glibc/sysdeps/unix/sysv/linux/arm
Aurelien Jarno fe20bb1d60 ARM: fix kernel assisted atomics with GCC 8 (bug 24034)
The pre-ARMv7 CPUs are missing atomic compare and exchange and/or
barrier instructions. Therefore those are implemented using kernel
assistance, calling a kernel function at a specific address, and passing
the arguments in the r0 to r4 registers. This is done by specifying
registers for local variables. The a_ptr variable is placed in the r2
register and declared with __typeof (mem). According to the GCC
documentation on local register variables, if mem is a constant pointer,
the compiler may substitute the variable with its initializer in asm
statements, which may cause the corresponding operand to appear in a
different register.

This happens in __libc_start_main with the pointer to the thread counter
for static binaries (but not the shared ones):

  # ifdef SHARED
        unsigned int *ptr = __libc_pthread_functions.ptr_nthreads;
  #  ifdef PTR_DEMANGLE
        PTR_DEMANGLE (ptr);
  #  endif
  # else
        extern unsigned int __nptl_nthreads __attribute ((weak));
        unsigned int *const ptr = &__nptl_nthreads;
  # endif

This causes static binaries using threads to crash when the GNU libc is
built with GCC 8 and most notably tst-cancel21-static.

To fix that, use the same trick than for the volatile qualifier,
defining a_ptr as a union.

Changelog:
	[BZ #24034]
	* sysdeps/unix/sysv/linux/arm/atomic-machine.h
	(__arm_assisted_compare_and_exchange_val_32_acq): Use uint32_t rather
	than __typeof (...) for the a_ptr variable.
2019-01-02 18:21:18 +01:00
..
bits Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
sys Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
Implies NPTL is no longer an add-on! 2014-07-07 09:29:06 -07:00
Makefile Remove abi-*-options compiler flags 2017-08-28 17:16:53 +02:00
Versions network: recvmsg and sendmsg standard compliance (BZ#16919) 2016-05-25 17:39:01 -03:00
____longjmp_chk.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
aeabi_read_tp.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
arm-features.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
atomic-machine.h ARM: fix kernel assisted atomics with GCC 8 (bug 24034) 2019-01-02 18:21:18 +01:00
brk.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
c++-types.data Verbatim NPTL file moves for ARM/Linux. 2014-05-13 10:04:20 -07:00
clone.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
dl-cache.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
dl-machine.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
dl-procinfo.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
dl-procinfo.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
fxstat.c
fxstatat.c
getcontext.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
init-first.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
ioperm.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
jmp_buf-macros.h Add jmp_buf-macros.h 2017-11-09 05:10:03 -08:00
kernel-features.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
ld.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
ldconfig.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
ldsodefs.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
libBrokenLocale.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libanl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libc-do-syscall.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
libc-vdso.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
libc.abilist Add getcpu 2018-12-07 09:17:50 -08:00
libcrypt.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libdl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libm.abilist Remove the error handling wrapper from pow 2018-11-21 09:58:36 +00:00
libnsl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libpthread.abilist nptl: Add abilist symbols for C11 threads 2018-07-24 14:07:18 -03:00
libresolv.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
librt.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libthread_db.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libutil.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
localplt.data ld.so: Introduce struct dl_exception 2017-08-10 16:54:57 +02:00
lockf64.c
lxstat.c
makecontext.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
profil-counter.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
readelflib.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
register-dump.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
setcontext.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
shlib-versions Remove configuration name patterns from shlib-versions. 2014-09-12 12:28:47 +00:00
sigaction.c Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
sigcontextinfo.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
sigrestorer.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
swapcontext.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
syscall.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
syscalls.list Consolidate Linux send implementation 2017-03-09 15:22:06 +01:00
sysdep.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
sysdep.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
tls.h Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
ucontext_i.sym
vfork.S Update copyright dates with scripts/update-copyrights. 2019-01-01 00:11:28 +00:00
xstat.c