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Make garbage collection thread safe

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- You can now use _gc(malloc()) in multithreaded programs
- This change fixes a bug where fork() on NT disabled TLS
- Fixed TLS code morphing on XNU/NT, for R8-R15 registers
This commit is contained in:
Justine Tunney 2022-09-08 02:33:01 -07:00
parent 571c2c3c69
commit 0e2b1bfeed
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
37 changed files with 310 additions and 189 deletions
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4
libc/runtime/enable_tls.c
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@ -230,7 +230,7 @@ privileged void __enable_tls(void) {
// we're checking for the following expression:
// 0144 == p[0] && // %fs
// 0110 == p[1] && // rex.w (64-bit operand size)
// 0110 == (p[1] & 0373) && // rex.w (and ignore rex.r)
// (0213 == p[2] || // mov reg/mem → reg (word-sized)
// 0003 == p[2]) && // add reg/mem → reg (word-sized)
// 0004 == (p[3] & 0307) && // mod/rm (4,reg,0) means sib → reg
@ -239,7 +239,7 @@ privileged void __enable_tls(void) {
// 0000 == p[6] && // displacement
// 0000 == p[7] && // displacement
// 0000 == p[8] // displacement
w = READ64LE(p) & READ64LE("\377\377\377\307\377\377\377\377");
w = READ64LE(p) & READ64LE("\377\373\377\307\377\377\377\377");
if ((w == READ64LE("\144\110\213\004\045\000\000\000") ||
w == READ64LE("\144\110\003\004\045\000\000\000")) &&
!p[8]) {

3
libc/runtime/fork-nt.c
View file

@ -29,6 +29,7 @@
#include "libc/mem/alloca.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/nt2sysv.h"
#include "libc/nexgen32e/threaded.h"
#include "libc/nt/console.h"
#include "libc/nt/createfile.h"
#include "libc/nt/enum/accessmask.h"
@ -88,7 +89,6 @@ static inline textwindows ssize_t ForkIo(int64_t h, char *p, size_t n,
static dontinline textwindows bool ForkIo2(int64_t h, void *buf, size_t n,
bool32 (*fn)(), const char *sf) {
ssize_t rc = ForkIo(h, buf, n, fn);
__tls_enabled = false; // prevent tls crash in kprintf
NTTRACE("%s(%ld, %p, %'zu) → %'zd% m", sf, h, buf, n, rc);
return rc != -1;
}
@ -98,6 +98,7 @@ static dontinline textwindows bool WriteAll(int64_t h, void *buf, size_t n) {
}
static textwindows dontinline void ReadOrDie(int64_t h, void *buf, size_t n) {
__tls_enabled = false; // prevent tls crash in kprintf
if (!ForkIo2(h, buf, n, ReadFile, "ReadFile")) {
AbortFork("ReadFile");
}

31
libc/runtime/gc.h
View file

@ -1,27 +1,24 @@
#ifndef COSMOPOLITAN_LIBC_RUNTIME_GC_H_
#define COSMOPOLITAN_LIBC_RUNTIME_GC_H_
#include "libc/calls/calls.h"
#include "libc/nexgen32e/stackframe.h"
#include "libc/runtime/runtime.h"
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
void *_gc(void *) hidden;
void *_defer(void *, void *) hidden;
void __defer(struct StackFrame *, void *, void *) hidden;
void __deferer(struct StackFrame *, void *, void *) hidden;
void _gclongjmp(jmp_buf, int) dontthrow wontreturn;
void *_gc(void *);
void *_defer(void *, void *);
void __defer(void *, void *, void *);
void _gclongjmp(void *, int) dontthrow wontreturn;
void _gc_free(void *);
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
#define _gc(THING) _defer((void *)_weakfree, (void *)(THING))
#define _defer(FN, ARG) \
({ \
autotype(ARG) Arg = (ARG); \
/* prevent weird opts like tail call */ \
asm volatile("" : "+g"(Arg) : : "memory"); \
__defer((struct StackFrame *)__builtin_frame_address(0), FN, Arg); \
asm volatile("" : "+g"(Arg) : : "memory"); \
Arg; \
#define _gc(THING) _defer((void *)_gc_free, (void *)(THING))
#define _defer(FN, ARG) \
({ \
autotype(ARG) Arg = (ARG); \
/* prevent weird opts like tail call */ \
asm volatile("" : "+g"(Arg) : : "memory"); \
__defer(__builtin_frame_address(0), FN, Arg); \
asm volatile("" : "+g"(Arg) : : "memory"); \
Arg; \
})
#endif /* defined(__GNUC__) && !defined(__STRICT_ANSI__) */