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LoongArch: Add USER_STACKTRACE support

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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>
This commit is contained in:
Qing Zhang 2022-08-06 16:10:05 +08:00 committed by Huacai Chen
parent 93a4fa622e
commit 4d7bf939df
3 changed files with 47 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
arch/loongarch/Kconfig
View file

@ -119,6 +119,7 @@ config LOONGARCH
select SWIOTLB
select TRACE_IRQFLAGS_SUPPORT
select USE_PERCPU_NUMA_NODE_ID
select USER_STACKTRACE_SUPPORT
select ZONE_DMA32
config 32BIT

5
arch/loongarch/include/asm/stacktrace.h
View file

@ -21,6 +21,11 @@ struct stack_info {
unsigned long begin, end, next_sp;
};
struct stack_frame {
unsigned long fp;
unsigned long ra;
};
bool in_irq_stack(unsigned long stack, struct stack_info *info);
bool in_task_stack(unsigned long stack, struct task_struct *task, struct stack_info *info);
int get_stack_info(unsigned long stack, struct task_struct *task, struct stack_info *info);

41
arch/loongarch/kernel/stacktrace.c
View file

@ -6,6 +6,7 @@
*/
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
@ -35,3 +36,43 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
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;
}
}