Re: [PATCH][RFA/RFC] Stack clash mitigation patch 02/08

[Segher Boessenkool <segher@kernel.crashing.org>]

On Tue, Jul 11, 2017 at 03:20:12PM -0600, Jeff Law wrote:
>	* conifg/mips/mips.c (mips_expand_prologue): Likewise.

Typo ("conifg").

> --- a/gcc/defaults.h
> +++ b/gcc/defaults.h
> @@ -1408,8 +1408,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>  #endif
>  
>  /* The default is not to move the stack pointer.  */
> +/* The default is not to move the stack pointer, unless we are using
> +   stack clash prevention stack checking.  */
>  #ifndef STACK_CHECK_MOVING_SP
> -#define STACK_CHECK_MOVING_SP 0
> +#define STACK_CHECK_MOVING_SP\
> +  (flag_stack_check == STACK_CLASH_BUILTIN_STACK_CHECK)
>  #endif

Missing space before that backslash.

The documentation for STACK_CHECK_CONFIG_SP needs updating (its default
is no longer zero, for one).

I don't really see why this is so complicated, and why the rs6000
target changes (a later patch) are so big.  Why isn't it just simple
patches to allocate_stack (and the prologue thing), that check the
flag and if it is set do some probes?

I'll go sleep now, maybe I'll see it in the morning :-)


Segher