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Make _Thread_local more seamlessly working

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This commit is contained in:
Justine Tunney 2022-07-10 08:27:50 -07:00
parent 5f4f6b0e69
commit 5fa77f1e8f
23 changed files with 217 additions and 283 deletions
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26
libc/runtime/clone.c
View file

@ -64,10 +64,7 @@ struct CloneArgs {
uint32_t utid;
int64_t tid64;
};
union {
char lock;
void *oldrsp;
};
char lock;
int *ptid;
int *ctid;
int *ztid;
@ -287,6 +284,15 @@ static int CloneFreebsd(int (*func)(void *, int), char *stk, size_t stksz,
////////////////////////////////////////////////////////////////////////////////
// OPEN BESIYATA DISHMAYA
static void *oldrsp;
__attribute__((__constructor__)) static void OpenbsdGetSafeRsp(void) {
// main thread stack should never be freed during process lifetime. we
// won't actually change this stack below. we just need need a place
// where threads can park RSP for a few instructions while dying.
oldrsp = __builtin_frame_address(0);
}
static wontreturn void OpenbsdThreadMain(void *p) {
struct CloneArgs *wt = p;
*wt->ptid = wt->tid;
@ -303,7 +309,7 @@ static wontreturn void OpenbsdThreadMain(void *p) {
"movl\t$0,(%%rdi)\n\t" // *wt->ztid = 0
"syscall" // __threxit()
: "=m"(*wt->ztid)
: "a"(302), "m"(wt->oldrsp), "D"(wt->ztid)
: "a"(302), "m"(oldrsp), "D"(wt->ztid)
: "rcx", "r11", "memory");
unreachable;
}
@ -325,7 +331,6 @@ static int CloneOpenbsd(int (*func)(void *, int), char *stk, size_t stksz,
wt->ptid = flags & CLONE_PARENT_SETTID ? ptid : &wt->tid;
wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid;
wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid;
wt->oldrsp = __builtin_frame_address(0);
wt->arg = arg;
wt->func = func;
tf->tf_stack = (char *)wt - 8;
@ -591,13 +596,8 @@ int clone(void *func, void *stk, size_t stksz, int flags, void *arg, int *ptid,
int rc;
struct CloneArgs *wt;
if ((flags & CLONE_SETTLS) && !__tls_enabled) {
__enable_tls();
}
if ((flags & CLONE_THREAD) && !__threaded) {
__enable_threads();
}
if (flags & CLONE_SETTLS) __enable_tls();
if (flags & CLONE_THREAD) __enable_threads();
if (!func) {
rc = einval();

17
libc/runtime/cosmo.S
View file

@ -76,6 +76,23 @@ cosmo: push %rbp
ret
.endfn cosmo,weak
#if !IsTiny()
// Enable TLS early if _Thread_local is used
// In MODE=tiny you may need to explicitly call __enable_tls()
// Otherwise this would bloat life.com from 16kb → 32kb D:
.init.start 304,_init_tls
mov $_tls_content,%eax
test %eax,%eax
jz 1f
push %rdi
push %rsi
call __enable_tls
pop %rsi
pop %rdi
jz 1f
1: .init.end 304,_init_tls
#endif
#if !IsTiny()
// Creates deterministically addressed stack we can use
//

57
libc/runtime/enable_threads.c Normal file
View file

@ -0,0 +1,57 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net 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/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/strace.internal.h"
#include "libc/nexgen32e/threaded.h"
#include "libc/runtime/runtime.h"
extern int __threadcalls_end[];
extern int __threadcalls_start[];
privileged void __enable_threads(void) {
if (__threaded) return;
STRACE("__enable_threads()");
__threaded = gettid();
__morph_begin();
/*
* _NOPL("__threadcalls", func)
*
* The big ugly macro above is used by Cosmopolitan Libc to unser
* locking primitive (e.g. flockfile, funlockfile) have zero impact on
* performance and binary size when threads aren't actually in play.
*
* we have this
*
* 0f 1f 05 b1 19 00 00 nopl func(%rip)
*
* we're going to turn it into this
*
* 67 67 e8 b1 19 00 00 addr32 addr32 call func
*
* This is cheap and fast because the big ugly macro stored in the
* binary the offsets of all the instructions we need to change.
*/
for (int *p = __threadcalls_start; p < __threadcalls_end; ++p) {
_base[*p + 0] = 0x67;
_base[*p + 1] = 0x67;
_base[*p + 2] = 0xe8;
}
__morph_end();
}

66
libc/runtime/threadmode.c → libc/runtime/enable_tls.c
View file

@ -16,17 +16,14 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/calls/calls.h"
#include "libc/calls/strace.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/macros.internal.h"
#include "libc/nexgen32e/threaded.h"
#include "libc/nt/thread.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
@ -48,14 +45,14 @@
#define _TLDZ ((intptr_t)_tdata_size)
#define _TIBZ sizeof(struct cthread_descriptor_t)
extern int __threadcalls_end[];
extern int __threadcalls_start[];
extern unsigned char __get_tls_nt_rax[];
__msabi extern typeof(TlsAlloc) *const __imp_TlsAlloc;
extern unsigned char __tls_mov_nt_rax[];
extern unsigned char __tls_add_nt_rax[];
privileged void __enable_tls(void) {
assert(!__threaded);
assert(!__tls_enabled);
if (__tls_enabled) return;
STRACE("__enable_tls()");
// allocate tls memory for main process
//
@ -119,6 +116,7 @@ privileged void __enable_tls(void) {
* -mno-tls-direct-seg-refs flag which generates code like this
*
* 64 48 8b 0R4 25 00 00 00 00 mov %fs:0,%R
* 64 48 03 0R4 25 00 00 00 00 add %fs:0,%R
*
* Which on Mac we can replace with this:
*
@ -127,17 +125,22 @@ privileged void __enable_tls(void) {
* Whereas on Windows we'll replace it with this:
*
* 0f 1f 40 00 fatnop4
* e8 xx xx xx xx call __get_tls_nt_%R
* e8 xx xx xx xx call __tls_mov_nt_%R
*
* Since we have no idea where the TLS instructions exist in the
* binary, we need to disassemble the whole program image. This'll
* potentially take a few milliseconds for some larger programs.
*
* We check `_tls_content` which is generated by the linker script
* since it lets us determine ahead of time if _Thread_local vars
* have actually been linked into this program.
*
* TODO(jart): compute probability this is just overkill
*/
if (IsWindows() || IsXnu()) {
if ((intptr_t)_tls_content && (IsWindows() || IsXnu())) {
int n, reg, dis;
unsigned char *p;
const unsigned char *impl;
struct XedDecodedInst xedd;
__morph_begin();
@ -154,7 +157,8 @@ privileged void __enable_tls(void) {
if (xedd.length == 9 && //
0144 == p[0] && // fs
0110 == p[1] && // rex.w (64-bit operand size)
0213 == p[2] && // mov reg/mem → reg (word-sized)
(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
0045 == p[4] && // sib (5,4,0) → (rbp,rsp,0) → disp32
0000 == p[5] && // displacement (von Neumann endian)
@ -175,8 +179,13 @@ privileged void __enable_tls(void) {
// that's the same as the mov destination. When setting
// function displacement, &CALL+5+DISP must equal &FUNC.
else {
if (p[2] == 3) {
impl = __tls_add_nt_rax;
} else {
impl = __tls_mov_nt_rax;
}
reg = (p[3] & 070) >> 3;
dis = (__get_tls_nt_rax + reg * 18) - (p + 9);
dis = (impl + reg * 18) - (p + 9);
p[0] = 0017; // map1
p[1] = 0037; // nopl (onl if reg=0)
p[2] = 0100; // mod/rm (%rax)+disp8
@ -202,35 +211,6 @@ privileged void __enable_tls(void) {
}
// we are now allowed to use tls
// setting this variable
__tls_enabled = true;
}
privileged void __enable_threads(void) {
assert(!__threaded);
__threaded = gettid();
__morph_begin();
/*
* _NOPL("__threadcalls", func)
*
* The big ugly macro above is used by Cosmopolitan Libc to unser
* locking primitive (e.g. flockfile, funlockfile) have zero impact on
* performance and binary size when threads aren't actually in play.
*
* we have this
*
* 0f 1f 05 b1 19 00 00 nopl func(%rip)
*
* we're going to turn it into this
*
* 67 67 e8 b1 19 00 00 addr32 addr32 call func
*
* This is cheap and fast because the big ugly macro stored in the
* binary the offsets of all the instructions we need to change.
*/
for (int *p = __threadcalls_start; p < __threadcalls_end; ++p) {
_base[*p + 0] = 0x67;
_base[*p + 1] = 0x67;
_base[*p + 2] = 0xe8;
}
__morph_end();
}

1
libc/runtime/internal.h
View file

@ -24,6 +24,7 @@ extern unsigned char _tdata_size[];
extern unsigned char _tbss_start[];
extern unsigned char _tbss_end[];
extern unsigned char _tls_size[];
extern unsigned char _tls_content[];
void _init(void) hidden;
void __enable_tls(void) hidden;

3
libc/runtime/morph.greg.c
View file

@ -19,6 +19,7 @@
#define ShouldUseMsabiAttribute() 1
#include "libc/bits/asmflag.h"
#include "libc/calls/internal.h"
#include "libc/calls/strace.internal.h"
#include "libc/calls/struct/sigset.h"
#include "libc/dce.h"
#include "libc/errno.h"
@ -58,6 +59,7 @@ static privileged void __morph_mprotect(void *addr, size_t size, int prot,
*/
privileged void __morph_begin(void) {
sigset_t ss = {{-1, -1}};
STRACE("__morph_begin()");
if (!IsWindows()) {
sys_sigprocmask(SIG_BLOCK, &ss, &oldss);
}
@ -74,4 +76,5 @@ privileged void __morph_end(void) {
if (!IsWindows()) {
sys_sigprocmask(SIG_SETMASK, &oldss, 0);
}
STRACE("__morph_end()");
}