Commit 4d7bf939 authored by Qing Zhang's avatar Qing Zhang Committed by Huacai Chen
Browse files

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: default avatarQing Zhang <zhangqing@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 93a4fa62

arch/loongarch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/loongarch/include/asm/stacktrace.h

+5 −0
Original line number Diff line number Diff line
@@ -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);

arch/loongarch/kernel/stacktrace.c

+41 −0
Original line number Diff line number Diff line
@@ -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;

	}

}