Re: [PATCH v4 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter

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

Le 05/08/2019 à 08:43, Jason Yan a écrit :
> One may want to disable kaslr when boot, so provide a cmdline parameter
> 'nokaslr' to support this.
> 
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> Cc: Diana Craciun <diana.craciun@nxp.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Kees Cook <keescook@chromium.org>
> Reviewed-by: Diana Craciun <diana.craciun@nxp.com>
> Tested-by: Diana Craciun <diana.craciun@nxp.com>

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

Tiny comment below.

> ---
>   arch/powerpc/kernel/kaslr_booke.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c
> index 4b3f19a663fc..7c3cb41e7122 100644
> --- a/arch/powerpc/kernel/kaslr_booke.c
> +++ b/arch/powerpc/kernel/kaslr_booke.c
> @@ -361,6 +361,18 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
>   	return kaslr_offset;
>   }
>   
> +static inline __init bool kaslr_disabled(void)
> +{
> +	char *str;
> +
> +	str = strstr(boot_command_line, "nokaslr");
> +	if ((str == boot_command_line) ||
> +	    (str > boot_command_line && *(str - 1) == ' '))
> +		return true;

I don't think additional () are needed for the left part 'str == 
boot_command_line'

> +
> +	return false;
> +}
> +
>   /*
>    * To see if we need to relocate the kernel to a random offset
>    * void *dt_ptr - address of the device tree
> @@ -376,6 +388,8 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
>   	kernel_sz = (unsigned long)_end - KERNELBASE;
>   
>   	kaslr_get_cmdline(dt_ptr);
> +	if (kaslr_disabled())
> +		return;
>   
>   	offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
>   
>