linux-kernel - [PATCH 1/2] riscv: stacktrace: use arch_stack_walk() in place of walk

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Message-Id: <20240328184020.34278-2-puranjay12@gmail.com>
Date: Thu, 28 Mar 2024 18:40:19 +0000
From: Puranjay Mohan <puranjay12@...il.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Björn Töpel <bjorn@...osinc.com>
Cc: puranjay12@...il.com
Subject: [PATCH 1/2] riscv: stacktrace: use arch_stack_walk() in place of walk_stackframe

Currently, dump_backtrace(), __get_wchan(), and perf_callchain_kernel()
directly call walk_stackframe(). Make then call arch_stack_walk() which
is a wrapper around walk_stackframe() and make walk_stackframe() static.

This allows making changes to walk_stackframe() without disturbing the
users of arch_stack_walk() which is the exposed function.

Signed-off-by: Puranjay Mohan <puranjay12@...il.com>
---
 arch/riscv/include/asm/stacktrace.h |  2 --
 arch/riscv/kernel/perf_callchain.c  |  2 +-
 arch/riscv/kernel/stacktrace.c      | 26 ++++++++++++++------------
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/arch/riscv/include/asm/stacktrace.h b/arch/riscv/include/asm/stacktrace.h
index b1495a7e06ce6..32213e37c379f 100644
--- a/arch/riscv/include/asm/stacktrace.h
+++ b/arch/riscv/include/asm/stacktrace.h
@@ -11,8 +11,6 @@ struct stackframe {
 	unsigned long ra;
 };
 
-extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
-				    bool (*fn)(void *, unsigned long), void *arg);
 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 			   const char *loglvl);
 
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 3348a61de7d99..c023e0b1eb814 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -74,5 +74,5 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	walk_stackframe(NULL, regs, fill_callchain, entry);
+	arch_stack_walk(fill_callchain, entry, NULL, regs);
 }
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 64a9c093aef93..e28f7b2e4b6a6 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -18,8 +18,9 @@
 
 extern asmlinkage void ret_from_exception(void);
 
-void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
-			     bool (*fn)(void *, unsigned long), void *arg)
+static __always_inline void
+walk_stackframe(struct task_struct *task, struct pt_regs *regs,
+		bool (*fn)(void *, unsigned long), void *arg)
 {
 	unsigned long fp, sp, pc;
 	int level = 0;
@@ -76,8 +77,9 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 
 #else /* !CONFIG_FRAME_POINTER */
 
-void notrace walk_stackframe(struct task_struct *task,
-	struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
+static __always_inline void
+walk_stackframe(struct task_struct *task, struct pt_regs *regs,
+		bool (*fn)(void *, unsigned long), void *arg)
 {
 	unsigned long sp, pc;
 	unsigned long *ksp;
@@ -107,6 +109,12 @@ void notrace walk_stackframe(struct task_struct *task,
 
 #endif /* CONFIG_FRAME_POINTER */
 
+noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+				      struct task_struct *task, struct pt_regs *regs)
+{
+	walk_stackframe(task, regs, consume_entry, cookie);
+}
+
 static bool print_trace_address(void *arg, unsigned long pc)
 {
 	const char *loglvl = arg;
@@ -118,7 +126,7 @@ static bool print_trace_address(void *arg, unsigned long pc)
 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 		    const char *loglvl)
 {
-	walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
+	arch_stack_walk(print_trace_address, (void *)loglvl, task, regs);
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
@@ -143,13 +151,7 @@ unsigned long __get_wchan(struct task_struct *task)
 
 	if (!try_get_task_stack(task))
 		return 0;
-	walk_stackframe(task, NULL, save_wchan, &pc);
+	arch_stack_walk(save_wchan, &pc, task, NULL);
 	put_task_stack(task);
 	return pc;
 }
-
-noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
-		     struct task_struct *task, struct pt_regs *regs)
-{
-	walk_stackframe(task, regs, consume_entry, cookie);
-}
-- 
2.40.1