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Refactor internal-signals.h 

The main drive is to optimize the internal usage and required size
when sigset_t is embedded in other data structures.  On Linux, the
current supported signal set requires up to 8 bytes (16 on mips),
was lower than the user defined sigset_t (128 bytes).

A new internal type internal_sigset_t is added, along with the
functions to operate on it similar to the ones for sigset_t.  The
internal-signals.h is also refactored to remove unused functions

Besides small stack usage on some functions (posix_spawn, abort)
it lower the struct pthread by about 120 bytes (112 on mips).

Checked on x86_64-linux-gnu.

Reviewed-by: Arjun Shankar <arjun@redhat.com>
This commit is contained in:
Adhemerval Zanella 2022-04-21 09:41:59 -03:00
parent c22d2021a9
commit a1bdd81664
18 changed files with 184 additions and 98 deletions
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3
nptl/descr.h
View File

@ -35,6 +35,7 @@
#include <kernel-features.h>
#include <tls-internal-struct.h>
#include <sys/rseq.h>
#include <internal-sigset.h>
#ifndef TCB_ALIGNMENT
# define TCB_ALIGNMENT 32
@ -387,7 +388,7 @@ struct pthread
/* Signal mask for the new thread. Used during thread startup to
restore the signal mask. (Threads are launched with all signals
masked.) */
sigset_t sigmask;
internal_sigset_t sigmask;
/* Indicates whether is a C11 thread created by thrd_creat. */
bool c11;

2
nptl/pthread_attr_setsigmask.c
View File

@ -28,7 +28,7 @@ pthread_attr_setsigmask_np (pthread_attr_t *attr, const sigset_t *sigmask)
/* Filter out internal signals. */
struct pthread_attr *iattr = (struct pthread_attr *) attr;
__clear_internal_signals (&iattr->extension->sigmask);
clear_internal_signals (&iattr->extension->sigmask);
return 0;
}

16
nptl/pthread_create.c
View File

@ -423,7 +423,7 @@ start_thread (void *arg)
/* Store the new cleanup handler info. */
THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
__libc_signal_restore_set (&pd->sigmask);
internal_signal_restore_set (&pd->sigmask);
LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);
@ -501,8 +501,8 @@ start_thread (void *arg)
signal to be delivered. (SIGSETXID cannot run application code,
nor does it use pthread_kill.) Reuse the pd->sigmask space for
computing the signal mask, to save stack space. */
__sigfillset (&pd->sigmask);
__sigdelset (&pd->sigmask, SIGSETXID);
internal_sigfillset (&pd->sigmask);
internal_sigdelset (&pd->sigmask, SIGSETXID);
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &pd->sigmask, NULL,
__NSIG_BYTES);
@ -769,14 +769,14 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
/* Block all signals, so that the new thread starts out with
signals disabled. This avoids race conditions in the thread
startup. */
sigset_t original_sigmask;
__libc_signal_block_all (&original_sigmask);
internal_sigset_t original_sigmask;
internal_signal_block_all (&original_sigmask);
if (iattr->extension != NULL && iattr->extension->sigmask_set)
/* Use the signal mask in the attribute. The internal signals
have already been filtered by the public
pthread_attr_setsigmask_np interface. */
pd->sigmask = iattr->extension->sigmask;
internal_sigset_from_sigset (&pd->sigmask, &iattr->extension->sigmask);
else
{
/* Conceptually, the new thread needs to inherit the signal mask
@ -786,7 +786,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
pd->sigmask = original_sigmask;
/* Reset the cancellation signal mask in case this thread is
running cancellation. */
__sigdelset (&pd->sigmask, SIGCANCEL);
internal_sigdelset (&pd->sigmask, SIGCANCEL);
}
/* Start the thread. */
@ -833,7 +833,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
/* Return to the previous signal mask, after creating the new
thread. */
__libc_signal_restore_set (&original_sigmask);
internal_signal_restore_set (&original_sigmask);
if (__glibc_unlikely (retval != 0))
{

10
nptl/pthread_kill.c
View File

@ -45,8 +45,8 @@ __pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
}
/* Block all signals, as required by pd->exit_lock. */
sigset_t old_mask;
__libc_signal_block_all (&old_mask);
internal_sigset_t old_mask;
internal_signal_block_all (&old_mask);
__libc_lock_lock (pd->exit_lock);
int ret;
@ -64,7 +64,7 @@ __pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
}
__libc_lock_unlock (pd->exit_lock);
__libc_signal_restore_set (&old_mask);
internal_signal_restore_set (&old_mask);
return ret;
}
@ -83,7 +83,7 @@ __pthread_kill (pthread_t threadid, int signo)
{
/* Disallow sending the signal we use for cancellation, timers,
for the setxid implementation. */
if (__is_internal_signal (signo))
if (is_internal_signal (signo))
return EINVAL;
return __pthread_kill_internal (threadid, signo);
@ -102,7 +102,7 @@ int
attribute_compat_text_section
__pthread_kill_esrch (pthread_t threadid, int signo)
{
if (__is_internal_signal (signo))
if (is_internal_signal (signo))
return EINVAL;
return __pthread_kill_implementation (threadid, signo, ESRCH);

2
nptl/pthread_sigmask.c
View File

@ -32,7 +32,7 @@ __pthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask)
|| __glibc_unlikely (__sigismember (newmask, SIGSETXID))))
{
local_newmask = *newmask;
__clear_internal_signals (&local_newmask);
clear_internal_signals (&local_newmask);
newmask = &local_newmask;
}

2
rt/tst-timer-sigmask.c
View File

@ -43,7 +43,7 @@ thread_handler (union sigval sv)
if (sigismember (&ss, sig))
{
TEST_VERIFY (sig != SIGKILL && sig != SIGSTOP);
TEST_VERIFY (!__is_internal_signal (sig));
TEST_VERIFY (!is_internal_signal (sig));
}
if (test_verbose && sigismember (&ss, sig))
printf ("%d, ", sig);

2
signal/sigaction.c
View File

@ -24,7 +24,7 @@
int
__sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
{
if (sig <= 0 || sig >= NSIG || __is_internal_signal (sig))
if (sig <= 0 || sig >= NSIG || is_internal_signal (sig))
{
__set_errno (EINVAL);
return -1;

2
signal/sigaddset.c
View File

@ -25,7 +25,7 @@ int
sigaddset (sigset_t *set, int signo)
{
if (set == NULL || signo <= 0 || signo >= NSIG
|| __is_internal_signal (signo))
|| is_internal_signal (signo))
{
__set_errno (EINVAL);
return -1;

2
signal/sigdelset.c
View File

@ -25,7 +25,7 @@ int
sigdelset (sigset_t *set, int signo)
{
if (set == NULL || signo <= 0 || signo >= NSIG
|| __is_internal_signal (signo))
|| is_internal_signal (signo))
{
__set_errno (EINVAL);
return -1;

2
signal/sigfillset.c
View File

@ -31,7 +31,7 @@ sigfillset (sigset_t *set)
}
__sigfillset (set);
__clear_internal_signals (set);
clear_internal_signals (set);
return 0;
}
libc_hidden_def (sigfillset)

10
stdlib/abort.c
View File

@ -21,7 +21,7 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sigsetops.h>
#include <internal-signals.h>
/* Try to get a machine dependent instruction which will make the
program crash. This is used in case everything else fails. */
@ -48,7 +48,6 @@ void
abort (void)
{
struct sigaction act;
sigset_t sigs;
/* First acquire the lock. */
__libc_lock_lock_recursive (lock);
@ -59,9 +58,10 @@ abort (void)
if (stage == 0)
{
++stage;
__sigemptyset (&sigs);
__sigaddset (&sigs, SIGABRT);
__sigprocmask (SIG_UNBLOCK, &sigs, 0);
internal_sigset_t sigs;
internal_sigemptyset (&sigs);
internal_sigaddset (&sigs, SIGABRT);
internal_sigprocmask (SIG_UNBLOCK, &sigs, NULL);
}
/* Send signal which possibly calls a user handler. */

31
sysdeps/generic/internal-signals.h
View File

@ -29,39 +29,20 @@
#define RESERVED_SIGRT 0
static inline bool
__is_internal_signal (int sig)
is_internal_signal (int sig)
{
return false;
}
static inline void
__clear_internal_signals (sigset_t *set)
clear_internal_signals (sigset_t *set)
{
}
static inline void
__libc_signal_block_all (sigset_t *set)
{
sigset_t allset;
__sigfillset (&allset);
__sigprocmask (SIG_BLOCK, &allset, set);
}
static inline void
__libc_signal_block_app (sigset_t *set)
{
sigset_t allset;
__sigfillset (&allset);
__clear_internal_signals (&allset);
__sigprocmask (SIG_BLOCK, &allset, set);
}
/* Restore current process signal mask. */
static inline void
__libc_signal_restore_set (const sigset_t *set)
{
__sigprocmask (SIG_SETMASK, set, NULL);
}
typedef sigset_t internal_sigset_t;
#define internal_sigemptyset(__s) sigemptyset (__s)
#define internal_sigaddset(__s, __i) sigaddset (__s, __i)
#define internal_sigprocmask(__h, __s, __o) sigprocmask (__h, __s, __o)
#endif /* __INTERNAL_SIGNALS_H */

2
sysdeps/posix/signal.c
View File

@ -32,7 +32,7 @@ __bsd_signal (int sig, __sighandler_t handler)
/* Check signal extents to protect __sigismember. */
if (handler == SIG_ERR || sig < 1 || sig >= NSIG
|| __is_internal_signal (sig))
|| is_internal_signal (sig))
{
__set_errno (EINVAL);
return SIG_ERR;

2
sysdeps/unix/sysv/linux/ia64/unwind_longjmp.c
View File

@ -34,7 +34,7 @@ __libc_unwind_longjmp (sigjmp_buf env, int val)
if (env[0].__mask_was_saved)
/* Restore the saved signal mask. */
__libc_signal_restore_set (&env[0].__saved_mask);
__sigprocmask (SIG_SETMASK, &env[0].__saved_mask, NULL);
/* Call the machine-dependent function to restore machine state. */
__sigstack_longjmp (env[0].__jmpbuf, val ?: 1);

73
sysdeps/unix/sysv/linux/internal-signals.h
View File

@ -19,10 +19,11 @@
#ifndef __INTERNAL_SIGNALS_H
# define __INTERNAL_SIGNALS_H
#include <internal-sigset.h>
#include <limits.h>
#include <signal.h>
#include <sigsetops.h>
#include <stdbool.h>
#include <limits.h>
#include <stddef.h>
#include <sysdep.h>
@ -47,67 +48,63 @@
/* Return is sig is used internally. */
static inline bool
__is_internal_signal (int sig)
is_internal_signal (int sig)
{
return (sig == SIGCANCEL) || (sig == SIGSETXID);
}
/* Remove internal glibc signal from the mask. */
static inline void
__clear_internal_signals (sigset_t *set)
clear_internal_signals (sigset_t *set)
{
__sigdelset (set, SIGCANCEL);
__sigdelset (set, SIGSETXID);
}
static const sigset_t sigall_set = {
.__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
static const internal_sigset_t sigall_set = {
.__val = {[0 ... __NSIG_WORDS-1 ] = -1 }
};
static const sigset_t sigtimer_set = {
.__val = { [0] = __sigmask (SIGTIMER),
[1 ... _SIGSET_NWORDS-1] = 0 }
};
/* Obtain and change blocked signals, including internal glibc ones. */
static inline int
internal_sigprocmask (int how, const internal_sigset_t *set,
internal_sigset_t *oldset)
{
return INTERNAL_SYSCALL_CALL (rt_sigprocmask, how, set, oldset,
__NSIG_BYTES);
}
/* Block all signals, including internal glibc ones. */
static inline void
__libc_signal_block_all (sigset_t *set)
internal_signal_block_all (internal_sigset_t *oset)
{
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, set,
__NSIG_BYTES);
}
/* Block all application signals (excluding internal glibc ones). */
static inline void
__libc_signal_block_app (sigset_t *set)
{
sigset_t allset = sigall_set;
__clear_internal_signals (&allset);
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &allset, set,
__NSIG_BYTES);
}
/* Block only SIGTIMER and return the previous set on SET. */
static inline void
__libc_signal_block_sigtimer (sigset_t *set)
{
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigtimer_set, set,
__NSIG_BYTES);
}
/* Unblock only SIGTIMER and return the previous set on SET. */
static inline void
__libc_signal_unblock_sigtimer (sigset_t *set)
{
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, set,
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, oset,
__NSIG_BYTES);
}
/* Restore current process signal mask. */
static inline void
__libc_signal_restore_set (const sigset_t *set)
internal_signal_restore_set (const internal_sigset_t *set)
{
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
__NSIG_BYTES);
}
/* It is used on timer_create code directly on sigwaitinfo call, so it can not
use the internal_sigset_t definitions. */
static const sigset_t sigtimer_set = {
.__val = { [0] = __sigmask (SIGTIMER),
[1 ... _SIGSET_NWORDS-1] = 0
}
};
/* Unblock only SIGTIMER. */
static inline void
signal_unblock_sigtimer (void)
{
INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, NULL,
__NSIG_BYTES);
}
#endif

105
sysdeps/unix/sysv/linux/internal-sigset.h Normal file
View File

@ -0,0 +1,105 @@
/* Internal sigset_t definition.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _INTERNAL_SIGSET_H
#define _INTERNAL_SIGSET_H
#include <sigsetops.h>
typedef struct
{
unsigned long int __val[__NSIG_WORDS];
} internal_sigset_t;
static inline void
internal_sigset_from_sigset (internal_sigset_t *iset, const sigset_t *set)
{
int cnt = __NSIG_WORDS;
while (--cnt >= 0)
iset->__val[cnt] = set->__val[cnt];
}
static inline void
internal_sigemptyset (internal_sigset_t *set)
{
int cnt = __NSIG_WORDS;
while (--cnt >= 0)
set->__val[cnt] = 0;
}
static inline void
internal_sigfillset (internal_sigset_t *set)
{
int cnt = __NSIG_WORDS;
while (--cnt >= 0)
set->__val[cnt] = ~0UL;
}
static inline int
internal_sigisemptyset (const internal_sigset_t *set)
{
int cnt = __NSIG_WORDS;
int ret = set->__val[--cnt];
while (ret == 0 && --cnt >= 0)
ret = set->__val[cnt];
return ret == 0;
}
static inline void
internal_sigandset (internal_sigset_t *dest, const internal_sigset_t *left,
const internal_sigset_t *right)
{
int cnt = __NSIG_WORDS;
while (--cnt >= 0)
dest->__val[cnt] = left->__val[cnt] & right->__val[cnt];
}
static inline void
internal_sigorset (internal_sigset_t *dest, const internal_sigset_t *left,
const internal_sigset_t *right)
{
int cnt = __NSIG_WORDS;
while (--cnt >= 0)
dest->__val[cnt] = left->__val[cnt] | right->__val[cnt];
}
static inline int
internal_sigismember (const internal_sigset_t *set, int sig)
{
unsigned long int mask = __sigmask (sig);
unsigned long int word = __sigword (sig);
return set->__val[word] & mask ? 1 : 0;
}
static inline void
internal_sigaddset (internal_sigset_t *set, int sig)
{
unsigned long int mask = __sigmask (sig);
unsigned long int word = __sigword (sig);
set->__val[word] |= mask;
}
static inline void
internal_sigdelset (internal_sigset_t *set, int sig)
{
unsigned long int mask = __sigmask (sig);
unsigned long int word = __sigword (sig);
set->__val[word] &= ~mask;
}
#endif /* _INTERNAL_SIGSET_H */

14
sysdeps/unix/sysv/linux/spawni.c
View File

@ -57,7 +57,7 @@
struct posix_spawn_args
{
sigset_t oldmask;
internal_sigset_t oldmask;
const char *file;
int (*exec) (const char *, char *const *, char *const *);
const posix_spawn_file_actions_t *fa;
@ -124,7 +124,7 @@ __spawni_child (void *arguments)
}
else if (__sigismember (&hset, sig))
{
if (__is_internal_signal (sig))
if (is_internal_signal (sig))
sa.sa_handler = SIG_IGN;
else
{
@ -284,8 +284,10 @@ __spawni_child (void *arguments)
/* Set the initial signal mask of the child if POSIX_SPAWN_SETSIGMASK
is set, otherwise restore the previous one. */
__sigprocmask (SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
? &attr->__ss : &args->oldmask, 0);
if (attr->__flags & POSIX_SPAWN_SETSIGMASK)
__sigprocmask (SIG_SETMASK, &attr->__ss, NULL);
else
internal_sigprocmask (SIG_SETMASK, &args->oldmask, NULL);
args->exec (args->file, args->argv, args->envp);
@ -368,7 +370,7 @@ __spawnix (pid_t * pid, const char *file,
args.envp = envp;
args.xflags = xflags;
__libc_signal_block_all (&args.oldmask);
internal_signal_block_all (&args.oldmask);
/* The clone flags used will create a new child that will run in the same
memory space (CLONE_VM) and the execution of calling thread will be
@ -416,7 +418,7 @@ __spawnix (pid_t * pid, const char *file,
if ((ec == 0) && (pid != NULL))
*pid = new_pid;
__libc_signal_restore_set (&args.oldmask);
internal_signal_restore_set (&args.oldmask);
__pthread_setcancelstate (state, NULL);

2
sysdeps/unix/sysv/linux/timer_routines.c
View File

@ -41,7 +41,7 @@ struct thread_start_data
static void *
timer_sigev_thread (void *arg)
{
__libc_signal_unblock_sigtimer (NULL);
signal_unblock_sigtimer ();
struct thread_start_data *td = (struct thread_start_data *) arg;
void (*thrfunc) (sigval_t) = td->thrfunc;