[PATCH v3] arm64: Add USER_STACKTRACE support
qiwuchen55 at gmail.com
qiwuchen55 at gmail.com
Wed Nov 29 08:01:19 PST 2023
From: chenqiwu <qiwu.chen at transsion.com>
1. Use the perf_callchain_user() code as blueprint to implement
arch_stack_walk_user() which add userstacktrace support on arm64.
2. Use arch_stack_walk_user() to simplify the implementation of
perf_callchain_user().
3. With this patch, tracer can get userstacktrace by below callchain:
ftrace_trace_userstack ->
stack_trace_save_user ->
arch_stack_walk_user
An example ftrace test case is as shown below:
# cd /sys/kernel/debug/tracing
# echo 1 > options/userstacktrace
# echo 1 > options/sym-userobj
# echo 1 > events/sched/sched_process_fork/enable
# cat trace
......
bash-418 [000] ..... 121.820661: sched_process_fork: comm=bash pid=418 child_comm=bash child_pid=441
bash-418 [000] ..... 121.821340: <user stack trace>
=> /lib/aarch64-linux-gnu/libc-2.32.so[+0xa76d8]
=> /bin/bash[+0x5f354]
=> /bin/bash[+0x47fe8]
=> /bin/bash[+0x493f8]
=> /bin/bash[+0x4aec4]
=> /bin/bash[+0x4c31c]
=> /bin/bash[+0x339b0]
=> /bin/bash[+0x322f8]
changes in v3:
- update perf_callchain_user() to use arch_stack_walk_user()
and delete the redundant code as Mark's suggestion.
- update the commit message.
Tested-by: chenqiwu <qiwu.chen at transsion.com>
Signed-off-by: chenqiwu <qiwu.chen at transsion.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/perf_callchain.c | 118 +---------------------------
arch/arm64/kernel/stacktrace.c | 120 +++++++++++++++++++++++++++++
3 files changed, 125 insertions(+), 114 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b071a00425d..4c5066f88dd2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -255,6 +255,7 @@ config ARM64
select TRACE_IRQFLAGS_SUPPORT
select TRACE_IRQFLAGS_NMI_SUPPORT
select HAVE_SOFTIRQ_ON_OWN_STACK
+ select USER_STACKTRACE_SUPPORT
help
ARM 64-bit (AArch64) Linux support.
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 6d157f32187b..e8ed5673f481 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -10,94 +10,12 @@
#include <asm/pointer_auth.h>
-struct frame_tail {
- struct frame_tail __user *fp;
- unsigned long lr;
-} __attribute__((packed));
-
-/*
- * Get the return address for a single stackframe and return a pointer to the
- * next frame tail.
- */
-static struct frame_tail __user *
-user_backtrace(struct frame_tail __user *tail,
- struct perf_callchain_entry_ctx *entry)
-{
- struct frame_tail buftail;
- unsigned long err;
- unsigned long lr;
-
- /* Also check accessibility of one struct frame_tail beyond */
- if (!access_ok(tail, sizeof(buftail)))
- return NULL;
-
- pagefault_disable();
- err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
- pagefault_enable();
-
- if (err)
- return NULL;
-
- lr = ptrauth_strip_user_insn_pac(buftail.lr);
-
- perf_callchain_store(entry, lr);
-
- /*
- * Frame pointers should strictly progress back up the stack
- * (towards higher addresses).
- */
- if (tail >= buftail.fp)
- return NULL;
-
- return buftail.fp;
-}
-
-#ifdef CONFIG_COMPAT
-/*
- * The registers we're interested in are at the end of the variable
- * length saved register structure. The fp points at the end of this
- * structure so the address of this struct is:
- * (struct compat_frame_tail *)(xxx->fp)-1
- *
- * This code has been adapted from the ARM OProfile support.
- */
-struct compat_frame_tail {
- compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */
- u32 sp;
- u32 lr;
-} __attribute__((packed));
-
-static struct compat_frame_tail __user *
-compat_user_backtrace(struct compat_frame_tail __user *tail,
- struct perf_callchain_entry_ctx *entry)
+static bool callchain_trace(void *data, unsigned long pc)
{
- struct compat_frame_tail buftail;
- unsigned long err;
-
- /* Also check accessibility of one struct frame_tail beyond */
- if (!access_ok(tail, sizeof(buftail)))
- return NULL;
-
- pagefault_disable();
- err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
- pagefault_enable();
-
- if (err)
- return NULL;
-
- perf_callchain_store(entry, buftail.lr);
-
- /*
- * Frame pointers should strictly progress back up the stack
- * (towards higher addresses).
- */
- if (tail + 1 >= (struct compat_frame_tail __user *)
- compat_ptr(buftail.fp))
- return NULL;
+ struct perf_callchain_entry_ctx *entry = data;
- return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
+ return perf_callchain_store(entry, pc) == 0;
}
-#endif /* CONFIG_COMPAT */
void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
@@ -107,35 +25,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
return;
}
- perf_callchain_store(entry, regs->pc);
-
- if (!compat_user_mode(regs)) {
- /* AARCH64 mode */
- struct frame_tail __user *tail;
-
- tail = (struct frame_tail __user *)regs->regs[29];
-
- while (entry->nr < entry->max_stack &&
- tail && !((unsigned long)tail & 0x7))
- tail = user_backtrace(tail, entry);
- } else {
-#ifdef CONFIG_COMPAT
- /* AARCH32 compat mode */
- struct compat_frame_tail __user *tail;
-
- tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
-
- while ((entry->nr < entry->max_stack) &&
- tail && !((unsigned long)tail & 0x3))
- tail = compat_user_backtrace(tail, entry);
-#endif
- }
-}
-
-static bool callchain_trace(void *data, unsigned long pc)
-{
- struct perf_callchain_entry_ctx *entry = data;
- return perf_callchain_store(entry, pc) == 0;
+ arch_stack_walk_user(callchain_trace, entry, regs);
}
void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 17f66a74c745..7f9ab5a37096 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -240,3 +240,123 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
dump_backtrace(NULL, tsk, loglvl);
barrier();
}
+
+/*
+ * The struct defined for userspace stack frame in AARCH64 mode.
+ */
+struct frame_tail {
+ struct frame_tail __user *fp;
+ unsigned long lr;
+} __attribute__((packed));
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static struct frame_tail __user *
+unwind_user_frame(struct frame_tail __user *tail, void *cookie,
+ stack_trace_consume_fn consume_entry)
+{
+ struct frame_tail buftail;
+ unsigned long err;
+ unsigned long lr;
+
+ /* Also check accessibility of one struct frame_tail beyond */
+ if (!access_ok(tail, sizeof(buftail)))
+ return NULL;
+
+ pagefault_disable();
+ err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
+ pagefault_enable();
+
+ if (err)
+ return NULL;
+
+ lr = ptrauth_strip_user_insn_pac(buftail.lr);
+
+ if (!consume_entry(cookie, lr))
+ return NULL;
+
+ /*
+ * Frame pointers should strictly progress back up the stack
+ * (towards higher addresses).
+ */
+ if (tail >= buftail.fp)
+ return NULL;
+
+ return buftail.fp;
+}
+
+#ifdef CONFIG_COMPAT
+/*
+ * The registers we're interested in are at the end of the variable
+ * length saved register structure. The fp points at the end of this
+ * structure so the address of this struct is:
+ * (struct compat_frame_tail *)(xxx->fp)-1
+ *
+ * This code has been adapted from the ARM OProfile support.
+ */
+struct compat_frame_tail {
+ compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */
+ u32 sp;
+ u32 lr;
+} __attribute__((packed));
+
+static struct compat_frame_tail __user *
+unwind_compat_user_frame(struct compat_frame_tail __user *tail, void *cookie,
+ stack_trace_consume_fn consume_entry)
+{
+ struct compat_frame_tail buftail;
+ unsigned long err;
+
+ /* Also check accessibility of one struct frame_tail beyond */
+ if (!access_ok(tail, sizeof(buftail)))
+ return NULL;
+
+ pagefault_disable();
+ err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
+ pagefault_enable();
+
+ if (err)
+ return NULL;
+
+ if (!consume_entry(cookie, buftail.lr))
+ return NULL;
+
+ /*
+ * Frame pointers should strictly progress back up the stack
+ * (towards higher addresses).
+ */
+ if (tail + 1 >= (struct compat_frame_tail __user *)
+ compat_ptr(buftail.fp))
+ return NULL;
+
+ return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
+}
+#endif /* CONFIG_COMPAT */
+
+
+void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
+ const struct pt_regs *regs)
+{
+ if (!consume_entry(cookie, regs->pc))
+ return;
+
+ if (!compat_user_mode(regs)) {
+ /* AARCH64 mode */
+ struct frame_tail __user *tail;
+
+ tail = (struct frame_tail __user *)regs->regs[29];
+ while (tail && !((unsigned long)tail & 0x7))
+ tail = unwind_user_frame(tail, cookie, consume_entry);
+ } else {
+#ifdef CONFIG_COMPAT
+ /* AARCH32 compat mode */
+ struct compat_frame_tail __user *tail;
+
+ tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
+ while (tail && !((unsigned long)tail & 0x3))
+ tail = unwind_compat_user_frame(tail, cookie, consume_entry);
+#endif
+ }
+}
--
2.25.1
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