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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>, X86 ML <x86@kernel.org>,
	Daniel Xu <dxu@dxuuu.xyz>,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	kuba@kernel.org, mingo@redhat.com, ast@kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	kernel-team@fb.com, yhs@fb.com, linux-ia64@vger.kernel.org,
	Abhishek Sagar <sagar.abhishek@gmail.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: Re: [PATCH -tip v8 09/13] kprobes: Enable stacktrace from pt_regs in kretprobe handler
Date: Fri, 18 Jun 2021 09:04:32 -0500	[thread overview]
Message-ID: <20210618140432.icuopdgxt2urngmy@treble> (raw)
In-Reply-To: <162400000592.506599.4695807810528866713.stgit@devnote2>

On Fri, Jun 18, 2021 at 04:06:46PM +0900, Masami Hiramatsu wrote:
> Since the ORC unwinder from pt_regs requires setting up regs->ip
> correctly, set the correct return address to the regs->ip before
> calling user kretprobe handler.
> 
> This allows the kretrprobe handler to trace stack from the
> kretprobe's pt_regs by stack_trace_save_regs() (eBPF will do
> this), instead of stack tracing from the handler context by
> stack_trace_save() (ftrace will do this).
> 
> Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Tested-by: Andrii Nakryik <andrii@kernel.org>

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>

> ---
>  Changes in v8:
>   - Update comment to clarify why this is needed.
>  Changes in v3:
>   - Cast the correct_ret_addr to unsigned long.
> ---
>  kernel/kprobes.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 650cbe738666..ba729ed05cb3 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1896,6 +1896,9 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
>  		BUG_ON(1);
>  	}
>  
> +	/* Set the instruction pointer to the correct address */
> +	instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
> +
>  	/* Run them. */
>  	first = current->kretprobe_instances.first;
>  	while (first) {
> 

-- 
Josh


  reply	other threads:[~2021-06-18 14:04 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18  7:05 [PATCH -tip v8 00/13] kprobes: Fix stacktrace with kretprobes on x86 Masami Hiramatsu
2021-06-18  7:05 ` [PATCH -tip v8 01/13] ia64: kprobes: Fix to pass correct trampoline address to the handler Masami Hiramatsu
2021-07-05  7:46   ` Ingo Molnar
2021-07-05 10:05     ` Masami Hiramatsu
2021-06-18  7:05 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Masami Hiramatsu
2021-07-05  7:48   ` Ingo Molnar
2021-07-05 12:03     ` Masami Hiramatsu
2021-07-07 18:28   ` Andrii Nakryiko
2021-07-08  4:08     ` Masami Hiramatsu
2021-06-18  7:05 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Masami Hiramatsu
2021-07-05  7:03   ` Ingo Molnar
2021-07-05 10:03     ` Masami Hiramatsu
2021-07-05  7:49   ` Ingo Molnar
2021-06-18  7:05 ` [PATCH -tip v8 04/13] kprobes: Add kretprobe_find_ret_addr() for searching return address Masami Hiramatsu
2021-07-05  7:42   ` Ingo Molnar
2021-07-05 14:11     ` Masami Hiramatsu
2021-06-18  7:06 ` [PATCH -tip v8 05/13] x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline code Masami Hiramatsu
2021-07-05  8:02   ` Ingo Molnar
2021-07-09 15:31     ` Masami Hiramatsu
2021-07-10  1:41       ` Masami Hiramatsu
2021-07-10 19:01         ` Josh Poimboeuf
2021-07-10 19:24           ` [PATCH 1/2] objtool: Add frame-pointer-specific function ignore Josh Poimboeuf
2021-07-11  1:16             ` Masami Hiramatsu
2021-07-29  2:31             ` Masami Hiramatsu
2021-07-10 19:25           ` [PATCH 2/2] objtool: Ignore unwind hints for ignored functions Josh Poimboeuf
2021-07-11  2:07             ` Masami Hiramatsu
2021-06-18  7:06 ` [PATCH -tip v8 06/13] ARC: Add instruction_pointer_set() API Masami Hiramatsu
2021-06-18  7:06 ` [PATCH -tip v8 07/13] ia64: " Masami Hiramatsu
2021-06-18  7:06 ` [PATCH -tip v8 08/13] arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline Masami Hiramatsu
2021-07-05  8:04   ` Ingo Molnar
2021-07-05 14:40     ` Masami Hiramatsu
2021-06-18  7:06 ` [PATCH -tip v8 09/13] kprobes: Enable stacktrace from pt_regs in kretprobe handler Masami Hiramatsu
2021-06-18 14:04   ` Josh Poimboeuf [this message]
2021-06-18  7:06 ` [PATCH -tip v8 10/13] x86/kprobes: Push a fake return address at kretprobe_trampoline Masami Hiramatsu
2021-07-05  8:17   ` Ingo Molnar
2021-07-09 14:55     ` Masami Hiramatsu
2021-06-18  7:07 ` [PATCH -tip v8 11/13] x86/unwind: Recover kretprobe trampoline entry Masami Hiramatsu
2021-07-05 11:36   ` Peter Zijlstra
2021-07-05 15:42     ` Masami Hiramatsu
2021-07-06  7:55       ` Peter Zijlstra
2021-07-06 15:11         ` Steven Rostedt
2021-07-07  8:20           ` Peter Zijlstra
2021-07-07  8:36             ` Peter Zijlstra
2021-07-07 10:15             ` Masami Hiramatsu
2021-07-07 10:20               ` Peter Zijlstra
2021-07-07 10:45                 ` Masami Hiramatsu
2021-07-07 13:29                   ` Masami Hiramatsu
2021-07-07 14:42                     ` Matt Wu
2021-07-11 14:09                       ` Masami Hiramatsu
2021-07-11 15:28                         ` Matt Wu
2021-07-12  4:57                           ` Masami Hiramatsu
2021-06-18  7:07 ` [PATCH -tip v8 12/13] tracing: Show kretprobe unknown indicator only for kretprobe_trampoline Masami Hiramatsu
2021-06-18  7:07 ` [PATCH -tip v8 13/13] x86/kprobes: Fixup return address in generic trampoline handler Masami Hiramatsu
2021-07-05  8:34   ` Ingo Molnar
2021-07-06 12:57     ` Masami Hiramatsu
2021-06-18 17:44 ` [PATCH -tip v8 00/13] kprobes: Fix stacktrace with kretprobes on x86 Andrii Nakryiko
2021-06-28 13:50 ` Masami Hiramatsu

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