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 7/8] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Date: Fri, 8 Oct 2021 21:29:17 +0900 [thread overview] Message-ID: <163369615714.636038.1154348556499203165.stgit@devnote2> (raw) In-Reply-To: <163369609308.636038.15295764725220907794.stgit@devnote2> Currently kretprobe on ARM just fills r0-r11 of pt_regs, but that is not enough for the stacktrace. Moreover, from the user kretprobe handler, stacktrace needs a frame pointer on the __kretprobe_trampoline. This adds a frame pointer on __kretprobe_trampoline for both gcc and clang case. Those have different frame pointer so we need different but similar stack on pt_regs. Gcc makes the frame pointer (fp) to point the 'pc' address of the {fp, ip (=sp), lr, pc}, this means {r11, r13, r14, r15}. Thus if we save the r11 (fp) on pt_regs->r12, we can make this set on the end of pt_regs. On the other hand, Clang makes the frame pointer to point the 'fp' address of {fp, lr} on stack. Since the next to the pt_regs->lr is pt_regs->sp, I reused the pair of pt_regs->fp and pt_regs->ip. So this stores the 'lr' on pt_regs->ip and make the fp to point pt_regs->fp. For both cases, saves __kretprobe_trampoline address to pt_regs->lr, so that the stack tracer can identify this frame pointer has been made by the __kretprobe_trampoline. Note that if the CONFIG_FRAME_POINTER is not set, this keeps fp as is. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- arch/arm/probes/kprobes/core.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index 95f23b47ba27..7cbd65a22769 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -368,16 +368,35 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, /* * When a retprobed function returns, trampoline_handler() is called, * calling the kretprobe's handler. We construct a struct pt_regs to - * give a view of registers r0-r11 to the user return-handler. This is - * not a complete pt_regs structure, but that should be plenty sufficient - * for kretprobe handlers which should normally be interested in r0 only - * anyway. + * give a view of registers r0-r11, sp, lr, and pc to the user + * return-handler. This is not a complete pt_regs structure, but that + * should be enough for stacktrace from the return handler with or + * without pt_regs. */ void __naked __kprobes __kretprobe_trampoline(void) { __asm__ __volatile__ ( - "sub sp, sp, #16 \n\t" + "ldr lr, =__kretprobe_trampoline \n\t" + "stmdb sp!, {sp, lr, pc} \n\t" +#ifdef CONFIG_FRAME_POINTER + /* __kretprobe_trampoline makes a framepointer on pt_regs. */ +#ifdef CONFIG_CC_IS_CLANG + /* In clang case, pt_regs->ip = lr. */ + "stmdb sp!, {lr} \n\t" "stmdb sp!, {r0 - r11} \n\t" + /* fp points regs->r11 (fp) */ + "add fp, sp, #44 \n\t" +#else /* !CONFIG_CC_IS_CLANG */ + /* In gcc case, pt_regs->ip = fp. */ + "stmdb sp!, {fp} \n\t" + "stmdb sp!, {r0 - r11} \n\t" + /* fp points regs->r15 (pc) */ + "add fp, sp, #60 \n\t" +#endif /* CONFIG_CC_IS_CLANG */ +#else /* !CONFIG_FRAME_POINTER */ + "sub sp, sp, #4 \n\t" + "stmdb sp!, {r0 - r11} \n\t" +#endif /* CONFIG_FRAME_POINTER */ "mov r0, sp \n\t" "bl trampoline_handler \n\t" "mov lr, r0 \n\t"
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 7/8] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Date: Fri, 8 Oct 2021 21:29:17 +0900 [thread overview] Message-ID: <163369615714.636038.1154348556499203165.stgit@devnote2> (raw) In-Reply-To: <163369609308.636038.15295764725220907794.stgit@devnote2> Currently kretprobe on ARM just fills r0-r11 of pt_regs, but that is not enough for the stacktrace. Moreover, from the user kretprobe handler, stacktrace needs a frame pointer on the __kretprobe_trampoline. This adds a frame pointer on __kretprobe_trampoline for both gcc and clang case. Those have different frame pointer so we need different but similar stack on pt_regs. Gcc makes the frame pointer (fp) to point the 'pc' address of the {fp, ip (=sp), lr, pc}, this means {r11, r13, r14, r15}. Thus if we save the r11 (fp) on pt_regs->r12, we can make this set on the end of pt_regs. On the other hand, Clang makes the frame pointer to point the 'fp' address of {fp, lr} on stack. Since the next to the pt_regs->lr is pt_regs->sp, I reused the pair of pt_regs->fp and pt_regs->ip. So this stores the 'lr' on pt_regs->ip and make the fp to point pt_regs->fp. For both cases, saves __kretprobe_trampoline address to pt_regs->lr, so that the stack tracer can identify this frame pointer has been made by the __kretprobe_trampoline. Note that if the CONFIG_FRAME_POINTER is not set, this keeps fp as is. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- arch/arm/probes/kprobes/core.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index 95f23b47ba27..7cbd65a22769 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -368,16 +368,35 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, /* * When a retprobed function returns, trampoline_handler() is called, * calling the kretprobe's handler. We construct a struct pt_regs to - * give a view of registers r0-r11 to the user return-handler. This is - * not a complete pt_regs structure, but that should be plenty sufficient - * for kretprobe handlers which should normally be interested in r0 only - * anyway. + * give a view of registers r0-r11, sp, lr, and pc to the user + * return-handler. This is not a complete pt_regs structure, but that + * should be enough for stacktrace from the return handler with or + * without pt_regs. */ void __naked __kprobes __kretprobe_trampoline(void) { __asm__ __volatile__ ( - "sub sp, sp, #16 \n\t" + "ldr lr, =__kretprobe_trampoline \n\t" + "stmdb sp!, {sp, lr, pc} \n\t" +#ifdef CONFIG_FRAME_POINTER + /* __kretprobe_trampoline makes a framepointer on pt_regs. */ +#ifdef CONFIG_CC_IS_CLANG + /* In clang case, pt_regs->ip = lr. */ + "stmdb sp!, {lr} \n\t" "stmdb sp!, {r0 - r11} \n\t" + /* fp points regs->r11 (fp) */ + "add fp, sp, #44 \n\t" +#else /* !CONFIG_CC_IS_CLANG */ + /* In gcc case, pt_regs->ip = fp. */ + "stmdb sp!, {fp} \n\t" + "stmdb sp!, {r0 - r11} \n\t" + /* fp points regs->r15 (pc) */ + "add fp, sp, #60 \n\t" +#endif /* CONFIG_CC_IS_CLANG */ +#else /* !CONFIG_FRAME_POINTER */ + "sub sp, sp, #4 \n\t" + "stmdb sp!, {r0 - r11} \n\t" +#endif /* CONFIG_FRAME_POINTER */ "mov r0, sp \n\t" "bl trampoline_handler \n\t" "mov lr, r0 \n\t" _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev 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 ` [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace Masami Hiramatsu 2021-10-08 12:29 ` 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 ` Masami Hiramatsu [this message] 2021-10-08 12:29 ` [PATCH 7/8] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline 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
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=163369615714.636038.1154348556499203165.stgit@devnote2 \ --to=mhiramat@kernel.org \ --cc=ananth@linux.ibm.com \ --cc=catalin.marinas@arm.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux@armlinux.org.uk \ --cc=mingo@kernel.org \ --cc=nathan@kernel.org \ --cc=naveen.n.rao@linux.vnet.ibm.com \ --cc=ndesaulniers@google.com \ --cc=rostedt@goodmis.org \ --cc=svens@linux.ibm.com \ --cc=will@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.