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>

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 947cb63..2f110a0 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -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

diff --git a/arch/loongarch/include/asm/stacktrace.h b/arch/loongarch/include/asm/stacktrace.h
index 5820a0c..f23adb1 100644 (file)
--- a/arch/loongarch/include/asm/stacktrace.h
+++ b/arch/loongarch/include/asm/stacktrace.h
@@ -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);

diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index e690c1c..3a690f9 100644 (file)
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -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;
+       }
+}