mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-25 10:59:05 +00:00
20380bb390
Function graph tracer modifies a return address (LR) in a stack frame
to hook a function return. This will result in many useless entries
(return_to_handler) showing up in
a) a stack tracer's output
b) perf call graph (with perf record -g)
c) dump_backtrace (at panic et al.)
For example, in case of a),
$ echo function_graph > /sys/kernel/debug/tracing/current_tracer
$ echo 1 > /proc/sys/kernel/stack_trace_enabled
$ cat /sys/kernel/debug/tracing/stack_trace
Depth Size Location (54 entries)
----- ---- --------
0) 4504 16 gic_raise_softirq+0x28/0x150
1) 4488 80 smp_cross_call+0x38/0xb8
2) 4408 48 return_to_handler+0x0/0x40
3) 4360 32 return_to_handler+0x0/0x40
...
In case of b),
$ echo function_graph > /sys/kernel/debug/tracing/current_tracer
$ perf record -e mem:XXX:x -ag -- sleep 10
$ perf report
...
| | |--0.22%-- 0x550f8
| | | 0x10888
| | | el0_svc_naked
| | | sys_openat
| | | return_to_handler
| | | return_to_handler
...
In case of c),
$ echo function_graph > /sys/kernel/debug/tracing/current_tracer
$ echo c > /proc/sysrq-trigger
...
Call trace:
[<ffffffc00044d3ac>] sysrq_handle_crash+0x24/0x30
[<ffffffc000092250>] return_to_handler+0x0/0x40
[<ffffffc000092250>] return_to_handler+0x0/0x40
...
This patch replaces such entries with real addresses preserved in
current->ret_stack[] at unwind_frame(). This way, we can cover all
the cases.
Reviewed-by: Jungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
[will: fixed minor context changes conflicting with irq stack bits]
Signed-off-by: Will Deacon <will.deacon@arm.com>
84 lines
2.1 KiB
C
84 lines
2.1 KiB
C
/*
|
|
* Based on arch/arm/kernel/time.c
|
|
*
|
|
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
|
|
* Modifications for ARM (C) 1994-2001 Russell King
|
|
* Copyright (C) 2012 ARM Ltd.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <linux/clockchips.h>
|
|
#include <linux/export.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/time.h>
|
|
#include <linux/init.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/timex.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/profile.h>
|
|
#include <linux/syscore_ops.h>
|
|
#include <linux/timer.h>
|
|
#include <linux/irq.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/clocksource.h>
|
|
#include <linux/clk-provider.h>
|
|
#include <linux/acpi.h>
|
|
|
|
#include <clocksource/arm_arch_timer.h>
|
|
|
|
#include <asm/thread_info.h>
|
|
#include <asm/stacktrace.h>
|
|
|
|
unsigned long profile_pc(struct pt_regs *regs)
|
|
{
|
|
struct stackframe frame;
|
|
|
|
if (!in_lock_functions(regs->pc))
|
|
return regs->pc;
|
|
|
|
frame.fp = regs->regs[29];
|
|
frame.sp = regs->sp;
|
|
frame.pc = regs->pc;
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
frame.graph = -1; /* no task info */
|
|
#endif
|
|
do {
|
|
int ret = unwind_frame(NULL, &frame);
|
|
if (ret < 0)
|
|
return 0;
|
|
} while (in_lock_functions(frame.pc));
|
|
|
|
return frame.pc;
|
|
}
|
|
EXPORT_SYMBOL(profile_pc);
|
|
|
|
void __init time_init(void)
|
|
{
|
|
u32 arch_timer_rate;
|
|
|
|
of_clk_init(NULL);
|
|
clocksource_probe();
|
|
|
|
tick_setup_hrtimer_broadcast();
|
|
|
|
arch_timer_rate = arch_timer_get_rate();
|
|
if (!arch_timer_rate)
|
|
panic("Unable to initialise architected timer.\n");
|
|
|
|
/* Calibrate the delay loop directly */
|
|
lpj_fine = arch_timer_rate / HZ;
|
|
}
|