Re: [RFC PATCH 5/5] Revert "meson.build: Disable -fzero-call-used-regs on OpenBSD"

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, May 08, 2025 at 04:41:20PM +0200, Thomas Huth wrote:
> From: Thomas Huth <thuth@redhat.com>
> 
> This reverts commit 2d6d995709482cc8b6a76dbb5334a28001a14a9a.
> 
> OpenBSD 7.7 fixed the problem with the -fzero-call-used-regs on OpenBSD,
> see https://github.com/openbsd/src/commit/03eca72d1e030b7a542cd6aec1 for
> the fix there.
> 
> Suggested-by: Brad Smith <brad@comstyle.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  Note: Marked as RFC since we likely can include this only once OpenBSD
>  7.6 goes out of service, see:
>  https://lists.libreplanet.org/archive/html/qemu-arm/2025-05/msg00559.html

Yep, we have to wait a bit longer, unless someone can confirm the
fix was backported to 7.6

> 
>  meson.build | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/meson.build b/meson.build
> index 6c61e1dcaec..5f0e6a65cb0 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -699,11 +699,7 @@ hardening_flags = [
>  #
>  # NB: Clang 17 is broken and SEGVs
>  # https://github.com/llvm/llvm-project/issues/75168
> -#
> -# NB2: This clashes with the "retguard" extension of OpenBSD's Clang
> -# https://gitlab.com/qemu-project/qemu/-/issues/2278
> -if host_os != 'openbsd' and \
> -   cc.compiles('extern struct { void (*cb)(void); } s; void f(void) { s.cb(); }',
> +if cc.compiles('extern struct { void (*cb)(void); } s; void f(void) { s.cb(); }',
>                 name: '-fzero-call-used-regs=used-gpr',
>                 args: ['-O2', '-fzero-call-used-regs=used-gpr'])
>      hardening_flags += '-fzero-call-used-regs=used-gpr'
> -- 
> 2.49.0
> 

With regards,
Daniel
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