[PATCH] Fix strstr/strcasestr/fma/fmaf on x86_64

[PATCH] Fix strstr/strcasestr/fma/fmaf on x86_64

[Jakub Jelinek]

Hi!

Without this patch e.g. strstr IFUNC looks like:
0000000000089090 <strstr>:
   89090:       48 83 ec 08             sub    $0x8,%rsp
   89094:       8b 05 86 51 2f 00       mov    0x2f5186(%rip),%eax        # 37e220 <__cpu_features>
   8909a:       85 c0                   test   %eax,%eax
   8909c:       74 22                   je     890c0 <strstr+0x30>
   8909e:       f6 05 8d 51 2f 00 10    testb  $0x10,0x2f518d(%rip)       # 37e232 <__cpu_features+0x12>
   890a5:       48 8b 05 44 fd 2e 00    mov    0x2efd44(%rip),%rax        # 378df0 <_DYNAMIC+0x2d0>
   890ac:       48 0f 45 05 04 fe 2e    cmovne 0x2efe04(%rip),%rax        # 378eb8 <_DYNAMIC+0x398>
   890b3:       00 
   890b4:       48 83 c4 08             add    $0x8,%rsp
   890b8:       c3                      retq   
   890b9:       0f 1f 80 00 00 00 00    nopl   0x0(%rax)
   890c0:       e8 2b 5e f9 ff          callq  1eef0 <__init_cpu_features>
   890c5:       eb d7                   jmp    8909e <strstr+0xe>
   890c7:       66 0f 1f 84 00 00 00    nopw   0x0(%rax,%rax,1)
   890ce:       00 00 
Note that __strstr_sse2 and __strstr_sse42 addresses are read from GOT where
they have RELATIVE relocation on them.  This is completely unnecessary (they
are not exported from libc.so), and worse it breaks when some library has
e.g. strstr relocation resolved (with LD_BIND_NOW=1) before libc.so has been
relocated.  Even with this patch, I still wonder how can fma/fmaf actually
work with LD_BIND_NOW=1, because those IFUNC functions actually make a PLT
call.  If libm.so's relocation hasn't been started yet, I wonder what will
happen.

2009-09-02  Jakub Jelinek  <jakub@redhat.com>

	* sysdeps/x86_64/multiarch/strstr-c.c (__strstr_sse42, __strstr_sse2):
	Add attribute_hidden.
	* sysdeps/x86_64/multiarch/strcasestr-c.c (__strcasestr_sse42,
	__strcasestr_sse2): Likewise.
	* sysdeps/x86_64/multiarch/s_fma.c (__fma_sse2): Add attribute_hidden.
	(__fma_fma): Make static.
	* sysdeps/x86_64/multiarch/s_fmaf.c (__fmaf_sse2): Add attribute_hidden.
	(__fmaf_fma): Make static.

--- libc/sysdeps/x86_64/multiarch/strstr-c.c.jj	2009-07-23 08:59:29.000000000 +0200
+++ libc/sysdeps/x86_64/multiarch/strstr-c.c	2009-09-02 10:34:48.000000000 +0200
@@ -7,6 +7,7 @@
 
 #include "string/strstr.c"
 
-extern char *__strstr_sse42 (const char *, const char *);
+extern char *__strstr_sse42 (const char *, const char *) attribute_hidden;
+extern __typeof (__strstr_sse2) __strstr_sse2 attribute_hidden;
 
 libc_ifunc (strstr, HAS_SSE4_2 ? __strstr_sse42 : __strstr_sse2);
--- libc/sysdeps/x86_64/multiarch/strcasestr-c.c.jj	2009-07-23 08:59:29.000000000 +0200
+++ libc/sysdeps/x86_64/multiarch/strcasestr-c.c	2009-09-02 10:36:07.000000000 +0200
@@ -7,7 +7,8 @@
 
 #include "string/strcasestr.c"
 
-extern char *__strcasestr_sse42 (const char *, const char *);
+extern char *__strcasestr_sse42 (const char *, const char *) attribute_hidden;
+extern __typeof (__strcasestr_sse2) __strcasestr_sse2 attribute_hidden;
 
 #if 1
 libc_ifunc (__strcasestr,
--- libc/sysdeps/x86_64/multiarch/s_fma.c.jj	2009-07-31 12:52:08.000000000 +0200
+++ libc/sysdeps/x86_64/multiarch/s_fma.c	2009-09-02 10:38:00.000000000 +0200
@@ -24,10 +24,10 @@
 
 #ifdef HAVE_AVX_SUPPORT
 
-extern double __fma_sse2 (double x, double y, double z);
+extern double __fma_sse2 (double x, double y, double z) attribute_hidden;
 
 
-double
+static double
 __fma_fma (double x, double y, double z)
 {
   asm ("vfmadd213sd %3, %2, %0" : "=x" (x) : "0" (x), "x" (y), "xm" (z));
--- libc/sysdeps/x86_64/multiarch/s_fmaf.c.jj	2009-07-31 12:52:08.000000000 +0200
+++ libc/sysdeps/x86_64/multiarch/s_fmaf.c	2009-09-02 10:38:22.000000000 +0200
@@ -23,10 +23,10 @@
 
 #ifdef HAVE_AVX_SUPPORT
 
-extern float __fmaf_sse2 (float x, float y, float z);
+extern float __fmaf_sse2 (float x, float y, float z) attribute_hidden;
 
 
-float
+static float
 __fmaf_fma (float x, float y, float z)
 {
   asm ("vfmadd213ss %3, %2, %0" : "=x" (x) : "0" (x), "x" (y), "xm" (z));

	Jakub

Re: [PATCH] Fix strstr/strcasestr/fma/fmaf on x86_64

[Andreas Schwab]

Jakub Jelinek <jakub@redhat.com> writes:

> --- libc/sysdeps/x86_64/multiarch/strstr-c.c.jj	2009-07-23 08:59:29.000000000 +0200
> +++ libc/sysdeps/x86_64/multiarch/strstr-c.c	2009-09-02 10:34:48.000000000 +0200
> @@ -7,6 +7,7 @@
>  
>  #include "string/strstr.c"
>  
> -extern char *__strstr_sse42 (const char *, const char *);
> +extern char *__strstr_sse42 (const char *, const char *) attribute_hidden;
> +extern __typeof (__strstr_sse2) __strstr_sse2 attribute_hidden;

Shouldn't those use the libc_hidden* macros?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."