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https://github.com/jart/cosmopolitan.git
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a15958edc6
Function trace logs will report stack usage accurately. It won't include the argv/environ block. Our clone() polyfill is now simpler and does not use as much stack memory. Function call tracing on x86 is now faster too
92 lines
4.6 KiB
C
92 lines
4.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/intrin/ulock.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/strace.h"
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#include "libc/intrin/ulock.h"
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// XNU futexes
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// https://opensource.apple.com/source/xnu/xnu-7195.50.7.100.1/bsd/sys/ulock.h.auto.html
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// https://opensource.apple.com/source/xnu/xnu-3789.41.3/bsd/kern/sys_ulock.c.auto.html
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int sys_ulock_wait(uint32_t operation, void *addr, uint64_t value,
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uint32_t timeout_micros) asm("sys_futex_cp");
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// returns number of other waiters, or -1 w/ errno
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//
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// - EINTR means a signal handler was called. This is how we support
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// things like POSIX thread cancelation.
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//
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// - EFAULT if XNU couldn't read `addr`. This is normally considered a
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// programming error, but with ulock it can actually be a transient
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// error due to low memory conditions. Apple recommends retrying.
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//
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// - ENOMEM means XNU wasn't able to allocate memory for kernel internal
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// data structures. Apple doesn't provide any advice on what to do. We
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// simply turn this into EAGAIN.
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//
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// - EAGAIN if XNU told us EFAULT but cosmo believes the address exists.
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// This value is also used as a substitute for ENOMEM.
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//
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// - EINVAL could mean operation is invalid, addr is null or misaligned;
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// it could also mean another thread calling ulock on this address was
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// configured (via operation) in an inconsistent way.
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//
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// see also os_sync_wait_on_address.h from xcode sdk
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int ulock_wait(uint32_t operation, void *addr, uint64_t value,
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uint32_t timeout_micros) {
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int rc;
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operation |= ULF_WAIT_CANCEL_POINT;
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LOCKTRACE("ulock_wait(%#x, %p, %lx, %u) → ...", operation, addr, value,
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timeout_micros);
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rc = sys_ulock_wait(operation, addr, value, timeout_micros);
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if (rc == -1) {
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if (errno == ENOMEM)
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errno = EAGAIN;
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if (errno == EFAULT)
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if (!kisdangerous(addr))
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errno = EAGAIN;
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}
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LOCKTRACE("ulock_wait(%#x, %p, %lx, %u) → %d% m", operation, addr, value,
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timeout_micros, rc);
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return rc;
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}
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// returns -errno
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//
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// - ENOENT means there wasn't anyone to wake
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//
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// - EINVAL could mean operation is invalid, addr is null or misaligned;
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// it could also mean another thread calling ulock on this address was
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// configured (via operation) in an inconsistent way.
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//
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// should be dontinstrument because SiliconThreadMain() calls this from
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// a stack managed by apple libc.
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//
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dontinstrument int ulock_wake(uint32_t operation, void *addr,
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uint64_t wake_value) {
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int rc;
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rc = __syscall3i(operation, (long)addr, wake_value, 0x2000000 | 516);
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LOCKTRACE("ulock_wake(%#x, %p, %lx) → %s", operation, addr, wake_value,
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DescribeErrno(rc));
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return rc;
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}
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