The gic_handle_irq() is defined with __exception_irq_entry attribute.
A single remaining work is to add its definition as ARM did. Below
shows how function graph data is changed with these hunks.
A prologue of an interrupt handler is drawn as follows.
- current status
0) 0.208 us | cpuidle_not_available();
0) | default_idle_call() {
0) | arch_cpu_idle() {
0) | __handle_domain_irq() {
0) | irq_enter() {
0) 0.313 us | rcu_irq_enter();
0) 0.261 us | __local_bh_disable_ip();
- with this change
0) 0.625 us | cpuidle_not_available();
0) | default_idle_call() {
0) | arch_cpu_idle() {
0) ==========> |
0) | gic_handle_irq() {
0) | __handle_domain_irq() {
0) | irq_enter() {
0) 0.885 us | rcu_irq_enter();
0) 0.781 us | __local_bh_disable_ip();
An epilogue of an interrupt handler is recorded as follows.
- current status
0) 0.261 us | idle_cpu();
0) | rcu_irq_exit() {
0) 0.521 us | rcu_eqs_enter_common.isra.46();
0) 2.552 us | }
0) ! 322.448 us | }
0) ! 583.437 us | }
0) # 1656.041 us | }
0) # 1658.073 us | }
- with this change
0) 0.677 us | idle_cpu();
0) | rcu_irq_exit() {
0) 1.770 us | rcu_eqs_enter_common.isra.46();
0) 7.968 us | }
0) # 1803.541 us | }
0) # 2626.667 us | }
0) # 2632.969 us | }
0) <========== |
0) # 14425.00 us | }
0) # 14430.98 us | }
Cc: AKASHI Takahiro <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Rabin Vincent <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Jungseok Lee <[email protected]>
---
arch/arm64/include/asm/exception.h | 6 +++++
arch/arm64/include/asm/traps.h | 23 ++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 0303705..6cb7e1a 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -18,7 +18,13 @@
#ifndef __ASM_EXCEPTION_H
#define __ASM_EXCEPTION_H
+#include <linux/ftrace.h>
+
#define __exception __attribute__((section(".exception.text")))
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#define __exception_irq_entry __irq_entry
+#else
#define __exception_irq_entry __exception
+#endif
#endif /* __ASM_EXCEPTION_H */
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 232e4ba..0cc2f29 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -34,13 +34,32 @@ struct undef_hook {
void register_undef_hook(struct undef_hook *hook);
void unregister_undef_hook(struct undef_hook *hook);
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static inline int __in_irqentry_text(unsigned long ptr)
+{
+ extern char __irqentry_text_start[];
+ extern char __irqentry_text_end[];
+
+ return ptr >= (unsigned long)&__irqentry_text_start &&
+ ptr < (unsigned long)&__irqentry_text_end;
+}
+#else
+static inline int __in_irqentry_text(unsigned long ptr)
+{
+ return 0;
+}
+#endif
+
static inline int in_exception_text(unsigned long ptr)
{
extern char __exception_text_start[];
extern char __exception_text_end[];
+ int in;
+
+ in = ptr >= (unsigned long)&__exception_text_start &&
+ ptr < (unsigned long)&__exception_text_end;
- return ptr >= (unsigned long)&__exception_text_start &&
- ptr < (unsigned long)&__exception_text_end;
+ return in ? : __in_irqentry_text(ptr);
}
#endif
--
1.9.1
On Wed, Aug 12, 2015 at 03:16:19PM +0100, Jungseok Lee wrote:
> The gic_handle_irq() is defined with __exception_irq_entry attribute.
> A single remaining work is to add its definition as ARM did. Below
> shows how function graph data is changed with these hunks.
[...]
> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
> index 232e4ba..0cc2f29 100644
> --- a/arch/arm64/include/asm/traps.h
> +++ b/arch/arm64/include/asm/traps.h
> @@ -34,13 +34,32 @@ struct undef_hook {
> void register_undef_hook(struct undef_hook *hook);
> void unregister_undef_hook(struct undef_hook *hook);
>
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +static inline int __in_irqentry_text(unsigned long ptr)
> +{
> + extern char __irqentry_text_start[];
> + extern char __irqentry_text_end[];
> +
> + return ptr >= (unsigned long)&__irqentry_text_start &&
> + ptr < (unsigned long)&__irqentry_text_end;
> +}
> +#else
> +static inline int __in_irqentry_text(unsigned long ptr)
> +{
> + return 0;
> +}
> +#endif
> +
> static inline int in_exception_text(unsigned long ptr)
> {
> extern char __exception_text_start[];
> extern char __exception_text_end[];
> + int in;
> +
> + in = ptr >= (unsigned long)&__exception_text_start &&
> + ptr < (unsigned long)&__exception_text_end;
>
> - return ptr >= (unsigned long)&__exception_text_start &&
> - ptr < (unsigned long)&__exception_text_end;
> + return in ? : __in_irqentry_text(ptr);
> }
On arm64, this function is only called from dump_backtrace, so I'm
struggling to see why this change makes any difference to the ftrace
output.
What am I missing?
Will
On Aug 13, 2015, at 12:02 AM, Will Deacon wrote:
Hi Will,
> On Wed, Aug 12, 2015 at 03:16:19PM +0100, Jungseok Lee wrote:
>> The gic_handle_irq() is defined with __exception_irq_entry attribute.
>> A single remaining work is to add its definition as ARM did. Below
>> shows how function graph data is changed with these hunks.
>
> [...]
>
>> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
>> index 232e4ba..0cc2f29 100644
>> --- a/arch/arm64/include/asm/traps.h
>> +++ b/arch/arm64/include/asm/traps.h
>> @@ -34,13 +34,32 @@ struct undef_hook {
>> void register_undef_hook(struct undef_hook *hook);
>> void unregister_undef_hook(struct undef_hook *hook);
>>
>> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>> +static inline int __in_irqentry_text(unsigned long ptr)
>> +{
>> + extern char __irqentry_text_start[];
>> + extern char __irqentry_text_end[];
>> +
>> + return ptr >= (unsigned long)&__irqentry_text_start &&
>> + ptr < (unsigned long)&__irqentry_text_end;
>> +}
>> +#else
>> +static inline int __in_irqentry_text(unsigned long ptr)
>> +{
>> + return 0;
>> +}
>> +#endif
>> +
>> static inline int in_exception_text(unsigned long ptr)
>> {
>> extern char __exception_text_start[];
>> extern char __exception_text_end[];
>> + int in;
>> +
>> + in = ptr >= (unsigned long)&__exception_text_start &&
>> + ptr < (unsigned long)&__exception_text_end;
>>
>> - return ptr >= (unsigned long)&__exception_text_start &&
>> - ptr < (unsigned long)&__exception_text_end;
>> + return in ? : __in_irqentry_text(ptr);
>> }
>
> On arm64, this function is only called from dump_backtrace, so I'm
> struggling to see why this change makes any difference to the ftrace
> output.
>
> What am I missing?
As you mentioned, the above hunk does not change the ftrace behavior.
The first diff directly affects the first condition check in print_graph_irq
function in kernel/trace/trace_functions_graph.c. The code snippet is as follows.
if (addr < (unsigned long)__irqentry_text_start ||
addr >= (unsigned long)__irqentry_text_end)
return;
I hope it would be helpful.
Best Regards
Jungseok Lee-
On Wed, Aug 12, 2015 at 04:18:49PM +0100, Jungseok Lee wrote:
> On Aug 13, 2015, at 12:02 AM, Will Deacon wrote:
> > On Wed, Aug 12, 2015 at 03:16:19PM +0100, Jungseok Lee wrote:
> >> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
> >> index 232e4ba..0cc2f29 100644
> >> --- a/arch/arm64/include/asm/traps.h
> >> +++ b/arch/arm64/include/asm/traps.h
> >> @@ -34,13 +34,32 @@ struct undef_hook {
> >> void register_undef_hook(struct undef_hook *hook);
> >> void unregister_undef_hook(struct undef_hook *hook);
> >>
> >> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> >> +static inline int __in_irqentry_text(unsigned long ptr)
> >> +{
> >> + extern char __irqentry_text_start[];
> >> + extern char __irqentry_text_end[];
> >> +
> >> + return ptr >= (unsigned long)&__irqentry_text_start &&
> >> + ptr < (unsigned long)&__irqentry_text_end;
> >> +}
> >> +#else
> >> +static inline int __in_irqentry_text(unsigned long ptr)
> >> +{
> >> + return 0;
> >> +}
> >> +#endif
> >> +
> >> static inline int in_exception_text(unsigned long ptr)
> >> {
> >> extern char __exception_text_start[];
> >> extern char __exception_text_end[];
> >> + int in;
> >> +
> >> + in = ptr >= (unsigned long)&__exception_text_start &&
> >> + ptr < (unsigned long)&__exception_text_end;
> >>
> >> - return ptr >= (unsigned long)&__exception_text_start &&
> >> - ptr < (unsigned long)&__exception_text_end;
> >> + return in ? : __in_irqentry_text(ptr);
> >> }
> >
> > On arm64, this function is only called from dump_backtrace, so I'm
> > struggling to see why this change makes any difference to the ftrace
> > output.
> >
> > What am I missing?
>
> As you mentioned, the above hunk does not change the ftrace behavior.
>
> The first diff directly affects the first condition check in print_graph_irq
> function in kernel/trace/trace_functions_graph.c. The code snippet is as follows.
>
> if (addr < (unsigned long)__irqentry_text_start ||
> addr >= (unsigned long)__irqentry_text_end)
> return;
>
> I hope it would be helpful.
Gotcha, thanks for the explanation.
Will