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Don't use IFUNC resolver for longjmp or system in libpthread (bug 21041)

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Unlike the vfork forwarder and like the fork forwarder as in bug 19861,
there won't be a problem when the compiler does not turn this into a tail
call.
This commit is contained in:
Andreas Schwab 2017-08-08 16:21:58 +02:00
parent 852d631207
commit fc5ad7024c
3 changed files with 24 additions and 37 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2017-08-08 Andreas Schwab <schwab@suse.de>
[BZ #21041]
* nptl/pt-longjmp.c (longjmp, siglongjmp): Don't use IFUNC resolver.
* nptl/pt-system.c (system): Likewise.
2017-08-07 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #21780]

31
nptl/pt-longjmp.c
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@ -25,36 +25,25 @@
symbol in libpthread, but the historical ABI requires it. For static
linking, there is no need to provide anything here--the libc version
will be linked in. For shared library ABI compatibility, there must be
longjmp and siglongjmp symbols in libpthread.so; so we define them using
IFUNC to redirect to the libc function. */
longjmp and siglongjmp symbols in libpthread.so.
With an IFUNC resolver, it would be possible to avoid the indirection,
but the IFUNC resolver might run before the __libc_longjmp symbol has
been relocated, in which case the IFUNC resolver would not be able to
provide the correct address. */
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
# if HAVE_IFUNC
# undef INIT_ARCH
# define INIT_ARCH()
# define DEFINE_LONGJMP(name) libc_ifunc (name, &__libc_longjmp)
extern __typeof(longjmp) longjmp_ifunc;
extern __typeof(siglongjmp) siglongjmp_ifunc;
# else /* !HAVE_IFUNC */
static void __attribute__ ((noreturn, used))
longjmp_compat (jmp_buf env, int val)
{
__libc_longjmp (env, val);
}
# define DEFINE_LONGJMP(name) strong_alias (longjmp_compat, name)
strong_alias (longjmp_compat, longjmp_alias)
compat_symbol (libpthread, longjmp_alias, longjmp, GLIBC_2_0);
# endif /* HAVE_IFUNC */
DEFINE_LONGJMP (longjmp_ifunc)
compat_symbol (libpthread, longjmp_ifunc, longjmp, GLIBC_2_0);
strong_alias (longjmp_ifunc, siglongjmp_ifunc)
compat_symbol (libpthread, siglongjmp_ifunc, siglongjmp, GLIBC_2_0);
strong_alias (longjmp_alias, siglongjmp_alias)
compat_symbol (libpthread, siglongjmp_alias, siglongjmp, GLIBC_2_0);
#endif

24
nptl/pt-system.c
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@ -25,29 +25,21 @@
libpthread, but the historical ABI requires it. For static linking,
there is no need to provide anything here--the libc version will be
linked in. For shared library ABI compatibility, there must be a
'system' symbol in libpthread.so; so we define it using IFUNC to
redirect to the libc function. */
'system' symbol in libpthread.so.
With an IFUNC resolver, it would be possible to avoid the indirection,
but the IFUNC resolver might run before the __libc_system symbol has
been relocated, in which case the IFUNC resolver would not be able to
provide the correct address. */
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
# if HAVE_IFUNC
extern __typeof(system) system_ifunc;
# undef INIT_ARCH
# define INIT_ARCH()
libc_ifunc (system_ifunc, &__libc_system)
# else /* !HAVE_IFUNC */
static int __attribute__ ((used))
system_compat (const char *line)
{
return __libc_system (line);
}
strong_alias (system_compat, system_ifunc)
# endif /* HAVE_IFUNC */
compat_symbol (libpthread, system_ifunc, system, GLIBC_2_0);
strong_alias (system_compat, system_alias)
compat_symbol (libpthread, system_alias, system, GLIBC_2_0);
#endif