| Message ID | 54afd0132a909969862bb2ce96bd5e95beab324a.1611155254.git.szabolcs.nagy@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | fix ifunc with static pie [BZ #27072] | expand |
On 20/01/2021 12:31, Szabolcs Nagy via Libc-alpha wrote: > Extern symbol access in position independent code usually involves GOT > indirection which needs RELATIVE reloc in a static linked PIE. (On > some targets this is avoided e.g. because the linker can relax a GOT > access to a pc-relative access, but this is not generally true.) Code > that runs before static PIE self relocation must avoid relying on > dynamic relocations which can be ensured by using hidden visibility. > However we cannot just make all symbols hidden: > > On i386, all calls to IFUNC functions must go through PLT and calls to > hidden functions CANNOT go through PLT in PIE since EBX used in PIE PLT > may not be set up for local calls to hidden IFUNC functions. > > This patch aims to make symbol references hidden in code that is used > before and by _dl_relocate_static_pie when building a static PIE libc. > Note: for an object that is used in the startup code, its references > and definition may not have consistent visibility: it is only forced > hidden in the startup code. > > This is needed for fixing bug 27072. > > Co-authored-by: H.J. Lu <hjl.tools@gmail.com> LGTM, thanks. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > --- > csu/libc-start.c | 4 ++++ > elf/dl-reloc-static-pie.c | 2 ++ > elf/dl-support.c | 6 ++++++ > elf/dl-tunables.c | 4 ++++ > elf/enbl-secure.c | 4 ++++ > misc/sbrk.c | 4 ++++ > sysdeps/unix/sysv/linux/aarch64/libc-start.c | 5 +++++ > sysdeps/x86/libc-start.c | 5 +++++ > 8 files changed, 34 insertions(+) > > diff --git a/csu/libc-start.c b/csu/libc-start.c > index 5b9ce1d158..a2f6e12728 100644 > --- a/csu/libc-start.c > +++ b/csu/libc-start.c > @@ -15,6 +15,10 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <assert.h> > #include <stdlib.h> > #include <stdio.h> Ok. > diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c > index a8d964061e..d5bd2f31e9 100644 > --- a/elf/dl-reloc-static-pie.c > +++ b/elf/dl-reloc-static-pie.c > @@ -17,6 +17,8 @@ > <https://www.gnu.org/licenses/>. */ > > #if ENABLE_STATIC_PIE > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +# pragma GCC visibility push(hidden) > #include <unistd.h> > #include <ldsodefs.h> > #include "dynamic-link.h" Ok. > diff --git a/elf/dl-support.c b/elf/dl-support.c > index 2434c470c7..7abb65d8e3 100644 > --- a/elf/dl-support.c > +++ b/elf/dl-support.c > @@ -19,6 +19,12 @@ > /* This file defines some things that for the dynamic linker are defined in > rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */ > > +#include <string.h> > +/* Mark symbols hidden in static PIE for early self relocation to work. > + Note: string.h may have ifuncs which cannot be hidden on i686. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <errno.h> > #include <libintl.h> > #include <stdlib.h> Ok. > diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c > index e44476f204..b1a50b8469 100644 > --- a/elf/dl-tunables.c > +++ b/elf/dl-tunables.c > @@ -18,6 +18,10 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <startup.h> > #include <stdint.h> > #include <stdbool.h> Ok. > diff --git a/elf/enbl-secure.c b/elf/enbl-secure.c > index 5dcf649626..9e47526bd3 100644 > --- a/elf/enbl-secure.c > +++ b/elf/enbl-secure.c > @@ -19,6 +19,10 @@ > /* This file is used in the static libc. For the shared library, > dl-sysdep.c defines and initializes __libc_enable_secure. */ > > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <startup.h> > #include <libc-internal.h> > Ok. > diff --git a/misc/sbrk.c b/misc/sbrk.c > index 99b3fb517e..95800b32aa 100644 > --- a/misc/sbrk.c > +++ b/misc/sbrk.c > @@ -15,6 +15,10 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <errno.h> > #include <libc-internal.h> > #include <stdbool.h> Ok. > diff --git a/sysdeps/unix/sysv/linux/aarch64/libc-start.c b/sysdeps/unix/sysv/linux/aarch64/libc-start.c > index f816f04ee1..e1604a6ed0 100644 > --- a/sysdeps/unix/sysv/linux/aarch64/libc-start.c > +++ b/sysdeps/unix/sysv/linux/aarch64/libc-start.c > @@ -17,6 +17,11 @@ > <https://www.gnu.org/licenses/>. */ > > #ifndef SHARED > + > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +# if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +# endif > # include <ldsodefs.h> > # include <cpu-features.c> > Ok. > diff --git a/sysdeps/x86/libc-start.c b/sysdeps/x86/libc-start.c > index 4bbd7d555b..d30aec2aa1 100644 > --- a/sysdeps/x86/libc-start.c > +++ b/sysdeps/x86/libc-start.c > @@ -16,6 +16,11 @@ > <https://www.gnu.org/licenses/>. */ > > #ifndef SHARED > + > +/* Mark symbols hidden in static PIE for early self relocation to work. */ > +# if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +# endif > /* Define I386_USE_SYSENTER to support syscall during startup in static > PIE. */ > # include <startup.h> > Ok.
diff --git a/csu/libc-start.c b/csu/libc-start.c index 5b9ce1d158..a2f6e12728 100644 --- a/csu/libc-start.c +++ b/csu/libc-start.c @@ -15,6 +15,10 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <assert.h> #include <stdlib.h> #include <stdio.h> diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c index a8d964061e..d5bd2f31e9 100644 --- a/elf/dl-reloc-static-pie.c +++ b/elf/dl-reloc-static-pie.c @@ -17,6 +17,8 @@ <https://www.gnu.org/licenses/>. */ #if ENABLE_STATIC_PIE +/* Mark symbols hidden in static PIE for early self relocation to work. */ +# pragma GCC visibility push(hidden) #include <unistd.h> #include <ldsodefs.h> #include "dynamic-link.h" diff --git a/elf/dl-support.c b/elf/dl-support.c index 2434c470c7..7abb65d8e3 100644 --- a/elf/dl-support.c +++ b/elf/dl-support.c @@ -19,6 +19,12 @@ /* This file defines some things that for the dynamic linker are defined in rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */ +#include <string.h> +/* Mark symbols hidden in static PIE for early self relocation to work. + Note: string.h may have ifuncs which cannot be hidden on i686. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <errno.h> #include <libintl.h> #include <stdlib.h> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index e44476f204..b1a50b8469 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -18,6 +18,10 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <startup.h> #include <stdint.h> #include <stdbool.h> diff --git a/elf/enbl-secure.c b/elf/enbl-secure.c index 5dcf649626..9e47526bd3 100644 --- a/elf/enbl-secure.c +++ b/elf/enbl-secure.c @@ -19,6 +19,10 @@ /* This file is used in the static libc. For the shared library, dl-sysdep.c defines and initializes __libc_enable_secure. */ +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <startup.h> #include <libc-internal.h> diff --git a/misc/sbrk.c b/misc/sbrk.c index 99b3fb517e..95800b32aa 100644 --- a/misc/sbrk.c +++ b/misc/sbrk.c @@ -15,6 +15,10 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <errno.h> #include <libc-internal.h> #include <stdbool.h> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc-start.c b/sysdeps/unix/sysv/linux/aarch64/libc-start.c index f816f04ee1..e1604a6ed0 100644 --- a/sysdeps/unix/sysv/linux/aarch64/libc-start.c +++ b/sysdeps/unix/sysv/linux/aarch64/libc-start.c @@ -17,6 +17,11 @@ <https://www.gnu.org/licenses/>. */ #ifndef SHARED + +/* Mark symbols hidden in static PIE for early self relocation to work. */ +# if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +# endif # include <ldsodefs.h> # include <cpu-features.c> diff --git a/sysdeps/x86/libc-start.c b/sysdeps/x86/libc-start.c index 4bbd7d555b..d30aec2aa1 100644 --- a/sysdeps/x86/libc-start.c +++ b/sysdeps/x86/libc-start.c @@ -16,6 +16,11 @@ <https://www.gnu.org/licenses/>. */ #ifndef SHARED + +/* Mark symbols hidden in static PIE for early self relocation to work. */ +# if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +# endif /* Define I386_USE_SYSENTER to support syscall during startup in static PIE. */ # include <startup.h>