[RFC PATCH v7 1/4] arm64: Make all stack walking functions use arch_stack_walk()
From: madvenka
Date: Thu Aug 12 2021 - 09:25:02 EST
From: "Madhavan T. Venkataraman" <madvenka@xxxxxxxxxxxxxxxxxxx>
Currently, there are multiple functions in ARM64 code that walk the
stack using start_backtrace() and unwind_frame(). Convert all of
them to use arch_stack_walk(). This makes maintenance easier.
Here is the list of functions:
perf_callchain_kernel()
get_wchan()
return_address()
dump_backtrace()
profile_pc()
Signed-off-by: Madhavan T. Venkataraman <madvenka@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/stacktrace.h | 3 ---
arch/arm64/kernel/perf_callchain.c | 5 +---
arch/arm64/kernel/process.c | 39 ++++++++++++++++++-----------
arch/arm64/kernel/return_address.c | 6 +----
arch/arm64/kernel/stacktrace.c | 38 +++-------------------------
arch/arm64/kernel/time.c | 22 +++++++++-------
6 files changed, 43 insertions(+), 70 deletions(-)
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index 8aebc00c1718..e43dea1c6b41 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -61,9 +61,6 @@ struct stackframe {
#endif
};
-extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
-extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
- bool (*fn)(void *, unsigned long), void *data);
extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl);
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 4a72c2727309..2f289013c9c9 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -147,15 +147,12 @@ static bool callchain_trace(void *data, unsigned long pc)
void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
- struct stackframe frame;
-
if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
/* We don't support guest os callchain now */
return;
}
- start_backtrace(&frame, regs->regs[29], regs->pc);
- walk_stackframe(current, &frame, callchain_trace, entry);
+ arch_stack_walk(callchain_trace, entry, current, regs);
}
unsigned long perf_instruction_pointer(struct pt_regs *regs)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index c8989b999250..52c12fd26407 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -544,11 +544,28 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
return last;
}
+struct wchan_info {
+ unsigned long pc;
+ int count;
+};
+
+static bool get_wchan_cb(void *arg, unsigned long pc)
+{
+ struct wchan_info *wchan_info = arg;
+
+ if (!in_sched_functions(pc)) {
+ wchan_info->pc = pc;
+ return false;
+ }
+ wchan_info->count--;
+ return !!wchan_info->count;
+}
+
unsigned long get_wchan(struct task_struct *p)
{
- struct stackframe frame;
- unsigned long stack_page, ret = 0;
- int count = 0;
+ unsigned long stack_page;
+ struct wchan_info wchan_info;
+
if (!p || p == current || task_is_running(p))
return 0;
@@ -556,20 +573,12 @@ unsigned long get_wchan(struct task_struct *p)
if (!stack_page)
return 0;
- start_backtrace(&frame, thread_saved_fp(p), thread_saved_pc(p));
+ wchan_info.pc = 0;
+ wchan_info.count = 16;
+ arch_stack_walk(get_wchan_cb, &wchan_info, p, NULL);
- do {
- if (unwind_frame(p, &frame))
- goto out;
- if (!in_sched_functions(frame.pc)) {
- ret = frame.pc;
- goto out;
- }
- } while (count++ < 16);
-
-out:
put_task_stack(p);
- return ret;
+ return wchan_info.pc;
}
unsigned long arch_align_stack(unsigned long sp)
diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c
index a6d18755652f..92a0f4d434e4 100644
--- a/arch/arm64/kernel/return_address.c
+++ b/arch/arm64/kernel/return_address.c
@@ -35,15 +35,11 @@ NOKPROBE_SYMBOL(save_return_addr);
void *return_address(unsigned int level)
{
struct return_address_data data;
- struct stackframe frame;
data.level = level + 2;
data.addr = NULL;
- start_backtrace(&frame,
- (unsigned long)__builtin_frame_address(0),
- (unsigned long)return_address);
- walk_stackframe(current, &frame, save_return_addr, &data);
+ arch_stack_walk(save_return_addr, &data, current, NULL);
if (!data.level)
return data.addr;
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 8982a2b78acf..1800310f92be 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -151,23 +151,21 @@ void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
}
NOKPROBE_SYMBOL(walk_stackframe);
-static void dump_backtrace_entry(unsigned long where, const char *loglvl)
+static bool dump_backtrace_entry(void *arg, unsigned long where)
{
+ char *loglvl = arg;
printk("%s %pSb\n", loglvl, (void *)where);
+ return true;
}
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl)
{
- struct stackframe frame;
- int skip = 0;
-
pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
if (regs) {
if (user_mode(regs))
return;
- skip = 1;
}
if (!tsk)
@@ -176,36 +174,8 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
if (!try_get_task_stack(tsk))
return;
- if (tsk == current) {
- start_backtrace(&frame,
- (unsigned long)__builtin_frame_address(0),
- (unsigned long)dump_backtrace);
- } else {
- /*
- * task blocked in __switch_to
- */
- start_backtrace(&frame,
- thread_saved_fp(tsk),
- thread_saved_pc(tsk));
- }
-
printk("%sCall trace:\n", loglvl);
- do {
- /* skip until specified stack frame */
- if (!skip) {
- dump_backtrace_entry(frame.pc, loglvl);
- } else if (frame.fp == regs->regs[29]) {
- skip = 0;
- /*
- * Mostly, this is the case where this function is
- * called in panic/abort. As exception handler's
- * stack frame does not contain the corresponding pc
- * at which an exception has taken place, use regs->pc
- * instead.
- */
- dump_backtrace_entry(regs->pc, loglvl);
- }
- } while (!unwind_frame(tsk, &frame));
+ arch_stack_walk(dump_backtrace_entry, (void *)loglvl, tsk, regs);
put_task_stack(tsk);
}
diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index eebbc8d7123e..671b3038a772 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -32,22 +32,26 @@
#include <asm/stacktrace.h>
#include <asm/paravirt.h>
+static bool profile_pc_cb(void *arg, unsigned long pc)
+{
+ unsigned long *prof_pc = arg;
+
+ if (in_lock_functions(pc))
+ return true;
+ *prof_pc = pc;
+ return false;
+}
+
unsigned long profile_pc(struct pt_regs *regs)
{
- struct stackframe frame;
+ unsigned long prof_pc = 0;
if (!in_lock_functions(regs->pc))
return regs->pc;
- start_backtrace(&frame, regs->regs[29], regs->pc);
-
- do {
- int ret = unwind_frame(NULL, &frame);
- if (ret < 0)
- return 0;
- } while (in_lock_functions(frame.pc));
+ arch_stack_walk(profile_pc_cb, &prof_pc, current, regs);
- return frame.pc;
+ return prof_pc;
}
EXPORT_SYMBOL(profile_pc);
--
2.25.1