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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2019-12-09 15:50:29 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2019-12-19 10:30:49 -0300
commit1b132d55e2d3a4eb421c0f77f63b67b5022c22e3 (patch)
tree1e08bb5248f6418de138de92c283be6f5f937205
parent0331bffe1be698d32c3b4a93b6e7f02d1f1b47fb (diff)
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Fix __libc_signal_block_all on sparc64
The posix_spawn on sparc issues invalid sigprocmask calls: rt_sigprocmask(0xffe5e15c /* SIG_??? */, ~[], 0xffe5e1dc, 8) = -1 EINVAL (Invalid argument) Which make support/tst-support_capture_subprocess fails with random output (due the child signal being wrongly captured by the parent). Tracking the culprit it seems to be a wrong code generation in the INTERNAL_SYSCALL due the automatic sigset_t used on __libc_signal_block_all: return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET, set, _NSIG / 8); Where SIGALL_SET is defined as: ((__sigset_t) { .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 } }) Building the expanded __libc_signal_block_all on sparc64 with recent compiler (gcc 8.3.1 and 9.1.1): #include <signal> int _libc_signal_block_all (sigset_t *set) { INTERNAL_SYSCALL_DECL (err); return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET, set, _NSIG / 8); } The first argument (SIG_BLOCK) is not correctly set on 'o0' register: __libc_signal_block_all: save %sp, -304, %sp add %fp, 1919, %o0 mov 128, %o2 sethi %hi(.LC0), %o1 call memcpy, 0 or %o1, %lo(.LC0), %o1 add %fp, 1919, %o1 mov %i0, %o2 mov 8, %o3 mov 103, %g1 ta 0x6d; bcc,pt %xcc, 1f mov 0, %g1 sub %g0, %o0, %o0 mov 1, %g1 1: sra %o0, 0, %i0 return %i7+8 nop Where if SIGALL_SET is defined a const object, gcc correctly sets the expected kernel argument in correct register: sethi %hi(.LC0), %o1 call memcpy, 0 or %o1, %lo(.LC0), %o1 -> mov 1, %o0 add %fp, 1919, %o1 Another possible fix is use a static const object. Although there should not be a difference between a const compound literal and a static const object, the gcc C99 status page [1] has a note stating that this optimization is not implemented: "const-qualified compound literals could share storage with each other and with string literals, but currently don't.". This patch fixes it by moving both sigset_t that represent the signal sets to static const data object. It generates slight better code where the object reference is used directly instead of a stack allocation plus the content materialization. Checked on x86_64-linux-gnu, i686-linux-gnu, and sparc64-linux-gnu. [1] https://gcc.gnu.org/c99status.html
-rw-r--r--sysdeps/unix/sysv/linux/internal-signals.h14
1 files changed, 8 insertions, 6 deletions
diff --git a/sysdeps/unix/sysv/linux/internal-signals.h b/sysdeps/unix/sysv/linux/internal-signals.h
index 01d8bf0..a496c71 100644
--- a/sysdeps/unix/sysv/linux/internal-signals.h
+++ b/sysdeps/unix/sysv/linux/internal-signals.h
@@ -22,6 +22,7 @@
#include <signal.h>
#include <sigsetops.h>
#include <stdbool.h>
+#include <limits.h>
#include <sysdep.h>
/* The signal used for asynchronous cancelation. */
@@ -53,15 +54,16 @@ __clear_internal_signals (sigset_t *set)
__sigdelset (set, SIGSETXID);
}
-#define SIGALL_SET \
- ((__sigset_t) { .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 } })
+static const sigset_t sigall_set = {
+ .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
+};
/* Block all signals, including internal glibc ones. */
static inline int
__libc_signal_block_all (sigset_t *set)
{
INTERNAL_SYSCALL_DECL (err);
- return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
+ return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &sigall_set,
set, _NSIG / 8);
}
@@ -69,11 +71,11 @@ __libc_signal_block_all (sigset_t *set)
static inline int
__libc_signal_block_app (sigset_t *set)
{
- sigset_t allset = SIGALL_SET;
+ sigset_t allset = sigall_set;
__clear_internal_signals (&allset);
INTERNAL_SYSCALL_DECL (err);
- return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
- _NSIG / 8);
+ return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset,
+ set, _NSIG / 8);
}
/* Restore current process signal mask. */