On 10/24/21 9:18 PM, nobuta.keiya@fujitsu.com wrote:

Hi,

quoted

-----Original Message-----
From: madvenka@linux.microsoft.com <redacted>
Sent: Friday, October 15, 2021 11:59 AM
To: mark.rutland@arm.com; broonie@kernel.org; jpoimboe@redhat.com; ardb@kernel.org; Nobuta, Keiya/信田 圭哉
[off-list ref]; sjitindarsingh@gmail.com; catalin.marinas@arm.com; will@kernel.org; jmorris@namei.org;
linux-arm-kernel@lists.infradead.org; live-patching@vger.kernel.org; linux-kernel@vger.kernel.org;
madvenka@linux.microsoft.com
Subject: [PATCH v10 06/11] arm64: Make profile_pc() use arch_stack_walk()

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;

-	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

I've got build error with CONFIG_ACPI=n:
====
arch/arm64/kernel/time.c: In function 'profile_pc':
arch/arm64/kernel/time.c:52:2: error: implicit declaration of function 'arch_stack_walk' [-Werror=implicit-function-declaration]
   52 |  arch_stack_walk(profile_pc_cb, &prof_pc, current, regs);
      |  ^~~~~~~~~~~~~~~
====

I think it should include <linux/stacktrace.h> instead of <asm/stacktrace.h>.

OK. I will fix this.
Thanks for catching this.

Madhavan