Re: [PATCH -v5 13/17] arm/ftrace: Use __patch_text_real()

[Peter Zijlstra]

On Mon, Nov 11, 2019 at 06:19:55PM +0100, Peter Zijlstra wrote:

> If you can give me a Tested-by, I'll replace it with the below... :-)
> 
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -22,6 +22,7 @@
>  #include <asm/ftrace.h>
>  #include <asm/insn.h>
>  #include <asm/set_memory.h>
> +#include <asm/patch.h>
>  
>  #ifdef CONFIG_THUMB2_KERNEL
>  #define	NOP		0xf85deb04	/* pop.w {lr} */
> @@ -35,9 +36,7 @@ static int __ftrace_modify_code(void *da
>  {
>  	int *command = data;
>  
> -	set_kernel_text_rw();
>  	ftrace_modify_all_code(*command);
> -	set_kernel_text_ro();
>  
>  	return 0;
>  }
> @@ -59,13 +58,11 @@ static unsigned long adjust_address(stru
>  
>  int ftrace_arch_code_modify_prepare(void)
>  {
> -	set_all_modules_text_rw();
>  	return 0;
>  }
>  
>  int ftrace_arch_code_modify_post_process(void)
>  {
> -	set_all_modules_text_ro();
>  	/* Make sure any TLB misses during machine stop are cleared. */
>  	flush_tlb_all();
>  	return 0;
> @@ -97,10 +94,7 @@ static int ftrace_modify_code(unsigned l
>  			return -EINVAL;
>  	}
>  
> -	if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
> -		return -EPERM;
> -
> -	flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
> +	__patch_text_real((void *)pc, new, true);

I'll even make that: __patch_text((void *)pc, new);

>  
>  	return 0;
>  }