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

Peter Zijlstra
2019-11-11T17:26:32Z

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;
> }