Re: [Xen-devel] [PATCH 5/5] xen: Disallow variable length arrays

[Julien Grall <julien.grall@xxxxxxx>]

On 09/24/2018 02:00 PM, Andrew Cooper wrote:
> Variable length arrays result in excess stack utilisation, with a risk
> of stack overflow if the length is too large.  It also results in fairly
> poor asm generation, because of requiring a divide as part of the space
> calcuation.
>
> Xen no longer has any variable length arrays, so take the opportunity to
> formally disallow them.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

> ---
> CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Tim Deegan <tim@xxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
>   xen/Rules.mk | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/xen/Rules.mk b/xen/Rules.mk
> index ac0a8ea..bd11e26 100644
> --- a/xen/Rules.mk
> +++ b/xen/Rules.mk
> @@ -58,6 +58,7 @@ CFLAGS += -Werror -Wredundant-decls -Wno-pointer-arith
>   CFLAGS += -pipe -D__XEN__ -include $(BASEDIR)/include/xen/config.h
>   CFLAGS-$(CONFIG_DEBUG_INFO) += -g
>   CFLAGS += '-D__OBJECT_FILE__="$@"'
> +$(call cc-option-add,CFLAGS,CC,-Wvla)
>   
>   ifneq ($(clang),y)
>   # Clang doesn't understand this command line argument, and doesn't appear to
--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel