Christophe Leroy <christophe.le...@c-s.fr> writes:
> diff --git a/arch/powerpc/include/asm/stackprotector.h
> b/arch/powerpc/include/asm/stackprotector.h
> new file mode 100644
> index 0000000..de00332
> --- /dev/null
> +++ b/arch/powerpc/include/asm/stackprotector.h
> @@ -0,0 +1,38 @@
> +/*
> + * GCC stack protector support.
> + *
> + * Stack protector works by putting predefined pattern at the start of
> + * the stack frame and verifying that it hasn't been overwritten when
> + * returning from the function. The pattern is called stack canary
> + * and gcc expects it to be defined by a global variable called
> + * "__stack_chk_guard" on ARM. This unfortunately means that on SMP
^
PPC
> + * we cannot have a different canary value per task.
> + */
> +
> +#ifndef _ASM_STACKPROTECTOR_H
> +#define _ASM_STACKPROTECTOR_H 1
We usually just define it, not define it to 1.
> +
> +#include <linux/random.h>
> +#include <linux/version.h>
> +
> +extern unsigned long __stack_chk_guard;
> +
> +/*
> + * Initialize the stackprotector canary value.
> + *
> + * NOTE: this must only be called from functions that never return,
> + * and it must always be inlined.
> + */
> +static __always_inline void boot_init_stack_canary(void)
> +{
> + unsigned long canary;
> +
> + /* Try to get a semi random initial value. */
> + get_random_bytes(&canary, sizeof(canary));
> + canary ^= LINUX_VERSION_CODE;
What about mixing in an mftb() as well ?
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index e59ed6a..4a62179 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -19,6 +19,11 @@ CFLAGS_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>
> +# -fstack-protector triggers protection checks in this code,
> +# but it is being used too early to link to meaningful stack_chk logic.
> +nossp_flags := $(call cc-option, -fno-stack-protector)
> +CFLAGS_prom_init.o := $(nossp_flags)
We've already assigned to CFLAGS_prom_init.o so I think you should be
using += not := shouldn't you?
Also it could just be a single line:
CFLAGS_prom_init.o += $(call cc-option, -fno-stack-protector)
cheers
