From 4d7bf939df08218e682f7a42952eee3bad4dceb7 Mon Sep 17 00:00:00 2001
From: Qing Zhang <zhangqing@loongson.cn>
Date: Sat, 6 Aug 2022 16:10:05 +0800
Subject: [PATCH] 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>
---
arch/loongarch/Kconfig | 1 +
arch/loongarch/include/asm/stacktrace.h | 5 +++
arch/loongarch/kernel/stacktrace.c | 41 +++++++++++++++++++++++++
3 files changed, 47 insertions(+)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 947cb633744b8..2f110a00a9302 100644
--- 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 5820a0cabe3a9..f23adb15f418f 100644
--- 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 e690c1c769f2e..3a690f96f00c1 100644
--- 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;
+ }
+}
--
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