diff options
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/cgocall.go | 12 | ||||
| -rw-r--r-- | src/runtime/proc.c | 39 | ||||
| -rw-r--r-- | src/runtime/runtime.h | 1 | ||||
| -rw-r--r-- | src/runtime/stubs.go | 1 |
4 files changed, 40 insertions, 13 deletions
diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go index a21474b01f..7fd91469eb 100644 --- a/src/runtime/cgocall.go +++ b/src/runtime/cgocall.go @@ -177,14 +177,22 @@ func cfree(p unsafe.Pointer) { // Call from C back to Go. //go:nosplit func cgocallbackg() { - if gp := getg(); gp != gp.m.curg { + gp := getg() + if gp != gp.m.curg { println("runtime: bad g in cgocallback") exit(2) } + // entersyscall saves the caller's SP to allow the GC to trace the Go + // stack. However, since we're returning to an earlier stack frame and + // need to pair with the entersyscall() call made by cgocall, we must + // save syscall* and let reentersyscall restore them. + savedsp := unsafe.Pointer(gp.syscallsp) + savedpc := gp.syscallpc exitsyscall() // coming out of cgo call cgocallbackg1() - entersyscall() // going back to cgo call + // going back to cgo call + reentersyscall(savedpc, savedsp) } func cgocallbackg1() { diff --git a/src/runtime/proc.c b/src/runtime/proc.c index 3f4179d473..564798be7b 100644 --- a/src/runtime/proc.c +++ b/src/runtime/proc.c @@ -1700,9 +1700,9 @@ goexit0(G *gp) #pragma textflag NOSPLIT static void -save(void *pc, uintptr sp) +save(uintptr pc, uintptr sp) { - g->sched.pc = (uintptr)pc; + g->sched.pc = pc; g->sched.sp = sp; g->sched.lr = 0; g->sched.ret = 0; @@ -1730,9 +1730,15 @@ static void entersyscall_gcwait(void); // In practice, this means that we make the fast path run through // entersyscall doing no-split things, and the slow path has to use onM // to run bigger things on the m stack. +// +// reentersyscall is the entry point used by cgo callbacks, where explicitly +// saved SP and PC are restored. This is needed when exitsyscall will be called +// from a function further up in the call stack than the parent, as g->syscallsp +// must always point to a valid stack frame. entersyscall below is the normal +// entry point for syscalls, which obtains the SP and PC from the caller. #pragma textflag NOSPLIT void -·entersyscall(int32 dummy) +runtime·reentersyscall(uintptr pc, uintptr sp) { void (*fn)(void); @@ -1748,9 +1754,9 @@ void g->throwsplit = 1; // Leave SP around for GC and traceback. - save(runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); - g->syscallsp = g->sched.sp; - g->syscallpc = g->sched.pc; + save(pc, sp); + g->syscallsp = sp; + g->syscallpc = pc; runtime·casgstatus(g, Grunning, Gsyscall); if(g->syscallsp < g->stack.lo || g->stack.hi < g->syscallsp) { fn = entersyscall_bad; @@ -1760,7 +1766,7 @@ void if(runtime·atomicload(&runtime·sched.sysmonwait)) { // TODO: fast atomic fn = entersyscall_sysmon; runtime·onM(&fn); - save(runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); + save(pc, sp); } g->m->mcache = nil; @@ -1769,7 +1775,7 @@ void if(runtime·sched.gcwaiting) { fn = entersyscall_gcwait; runtime·onM(&fn); - save(runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); + save(pc, sp); } // Goroutines must not split stacks in Gsyscall status (it would corrupt g->sched). @@ -1779,6 +1785,14 @@ void g->m->locks--; } +// Standard syscall entry used by the go syscall library and normal cgo calls. +#pragma textflag NOSPLIT +void +·entersyscall(int32 dummy) +{ + runtime·reentersyscall((uintptr)runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); +} + static void entersyscall_bad(void) { @@ -1826,7 +1840,7 @@ void g->stackguard0 = StackPreempt; // see comment in entersyscall // Leave SP around for GC and traceback. - save(runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); + save((uintptr)runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); g->syscallsp = g->sched.sp; g->syscallpc = g->sched.pc; runtime·casgstatus(g, Grunning, Gsyscall); @@ -1839,7 +1853,7 @@ void runtime·onM(&fn); // Resave for traceback during blocked call. - save(runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); + save((uintptr)runtime·getcallerpc(&dummy), runtime·getcallersp(&dummy)); g->m->locks--; } @@ -1856,12 +1870,15 @@ entersyscallblock_handoff(void) // from the low-level system calls used by the runtime. #pragma textflag NOSPLIT void -runtime·exitsyscall(void) +·exitsyscall(int32 dummy) { void (*fn)(G*); g->m->locks++; // see comment in entersyscall + if(runtime·getcallersp(&dummy) > g->syscallsp) + runtime·throw("exitsyscall: syscall frame is no longer valid"); + g->waitsince = 0; if(exitsyscallfast()) { // There's a cpu for us, so we can run. diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h index 7fefbc2997..3a6d3e3262 100644 --- a/src/runtime/runtime.h +++ b/src/runtime/runtime.h @@ -901,6 +901,7 @@ void runtime·goexit(void); void runtime·asmcgocall(void (*fn)(void*), void*); int32 runtime·asmcgocall_errno(void (*fn)(void*), void*); void runtime·entersyscall(void); +void runtime·reentersyscall(uintptr, uintptr); void runtime·entersyscallblock(void); void runtime·exitsyscall(void); G* runtime·newproc1(FuncVal*, byte*, int32, int32, void*); diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go index 2e6aadca7a..1381c7efdb 100644 --- a/src/runtime/stubs.go +++ b/src/runtime/stubs.go @@ -164,6 +164,7 @@ func noescape(p unsafe.Pointer) unsafe.Pointer { } func entersyscall() +func reentersyscall(pc uintptr, sp unsafe.Pointer) func entersyscallblock() func exitsyscall() |