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 07/10] ARM: clang: Do not rely on lr register for stacktrace
Date: Fri, 15 Oct 2021 21:51:46 +0900 [thread overview]
Message-ID: <163430230603.459050.13271391202951929788.stgit@devnote2> (raw)
In-Reply-To: <163430224341.459050.2369208860773018092.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)
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 07/10] ARM: clang: Do not rely on lr register for stacktrace
Date: Fri, 15 Oct 2021 21:51:46 +0900 [thread overview]
Message-ID: <163430230603.459050.13271391202951929788.stgit@devnote2> (raw)
In-Reply-To: <163430224341.459050.2369208860773018092.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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next prev parent reply other threads:[~2021-10-15 12:52 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-15 12:50 [PATCH 00/10] kprobes: Make KUnit and add stacktrace on kretprobe tests Masami Hiramatsu
2021-10-15 12:50 ` Masami Hiramatsu
2021-10-15 12:50 ` [PATCH 01/10] kprobes: convert tests to kunit Masami Hiramatsu
2021-10-15 12:50 ` Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 02/10] kprobes: Add a test case for stacktrace from kretprobe handler Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 03/10] x86/unwind: Compile kretprobe fixup code only if CONFIG_KRETPROBES=y Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-15 13:10 ` Masami Hiramatsu
2021-10-15 13:10 ` Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 04/10] arm64: kprobes: Record frame pointer with kretprobe instance Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 05/10] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 06/10] arm64: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu [this message]
2021-10-15 12:51 ` [PATCH 07/10] ARM: clang: Do not rely on lr register for stacktrace Masami Hiramatsu
2021-10-15 12:51 ` [PATCH 08/10] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-15 12:51 ` Masami Hiramatsu
2021-10-16 10:37 ` kernel test robot
2021-10-16 10:37 ` kernel test robot
2021-10-16 21:15 ` Russell King (Oracle)
2021-10-16 21:15 ` Russell King (Oracle)
2021-10-18 5:55 ` Masami Hiramatsu
2021-10-18 5:55 ` Masami Hiramatsu
2021-10-15 12:52 ` [PATCH 09/10] ARM: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-15 12:52 ` Masami Hiramatsu
2021-10-15 12:52 ` [PATCH 10/10] [RFC] arm64: kprobes: Detect error of kretprobe return address fixup Masami Hiramatsu
2021-10-15 12:52 ` Masami Hiramatsu
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