From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> To: Josh Poimboeuf <jpoimboe@redhat.com> Cc: broonie@kernel.org, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3 1/4] arm64: Introduce stack trace reliability checks in the unwinder Date: Tue, 4 May 2021 18:13:39 -0500 [thread overview] Message-ID: <b000767b-26ca-01a9-a109-c9fc3357f832@linux.microsoft.com> (raw) In-Reply-To: <20210504215248.oi3zay3memgqri33@treble> On 5/4/21 4:52 PM, Josh Poimboeuf wrote: > On Mon, May 03, 2021 at 12:36:12PM -0500, madvenka@linux.microsoft.com wrote: >> @@ -44,6 +44,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) >> unsigned long fp = frame->fp; >> struct stack_info info; >> >> + frame->reliable = true; >> + > > Why set 'reliable' to true on every invocation of unwind_frame()? > Shouldn't it be remembered across frames? > This is mainly for debug purposes in case a caller wants to print the whole stack and also print which functions are unreliable. For livepatch, it does not make any difference. It will quit as soon as it encounters an unreliable frame. > Also, it looks like there are several error scenarios where it returns > -EINVAL but doesn't set 'reliable' to false. > I wanted to make a distinction between an error situation (like stack corruption where unwinding has to stop) and an unreliable situation (where unwinding can still proceed). E.g., when a stack trace is taken for informational purposes or debug purposes, the unwinding will try to proceed until either the stack trace ends or an error happens. Madhavan
WARNING: multiple messages have this Message-ID (diff)
From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> To: Josh Poimboeuf <jpoimboe@redhat.com> Cc: broonie@kernel.org, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3 1/4] arm64: Introduce stack trace reliability checks in the unwinder Date: Tue, 4 May 2021 18:13:39 -0500 [thread overview] Message-ID: <b000767b-26ca-01a9-a109-c9fc3357f832@linux.microsoft.com> (raw) In-Reply-To: <20210504215248.oi3zay3memgqri33@treble> On 5/4/21 4:52 PM, Josh Poimboeuf wrote: > On Mon, May 03, 2021 at 12:36:12PM -0500, madvenka@linux.microsoft.com wrote: >> @@ -44,6 +44,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) >> unsigned long fp = frame->fp; >> struct stack_info info; >> >> + frame->reliable = true; >> + > > Why set 'reliable' to true on every invocation of unwind_frame()? > Shouldn't it be remembered across frames? > This is mainly for debug purposes in case a caller wants to print the whole stack and also print which functions are unreliable. For livepatch, it does not make any difference. It will quit as soon as it encounters an unreliable frame. > Also, it looks like there are several error scenarios where it returns > -EINVAL but doesn't set 'reliable' to false. > I wanted to make a distinction between an error situation (like stack corruption where unwinding has to stop) and an unreliable situation (where unwinding can still proceed). E.g., when a stack trace is taken for informational purposes or debug purposes, the unwinding will try to proceed until either the stack trace ends or an error happens. Madhavan _______________________________________________ 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:[~2021-05-04 23:13 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <65cf4dfbc439b010b50a0c46ec500432acde86d6> 2021-05-03 17:36 ` [RFC PATCH v3 0/4] arm64: Stack trace reliability checks in the unwinder madvenka 2021-05-03 17:36 ` madvenka 2021-05-03 17:36 ` [RFC PATCH v3 1/4] arm64: Introduce stack " madvenka 2021-05-03 17:36 ` madvenka 2021-05-04 15:50 ` Mark Brown 2021-05-04 15:50 ` Mark Brown 2021-05-04 19:14 ` Madhavan T. Venkataraman 2021-05-04 19:14 ` Madhavan T. Venkataraman 2021-05-04 21:52 ` Josh Poimboeuf 2021-05-04 21:52 ` Josh Poimboeuf 2021-05-04 23:13 ` Madhavan T. Venkataraman [this message] 2021-05-04 23:13 ` Madhavan T. Venkataraman 2021-05-05 0:07 ` Josh Poimboeuf 2021-05-05 0:07 ` Josh Poimboeuf 2021-05-05 0:21 ` Madhavan T. Venkataraman 2021-05-05 0:21 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections madvenka 2021-05-03 17:36 ` madvenka 2021-05-04 16:05 ` Mark Brown 2021-05-04 16:05 ` Mark Brown 2021-05-04 19:03 ` Madhavan T. Venkataraman 2021-05-04 19:03 ` Madhavan T. Venkataraman 2021-05-04 19:32 ` Madhavan T. Venkataraman 2021-05-04 19:32 ` Madhavan T. Venkataraman 2021-05-05 16:46 ` Mark Brown 2021-05-05 16:46 ` Mark Brown 2021-05-05 18:48 ` Madhavan T. Venkataraman 2021-05-05 18:48 ` Madhavan T. Venkataraman 2021-05-05 18:50 ` Madhavan T. Venkataraman 2021-05-05 18:50 ` Madhavan T. Venkataraman 2021-05-06 13:45 ` Mark Brown 2021-05-06 13:45 ` Mark Brown 2021-05-06 15:21 ` Madhavan T. Venkataraman 2021-05-06 15:21 ` Madhavan T. Venkataraman 2021-05-05 16:34 ` Mark Brown 2021-05-05 16:34 ` Mark Brown 2021-05-05 17:51 ` Madhavan T. Venkataraman 2021-05-05 17:51 ` Madhavan T. Venkataraman 2021-05-05 19:30 ` Ard Biesheuvel 2021-05-05 19:30 ` Ard Biesheuvel 2021-05-05 20:00 ` Madhavan T. Venkataraman 2021-05-05 20:00 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 3/4] arm64: Handle miscellaneous functions in .text and .init.text madvenka 2021-05-03 17:36 ` madvenka 2021-05-06 14:12 ` Mark Brown 2021-05-06 14:12 ` Mark Brown 2021-05-06 15:30 ` Madhavan T. Venkataraman 2021-05-06 15:30 ` Madhavan T. Venkataraman 2021-05-06 15:32 ` Madhavan T. Venkataraman 2021-05-06 15:32 ` Madhavan T. Venkataraman 2021-05-06 15:44 ` Mark Brown 2021-05-06 15:44 ` Mark Brown 2021-05-06 15:56 ` Madhavan T. Venkataraman 2021-05-06 15:56 ` Madhavan T. Venkataraman 2021-05-06 15:37 ` Mark Brown 2021-05-06 15:37 ` Mark Brown 2021-05-06 15:57 ` Madhavan T. Venkataraman 2021-05-06 15:57 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 4/4] arm64: Handle funtion graph tracer better in the unwinder madvenka 2021-05-03 17:36 ` madvenka 2021-05-06 14:43 ` Mark Brown 2021-05-06 14:43 ` Mark Brown 2021-05-06 15:20 ` Madhavan T. Venkataraman 2021-05-06 15:20 ` Madhavan T. Venkataraman
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