On 07/21/2015 08:53 AM, AKASHI Takahiro wrote:
Hi
So i don't have to repost my patch here. Please use the original
commit log message[1/3] as is.
But please keep in mind that there is still an issue that I mentioned
in the cover letter; 'Size' field is inaccurate.
<reported size> = <its own dynamic local variables>
+ <child's local variables>
and
<real size> = <reported size> + <its local variables>
- <child's local variables>
where "dynamic" means, for example, a variable allocated like the below:
int foo(int num) {
int array[num];
...
}
(See more details in my ascii art.)
Such usage is seldom seen in the kernel, and <reported size> is
likely equal to <child's local variables>. In other words, we will
see one-line *displacement* in most cases.
Well, I have a quick fix now, but it looks ugly.
In addition, I found another issue; With function_graph tracer,
the output is like:
# cat /sys/kernel/tracing/stack_trace
Depth Size Location (78 entries)
----- ---- --------
0) 6184 32 update_min_vruntime+0x14/0x74
1) 6152 48 update_curr+0x6c/0x150
2) 6104 128 enqueue_task_fair+0x2f4/0xb9c
3) 5976 48 enqueue_task+0x48/0x90
...
18) 5160 112 hrtimer_interrupt+0xa0/0x214
19) 5048 32 arch_timer_handler_phys+0x38/0x48
20) 5016 0 ftrace_graph_caller+0x2c/0x30
21) 5016 64 ftrace_graph_caller+0x2c/0x30
22) 4952 32 ftrace_graph_caller+0x2c/0x30
23) 4920 64 ftrace_graph_caller+0x2c/0x30
...
Since, with function_graph tracer, we modify LR register in a stack frame
when we enter into a function, we have to manage such special cases
in save_stack_trace() or check_stack() as x86 does in
print_ftrace_graph_addr().
Thanks,
-Takahiro AKASHI
(We'd better mention it explicitly in the commmit?)
Thanks,
-Takahiro AKASHI
On 07/21/2015 01:20 AM, Will Deacon wrote:
Hi all,
On Fri, Jul 17, 2015 at 04:34:21PM +0100, Jungseok Lee wrote:
On Jul 17, 2015, at 11:59 PM, Jungseok Lee wrote:
On Jul 17, 2015, at 11:41 PM, Steven Rostedt wrote:
Thanks! Can you repost patch 1 with the changes I recommended, so that
I can get an Acked-by from the arm64 maintainers and pull all the
changes in together. This is fine for a 4.3 release, right? That is, it
doesn't need to go into 4.2-rcs.
It's not hard to repost a patch, but I feel like we have to wait for Akashi's
response.
Also, it might be needed to consider Mark's comment on arch part.
If they are okay, I will proceed.
The [RFC 1/3] patch used in my environment is shaped as follows.
I leave the hunk for *only* clear synchronization. This is why I choose this
format
instead of reposting a patch. I hope it would help to track down this thread.
I think this is my best at this point.
----8<----
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index c5534fa..2b43e20 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -13,8 +13,9 @@
#include <asm/insn.h>
-#define MCOUNT_ADDR ((unsigned long)_mcount)
-#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE
+#define MCOUNT_ADDR ((unsigned long)_mcount)
+#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE
+#define FTRACE_STACK_FRAME_OFFSET AARCH64_INSN_SIZE
#ifndef __ASSEMBLY__
#include <linux/compat.h>
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 407991b..9ab67af 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -20,6 +20,7 @@
#include <linux/sched.h>
#include <linux/stacktrace.h>
+#include <asm/insn.h>
#include <asm/stacktrace.h>
/*
@@ -52,7 +53,7 @@ int notrace unwind_frame(struct stackframe *frame)
* -4 here because we care about the PC at time of bl,
* not where the return will go.
*/
- frame->pc = *(unsigned long *)(fp + 8) - 4;
+ frame->pc = *(unsigned long *)(fp + 8) - AARCH64_INSN_SIZE;
return 0;
}
The arm64 bits look fine to me:
Acked-by: Will Deacon <will.dea...@arm.com>
Steve: feel free to take this along with the other ftrace changes. I don't
anticipate any conflicts, but if anything crops up in -next we can sort
it out then.
Thanks!
Will
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