On 16.12.2016 04:08, Michael Niedermayer wrote:
> On Fri, Dec 16, 2016 at 02:36:53AM +0100, Andreas Cadhalpun wrote:
>> Otherwise the build fails when configuring with --toolchain=hardened
>> --disable-pic on i386 using gcc 4.8:
>> error: PIC register clobbered by '%ebx' in 'asm'
>>
>> Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
>> ---
>> libswscale/x86/hscale_fast_bilinear_simd.c | 20 ++++++++++----------
>> 1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/libswscale/x86/hscale_fast_bilinear_simd.c
>> b/libswscale/x86/hscale_fast_bilinear_simd.c
>> index 2cba5f0..3f0f5f5 100644
>> --- a/libswscale/x86/hscale_fast_bilinear_simd.c
>> +++ b/libswscale/x86/hscale_fast_bilinear_simd.c
>> @@ -199,7 +199,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
>> #if ARCH_X86_64
>> uint64_t retsave;
>> #else
>> -#if defined(PIC)
>> +#if defined(PIC) || defined(__PIE__)
>
> please correct me if iam wrong
> our configure adds -DPIC to define PIC when its enabled,
> it does not add that in this case but gcc is still generating PIC code
> that doesnt seem good
gcc does not generate PIC, only PIE, which is subtly different.
What's wrong here is that this code in swscale tries to determine, whether
or not the ebx register can be used for asm, but doesn't check that correctly.
However, configure has a working check for that, the result of which can
be used here. Patch doing that is attached.
Best regards,
Andreas
>From 7b5d0714482a0ec42d317fa1e9fa095180e39ccd Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
Date: Fri, 16 Dec 2016 02:29:56 +0100
Subject: [PATCH] swscale: save ebx register when it is not available
Configure checks if the ebx register can be used for asm and it has to
be saved if and only if this is not the case.
Without this the build fails when configuring with --toolchain=hardened
--disable-pic on i386 using gcc 4.8:
error: PIC register clobbered by '%ebx' in 'asm'
In that case gcc 4.8 reserves the ebx register for the GOT needed for
PIE, so it can't be used in asm directly.
Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
libswscale/x86/hscale_fast_bilinear_simd.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/libswscale/x86/hscale_fast_bilinear_simd.c b/libswscale/x86/hscale_fast_bilinear_simd.c
index 2cba5f0a1c..60a2cbfc50 100644
--- a/libswscale/x86/hscale_fast_bilinear_simd.c
+++ b/libswscale/x86/hscale_fast_bilinear_simd.c
@@ -199,7 +199,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
#if ARCH_X86_64
uint64_t retsave;
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
uint64_t ebxsave;
#endif
#endif
@@ -209,7 +209,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
"mov -8(%%rsp), %%"FF_REG_a" \n\t"
"mov %%"FF_REG_a", %5 \n\t" // retsave
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
"mov %%"FF_REG_b", %5 \n\t" // ebxsave
#endif
#endif
@@ -255,7 +255,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
"mov %5, %%"FF_REG_a" \n\t"
"mov %%"FF_REG_a", -8(%%rsp) \n\t"
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
"mov %5, %%"FF_REG_b" \n\t"
#endif
#endif
@@ -264,12 +264,12 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
#if ARCH_X86_64
,"m"(retsave)
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
,"m" (ebxsave)
#endif
#endif
: "%"FF_REG_a, "%"FF_REG_c, "%"FF_REG_d, "%"FF_REG_S, "%"FF_REG_D
-#if ARCH_X86_64 || !defined(PIC)
+#if ARCH_X86_64 || HAVE_EBX_AVAILABLE
,"%"FF_REG_b
#endif
);
@@ -289,7 +289,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
#if ARCH_X86_64
DECLARE_ALIGNED(8, uint64_t, retsave);
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
DECLARE_ALIGNED(8, uint64_t, ebxsave);
#endif
#endif
@@ -298,7 +298,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
"mov -8(%%rsp), %%"FF_REG_a" \n\t"
"mov %%"FF_REG_a", %7 \n\t" // retsave
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
"mov %%"FF_REG_b", %7 \n\t" // ebxsave
#endif
#endif
@@ -332,7 +332,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
"mov %7, %%"FF_REG_a" \n\t"
"mov %%"FF_REG_a", -8(%%rsp) \n\t"
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
"mov %7, %%"FF_REG_b" \n\t"
#endif
#endif
@@ -341,12 +341,12 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
#if ARCH_X86_64
,"m"(retsave)
#else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
,"m" (ebxsave)
#endif
#endif
: "%"FF_REG_a, "%"FF_REG_c, "%"FF_REG_d, "%"FF_REG_S, "%"FF_REG_D
-#if ARCH_X86_64 || !defined(PIC)
+#if ARCH_X86_64 || HAVE_EBX_AVAILABLE
,"%"FF_REG_b
#endif
);
--
2.11.0
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