Re: [Buildroot] [PATCH] boot/at91bootstrap: disable PIE and stack-protector build flags

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Köry,

On Tue,  4 Oct 2022 14:52:41 +0200
Köry Maincent via buildroot <buildroot@buildroot.org> wrote:

> From: Kory Maincent <kory.maincent@bootlin.com>
> 
> The toolchain wrapper add automatically Position Independent Execution
> and stack protector flags in the build process when selected in the
> configuration. at91bootstrap does not support these, therefore I added a
> patch to disable them in the Makefiles
> 
> Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
> ---
>  ...ck-protector-and-the-PIE-build-flags.patch | 502 ++++++++++++++++++
>  1 file changed, 502 insertions(+)
>  create mode 100644 boot/at91bootstrap/0004-ensure-the-stack-protector-and-the-PIE-build-flags.patch

Thanks for the patch. However, the at91bootstrap patch was highly
repetitive, and we have no chance of merging it upstream since upstream
is essentially dead. So instead, I committed this:

+# The at91bootstrap Makefile doesn't support customizing
+# CFLAGS/LDFLAGS, so we cheat and pass our custom flags through CC and
+# LD.
 define AT91BOOTSTRAP_BUILD_CMDS
-       $(MAKE1) CROSS_COMPILE=$(TARGET_CROSS) -C $(@D)/$(AT91BOOTSTRAP_MAKE_SUBDIR)
+       $(MAKE1) CROSS_COMPILE=$(TARGET_CROSS) \
+               CC="$(TARGET_CC) -fno-stack-protector" \
+               LD="$(TARGET_CC) -fno-PIE" \
+               -C $(@D)/$(AT91BOOTSTRAP_MAKE_SUBDIR)
 endef

which achieves exactly the same, but is more concise.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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