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Get threads working on all platforms

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We now have a high-quality clone() implementation for creating
lightweight threads on Linux/Windows/FreeBSD/NetBSD/OpenBSD.
This commit is contained in:
Justine Tunney 2022-05-12 17:52:13 -07:00
parent 4e62cefa6e
commit fec396037a
43 changed files with 850 additions and 532 deletions
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29
libc/runtime/mmap.c
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@ -25,6 +25,7 @@
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/asancodes.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/spinlock.h"
@ -381,6 +382,10 @@ static noasan inline void *Mmap(void *addr, size_t size, int prot, int flags,
if (needguard) {
if (IsWindows()) _spunlock(&_mmi.lock);
mprotect(p, PAGESIZE, PROT_NONE);
if (IsAsan()) {
__repstosb((void *)(((intptr_t)p >> 3) + 0x7fff8000),
kAsanStackOverflow, PAGESIZE / 8);
}
if (IsWindows()) _spinlock(&_mmi.lock);
}
}
@ -408,7 +413,29 @@ static noasan inline void *Mmap(void *addr, size_t size, int prot, int flags,
* will be rounded up to FRAMESIZE automatically if MAP_ANONYMOUS
* is specified
* @param prot can have PROT_READ/PROT_WRITE/PROT_EXEC/PROT_NONE/etc.
* @param flags can have MAP_ANONYMOUS, MAP_SHARED, MAP_PRIVATE, etc.
* @param flags should have one of the following masked by `MAP_TYPE`
* - `MAP_FILE` in which case `fd != -1` should be the case
* - `MAP_PRIVATE` for copy-on-write behavior of writeable pages
* - `MAP_SHARED` to create shared memory between processes
* - `MAP_STACK` to create a grows-down alloc, where a guard page
* is automatically protected at the bottom: FreeBSD's behavior
* is polyfilled across platforms; uses MAP_GROWSDOWN on Linux
* too for extra oomph (do not use MAP_GROWSDOWN!) and this is
* completely mandatory on OpenBSD but helps perf elsewhere if
* you need to create 10,000 threads. This flag is the reason
* why `STACK_FRAME_UNLIMITED` toil is important, because this
* only allocates a 4096-byte guard page, thus we need the GCC
* compile-time checks to ensure some char[8192] vars will not
* create an undetectable overflow into another thread's stack
* Your `flags` may optionally bitwise or any of the following:
* - `MAP_FIXED` in which case `addr` becomes more than a hint
* - `MAP_FIXED_NOREPLACE` to protect existing maps (Linux-only)
* - `MAP_ANONYMOUS` in which case `fd == -1` should be the case
* - `MAP_CONCEAL` is FreeBSD/NetBSD/OpenBSD-only
* - `MAP_NORESERVE` is Linux/XNU/NetBSD-only
* - `MAP_LOCKED` is Linux-only
* - `MAP_POPULATE` is Linux-only
* - `MAP_NONBLOCK` is Linux-only
* @param fd is an open()'d file descriptor, whose contents shall be
* made available w/ automatic reading at the chosen address and
* must be -1 if MAP_ANONYMOUS is specified