Messages in this thread | | | From | Song Shuai <> | Date | Tue, 17 Jan 2023 09:32:16 +0000 | Subject | Re: [PATCH -next V7 6/7] samples: ftrace: Add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI] |
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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.
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 > > > > > > Regards, > Evgenii > >
-- Thanks, Song
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