mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 11:37:35 +00:00
af7bd80430
This change introduces a new deadlock detector for Cosmo's POSIX threads implementation. Error check mutexes will now track a DAG of nested locks and report EDEADLK when a deadlock is theoretically possible. These will occur rarely, but it's important for production hardening your code. You don't even need to change your mutexes to use the POSIX error check mode because `cosmocc -mdbg` will enable error checking on mutexes by default globally. When cycles are found, an error message showing your demangled symbols describing the strongly connected component are printed and then the SIGTRAP is raised, which means you'll also get a backtrace if you're using ShowCrashReports() too. This new error checker is so low-level and so pure that it's able to verify the relationships of every libc runtime lock, including those locks upon which the mutex implementation depends.
93 lines
4.1 KiB
C
93 lines
4.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2022 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ Permission to use, copy, modify, and/or distribute this software for │
|
|
│ any purpose with or without fee is hereby granted, provided that the │
|
|
│ above copyright notice and this permission notice appear in all copies. │
|
|
│ │
|
|
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
|
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
|
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
|
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
|
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
|
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
|
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
|
│ PERFORMANCE OF THIS SOFTWARE. │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/calls/syscall-sysv.internal.h"
|
|
#include "libc/dce.h"
|
|
#include "libc/intrin/kprintf.h"
|
|
#include "libc/nt/thread.h"
|
|
#include "libc/nt/thunk/msabi.h"
|
|
#include "libc/runtime/internal.h"
|
|
|
|
__msabi extern typeof(GetCurrentThreadId) *const __imp_GetCurrentThreadId;
|
|
|
|
// it's important that this be noinstrument because the child process
|
|
// created by fork() needs to update this value quickly, since ftrace
|
|
// will deadlock __maps_lock() if the wrong tid is accidentally used.
|
|
dontinstrument int sys_gettid(void) {
|
|
int64_t wut;
|
|
#ifdef __x86_64__
|
|
int tid;
|
|
if (IsWindows()) {
|
|
tid = __imp_GetCurrentThreadId();
|
|
} else if (IsLinux()) {
|
|
asm("syscall"
|
|
: "=a"(tid) // man says always succeeds
|
|
: "0"(186) // __NR_gettid
|
|
: "rcx", "r11", "memory");
|
|
} else if (IsXnu()) {
|
|
asm("syscall" // xnu/osfmk/kern/ipc_tt.c
|
|
: "=a"(tid) // assume success
|
|
: "0"(0x1000000 | 27) // Mach thread_self_trap()
|
|
: "rcx", "r8", "r9", "r10", "r11", "memory", "cc");
|
|
} else if (IsOpenbsd()) {
|
|
asm("syscall"
|
|
: "=a"(tid) // man says always succeeds
|
|
: "0"(299) // getthrid()
|
|
: "rcx", "r8", "r9", "r10", "r11", "memory", "cc");
|
|
} else if (IsNetbsd()) {
|
|
asm("syscall"
|
|
: "=a"(tid) // man says always succeeds
|
|
: "0"(311) // _lwp_self()
|
|
: "rcx", "rdx", "r8", "r9", "r10", "r11", "memory", "cc");
|
|
} else if (IsFreebsd()) {
|
|
asm("syscall"
|
|
: "=a"(tid), // only fails w/ EFAULT, which isn't possible
|
|
"=m"(wut) // must be 64-bit
|
|
: "0"(432), // thr_self()
|
|
"D"(&wut) // but not actually 64-bit
|
|
: "rcx", "r8", "r9", "r10", "r11", "memory", "cc");
|
|
tid = wut;
|
|
} else {
|
|
tid = __pid;
|
|
}
|
|
return tid;
|
|
#elif defined(__aarch64__)
|
|
// this can't be used on xnu
|
|
register long res asm("x0");
|
|
if (IsLinux()) {
|
|
asm volatile("mov\tx8,%1\n\t"
|
|
"svc\t0"
|
|
: "=r"(res)
|
|
: "i"(178)
|
|
: "x8", "memory");
|
|
} else if (IsFreebsd()) {
|
|
res = (long)&wut;
|
|
asm volatile("mov\tx8,%2\n\t"
|
|
"svc\t0"
|
|
: "+r"(res), "=m"(wut)
|
|
: "i"(432) // thr_self()
|
|
: "x8", "memory");
|
|
res = wut;
|
|
} else {
|
|
res = __pid;
|
|
}
|
|
return res;
|
|
#else
|
|
#error "arch unsupported"
|
|
#endif
|
|
}
|