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Improve locks and signals

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- Introduce fast spinlock API
- Double rand64() perf w/ spinlock
- Improve raise() on New Technology
- Support gettid() across platforms
- Implement SA_NODEFER on New Technology
- Move the lock intrinsics into LIBC_INTRIN
- Make SIGTRAP recoverable on New Technology
- Block SIGCHLD in wait4() on New Technology
- Add threading prototypes for XNU and FreeBSD
- Rewrite abort() fixing its minor bugs on XNU/NT
- Shave down a lot of the content in libc/bits/bits.h
- Let signal handlers modify CPU registers on New Technology
This commit is contained in:
Justine Tunney 2022-04-12 05:20:17 -07:00
parent f68f1789bd
commit 046c7ebd4a
110 changed files with 1514 additions and 876 deletions
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20
libc/thread/sem.c
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@ -17,6 +17,7 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/atomic.h"
#include "libc/intrin/atomic_load.h"
#include "libc/thread/sem.h"
#include "libc/thread/wait.h"
#include "libc/thread/yield.h"
@ -37,6 +38,7 @@ int cthread_sem_init(cthread_sem_t* sem, int count) {
sem->linux.count = count;
return 0;
}
int cthread_sem_destroy(cthread_sem_t* sem) {
(void)sem;
return 0;
@ -44,7 +46,7 @@ int cthread_sem_destroy(cthread_sem_t* sem) {
int cthread_sem_signal(cthread_sem_t* sem) {
uint64_t count;
asm volatile("lock xadd\t%1, %0"
asm volatile("lock xadd\t%1,%0"
: "+m"(sem->linux.count), "=r"(count)
: "1"(1)
: "cc");
@ -62,7 +64,7 @@ int cthread_sem_wait_futex(cthread_sem_t* sem, const struct timespec* timeout) {
uint64_t count;
// record current thread as waiter
asm volatile("lock xadd\t%1, %0"
asm volatile("lock xadd\t%1,%0"
: "+m"(sem->linux.count), "=r"(count)
: "1"((uint64_t)1 << CTHREAD_THREAD_VAL_BITS)
: "cc");
@ -77,7 +79,7 @@ int cthread_sem_wait_futex(cthread_sem_t* sem, const struct timespec* timeout) {
return 0;
}
}
// WARNING: an offset of 4 bytes would be required on little-endian archs
void* wait_address = &sem->linux.count;
cthread_memory_wait32(wait_address, count, timeout);
@ -91,16 +93,17 @@ int cthread_sem_wait_spin(cthread_sem_t* sem, uint64_t count, int spin,
const struct timespec* timeout) {
// spin on pause
for (int attempt = 0; attempt < spin; ++attempt) {
//if ((count >> CTHREAD_THREAD_VAL_BITS) != 0) break;
// if ((count >> CTHREAD_THREAD_VAL_BITS) != 0) break;
while ((uint32_t)count > 0) {
// spin is useful if multiple waiters can acquire the semaphore at the same time
// spin is useful if multiple waiters can acquire the semaphore at the
// same time
if (atomic_compare_exchange_weak(&sem->linux.count, count, count - 1)) {
return 0;
}
}
pause(attempt);
}
return cthread_sem_wait_futex(sem, timeout);
}
@ -110,11 +113,12 @@ int cthread_sem_wait(cthread_sem_t* sem, int spin,
// uncontended
while ((uint32_t)count > 0) {
// spin is useful if multiple waiters can acquire the semaphore at the same time
// spin is useful if multiple waiters can acquire the semaphore at the same
// time
if (atomic_compare_exchange_weak(&sem->linux.count, count, count - 1)) {
return 0;
}
}
return cthread_sem_wait_spin(sem, count, spin, timeout);
}