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PowerPC: Fix ftime gettimeofday internal call returning bogus data

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This patches fixes BZ#16430 by setting a different symbol for internal
GLIBC calls that points to ifunc resolvers. For PPC32, if the symbol
is defined as hidden (which is the case for gettimeofday and time) the
compiler will create local branches (symbol@local) and linker will not
create PLT calls (required for IFUNC). This will leads to internal symbol
calling the IFUNC resolver instead of the resolved symbol.
For PPC64 this behavior does not occur because a call to a function in
another translation unit might use a different toc pointer thus requiring
a PLT call.
This commit is contained in:
Adhemerval Zanella 2014-01-16 06:53:18 -06:00
parent 94d0cea0ad
commit 736c304a1a
3 changed files with 44 additions and 4 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2014-01-16 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
[BZ#16430]
* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
(__GI___gettimeofday): Alias for a different internal symbol to avoid
local calls issues by not having a PLT stub required for IFUNC calls.
* sysdeps/unix/sysv/linux/powerpc/time.c (__GI_time): Likewise.
2014-01-16 Joseph Myers <joseph@codesourcery.com>
* math/test-fpucw-ieee.c: Use <> in #include of test-fpucw.c.

20
sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
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@ -44,8 +44,24 @@ asm (".type __gettimeofday, %gnu_indirect_function");
/* This is doing "libc_hidden_def (__gettimeofday)" but the compiler won't
let us do it in C because it doesn't know we're defining __gettimeofday
here in this file. */
asm (".globl __GI___gettimeofday\n"
"__GI___gettimeofday = __gettimeofday");
asm (".globl __GI___gettimeofday");
/* __GI___gettimeofday is defined as hidden and for ppc32 it enables the
compiler make a local call (symbol@local) for internal GLIBC usage. It
means the PLT won't be used and the ifunc resolver will be called directly.
For ppc64 a call to a function in another translation unit might use a
different toc pointer thus disallowing direct branchess and making internal
ifuncs calls safe. */
#ifdef __powerpc64__
asm ("__GI___gettimeofday = __gettimeofday");
#else
int
__gettimeofday_vsyscall (struct timeval *tv, struct timezone *tz)
{
return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
}
asm ("__GI___gettimeofday = __gettimeofday_vsyscall");
#endif
#else

20
sysdeps/unix/sysv/linux/powerpc/time.c
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@ -54,8 +54,24 @@ asm (".type time, %gnu_indirect_function");
/* This is doing "libc_hidden_def (time)" but the compiler won't
* let us do it in C because it doesn't know we're defining time
* here in this file. */
asm (".globl __GI_time\n"
"__GI_time = time");
asm (".globl __GI_time");
/* __GI_time is defined as hidden and for ppc32 it enables the
compiler make a local call (symbol@local) for internal GLIBC usage. It
means the PLT won't be used and the ifunc resolver will be called directly.
For ppc64 a call to a function in another translation unit might use a
different toc pointer thus disallowing direct branchess and making internal
ifuncs calls safe. */
#ifdef __powerpc64__
asm ("__GI_time = time");
#else
time_t
__time_vsyscall (time_t *t)
{
return INLINE_VSYSCALL (time, 1, t);
}
asm ("__GI_time = __time_vsyscall");
#endif
#else