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Re: [RFC PATCH] configure: Poison (almost) all target-specific #defines
From: |
Claudio Fontana |
Subject: |
Re: [RFC PATCH] configure: Poison (almost) all target-specific #defines |
Date: |
Mon, 15 Mar 2021 15:07:39 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 |
On 3/15/21 2:54 PM, Thomas Huth wrote:
> We are generating a lot of target-specific defines in the *-config-devices.h
> and *-config-target.h files. Using them in common code is wrong and leads
> to very subtle bugs since a "#ifdef CONFIG_SOMETHING" is not working there
> as expected. To avoid these issues, we are already poisoning some of the
> macros in include/exec/poison.h - but maintaining this list manually is
> cumbersome. Thus let's generate the list of poisoned macros automatically
> instead.
> Note that CONFIG_TCG (which is also defined in config-host.h) and
> CONFIG_USER_ONLY are special, so we have to filter these out.
I have the impression that CONFIG_USER_ONLY should be poisoned too.
A lot of the
#ifndef CONFIG_USER_ONLY
end up currently doing the wrong thing in common modules includes,
especially due to the inverted nature of the check.
So the stuff that should be "hidden" for CONFIG_USER_ONLY, is actually
processed even for CONFIG_USER_ONLY in the common modules,
while in "specific" modules it isn't, which remains a potential for trouble IMO.
Ciao,
CLaudio
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> RFC since the shell stuff in "configure" is quite ugly ... maybe there's
> a better way to do this via meson, but my meson-foo is still lacking...
>
> Makefile | 2 +-
> configure | 5 +++++
> include/exec/poison.h | 2 ++
> 3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index bcbbec71a1..4cab10a2a4 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -213,7 +213,7 @@ qemu-%.tar.bz2:
>
> distclean: clean
> -$(quiet-@)test -f build.ninja && $(NINJA) $(NINJAFLAGS) -t clean -g ||
> :
> - rm -f config-host.mak config-host.h*
> + rm -f config-host.mak config-host.h* config-poison.h
> rm -f tests/tcg/config-*.mak
> rm -f config-all-disas.mak config.status
> rm -f roms/seabios/config.mak roms/vgabios/config.mak
> diff --git a/configure b/configure
> index f7d022a5db..c7b5df3a5c 100755
> --- a/configure
> +++ b/configure
> @@ -6441,6 +6441,11 @@ if test -n "${deprecated_features}"; then
> echo " features: ${deprecated_features}"
> fi
>
> +cat *-config-devices.h *-config-target.h | grep '^#define ' \
> + | grep -v CONFIG_TCG | grep -v CONFIG_USER_ONLY \
> + | sed -e 's/#define //' -e 's/ .*//' | sort -u \
> + | sed -e 's/^/#pragma GCC poison /' > config-poison.h
> +
> # Save the configure command line for later reuse.
> cat <<EOD >config.status
> #!/bin/sh
> diff --git a/include/exec/poison.h b/include/exec/poison.h
> index 4cd3f8abb4..9e55d5aec2 100644
> --- a/include/exec/poison.h
> +++ b/include/exec/poison.h
> @@ -4,6 +4,8 @@
> #ifndef HW_POISON_H
> #define HW_POISON_H
>
> +#include "config-poison.h"
> +
> #pragma GCC poison TARGET_I386
> #pragma GCC poison TARGET_X86_64
> #pragma GCC poison TARGET_AARCH64
>