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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 5/9] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline
Date: Thu, 21 Oct 2021 09:55:00 +0900	[thread overview]
Message-ID: <163477770064.264901.14799557129514500033.stgit@devnote2> (raw)
In-Reply-To: <163477765570.264901.3851692300287671122.stgit@devnote2>

Make a frame pointer (make the x29 register points the
address of pt_regs->regs[29]) on __kretprobe_trampoline.

This frame pointer will be used by the stacktracer when it is
called from the kretprobe handlers. In this case, the stack
tracer will unwind stack to trampoline_probe_handler() and
find the next frame pointer in the stack frame of the
__kretprobe_trampoline().

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/probes/kprobes_trampoline.S |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kernel/probes/kprobes_trampoline.S b/arch/arm64/kernel/probes/kprobes_trampoline.S
index 520ee8711db1..9a6499bed58b 100644
--- a/arch/arm64/kernel/probes/kprobes_trampoline.S
+++ b/arch/arm64/kernel/probes/kprobes_trampoline.S
@@ -66,6 +66,9 @@ SYM_CODE_START(__kretprobe_trampoline)
 
 	save_all_base_regs
 
+	/* Setup a frame pointer. */
+	add x29, sp, #S_FP
+
 	mov x0, sp
 	bl trampoline_probe_handler
 	/*
@@ -74,6 +77,7 @@ SYM_CODE_START(__kretprobe_trampoline)
 	 */
 	mov lr, x0
 
+	/* The frame pointer (x29) is restored with other registers. */
 	restore_all_base_regs
 
 	add sp, sp, #PT_REGS_SIZE


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  parent reply	other threads:[~2021-10-21  0:57 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 ` Masami Hiramatsu [this message]
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 ` [PATCH v3 7/9] ARM: clang: Do not rely on lr register for stacktrace Masami Hiramatsu
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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