Messages in this thread | | | From | Guo Ren <> | Date | Tue, 21 Feb 2023 12:02:04 +0800 | Subject | Re: [PATCH -next V7 6/7] samples: ftrace: Add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI] |
| |
On Sun, Feb 19, 2023 at 5:30 AM Palmer Dabbelt <palmer@dabbelt.com> wrote: > > On Wed, 18 Jan 2023 22:05:04 PST (-0800), guoren@kernel.org wrote: > > Thx Evgenii & Song, > > > > I got it; it would be put into v8. > > Sorry if I missed it, but I don't see a v8 on patchwork. I queued up > the first three patches onto for-next as they seem like pretty > independent fixes/cleanups, I'll hold off on the others until v8. Thx for approving. I would keep the patch series more independent next time.
> > Thanks! > > > > > On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin > > <e.shatokhin@yadro.com> wrote: > >> > >> On 18.01.2023 05:37, Song Shuai wrote: > >> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道: > >> >> > >> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote: > >> >>> Hi, Song, > >> >>> > >> >>> On 17.01.2023 12:32, Song Shuai wrote: > >> >>>> > >> >>>> Hi, Evgenii: > >> >>>> > >> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道: > >> >>>> > >> >>>>> > >> >>>>> Hi, > >> >>>>> > >> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote: > >> >>>>>> From: Song Shuai <suagrfillet@gmail.com> > >> >>>>>> > >> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI > >> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for > >> >>>>>> the ftrace-direct*.c files in samples/ftrace/. > >> >>>>>> > >> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com> > >> >>>>>> Tested-by: Guo Ren <guoren@kernel.org> > >> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org> > >> >>>>>> --- > >> >>>>>> arch/riscv/Kconfig | 2 ++ > >> >>>>>> samples/ftrace/ftrace-direct-modify.c | 33 ++++++++++++++++++ > >> >>>>>> samples/ftrace/ftrace-direct-multi-modify.c | 37 > >> >>>>>> +++++++++++++++++++++ > >> >>>>>> samples/ftrace/ftrace-direct-multi.c | 22 ++++++++++++ > >> >>>>>> samples/ftrace/ftrace-direct-too.c | 26 +++++++++++++++ > >> >>>>>> samples/ftrace/ftrace-direct.c | 22 ++++++++++++ > >> >>>>>> 6 files changed, 142 insertions(+) > >> >>>>> > >> >>>>> The samples were built OK now, but ftrace-direct-multi and > >> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems. > >> >>>>> > >> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked > >> >>>>> the messages in the trace: > >> >>>>> > >> >>>>> # TASK-PID CPU# ||||| TIMESTAMP FUNCTION > >> >>>>> # | | | ||||| | | > >> >>>>> migration/1-19 [001] ..... 3858.532131: my_direct_func1: my > >> >>>>> direct func1 ip 0 > >> >>>>> migration/0-15 [000] d.s2. 3858.532136: my_direct_func1: my > >> >>>>> direct func1 ip ff60000001ba9600 > >> >>>>> migration/0-15 [000] d..2. 3858.532204: my_direct_func1: my > >> >>>>> direct func1 ip ff60000003334d00 > >> >>>>> migration/0-15 [000] ..... 3858.532232: my_direct_func1: my > >> >>>>> direct func1 ip 0 > >> >>>>> rcu_sched-14 [001] ..... 3858.532257: my_direct_func1: my > >> >>>>> direct func1 ip 0 > >> >>>>> insmod-415 [000] ..... 3858.532270: my_direct_func1: my > >> >>>>> direct func1 ip 7fffffffffffffff > >> >>>>> <idle>-0 [001] ..s1. 3858.539051: my_direct_func1: my > >> >>>>> direct func1 ip ff60000001ba9600 > >> >>>>> <idle>-0 [001] dns2. 3858.539124: my_direct_func1: my > >> >>>>> direct func1 ip ff60000001ba9600 > >> >>>>> rcu_sched-14 [001] ..... 3858.539208: my_direct_func1: my > >> >>>>> direct func1 ip 0 > >> >>>>> [...] > >> >>>>> > >> >>>>> If I understand it right, my_direct_func1() should print the address of > >> >>>>> some location in the code, probably - at the beginning of the traced > >> >>>>> functions. > >> >>>>> > >> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code > >> >>>>> addresses. > >> >>>>> > >> >>>> The invalid code address is only printed by accessing the schedule() > >> >>>> function's first argument whose address stores in a0 register. > >> >>>> While schedule() actually has no parameter declared, so my_direct_func > >> >>>> just prints the a0 in the context of the schedule()'s caller and > >> >>>> the address maybe varies depending on the caller. > >> >>>> > >> >>>> I can't really understand why tracing the first argument of the > >> >>>> schedule() function, but it seems nonsense at this point. > >> >>> > >> >>> The question is, what should be passed as the argument(s) of > >> >>> my_direct_func() in this particular sample module. The kernel docs and > >> >>> commit logs seem to contain no info on that. > >> >>> > >> >>> With direct functions, I suppose, the trampoline can pass anything it > >> >>> wants to my_direct_func(), not just the arguments of the traced function. > >> >>> > >> >>> I'd check what these sample modules do on x86 and would try to match > >> >>> that behaviour on RISC-V. > >> >> > >> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko > >> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should > >> >> be passed to my_direct_func(). > >> >> > >> >> ftrace-direct-multi.ko: > >> >> # TASK-PID CPU# ||||| TIMESTAMP FUNCTION > >> >> # | | | ||||| | | > >> >> insmod-10829 [000] d.h1. 1719.518535: my_direct_func: ip > >> >> ffffffff87332f45 // wake_up_process+0x5 > >> >> rcu_tasks_kthre-11 [000] ..... 1719.518696: my_direct_func: ip > >> >> ffffffff8828d935 // schedule+0x5 > >> >> insmod-10829 [000] ..... 1719.518708: my_direct_func: ip > >> >> ffffffff8828d935 > >> >> systemd-journal-293 [001] ..... 1719.518823: my_direct_func: ip > >> >> ffffffff8828d935 > >> >> systemd-1 [000] ..... 1719.519141: my_direct_func: ip > >> >> ffffffff8828d935 > >> >> <idle>-0 [001] ..s1. 1719.521889: my_direct_func: ip > >> >> ffffffff87332f45 > >> >> <idle>-0 [000] d.s2. 1719.521901: my_direct_func: ip > >> >> ffffffff87332f45 > >> >> rcu_preempt-15 [001] ..... 1719.521917: my_direct_func: ip > >> >> ffffffff8828d935 > >> >> [...] > >> >> > >> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations > >> >> where the execution of the traced functions resumes after the Ftrace > >> >> trampoline has finished. > >> >> > >> >> The results with ftrace-direct-multi-modify.ko are similar to that. > >> >> > >> >> The samples look like a demonstration, that one can pass anything > >> >> necessary to the handler in case of "direct" functions. > >> >> > >> >> I suppose, the RISC-V-specific asm code in these two sample modules > >> >> could be updated to pass the saved pc value to my_direct_func() in a0. > >> > > >> > Yes, you're right. > >> > > >> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of > >> > traced function with mcount offset. > >> > > >> > Here is the updated patch for your reference. > >> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318 > >> > >> Thank you for the quick fix. This one looks good to me. > >> > >> ftrace-direct-multi*.ko now report the ip values corresponding to > >> schedule+0x8 and wake_up_process+0x8, which is what was expected here. > >> > >> One more thing: please change my "Co-developed-by:" into "Tested-by:" in > >> your patch, becase this is what I actually did: tested it and reported > >> the results. I cannot take your credit for development of this patch ;-) > >> > >> Looking forward for v8 of the series. > >> > > >> > > >> >> > >> >>> > >> >>>> > >> >>>> As for this patch, it just impls a simple mcount (direct_caller) to > >> >>>> trace kernel functions, and basically saves the necessary ABI, > >> >>>> call the tracing function, and restores the ABI, just like other > >> >>>> arches do. > >> >>>> so It shouldn't be blamed. > >> >>>> > >> >>>> I started an independent patch to replace schedule with kick_process > >> >>>> to make these samples more reasonable. And It has no conflict with the > >> >>>> current patch, so we can go on. > >> >>>> > >> >>>> Link: > >> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u > >> >>>> > >> >>>>> The same issue is with ftrace-direct-multi-modify.ko. > >> >>>>> > >> >>>>> Is anything missing here? > >> >>>>> > >> >>>>>> > >> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > >> >>>>>> index 307a9f413edd..e944af44f681 100644 > >> >>>>>> --- a/arch/riscv/Kconfig > >> >>>>>> +++ b/arch/riscv/Kconfig > >> >>>>>> @@ -112,6 +112,8 @@ config RISCV > >> >>>>>> select HAVE_POSIX_CPU_TIMERS_TASK_WORK > >> >>>>>> select HAVE_REGS_AND_STACK_ACCESS_API > >> >>>>>> select HAVE_FUNCTION_ARG_ACCESS_API > >> >>>>>> + select HAVE_SAMPLE_FTRACE_DIRECT > >> >>>>>> + select HAVE_SAMPLE_FTRACE_DIRECT_MULTI > >> >>>>>> select HAVE_STACKPROTECTOR > >> >>>>>> select HAVE_SYSCALL_TRACEPOINTS > >> >>>>>> select HAVE_RSEQ > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c > >> >>>>>> b/samples/ftrace/ftrace-direct-modify.c > >> >>>>>> index de5a0f67f320..be7bf472c3c7 100644 > >> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c > >> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *); > >> >>>>>> > >> >>>>>> static unsigned long my_ip = (unsigned long)schedule; > >> >>>>>> > >> >>>>>> +#ifdef CONFIG_RISCV > >> >>>>>> + > >> >>>>>> +asm (" .pushsection .text, \"ax\", @progbits\n" > >> >>>>>> +" .type my_tramp1, @function\n" > >> >>>>>> +" .globl my_tramp1\n" > >> >>>>>> +" my_tramp1:\n" > >> >>>>>> +" addi sp,sp,-16\n" > >> >>>>>> +" sd t0,0(sp)\n" > >> >>>>>> +" sd ra,8(sp)\n" > >> >>>>>> +" call my_direct_func1\n" > >> >>>>>> +" ld t0,0(sp)\n" > >> >>>>>> +" ld ra,8(sp)\n" > >> >>>>>> +" addi sp,sp,16\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp1, .-my_tramp1\n" > >> >>>>>> + > >> >>>>>> +" .type my_tramp2, @function\n" > >> >>>>>> +" .globl my_tramp2\n" > >> >>>>>> +" my_tramp2:\n" > >> >>>>>> +" addi sp,sp,-16\n" > >> >>>>>> +" sd t0,0(sp)\n" > >> >>>>>> +" sd ra,8(sp)\n" > >> >>>>>> +" call my_direct_func2\n" > >> >>>>>> +" ld t0,0(sp)\n" > >> >>>>>> +" ld ra,8(sp)\n" > >> >>>>>> +" addi sp,sp,16\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp2, .-my_tramp2\n" > >> >>>>>> +" .popsection\n" > >> >>>>>> +); > >> >>>>>> + > >> >>>>>> +#endif /* CONFIG_RISCV */ > >> >>>>>> + > >> >>>>>> #ifdef CONFIG_X86_64 > >> >>>>>> > >> >>>>>> #include <asm/ibt.h> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c > >> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c > >> >>>>>> index d52370cad0b6..10884bf418f7 100644 > >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c > >> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip) > >> >>>>>> extern void my_tramp1(void *); > >> >>>>>> extern void my_tramp2(void *); > >> >>>>>> > >> >>>>>> +#ifdef CONFIG_RISCV > >> >>>>>> + > >> >>>>>> +asm (" .pushsection .text, \"ax\", @progbits\n" > >> >>>>>> +" .type my_tramp1, @function\n" > >> >>>>>> +" .globl my_tramp1\n" > >> >>>>>> +" my_tramp1:\n" > >> >>>>>> +" addi sp,sp,-24\n" > >> >>>>>> +" sd a0,0(sp)\n" > >> >>>>>> +" sd t0,8(sp)\n" > >> >>>>>> +" sd ra,16(sp)\n" > >> >>>>>> +" call my_direct_func1\n" > >> >>>>>> +" ld a0,0(sp)\n" > >> >>>>>> +" ld t0,8(sp)\n" > >> >>>>>> +" ld ra,16(sp)\n" > >> >>>>>> +" addi sp,sp,24\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp1, .-my_tramp1\n" > >> >>>>>> + > >> >>>>>> +" .type my_tramp2, @function\n" > >> >>>>>> +" .globl my_tramp2\n" > >> >>>>>> +" my_tramp2:\n" > >> >>>>>> +" addi sp,sp,-24\n" > >> >>>>>> +" sd a0,0(sp)\n" > >> >>>>>> +" sd t0,8(sp)\n" > >> >>>>>> +" sd ra,16(sp)\n" > >> >>>>>> +" call my_direct_func2\n" > >> >>>>>> +" ld a0,0(sp)\n" > >> >>>>>> +" ld t0,8(sp)\n" > >> >>>>>> +" ld ra,16(sp)\n" > >> >>>>>> +" addi sp,sp,24\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp2, .-my_tramp2\n" > >> >>>>>> +" .popsection\n" > >> >>>>>> +); > >> >>>>>> + > >> >>>>>> +#endif /* CONFIG_RISCV */ > >> >>>>>> + > >> >>>>>> #ifdef CONFIG_X86_64 > >> >>>>>> > >> >>>>>> #include <asm/ibt.h> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c > >> >>>>>> b/samples/ftrace/ftrace-direct-multi.c > >> >>>>>> index ec1088922517..a35bf43bf6d7 100644 > >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c > >> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip) > >> >>>>>> > >> >>>>>> extern void my_tramp(void *); > >> >>>>>> > >> >>>>>> +#ifdef CONFIG_RISCV > >> >>>>>> + > >> >>>>>> +asm (" .pushsection .text, \"ax\", @progbits\n" > >> >>>>>> +" .type my_tramp, @function\n" > >> >>>>>> +" .globl my_tramp\n" > >> >>>>>> +" my_tramp:\n" > >> >>>>>> +" addi sp,sp,-24\n" > >> >>>>>> +" sd a0,0(sp)\n" > >> >>>>>> +" sd t0,8(sp)\n" > >> >>>>>> +" sd ra,16(sp)\n" > >> >>>>>> +" call my_direct_func\n" > >> >>>>>> +" ld a0,0(sp)\n" > >> >>>>>> +" ld t0,8(sp)\n" > >> >>>>>> +" ld ra,16(sp)\n" > >> >>>>>> +" addi sp,sp,24\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp, .-my_tramp\n" > >> >>>>>> +" .popsection\n" > >> >>>>>> +); > >> >>>>>> + > >> >>>>>> +#endif /* CONFIG_RISCV */ > >> >>>>>> + > >> >>>>>> #ifdef CONFIG_X86_64 > >> >>>>>> > >> >>>>>> #include <asm/ibt.h> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c > >> >>>>>> b/samples/ftrace/ftrace-direct-too.c > >> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644 > >> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c > >> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma, > >> >>>>>> > >> >>>>>> extern void my_tramp(void *); > >> >>>>>> > >> >>>>>> +#ifdef CONFIG_RISCV > >> >>>>>> + > >> >>>>>> +asm (" .pushsection .text, \"ax\", @progbits\n" > >> >>>>>> +" .type my_tramp, @function\n" > >> >>>>>> +" .globl my_tramp\n" > >> >>>>>> +" my_tramp:\n" > >> >>>>>> +" addi sp,sp,-40\n" > >> >>>>>> +" sd a0,0(sp)\n" > >> >>>>>> +" sd a1,8(sp)\n" > >> >>>>>> +" sd a2,16(sp)\n" > >> >>>>>> +" sd t0,24(sp)\n" > >> >>>>>> +" sd ra,32(sp)\n" > >> >>>>>> +" call my_direct_func\n" > >> >>>>>> +" ld a0,0(sp)\n" > >> >>>>>> +" ld a1,8(sp)\n" > >> >>>>>> +" ld a2,16(sp)\n" > >> >>>>>> +" ld t0,24(sp)\n" > >> >>>>>> +" ld ra,32(sp)\n" > >> >>>>>> +" addi sp,sp,40\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp, .-my_tramp\n" > >> >>>>>> +" .popsection\n" > >> >>>>>> +); > >> >>>>>> + > >> >>>>>> +#endif /* CONFIG_RISCV */ > >> >>>>>> + > >> >>>>>> #ifdef CONFIG_X86_64 > >> >>>>>> > >> >>>>>> #include <asm/ibt.h> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c > >> >>>>>> b/samples/ftrace/ftrace-direct.c > >> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644 > >> >>>>>> --- a/samples/ftrace/ftrace-direct.c > >> >>>>>> +++ b/samples/ftrace/ftrace-direct.c > >> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p) > >> >>>>>> > >> >>>>>> extern void my_tramp(void *); > >> >>>>>> > >> >>>>>> +#ifdef CONFIG_RISCV > >> >>>>>> + > >> >>>>>> +asm (" .pushsection .text, \"ax\", @progbits\n" > >> >>>>>> +" .type my_tramp, @function\n" > >> >>>>>> +" .globl my_tramp\n" > >> >>>>>> +" my_tramp:\n" > >> >>>>>> +" addi sp,sp,-24\n" > >> >>>>>> +" sd a0,0(sp)\n" > >> >>>>>> +" sd t0,8(sp)\n" > >> >>>>>> +" sd ra,16(sp)\n" > >> >>>>>> +" call my_direct_func\n" > >> >>>>>> +" ld a0,0(sp)\n" > >> >>>>>> +" ld t0,8(sp)\n" > >> >>>>>> +" ld ra,16(sp)\n" > >> >>>>>> +" addi sp,sp,24\n" > >> >>>>>> +" jr t0\n" > >> >>>>>> +" .size my_tramp, .-my_tramp\n" > >> >>>>>> +" .popsection\n" > >> >>>>>> +); > >> >>>>>> + > >> >>>>>> +#endif /* CONFIG_RISCV */ > >> >>>>>> + > >> >>>>>> #ifdef CONFIG_X86_64 > >> >>>>>> > >> >>>>>> #include <asm/ibt.h> > >> >>>>>> -- > >> >>>>>> 2.36.1 > >> >>>> > >> >>>> -- > >> >>>> Thanks, > >> >>>> Song > >> >>>> > >> >>> > >> >>> Regards, > >> >>> Evgenii > >> >> > >> >> > >> > > >> > > >> > -- > >> > Thanks, > >> > Song > >> > > >> > >> > > > > > > -- > > Best Regards > > Guo Ren
-- Best Regards Guo Ren
| |