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Date:   Tue, 14 Jul 2020 20:32:54 +0900
From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     guoren@kernel.org
Cc:     palmerdabbelt@google.com, paul.walmsley@sifive.com,
        oleg@redhat.com, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, anup@brainfault.org,
        linux-csky@vger.kernel.org, greentime.hu@sifive.com,
        zong.li@sifive.com, me@packi.ch, bjorn.topel@gmail.com,
        Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH v3 3/7] riscv: Fixup kprobes handler couldn't change pc
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On Mon, 13 Jul 2020 23:39:18 +0000
guoren@kernel.org wrote:

> From: Guo Ren <guoren@linux.alibaba.com>
> 
> The "Changing Execution Path" section in the Documentation/kprobes.txt
> said:
> 
> Since kprobes can probe into a running kernel code, it can change the
> register set, including instruction pointer.
> 

Looks Good to me:)

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you!

> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Palmer Dabbelt <palmerdabbelt@google.com>
> ---
>  arch/riscv/kernel/mcount-dyn.S | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
> index 35a6ed7..4b58b54 100644
> --- a/arch/riscv/kernel/mcount-dyn.S
> +++ b/arch/riscv/kernel/mcount-dyn.S
> @@ -123,6 +123,7 @@ ENDPROC(ftrace_caller)
>  	sd	ra, (PT_SIZE_ON_STACK+8)(sp)
>  	addi	s0, sp, (PT_SIZE_ON_STACK+16)
>  
> +	sd ra,  PT_EPC(sp)
>  	sd x1,  PT_RA(sp)
>  	sd x2,  PT_SP(sp)
>  	sd x3,  PT_GP(sp)
> @@ -157,6 +158,7 @@ ENDPROC(ftrace_caller)
>  	.endm
>  
>  	.macro RESTORE_ALL
> +	ld ra,  PT_EPC(sp)
>  	ld x1,  PT_RA(sp)
>  	ld x2,  PT_SP(sp)
>  	ld x3,  PT_GP(sp)
> @@ -190,7 +192,6 @@ ENDPROC(ftrace_caller)
>  	ld x31, PT_T6(sp)
>  
>  	ld	s0, (PT_SIZE_ON_STACK)(sp)
> -	ld	ra, (PT_SIZE_ON_STACK+8)(sp)
>  	addi	sp, sp, (PT_SIZE_ON_STACK+16)
>  	.endm
>  
> -- 
> 2.7.4
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>