[Buildroot] [PATCH v2 1/1] qemu: add patch to fix SSP support detection

[Arnout Vandecappelle]

On 12-11-15 00:49, Rodrigo Rebello wrote:
> Arnout,
> 
> 2015-11-11 21:30 GMT-02:00 Arnout Vandecappelle <arnout at mind.be>:
>> On 11-11-15 23:18, Rodrigo Rebello wrote:
[snip]
>>> +diff --git a/configure b/configure
>>> +index cd219d8..a6f4101 100755
>>> +--- a/configure
>>> ++++ b/configure
>>> +@@ -1471,6 +1471,24 @@ for flag in $gcc_flags; do
>>> + done
>>> +
>>> + if test "$stack_protector" != "no"; then
>>> ++  cat > $TMPC << EOF
>>> ++void foo(const char *c);
>>
>>  This declaration is unnecessary.
>>
> 
> Actually it is necessary, otherwise compiling the test code fails with:
> 
> config-temp/qemu-conf.c:3:6: error: no previous prototype for ‘foo’
> [-Werror=missing-prototypes]
>  void foo(const char *c)
>       ^
> 
> Because in configure, line 410, -Wmissing-prototypes is added to
> QEMU_FLAGS (used in every compile test), and tests are run with
> -Werror by default, unless --disable-werror is passed to the configure
> script.

 Right. And I guess declaring it static means that the whole function could be
elided so still no stack protection.

 I wonder what would happen if LTO were enabled, since in that case the function
could be elided again...

 To solve this fundamentally in buildroot, perhaps we should patch the gcc
wrapper to fail when -fstack-protector-* is passed when SSP is not enabled.

 Regards,
 Arnout

-- 
Arnout Vandecappelle      arnout dot vandecappelle at essensium dot com
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