Re: [PATCH] powerpc: use PTRRELOC during early init

[Christophe LEROY <christophe.leroy@c-s.fr>]

Hi Andreas,

Le 03/10/2018 à 00:33, Andreas Schwab a écrit :
> This fixes a crash on powerpc32 when using global data during early init
> without relocating its address.
> 
> Fixes: 51c3c62b58 (powerpc: Avoid code patching freed init sections)
> Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
> ---
>   arch/powerpc/lib/code-patching.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index 6ae2777c22..6192fdae36 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -29,7 +29,7 @@ static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
>   	int err;
>   
>   	/* Make sure we aren't patching a freed init section */
> -	if (init_mem_is_free && init_section_contains(exec_addr, 4)) {
> +	if (*PTRRELOC(&init_mem_is_free) && init_section_contains(exec_addr, 4)) {

That's not the best solution. In the past we already did our best to 
separate early use of patch_instruction() , that's how 
raw_patch_instruction() was born, see 
https://patchwork.ozlabs.org/patch/840974/

Here, it idea is similar, this test should not apply to 
raw_patch_instruction()

Did you try my proposed fix https://patchwork.ozlabs.org/patch/977195/ ?

Christophe

>   		pr_debug("Skipping init section patching addr: 0x%px\n", exec_addr);
>   		return 0;
>   	}
>