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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 v3 7/9] ARM: clang: Do not rely on lr register for stacktrace
Date: Thu, 21 Oct 2021 09:55:17 +0900	[thread overview]
Message-ID: <163477771763.264901.13199943018441108332.stgit@devnote2> (raw)
In-Reply-To: <163477765570.264901.3851692300287671122.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 (r11) of
the pt_regs to find the first frame address.

Note that this fixes kretprobe stacktrace issue only with
CONFIG_UNWINDER_FRAME_POINTER=y. For the CONFIG_UNWINDER_ARM,
we need another fix.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
 Changes in v2:
  - Fix typos in changelog.
---
 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:[~2021-10-21  0:58 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21  0:54 [PATCH v3 0/9] kprobes: Make KUnit and add stacktrace on kretprobe tests Masami Hiramatsu
2021-10-21  0:54 ` [PATCH v3 1/9] kprobes: convert tests to kunit Masami Hiramatsu
2021-10-21  0:54 ` [PATCH v3 2/9] kprobes: Add a test case for stacktrace from kretprobe handler Masami Hiramatsu
2021-10-22 16:15   ` Steven Rostedt
2021-10-22 18:23     ` Steven Rostedt
2021-10-25  2:34     ` Masami Hiramatsu
2021-10-21  0:54 ` [PATCH v3 3/9] x86/unwind: Compile kretprobe fixup code only if CONFIG_KRETPROBES=y Masami Hiramatsu
2021-10-21  0:54 ` [PATCH v3 4/9] arm64: kprobes: Record frame pointer with kretprobe instance Masami Hiramatsu
2021-10-21  0:55 ` [PATCH v3 5/9] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-21  0:55 ` [PATCH v3 6/9] arm64: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-21 10:15   ` Will Deacon
2021-10-21 14:26     ` Masami Hiramatsu
2021-10-21 14:49       ` Steven Rostedt
2021-10-21 16:52         ` Will Deacon
2021-10-21 16:59           ` Steven Rostedt
2021-10-21 18:38             ` Steven Rostedt
2021-10-21  0:55 ` Masami Hiramatsu [this message]
2021-10-21  0:55 ` [PATCH v3 8/9] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-12-03 20:37   ` Arnd Bergmann
2021-12-04  8:45     ` Ard Biesheuvel
2021-12-04 12:08       ` Arnd Bergmann
2021-12-08 12:26         ` Masami Hiramatsu
2021-10-21  0:55 ` [PATCH v3 9/9] ARM: Recover kretprobe modified return address in stacktrace Masami Hiramatsu

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