From 69a17d9d245dc3551792e95e1823cc2d877592f3 Mon Sep 17 00:00:00 2001 From: Paul Pluzhnikov Date: Wed, 18 Dec 2013 15:07:11 -0800 Subject: Patch [1/4] async-signal safe TLS. 2013-12-18 Andrew Hunter * sysdeps/generic/ldsodefs.h (_dl_mask_all_signals): New prototype. (_dl_unmask_signals): Likewise. * sysdeps/mach/hurd/dl-sysdep.h (_dl_mask_all_signals): New stub. (_dl_unmask_all_signals): Likewise. * sysdeps/unix/sysv/linux/dl-sysdep.h (_dl_mask_all_signals): New prototype. (_dl_unmask_all_signals): Likewise. * sysdeps/unix/sysv/linux/dl-sysdep.c (_dl_mask_all_signals): New function. (_dl_unmask_signals): Likewise. --- sysdeps/generic/ldsodefs.h | 5 ++++ sysdeps/mach/hurd/dl-sysdep.h | 7 ++++++ sysdeps/unix/sysv/linux/dl-sysdep.c | 46 +++++++++++++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/dl-sysdep.h | 4 ++++ 4 files changed, 62 insertions(+) (limited to 'sysdeps') diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 146aca4dfb..e919e4136c 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -234,6 +234,11 @@ extern int _dl_name_match_p (const char *__name, const struct link_map *__map) extern unsigned long int _dl_higher_prime_number (unsigned long int n) internal_function; +/* Mask every signal, returning the previous sigmask in OLD. */ +extern void _dl_mask_all_signals (sigset_t *old) internal_function; +/* Undo _dl_mask_all_signals. */ +extern void _dl_unmask_signals (sigset_t *old) internal_function; + /* Function used as argument for `_dl_receive_error' function. The arguments are the error code, error string, and the objname the error occurred in. */ diff --git a/sysdeps/mach/hurd/dl-sysdep.h b/sysdeps/mach/hurd/dl-sysdep.h index 52563b0ca0..0e7cac4ab0 100644 --- a/sysdeps/mach/hurd/dl-sysdep.h +++ b/sysdeps/mach/hurd/dl-sysdep.h @@ -29,3 +29,10 @@ # define DL_ARGV_NOT_RELRO 1 # define LIBC_STACK_END_NOT_RELRO 1 #endif + +#include +inline void _dl_mask_all_signals (sigset_t *) internal_function; +inline void _dl_mask_all_signals (sigset_t *) { } + +inline void _dl_unmask_all_signals (sigset_t *) internal_function; +inline void _dl_unmask_all_signals (sigset_t *) { } diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c index e80cb8d9f0..4b837acbc0 100644 --- a/sysdeps/unix/sysv/linux/dl-sysdep.c +++ b/sysdeps/unix/sysv/linux/dl-sysdep.c @@ -19,6 +19,7 @@ /* Linux needs some special initialization, but otherwise uses the generic dynamic linker system interface code. */ +#include #include #include #include @@ -130,3 +131,48 @@ _dl_discover_osversion (void) return version; } + +/* Mask every signal, returning the previous sigmask in OLD. */ +void +internal_function +_dl_mask_all_signals (sigset_t *old) +{ + int ret; + sigset_t new; + + sigfillset (&new); + + /* This function serves as a replacement to pthread_sigmask, which + isn't available from within the dynamic linker since it would require + linking with libpthread. We duplicate some of the functionality here + to avoid requiring libpthread. This isn't quite identical to + pthread_sigmask in that we do not mask internal signals used for + cancellation and setxid handling. This disables asynchronous + cancellation for the duration the signals are disabled, but it's a + small window, and prevents any problems with the use of TLS variables + in the signal handlers that would have executed. */ + + /* It's very important we don't touch errno here, as that's TLS; since this + gets called from get_tls_addr we might end up recursing. */ + + INTERNAL_SYSCALL_DECL (err); + + ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &new, old, + _NSIG / 8); + + assert (ret == 0); +} + +/* Return sigmask to what it was before a call to _dl_mask_all_signals. */ +void +internal_function +_dl_unmask_signals (sigset_t *old) +{ + int ret; + INTERNAL_SYSCALL_DECL (err); + + ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, old, NULL, + _NSIG / 8); + + assert (ret == 0); +} diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.h b/sysdeps/unix/sysv/linux/dl-sysdep.h index e1eab09025..0fe1e1c3d0 100644 --- a/sysdeps/unix/sysv/linux/dl-sysdep.h +++ b/sysdeps/unix/sysv/linux/dl-sysdep.h @@ -30,4 +30,8 @@ /* Get version of the OS. */ extern int _dl_discover_osversion (void) attribute_hidden; # define HAVE_DL_DISCOVER_OSVERSION 1 + +#include +void _dl_mask_all_signals (sigset_t *) internal_function; +void _dl_unmask_all_signals (sigset_t *) internal_function; #endif -- cgit v1.2.3