Re: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()

On 10/27/21 8:32 AM, Mark Rutland wrote:

On Thu, Oct 14, 2021 at 09:58:42PM -0500, madvenka@linux.microsoft.com wrote:

quoted

From: "Madhavan T. Venkataraman" <redacted>

Currently, profile_pc() in ARM64 code walks the stack using
start_backtrace() and unwind_frame(). Make it use arch_stack_walk()
instead. This makes maintenance easier.

Signed-off-by: Madhavan T. Venkataraman <redacted>
---
 arch/arm64/kernel/time.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

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;

This can go -- the first call to profile_pc_cb() will use regs->pc.

Agreed.

With that gone, and the include updates to use <linux/stacktrace.h>:

Reviewed-by: Mark Rutland <mark.rutland@arm.com>

I will make the two changes.

Madhavan