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Date:   Mon, 16 Jan 2023 17:30:13 +0300
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Subject: Re: [PATCH -next V7 6/7] samples: ftrace: Add riscv support for
 SAMPLE_FTRACE_DIRECT[_MULTI]
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To:     <guoren@kernel.org>, <suagrfillet@gmail.com>
CC:     <linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <anup@brainfault.org>, <paul.walmsley@sifive.com>,
        <palmer@dabbelt.com>, <conor.dooley@microchip.com>,
        <heiko@sntech.de>, <rostedt@goodmis.org>, <mhiramat@kernel.org>,
        <jolsa@redhat.com>, <bp@suse.de>, <jpoimboe@kernel.org>,
        <andy.chiu@sifive.com>, <linux@yadro.com>
References: <20230112090603.1295340-1-guoren@kernel.org>
 <20230112090603.1295340-7-guoren@kernel.org>
From:   Evgenii Shatokhin <e.shatokhin@yadro.com>
In-Reply-To: <20230112090603.1295340-7-guoren@kernel.org>
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Precedence: bulk

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 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