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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org, mhiramat@kernel.org,
	Sven Schnelle <svens@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace
Date: Fri,  8 Oct 2021 21:29:08 +0900	[thread overview]
Message-ID: <163369614818.636038.5019945597127474028.stgit@devnote2> (raw)
In-Reply-To: <163369609308.636038.15295764725220907794.stgit@devnote2>

Currently the stacktrace on clang compiled arm kernel uses the 'lr'
register to find the first frame address from pt_regs. However, that
is wrong after calling another function, because the 'lr' register
is used by 'bl' instruction and never be recovered.

As same as gcc arm kernel, directly use the frame pointer (x11) of
the pt_regs to find the first frame address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/arm/kernel/stacktrace.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 76ea4178a55c..db798eac7431 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -54,8 +54,7 @@ int notrace unwind_frame(struct stackframe *frame)
 
 	frame->sp = frame->fp;
 	frame->fp = *(unsigned long *)(fp);
-	frame->pc = frame->lr;
-	frame->lr = *(unsigned long *)(fp + 4);
+	frame->pc = *(unsigned long *)(fp + 4);
 #else
 	/* check current frame pointer is within bounds */
 	if (fp < low + 12 || fp > high - 4)


WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org, mhiramat@kernel.org,
	Sven Schnelle <svens@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace
Date: Fri,  8 Oct 2021 21:29:08 +0900	[thread overview]
Message-ID: <163369614818.636038.5019945597127474028.stgit@devnote2> (raw)
In-Reply-To: <163369609308.636038.15295764725220907794.stgit@devnote2>

Currently the stacktrace on clang compiled arm kernel uses the 'lr'
register to find the first frame address from pt_regs. However, that
is wrong after calling another function, because the 'lr' register
is used by 'bl' instruction and never be recovered.

As same as gcc arm kernel, directly use the frame pointer (x11) of
the pt_regs to find the first frame address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/arm/kernel/stacktrace.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 76ea4178a55c..db798eac7431 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -54,8 +54,7 @@ int notrace unwind_frame(struct stackframe *frame)
 
 	frame->sp = frame->fp;
 	frame->fp = *(unsigned long *)(fp);
-	frame->pc = frame->lr;
-	frame->lr = *(unsigned long *)(fp + 4);
+	frame->pc = *(unsigned long *)(fp + 4);
 #else
 	/* check current frame pointer is within bounds */
 	if (fp < low + 12 || fp > high - 4)


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  parent reply	other threads:[~2021-10-08 12:29 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08 12:28 [PATCH 0/8] kprobes: Make KUnit and add stacktrace on kretprobe tests Masami Hiramatsu
2021-10-08 12:28 ` Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 1/8] kprobes: convert tests to kunit Masami Hiramatsu
2021-10-08 12:28   ` Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 2/8] kprobes: Add a test case for stacktrace from kretprobe handler Masami Hiramatsu
2021-10-08 12:28   ` Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 3/8] arm64: kprobes: Record frame pointer with kretprobe instance Masami Hiramatsu
2021-10-08 12:28   ` Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon
2021-10-13  8:14     ` Will Deacon
2021-10-13 10:01   ` Mark Rutland
2021-10-13 10:01     ` Mark Rutland
2021-10-14  8:04     ` Masami Hiramatsu
2021-10-14  8:04       ` Masami Hiramatsu
2021-10-14  9:13       ` Mark Rutland
2021-10-14  9:13         ` Mark Rutland
2021-10-14 10:01         ` Masami Hiramatsu
2021-10-14 10:01           ` Masami Hiramatsu
2021-10-14 10:27           ` Mark Rutland
2021-10-14 10:27             ` Mark Rutland
2021-10-14 13:50             ` Masami Hiramatsu
2021-10-14 13:50               ` Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 4/8] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-08 12:28   ` Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon
2021-10-13  8:14     ` Will Deacon
2021-10-08 12:28 ` [PATCH 5/8] arm64: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-08 12:28   ` Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon
2021-10-13  8:14     ` Will Deacon
2021-10-14  8:05     ` Masami Hiramatsu
2021-10-14  8:05       ` Masami Hiramatsu
2021-10-13 10:13   ` Mark Rutland
2021-10-13 10:13     ` Mark Rutland
2021-10-14  9:57     ` Masami Hiramatsu
2021-10-14  9:57       ` Masami Hiramatsu
2021-10-08 12:29 ` Masami Hiramatsu [this message]
2021-10-08 12:29   ` [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace Masami Hiramatsu
2021-10-11 18:45   ` Nick Desaulniers
2021-10-11 18:45     ` Nick Desaulniers
2021-10-12 14:18     ` Masami Hiramatsu
2021-10-12 14:18       ` Masami Hiramatsu
2021-10-13 19:54       ` Nick Desaulniers
2021-10-13 19:54         ` Nick Desaulniers
2021-10-14 16:53   ` Russell King (Oracle)
2021-10-14 16:53     ` Russell King (Oracle)
2021-10-15  0:18     ` Masami Hiramatsu
2021-10-15  0:18       ` Masami Hiramatsu
2021-10-08 12:29 ` [PATCH 7/8] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-08 12:29   ` Masami Hiramatsu
2021-10-11 19:06   ` Nick Desaulniers
2021-10-11 19:06     ` Nick Desaulniers
2021-10-08 12:29 ` [PATCH 8/8] ARM: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-08 12:29   ` Masami Hiramatsu

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