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Date: Tue, 4 Aug 2015 16:44:07 +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 2/4] arm64: ftrace: add arch-specific stack tracer
This patch uses walk_stackframe(), instead of slurping stack contents
as orignal check_stack() does, to identify each stack frame.
return_to_handler() is handled in a special way because it is not
a function, but invoked via function graph tracer by faking a saved lr
register on stack.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
arch/arm64/include/asm/ftrace.h | 2 ++
arch/arm64/kernel/ftrace.c | 37 +++++++++++++++++++++++++
arch/arm64/kernel/stacktrace.c | 58 +++++++++++++++++++++++++++++++++++++--
3 files changed, 95 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 2b43e20..b7d597c 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -29,6 +29,8 @@ struct dyn_arch_ftrace {
extern unsigned long ftrace_graph_call;
+extern void return_to_handler(void);
+
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
/*
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index c851be7..d812870 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -176,3 +176,40 @@ int ftrace_disable_ftrace_graph_caller(void)
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_STACK_TRACER
+#define stack_top(fp) (((fp) & ~(THREAD_SIZE-1)) + THREAD_SIZE)
+#define stack_index(fp) (stack_top((fp)) - (fp))
+
+extern struct stack_trace max_stack_trace;
+extern void save_stack_trace_index(struct stack_trace *trace);
+
+void arch_check_stack(unsigned long ip, unsigned long *stack,
+ unsigned long *max_size, int *tracer_size)
+{
+ int i, j;
+
+ max_stack_trace.skip = 0;
+ save_stack_trace_index(&max_stack_trace);
+ max_stack_trace.nr_entries--; /* for '-1' entry */
+
+ /* Skip over the overhead of the stack tracer itself */
+ for (i = 0; i < max_stack_trace.nr_entries; i++) {
+ if ((max_stack_trace.entries[i] + FTRACE_STACK_FRAME_OFFSET)
+ == ip)
+ break;
+ }
+
+ if (unlikely(!*tracer_size)) {
+ *tracer_size = stack_index((unsigned long)stack)
+ - max_stack_trace.index[i];
+ *max_size -= *tracer_size;
+ }
+
+ max_stack_trace.nr_entries -= i;
+ for (j = 0; j < max_stack_trace.nr_entries; j++) {
+ max_stack_trace.index[j] = max_stack_trace.index[j + i];
+ max_stack_trace.entries[j] = max_stack_trace.entries[j + i];
+ }
+}
+#endif /* CONFIG_STACK_TRACER */
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index bc0689a..496ab0f 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -17,12 +17,15 @@
*/
#include <linux/kernel.h>
#include <linux/export.h>
+#include <linux/ftrace.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <asm/insn.h>
#include <asm/stacktrace.h>
+#define S_FRAME_SIZE sizeof(struct pt_regs) /* asm-offsets.h */
+
/*
* AArch64 PCS assigns the frame pointer to x29.
*
@@ -78,9 +81,29 @@ struct stack_trace_data {
struct stack_trace *trace;
unsigned int no_sched_functions;
unsigned int skip;
+#ifdef CONFIG_STACK_TRACER
+ int ftracer;
+ int ret_stack_index;
+#endif
};
-static int save_trace(struct stackframe *frame, void *d)
+#ifdef CONFIG_STACK_TRACER
+static void notrace arm64_stack_index(struct stackframe *frame,
+ struct stack_trace_data *data)
+{
+ struct stack_trace *trace = data->trace;
+ unsigned long top;
+ unsigned int x = trace->nr_entries;
+
+ top = (frame->fp & ~(THREAD_SIZE-1)) + THREAD_SIZE;
+ trace->index[x] = top - frame->fp;
+ /* should not go beyond this frame */
+ if (trace->index[x] == THREAD_SIZE)
+ trace->index[x] = 0;
+}
+#endif /* CONFIG_STACK_TRACER */
+
+static int notrace save_trace(struct stackframe *frame, void *d)
{
struct stack_trace_data *data = d;
struct stack_trace *trace = data->trace;
@@ -93,7 +116,13 @@ static int save_trace(struct stackframe *frame, void *d)
return 0;
}
- trace->entries[trace->nr_entries++] = addr;
+ trace->entries[trace->nr_entries] = addr;
+#ifdef CONFIG_STACK_TRACER
+ if (data->ftracer) {
+ arm64_stack_index(frame, data);
+ }
+#endif
+ trace->nr_entries++;
return trace->nr_entries >= trace->max_entries;
}
@@ -105,6 +134,9 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
data.trace = trace;
data.skip = trace->skip;
+#ifdef CONFIG_STACK_TRACER
+ data.ftracer = 0;
+#endif
if (tsk != current) {
data.no_sched_functions = 1;
@@ -128,4 +160,26 @@ void save_stack_trace(struct stack_trace *trace)
save_stack_trace_tsk(current, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);
+
+#ifdef CONFIG_STACK_TRACER
+void notrace save_stack_trace_index(struct stack_trace *trace)
+{
+ struct stack_trace_data data;
+ struct stackframe frame;
+
+ data.trace = trace;
+ data.skip = trace->skip;
+ data.ftracer = 1;
+ data.ret_stack_index = current->curr_ret_stack;
+
+ data.no_sched_functions = 0;
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_stack_pointer;
+ frame.pc = (unsigned long)save_stack_trace_index;
+
+ walk_stackframe(&frame, save_trace, &data);
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+#endif /* CONFIG_STACK_TRACER */
#endif
--
1.7.9.5
--
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