omit-frame-pointer";
2, compile your programs with "CC";
3, use uprobe to get stacktrace output.

...
     echo 'p:malloc /usr/lib64/libc.so.6:0x0a4704 size=%r4:u64' > uprobe_events
     echo 'p:free /usr/lib64/libc.so.6:0x0a4d50 ptr=%r4:x64' >> uprobe_events
     echo 'comm == "demo"' > ./events/uprobes/malloc/filter
     echo 'comm == "demo"' > ./events/uprobes/free/filter
     echo 1 > ./options/userstacktrace
     echo 1 > ./options/sym-userobj
...

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-08-12 13:10:11 +08:00

79 lines
1.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Stack trace management functions
*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
{
unsigned long addr;
struct pt_regs dummyregs;
struct unwind_state state;
regs = &dummyregs;
if (task == current) {
regs->regs[3] = (unsigned long)__builtin_frame_address(0);
regs->csr_era = (unsigned long)__builtin_return_address(0);
} else {
regs->regs[3] = thread_saved_fp(task);
regs->csr_era = thread_saved_ra(task);
}
regs->regs[1] = 0;
for (unwind_start(&state, task, regs);
!unwind_done(&state); unwind_next_frame(&state)) {
addr = unwind_get_return_address(&state);
if (!addr || !consume_entry(cookie, addr))
break;
}
}
static int
copy_stack_frame(unsigned long fp, struct stack_frame *frame)
{
int ret = 1;
unsigned long err;
unsigned long __user *user_frame_tail;
user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
if (!access_ok(user_frame_tail, sizeof(*frame)))
return 0;
pagefault_disable();
err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
if (err || (unsigned long)user_frame_tail >= frame->fp)
ret = 0;
pagefault_enable();
return ret;
}
void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
const struct pt_regs *regs)
{
unsigned long fp = regs->regs[22];
while (fp && !((unsigned long)fp & 0xf)) {
struct stack_frame frame;
frame.fp = 0;
frame.ra = 0;
if (!copy_stack_frame(fp, &frame))
break;
if (!frame.ra)
break;
if (!consume_entry(cookie, frame.ra))
break;
fp = frame.fp;
}
}