From: Jiri Slaby <jslaby@suse.cz>
To: Josh Poimboeuf <jpoimboe@redhat.com>, x86@kernel.org
Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 10/10] x86/unwind: add undwarf unwinder
Date: Wed, 14 Jun 2017 13:45:41 +0200 [thread overview]
Message-ID: <8854f3ea-51a0-e5c5-ef54-5515eb2c2f37@suse.cz> (raw)
In-Reply-To: <89552d4047e5aed843f7b6a54277f9af62da6a82.1496293620.git.jpoimboe@redhat.com>
On 06/01/2017, 07:44 AM, Josh Poimboeuf wrote:
> --- /dev/null
> +++ b/arch/x86/kernel/unwind_undwarf.c
> @@ -0,0 +1,402 @@
...
> +void __unwind_start(struct unwind_state *state, struct task_struct *task,
> + struct pt_regs *regs, unsigned long *first_frame)
> +{
> + memset(state, 0, sizeof(*state));
> + state->task = task;
> +
> + if (regs) {
> + if (user_mode(regs)) {
> + state->stack_info.type = STACK_TYPE_UNKNOWN;
> + return;
> + }
> +
> + state->ip = regs->ip;
> + state->sp = kernel_stack_pointer(regs);
> + state->bp = regs->bp;
> + state->regs = regs;
> +
> + } else if (task == current) {
> + register void *__sp asm(_ASM_SP);
> +
> + asm volatile("lea (%%rip), %0\n\t"
> + "mov %%rsp, %1\n\t"
> + "mov %%rbp, %2\n\t"
> + : "=r" (state->ip), "=r" (state->sp),
> + "=r" (state->bp), "+r" (__sp));
Maybe I don't understand this completely, but what is __sp used for here?
> + state->regs = NULL;
> +
> + } else {
In DWARF unwinder, we also used to do here:
+#ifdef CONFIG_SMP
+ } else if (task->on_cpu) {
+ return;
+#endif
} else {
> + struct inactive_task_frame *frame = (void *)task->thread.sp;
Since there is no inactive_task_frame for tasks currently running (on
other CPUs). At least this always held in the past.
Though, the test is indeed racy.
> + state->ip = frame->ret_addr;
> + state->sp = task->thread.sp;
> + state->bp = frame->bp;
> + state->regs = NULL;
> + }
thanks,
--
js
suse labs
next prev parent reply other threads:[~2017-06-14 11:45 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-01 5:44 [RFC PATCH 00/10] x86: undwarf unwinder Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 01/10] objtool: move checking code to check.c Josh Poimboeuf
2017-06-14 7:22 ` Jiri Slaby
2017-06-01 5:44 ` [RFC PATCH 02/10] objtool, x86: add several functions and files to the objtool whitelist Josh Poimboeuf
2017-06-14 7:24 ` Jiri Slaby
2017-06-14 13:03 ` Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 03/10] objtool: stack validation 2.0 Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 04/10] objtool: add undwarf debuginfo generation Josh Poimboeuf
2017-06-14 8:42 ` Jiri Slaby
2017-06-14 13:27 ` Josh Poimboeuf
2017-06-22 7:47 ` Jiri Slaby
2017-06-22 12:49 ` Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 05/10] objtool, x86: add facility for asm code to provide CFI hints Josh Poimboeuf
2017-06-01 13:57 ` Andy Lutomirski
2017-06-01 14:16 ` Josh Poimboeuf
2017-06-01 14:40 ` Andy Lutomirski
2017-06-01 15:02 ` Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 06/10] x86/entry: add CFI hint undwarf annotations Josh Poimboeuf
2017-06-01 14:03 ` Andy Lutomirski
2017-06-01 14:23 ` Josh Poimboeuf
2017-06-01 14:28 ` Josh Poimboeuf
2017-06-01 14:39 ` Andy Lutomirski
2017-06-01 15:01 ` Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 07/10] x86/asm: add CFI hint annotations to sync_core() Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 08/10] extable: rename 'sortextable' script to 'sorttable' Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 09/10] extable: add undwarf table sorting ability to sorttable script Josh Poimboeuf
2017-06-01 5:44 ` [RFC PATCH 10/10] x86/unwind: add undwarf unwinder Josh Poimboeuf
2017-06-01 11:05 ` Peter Zijlstra
2017-06-01 12:26 ` Josh Poimboeuf
2017-06-01 12:47 ` Jiri Slaby
2017-06-01 13:02 ` Josh Poimboeuf
2017-06-01 13:42 ` Peter Zijlstra
2017-06-01 13:10 ` Peter Zijlstra
2017-06-01 12:13 ` Peter Zijlstra
2017-06-01 12:36 ` Josh Poimboeuf
2017-06-01 13:12 ` Peter Zijlstra
2017-06-01 15:03 ` Josh Poimboeuf
2017-06-14 11:45 ` Jiri Slaby [this message]
2017-06-14 13:44 ` Josh Poimboeuf
2017-06-01 6:08 ` [RFC PATCH 00/10] x86: " Ingo Molnar
2017-06-01 11:58 ` Josh Poimboeuf
2017-06-01 12:17 ` Peter Zijlstra
2017-06-01 12:33 ` Jiri Slaby
2017-06-01 12:52 ` Josh Poimboeuf
2017-06-01 12:57 ` Jiri Slaby
2017-06-01 12:47 ` Josh Poimboeuf
2017-06-01 13:25 ` Peter Zijlstra
2017-06-06 14:14 ` Sergey Senozhatsky
2017-06-01 13:50 ` Andy Lutomirski
2017-06-01 13:50 ` Ingo Molnar
2017-06-01 13:58 ` Jiri Slaby
2017-06-02 8:30 ` Jiri Slaby
2017-06-01 14:05 ` Josh Poimboeuf
2017-06-01 14:08 ` Jiri Slaby
2017-06-02 10:40 ` Mel Gorman
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