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From: Steven Rostedt <rostedt@goodmis.org>
To: Jiping Ma <jiping.ma2@windriver.com>
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	linux-kernel@vger.kernel.org, mingo@redhat.com,
	joel@joelfernandes.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3] tracing: Function stack size and its name mismatch in arm64
Date: Fri, 2 Aug 2019 12:09:20 -0400	[thread overview]
Message-ID: <20190802120920.3b1f4351@gandalf.local.home> (raw)
In-Reply-To: <20190802112259.0530a648@gandalf.local.home>

[-- Attachment #1: Type: text/plain, Size: 1556 bytes --]

On Fri, 2 Aug 2019 11:22:59 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> I think you are not explaining the issue correctly. From looking at the
> document, I think what you want to say is that the LR is saved *after*
> the data for the function. Is that correct? If so, then yes, it would
> cause the stack tracing algorithm to be incorrect.
> 

[..]

> Can someone confirm that this is the real issue?

Does this patch fix your issue?

-- Steve

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 5ab5200b2bdc..13a4832cfb00 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -13,6 +13,7 @@
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 #define MCOUNT_ADDR		((unsigned long)_mcount)
 #define MCOUNT_INSN_SIZE	AARCH64_INSN_SIZE
+#define ARCH_RET_ADDR_AFTER_LOCAL_VARS 1
 
 #ifndef __ASSEMBLY__
 #include <linux/compat.h>
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 5d16f73898db..050c6bd9beac 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -158,6 +158,18 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 			i++;
 	}
 
+#ifdef ARCH_RET_ADDR_AFTER_LOCAL_VARS
+	/*
+	 * Most archs store the return address before storing the
+	 * function's local variables. But some archs do this backwards.
+	 */
+	if (x > 1) {
+		memmove(&stack_trace_index[0], &stack_trace_index[1],
+			sizeof(stack_trace_index[0]) * (x - 1));
+		x--;
+	}
+#endif
+
 	stack_trace_nr_entries = x;
 
 	if (task_stack_end_corrupted(current)) {

[-- Attachment #2: f.patch --]
[-- Type: text/x-patch, Size: 1100 bytes --]

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 5ab5200b2bdc..13a4832cfb00 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -13,6 +13,7 @@
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 #define MCOUNT_ADDR		((unsigned long)_mcount)
 #define MCOUNT_INSN_SIZE	AARCH64_INSN_SIZE
+#define ARCH_RET_ADDR_AFTER_LOCAL_VARS 1
 
 #ifndef __ASSEMBLY__
 #include <linux/compat.h>
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 5d16f73898db..050c6bd9beac 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -158,6 +158,18 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 			i++;
 	}
 
+#ifdef ARCH_RET_ADDR_AFTER_LOCAL_VARS
+	/*
+	 * Most archs store the return address before storing the
+	 * function's local variables. But some archs do this backwards.
+	 */
+	if (x > 1) {
+		memmove(&stack_trace_index[0], &stack_trace_index[1],
+			sizeof(stack_trace_index[0]) * (x - 1));
+		x--;
+	}
+#endif
+
 	stack_trace_nr_entries = x;
 
 	if (task_stack_end_corrupted(current)) {

[-- Attachment #3: Type: text/plain, Size: 176 bytes --]

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  reply	other threads:[~2019-08-02 16:09 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190802094103.163576-1-jiping.ma2@windriver.com>
2019-08-02 15:22 ` [PATCH v3] tracing: Function stack size and its name mismatch in arm64 Steven Rostedt
2019-08-02 16:09   ` Steven Rostedt [this message]
2019-08-02 16:11     ` Steven Rostedt
2019-08-06 15:48       ` Joel Fernandes
2019-08-06 16:34         ` Steven Rostedt
2019-08-06 17:03           ` Steven Rostedt
2019-08-06 17:25           ` Joel Fernandes
2019-08-03  8:26   ` Joel Fernandes
2019-08-03  8:32     ` Joel Fernandes
2019-08-05 11:25     ` Will Deacon
2019-08-05 13:59       ` Steven Rostedt
2019-08-06 13:00       ` Steven Rostedt
2019-08-06 14:47       ` Joel Fernandes

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