Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754388AbbGPA14 (ORCPT ); Wed, 15 Jul 2015 20:27:56 -0400 Received: from mail-pd0-f174.google.com ([209.85.192.174]:32808 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754261AbbGPA1y (ORCPT ); Wed, 15 Jul 2015 20:27:54 -0400 Message-ID: <55A6FA82.9000901@linaro.org> Date: Thu, 16 Jul 2015 09:27:46 +0900 From: AKASHI Takahiro User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Steven Rostedt CC: Jungseok Lee , catalin.marinas@arm.com, will.deacon@arm.com, olof@lixom.net, broonie@kernel.org, david.griego@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace() References: <1436765375-7119-1-git-send-email-takahiro.akashi@linaro.org> <1436765375-7119-3-git-send-email-takahiro.akashi@linaro.org> <20150714093154.4d73e551@gandalf.local.home> <55A5A75A.1060401@linaro.org> <20150714225105.6c1e4f15@gandalf.local.home> <55A646EE.6030402@linaro.org> <20150715105536.42949ea9@gandalf.local.home> <20150715121337.3b31aa84@gandalf.local.home> In-Reply-To: <20150715121337.3b31aa84@gandalf.local.home> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4455 Lines: 142 On 07/16/2015 01:13 AM, Steven Rostedt wrote: > On Wed, 15 Jul 2015 10:55:36 -0400 > Steven Rostedt wrote: > > >> I'll take a look at it and try to clean up the code. > > Does the following patch make sense for you? Looks nice. The patch greatly simplifies changes on arm64 side. - Takahiro AKASHI > -- Steve > > diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c > index 3f34496244e9..9384647d07c3 100644 > --- a/kernel/trace/trace_stack.c > +++ b/kernel/trace/trace_stack.c > @@ -18,12 +18,6 @@ > > #define STACK_TRACE_ENTRIES 500 > > -#ifdef CC_USING_FENTRY > -# define fentry 1 > -#else > -# define fentry 0 > -#endif > - > static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] = > { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX }; > static unsigned stack_dump_index[STACK_TRACE_ENTRIES]; > @@ -35,7 +29,7 @@ static unsigned stack_dump_index[STACK_TRACE_ENTRIES]; > */ > static struct stack_trace max_stack_trace = { > .max_entries = STACK_TRACE_ENTRIES - 1, > - .entries = &stack_dump_trace[1], > + .entries = &stack_dump_trace[0], > }; > > static unsigned long max_stack_size; > @@ -77,7 +71,7 @@ check_stack(unsigned long ip, unsigned long *stack) > unsigned long this_size, flags; unsigned long *p, *top, *start; > static int tracer_frame; > int frame_size = ACCESS_ONCE(tracer_frame); > - int i; > + int i, x; > > this_size = ((unsigned long)stack) & (THREAD_SIZE-1); > this_size = THREAD_SIZE - this_size; > @@ -105,26 +99,20 @@ check_stack(unsigned long ip, unsigned long *stack) > max_stack_size = this_size; > > max_stack_trace.nr_entries = 0; > - > - if (using_ftrace_ops_list_func()) > - max_stack_trace.skip = 4; > - else > - max_stack_trace.skip = 3; > + max_stack_trace.skip = 0; > > save_stack_trace(&max_stack_trace); > > - /* > - * Add the passed in ip from the function tracer. > - * Searching for this on the stack will skip over > - * most of the overhead from the stack tracer itself. > - */ > - stack_dump_trace[0] = ip; > - max_stack_trace.nr_entries++; > + /* Skip over the overhead of the stack tracer itself */ > + for (i = 0; i < max_stack_trace.nr_entries; i++) { > + if (stack_dump_trace[i] == ip) > + break; > + } > > /* > * Now find where in the stack these are. > */ > - i = 0; > + x = 0; > start = stack; > top = (unsigned long *) > (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); > @@ -139,12 +127,13 @@ check_stack(unsigned long ip, unsigned long *stack) > while (i < max_stack_trace.nr_entries) { > int found = 0; > > - stack_dump_index[i] = this_size; > + stack_dump_index[x] = this_size; > p = start; > > for (; p < top && i < max_stack_trace.nr_entries; p++) { > if (*p == stack_dump_trace[i]) { > - this_size = stack_dump_index[i++] = > + stack_dump_trace[x] = stack_dump_trace[i++]; > + this_size = stack_dump_index[x++] = > (top - p) * sizeof(unsigned long); > found = 1; > /* Start the search from here */ > @@ -168,6 +157,9 @@ check_stack(unsigned long ip, unsigned long *stack) > i++; > } > > + for (; x < max_stack_trace.nr_entries; x++) > + stack_dump_trace[x] = ULONG_MAX; > + > if (task_stack_end_corrupted(current)) { > print_max_stack(); > BUG(); > @@ -192,24 +184,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip, > if (per_cpu(trace_active, cpu)++ != 0) > goto out; > > - /* > - * When fentry is used, the traced function does not get > - * its stack frame set up, and we lose the parent. > - * The ip is pretty useless because the function tracer > - * was called before that function set up its stack frame. > - * In this case, we use the parent ip. > - * > - * By adding the return address of either the parent ip > - * or the current ip we can disregard most of the stack usage > - * caused by the stack tracer itself. > - * > - * The function tracer always reports the address of where the > - * mcount call was, but the stack will hold the return address. > - */ > - if (fentry) > - ip = parent_ip; > - else > - ip += MCOUNT_INSN_SIZE; > + ip += MCOUNT_INSN_SIZE; > > check_stack(ip, &stack); > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/