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Message-Id: <1438674249-3447-2-git-send-email-takahiro.akashi@linaro.org>
Date: Tue, 4 Aug 2015 16:44:06 +0900
From: AKASHI Takahiro <takahiro.akashi@...aro.org>
To: catalin.marinas@....com, will.deacon@....com, rostedt@...dmis.org
Cc: jungseoklee85@...il.com, olof@...om.net, broonie@...nel.org,
david.griego@...aro.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC v2 1/4] ftrace: allow arch-specific check_stack()
A stack frame pointer may be used in a different way depending on
cpu architecture. Thus it is not always appropriate to slurp the stack
contents, as currently done in check_stack(), in order to calcurate
a stack index (height) at a given function call. At least not on arm64.
This patch extract potentially arch-specific code from check_stack()
and puts it into a new arch_check_stack(), which is declared as weak.
So we will be able to add arch-specific and most efficient way of
stack traversing Later.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
include/linux/stacktrace.h | 4 ++
kernel/trace/trace_stack.c | 88 ++++++++++++++++++++++++++------------------
2 files changed, 56 insertions(+), 36 deletions(-)
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 0a34489..bfae605 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -10,6 +10,10 @@ struct pt_regs;
struct stack_trace {
unsigned int nr_entries, max_entries;
unsigned long *entries;
+#ifdef CONFIG_STACK_TRACER
+ unsigned *index;
+ unsigned long *sp;
+#endif
int skip; /* input argument: How many entries to skip */
};
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 3d9356b..021b8c3 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -27,9 +27,10 @@ static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
* us to remove most or all of the stack size overhead
* added by the stack tracer itself.
*/
-static struct stack_trace max_stack_trace = {
+ struct stack_trace max_stack_trace = {
.max_entries = STACK_TRACE_ENTRIES - 1,
.entries = &stack_dump_trace[0],
+ .index = &stack_dump_index[0],
};
static unsigned long max_stack_size;
@@ -65,42 +66,15 @@ static inline void print_max_stack(void)
}
}
-static inline void
-check_stack(unsigned long ip, unsigned long *stack)
+void __weak
+arch_check_stack(unsigned long ip, unsigned long *stack,
+ unsigned long *max_size, unsigned int *tracer_size)
{
- unsigned long this_size, flags; unsigned long *p, *top, *start;
- static int tracer_frame;
- int frame_size = ACCESS_ONCE(tracer_frame);
+ unsigned long *p, *top, *start;
+ unsigned long this_size;
int i, x;
- this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
- this_size = THREAD_SIZE - this_size;
- /* Remove the frame of the tracer */
- this_size -= frame_size;
-
- if (this_size <= max_stack_size)
- return;
-
- /* we do not handle interrupt stacks yet */
- if (!object_is_on_stack(stack))
- return;
-
- local_irq_save(flags);
- arch_spin_lock(&max_stack_lock);
-
- /* In case another CPU set the tracer_frame on us */
- if (unlikely(!frame_size))
- this_size -= tracer_frame;
-
- /* a race could have already updated it */
- if (this_size <= max_stack_size)
- goto out;
-
- max_stack_size = this_size;
-
- max_stack_trace.nr_entries = 0;
max_stack_trace.skip = 3;
-
save_stack_trace(&max_stack_trace);
/* Skip over the overhead of the stack tracer itself */
@@ -116,6 +90,7 @@ check_stack(unsigned long ip, unsigned long *stack)
start = stack;
top = (unsigned long *)
(((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
+ this_size = *max_size;
/*
* Loop through all the entries. One of the entries may
@@ -146,10 +121,10 @@ check_stack(unsigned long ip, unsigned long *stack)
* out what that is, then figure it out
* now.
*/
- if (unlikely(!tracer_frame)) {
- tracer_frame = (p - stack) *
+ if (unlikely(!*tracer_size)) {
+ *tracer_size = (p - stack) *
sizeof(unsigned long);
- max_stack_size -= tracer_frame;
+ *max_size -= *tracer_size;
}
}
}
@@ -161,6 +136,47 @@ check_stack(unsigned long ip, unsigned long *stack)
max_stack_trace.nr_entries = x;
for (; x < i; x++)
stack_dump_trace[x] = ULONG_MAX;
+}
+
+static inline void
+check_stack(unsigned long ip, unsigned long *stack)
+{
+ unsigned long this_size, flags;
+ static int tracer_frame;
+ int frame_size = ACCESS_ONCE(tracer_frame);
+
+ this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
+ this_size = THREAD_SIZE - this_size;
+ /* for safety, depending on arch_check_stack() */
+ if (this_size < frame_size)
+ return;
+
+ /* Remove the frame of the tracer */
+ this_size -= frame_size;
+
+ if (this_size <= max_stack_size)
+ return;
+
+ /* we do not handle interrupt stacks yet */
+ if (!object_is_on_stack(stack))
+ return;
+
+ local_irq_save(flags);
+ arch_spin_lock(&max_stack_lock);
+
+ /* In case another CPU set the tracer_frame on us */
+ if (unlikely(!frame_size))
+ this_size -= tracer_frame;
+
+ /* a race could have already updated it */
+ if (this_size <= max_stack_size)
+ goto out;
+
+ max_stack_size = this_size;
+
+ max_stack_trace.nr_entries = 0;
+
+ arch_check_stack(ip, stack, &max_stack_size, &tracer_frame);
if (task_stack_end_corrupted(current)) {
print_max_stack();
--
1.7.9.5
--
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