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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 05/10] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline
Date: Fri, 15 Oct 2021 21:51:29 +0900	[thread overview]
Message-ID: <163430228904.459050.16973178880543757481.stgit@devnote2> (raw)
In-Reply-To: <163430224341.459050.2369208860773018092.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


  parent reply	other threads:[~2021-10-15 12:51 UTC|newest]

Thread overview: 15+ 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 ` [PATCH 01/10] kprobes: convert tests to kunit 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 ` [PATCH 03/10] x86/unwind: Compile kretprobe fixup code only if CONFIG_KRETPROBES=y 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 [this message]
2021-10-15 12:51 ` [PATCH 06/10] arm64: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
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
2021-10-16 10:37   ` kernel test robot
2021-10-16 21:15   ` Russell King (Oracle)
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 ` [PATCH 10/10] [RFC] arm64: kprobes: Detect error of kretprobe return address fixup Masami Hiramatsu

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