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Message-ID: <CAEr6+EAKdvHC_eQXA3GWNAFtp9g0JSYZcQrqUqiTyCQpXMFSNw@mail.gmail.com>
Date: Fri, 25 Nov 2022 13:02:04 +0800
From: Jeff Xie <xiehuan09@...il.com>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Qing Zhang <zhangqing@...ngson.cn>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v8 0/9] LoongArch: Add ftrace support
On Sat, Nov 19, 2022 at 1:21 PM Huacai Chen <chenhuacai@...nel.org> wrote:
>
> Hi, Qing,
>
> I have applied this series to
> https://github.com/loongson/linux/commits/loongarch-next with some
> slight modifications, please test that branch to see if everything is
> correct.
I found the call trace relative issue for the branch:
https://github.com/loongson/linux/commits/loongarch-next
test01:
[root@...ngarch tracing]# echo do_sys_openat2 > ./set_ftrace_filter
[root@...ngarch tracing]# echo 1 > ./options/func_stack_trace
[root@...ngarch tracing]# echo function > ./current_tracer
[root@...ngarch tracing]# cat ./trace
# tracer: function
#
# entries-in-buffer/entries-written: 6/6 #P:1
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
sh-84 [000] ..... 37.784924: do_sys_openat2 <-sys_openat
sh-84 [000] ..... 37.786382: <stack trace>
=> sys_openat
=> do_syscall
=> handle_syscall
=> 0 // abnormal output
test02:
[root@...ngarch tracing]# echo do_sys_openat2:stacktrace > ./set_ftrace_filter
[root@...ngarch tracing]# cat ./trace
# tracer: nop
#
# entries-in-buffer/entries-written: 3/3 #P:1
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
sh-84 [000] .n.2. 107.946986: <stack trace>
=> do_syscall
=> handle_syscall
=> 0xd9ad812ae
sh-84 [000] ...2. 110.584354: <stack trace>
=> do_syscall
=> handle_syscall
=> 0xd9ad812ae // abnormal output
test03:
[root@...ngarch tracing]# echo 1 > ./options/stacktrace
[root@...ngarch tracing]# echo 1 > ./events/sched/sched_switch/enable
[root@...ngarch tracing]# cat ./trace
...
<idle>-0 [000] d..2. 27.981495: sched_switch:
prev_comm=swapper/0 prev_pid=0 prev_prio=120 prev_state=R ==>
next_comm=rcu_preempt next
_pid=15 next_prio=120
<idle>-0 [000] d..2. 27.981508: <stack trace>
=> __schedule
=> schedule_idle
=> cpu_startup_entry
=> kernel_init
=> 0x0074706d // abnormal output
>
> Huacai
>
> On Wed, Nov 16, 2022 at 4:23 PM Qing Zhang <zhangqing@...ngson.cn> wrote:
> >
> > This patch series to support basic and dynamic ftrace.
> >
> > 1) -pg
> > Use `-pg` makes stub like a child function `void _mcount(void *ra)`.
> > Thus, it can be seen store RA and open stack before `call _mcount`.
> > Find `open stack` at first, and then find `store RA`.
> >
> > 2) -fpatchable-function-entry=2
> > The compiler has inserted 2 NOPs before the regular function prologue.
> > T series registers are available and safe because of LoongArch psABI.
> >
> > At runtime, replace nop with bl to enable ftrace call and replace bl with
> > nop to disable ftrace call. The bl requires us to save the original RA value,
> > so here it saves RA at t0.
> > details are:
> >
> > | Compiled | Disabled | Enabled |
> > +------------+------------------------+------------------------+
> > | nop | move t0, ra | move t0, ra |
> > | nop | nop | bl ftrace_caller |
> > | func_body | func_body | func_body |
> >
> > The RA value will be recovered by ftrace_regs_entry, and restored into RA
> > before returning to the regular function prologue. When a function is not
> > being traced, the move t0, ra is not harmful.
> >
> > performs a series of startup tests on ftrace and The test cases in selftests
> > has passed on LoongArch.
> >
> > Changes in v2:
> > - Remove patch "LoongArch: ftrace: Add CALLER_ADDRx macros" there are other
> > better ways
> > Suggested by Steve:
> > - Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support (6/10)
> > Suggested by Jinyang:
> > - Change addu16id to lu12iw and Adjust module_finalize return value (7/10)
> > - Use the "jr" pseudo-instruction where applicable (1/10)
> > - Use the "la.pcrel" instead of "la" (3/10)
> >
> > Changes in v3:
> > Reported by Jeff:
> > - Fix unwind state when option func_stack_trace (10/10)
> >
> > Changes in v4:
> > - No comments. Just resend the series.
> > - Rebased onto v6.0.0-rc4.
> >
> > Changes in v5:
> > - Modify the indentation of Kconfig and small changes
> >
> > Changes in v6:
> > Suggested by Huacai:
> > - Adjusting the patch Sequence
> > - renamed mcount-dyn.S for consistency
> >
> > Changes in v7:
> > - delete redefinition
> >
> > Changes in v8:
> > - remove useless macro judgment and modify the return location
> > - move some code to Patch-3
> >
> > Qing Zhang (9):
> > LoongArch/ftrace: Add basic support
> > LoongArch/ftrace: Add recordmcount support
> > LoongArch/ftrace: Add dynamic function tracer support
> > LoongArch/ftrace: Add dynamic function graph tracer support
> > LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_REGS support
> > LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support
> > LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
> > LoongArch: modules/ftrace: Initialize PLT at load time
> > LoongArch: Enable CONFIG_KALLSYMS_ALL and CONFIG_DEBUG_FS
> >
> > arch/loongarch/Kconfig | 7 +
> > arch/loongarch/Makefile | 5 +
> > arch/loongarch/configs/loongson3_defconfig | 2 +
> > arch/loongarch/include/asm/ftrace.h | 59 +++++
> > arch/loongarch/include/asm/inst.h | 15 ++
> > arch/loongarch/include/asm/module.h | 5 +-
> > arch/loongarch/include/asm/module.lds.h | 1 +
> > arch/loongarch/include/asm/unwind.h | 3 +-
> > arch/loongarch/kernel/Makefile | 13 +
> > arch/loongarch/kernel/ftrace.c | 74 ++++++
> > arch/loongarch/kernel/ftrace_dyn.c | 264 +++++++++++++++++++++
> > arch/loongarch/kernel/inst.c | 127 ++++++++++
> > arch/loongarch/kernel/mcount.S | 94 ++++++++
> > arch/loongarch/kernel/mcount_dyn.S | 154 ++++++++++++
> > arch/loongarch/kernel/module-sections.c | 11 +
> > arch/loongarch/kernel/module.c | 21 ++
> > arch/loongarch/kernel/unwind_guess.c | 4 +-
> > arch/loongarch/kernel/unwind_prologue.c | 46 +++-
> > scripts/recordmcount.c | 23 ++
> > 19 files changed, 918 insertions(+), 10 deletions(-)
> > create mode 100644 arch/loongarch/include/asm/ftrace.h
> > create mode 100644 arch/loongarch/kernel/ftrace.c
> > create mode 100644 arch/loongarch/kernel/ftrace_dyn.c
> > create mode 100644 arch/loongarch/kernel/mcount.S
> > create mode 100644 arch/loongarch/kernel/mcount_dyn.S
> >
> > --
> > 2.36.0
> >
> >
--
Thanks,
JeffXie
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