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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "runtime.h"
#include "defs_GOOS_GOARCH.h"
#include "os_GOOS.h"
#include "signal_unix.h"
#include "stack.h"
#include "textflag.h"
extern SigTab runtime·sigtab[];
static Sigset sigset_none;
static Sigset sigset_all = { ~(uint32)0, ~(uint32)0 };
// Linux futex.
//
// futexsleep(uint32 *addr, uint32 val)
// futexwakeup(uint32 *addr)
//
// Futexsleep atomically checks if *addr == val and if so, sleeps on addr.
// Futexwakeup wakes up threads sleeping on addr.
// Futexsleep is allowed to wake up spuriously.
enum
{
FUTEX_WAIT = 0,
FUTEX_WAKE = 1,
};
// Atomically,
// if(*addr == val) sleep
// Might be woken up spuriously; that's allowed.
// Don't sleep longer than ns; ns < 0 means forever.
#pragma textflag NOSPLIT
void
runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
{
Timespec ts;
// Some Linux kernels have a bug where futex of
// FUTEX_WAIT returns an internal error code
// as an errno. Libpthread ignores the return value
// here, and so can we: as it says a few lines up,
// spurious wakeups are allowed.
if(ns < 0) {
runtime·futex(addr, FUTEX_WAIT, val, nil, nil, 0);
return;
}
// It's difficult to live within the no-split stack limits here.
// On ARM and 386, a 64-bit divide invokes a general software routine
// that needs more stack than we can afford. So we use timediv instead.
// But on real 64-bit systems, where words are larger but the stack limit
// is not, even timediv is too heavy, and we really need to use just an
// ordinary machine instruction.
// Sorry for the #ifdef.
// For what it's worth, the #ifdef eliminated an implicit little-endian assumption.
#ifdef _64BIT
ts.tv_sec = ns / 1000000000LL;
ts.tv_nsec = ns % 1000000000LL;
#else
ts.tv_nsec = 0;
ts.tv_sec = runtime·timediv(ns, 1000000000LL, (int32*)&ts.tv_nsec);
#endif
runtime·futex(addr, FUTEX_WAIT, val, &ts, nil, 0);
}
static void badfutexwakeup(void);
// If any procs are sleeping on addr, wake up at most cnt.
#pragma textflag NOSPLIT
void
runtime·futexwakeup(uint32 *addr, uint32 cnt)
{
int64 ret;
void (*fn)(void);
ret = runtime·futex(addr, FUTEX_WAKE, cnt, nil, nil, 0);
if(ret >= 0)
return;
// I don't know that futex wakeup can return
// EAGAIN or EINTR, but if it does, it would be
// safe to loop and call futex again.
g->m->ptrarg[0] = addr;
g->m->scalararg[0] = (int32)ret; // truncated but fine
fn = badfutexwakeup;
if(g == g->m->gsignal)
fn();
else
runtime·onM(&fn);
*(int32*)0x1006 = 0x1006;
}
static void
badfutexwakeup(void)
{
void *addr;
int64 ret;
addr = g->m->ptrarg[0];
ret = (int32)g->m->scalararg[0];
runtime·printf("futexwakeup addr=%p returned %D\n", addr, ret);
}
extern runtime·sched_getaffinity(uintptr pid, uintptr len, uintptr *buf);
static int32
getproccount(void)
{
uintptr buf[16], t;
int32 r, n, i;
r = runtime·sched_getaffinity(0, sizeof(buf), buf);
if(r <= 0)
return 1;
n = 0;
for(i = 0; i < r/sizeof(buf[0]); i++) {
t = buf[i];
while(t != 0) {
n += t&1;
t >>= 1;
}
}
if(n < 1)
n = 1;
return n;
}
// Clone, the Linux rfork.
enum
{
CLONE_VM = 0x100,
CLONE_FS = 0x200,
CLONE_FILES = 0x400,
CLONE_SIGHAND = 0x800,
CLONE_PTRACE = 0x2000,
CLONE_VFORK = 0x4000,
CLONE_PARENT = 0x8000,
CLONE_THREAD = 0x10000,
CLONE_NEWNS = 0x20000,
CLONE_SYSVSEM = 0x40000,
CLONE_SETTLS = 0x80000,
CLONE_PARENT_SETTID = 0x100000,
CLONE_CHILD_CLEARTID = 0x200000,
CLONE_UNTRACED = 0x800000,
CLONE_CHILD_SETTID = 0x1000000,
CLONE_STOPPED = 0x2000000,
CLONE_NEWUTS = 0x4000000,
CLONE_NEWIPC = 0x8000000,
};
void
runtime·newosproc(M *mp, void *stk)
{
int32 ret;
int32 flags;
Sigset oset;
/*
* note: strace gets confused if we use CLONE_PTRACE here.
*/
flags = CLONE_VM /* share memory */
| CLONE_FS /* share cwd, etc */
| CLONE_FILES /* share fd table */
| CLONE_SIGHAND /* share sig handler table */
| CLONE_THREAD /* revisit - okay for now */
;
mp->tls[0] = mp->id; // so 386 asm can find it
if(0){
runtime·printf("newosproc stk=%p m=%p g=%p clone=%p id=%d/%d ostk=%p\n",
stk, mp, mp->g0, runtime·clone, mp->id, (int32)mp->tls[0], &mp);
}
// Disable signals during clone, so that the new thread starts
// with signals disabled. It will enable them in minit.
runtime·rtsigprocmask(SIG_SETMASK, &sigset_all, &oset, sizeof oset);
ret = runtime·clone(flags, stk, mp, mp->g0, runtime·mstart);
runtime·rtsigprocmask(SIG_SETMASK, &oset, nil, sizeof oset);
if(ret < 0) {
runtime·printf("runtime: failed to create new OS thread (have %d already; errno=%d)\n", runtime·mcount(), -ret);
runtime·throw("runtime.newosproc");
}
}
void
runtime·osinit(void)
{
runtime·ncpu = getproccount();
}
// Random bytes initialized at startup. These come
// from the ELF AT_RANDOM auxiliary vector (vdso_linux_amd64.c).
byte* runtime·startup_random_data;
uint32 runtime·startup_random_data_len;
#pragma textflag NOSPLIT
void
runtime·get_random_data(byte **rnd, int32 *rnd_len)
{
if(runtime·startup_random_data != nil) {
*rnd = runtime·startup_random_data;
*rnd_len = runtime·startup_random_data_len;
} else {
#pragma dataflag NOPTR
static byte urandom_data[HashRandomBytes];
int32 fd;
fd = runtime·open("/dev/urandom", 0 /* O_RDONLY */, 0);
if(runtime·read(fd, urandom_data, HashRandomBytes) == HashRandomBytes) {
*rnd = urandom_data;
*rnd_len = HashRandomBytes;
} else {
*rnd = nil;
*rnd_len = 0;
}
runtime·close(fd);
}
}
void
runtime·goenvs(void)
{
runtime·goenvs_unix();
}
// Called to initialize a new m (including the bootstrap m).
// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
void
runtime·mpreinit(M *mp)
{
mp->gsignal = runtime·malg(32*1024); // OS X wants >=8K, Linux >=2K
mp->gsignal->m = mp;
}
// Called to initialize a new m (including the bootstrap m).
// Called on the new thread, can not allocate memory.
void
runtime·minit(void)
{
// Initialize signal handling.
runtime·signalstack((byte*)g->m->gsignal->stack.lo, 32*1024);
runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset));
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
uintptr
runtime·memlimit(void)
{
Rlimit rl;
extern byte runtime·text[], runtime·end[];
uintptr used;
if(runtime·getrlimit(RLIMIT_AS, &rl) != 0)
return 0;
if(rl.rlim_cur >= 0x7fffffff)
return 0;
// Estimate our VM footprint excluding the heap.
// Not an exact science: use size of binary plus
// some room for thread stacks.
used = runtime·end - runtime·text + (64<<20);
if(used >= rl.rlim_cur)
return 0;
// If there's not at least 16 MB left, we're probably
// not going to be able to do much. Treat as no limit.
rl.rlim_cur -= used;
if(rl.rlim_cur < (16<<20))
return 0;
return rl.rlim_cur - used;
}
#ifdef GOARCH_386
#define sa_handler k_sa_handler
#endif
/*
* This assembler routine takes the args from registers, puts them on the stack,
* and calls sighandler().
*/
extern void runtime·sigtramp(void);
extern void runtime·sigreturn(void); // calls rt_sigreturn, only used with SA_RESTORER
void
runtime·setsig(int32 i, GoSighandler *fn, bool restart)
{
SigactionT sa;
runtime·memclr((byte*)&sa, sizeof sa);
sa.sa_flags = SA_ONSTACK | SA_SIGINFO | SA_RESTORER;
if(restart)
sa.sa_flags |= SA_RESTART;
sa.sa_mask = ~0ULL;
// Although Linux manpage says "sa_restorer element is obsolete and
// should not be used". x86_64 kernel requires it. Only use it on
// x86.
#ifdef GOARCH_386
sa.sa_restorer = (void*)runtime·sigreturn;
#endif
#ifdef GOARCH_amd64
sa.sa_restorer = (void*)runtime·sigreturn;
#endif
if(fn == runtime·sighandler)
fn = (void*)runtime·sigtramp;
sa.sa_handler = fn;
// Qemu rejects rt_sigaction of SIGRTMAX (64).
if(runtime·rt_sigaction(i, &sa, nil, sizeof(sa.sa_mask)) != 0 && i != 64)
runtime·throw("rt_sigaction failure");
}
GoSighandler*
runtime·getsig(int32 i)
{
SigactionT sa;
runtime·memclr((byte*)&sa, sizeof sa);
if(runtime·rt_sigaction(i, nil, &sa, sizeof(sa.sa_mask)) != 0)
runtime·throw("rt_sigaction read failure");
if((void*)sa.sa_handler == runtime·sigtramp)
return runtime·sighandler;
return (void*)sa.sa_handler;
}
void
runtime·signalstack(byte *p, int32 n)
{
SigaltstackT st;
st.ss_sp = p;
st.ss_size = n;
st.ss_flags = 0;
if(p == nil)
st.ss_flags = SS_DISABLE;
runtime·sigaltstack(&st, nil);
}
void
runtime·unblocksignals(void)
{
runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof sigset_none);
}
#pragma textflag NOSPLIT
int8*
runtime·signame(int32 sig)
{
return runtime·sigtab[sig].name;
}