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Diffstat (limited to 'src/pkg/runtime/cgocall.c')
| -rw-r--r-- | src/pkg/runtime/cgocall.c | 322 |
1 files changed, 0 insertions, 322 deletions
diff --git a/src/pkg/runtime/cgocall.c b/src/pkg/runtime/cgocall.c deleted file mode 100644 index 75d3850ef..000000000 --- a/src/pkg/runtime/cgocall.c +++ /dev/null @@ -1,322 +0,0 @@ -// 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 "arch_GOARCH.h" -#include "stack.h" -#include "cgocall.h" -#include "race.h" -#include "../../cmd/ld/textflag.h" - -// Cgo call and callback support. -// -// To call into the C function f from Go, the cgo-generated code calls -// runtime.cgocall(_cgo_Cfunc_f, frame), where _cgo_Cfunc_f is a -// gcc-compiled function written by cgo. -// -// runtime.cgocall (below) locks g to m, calls entersyscall -// so as not to block other goroutines or the garbage collector, -// and then calls runtime.asmcgocall(_cgo_Cfunc_f, frame). -// -// runtime.asmcgocall (in asm_$GOARCH.s) switches to the m->g0 stack -// (assumed to be an operating system-allocated stack, so safe to run -// gcc-compiled code on) and calls _cgo_Cfunc_f(frame). -// -// _cgo_Cfunc_f invokes the actual C function f with arguments -// taken from the frame structure, records the results in the frame, -// and returns to runtime.asmcgocall. -// -// After it regains control, runtime.asmcgocall switches back to the -// original g (m->curg)'s stack and returns to runtime.cgocall. -// -// After it regains control, runtime.cgocall calls exitsyscall, which blocks -// until this m can run Go code without violating the $GOMAXPROCS limit, -// and then unlocks g from m. -// -// The above description skipped over the possibility of the gcc-compiled -// function f calling back into Go. If that happens, we continue down -// the rabbit hole during the execution of f. -// -// To make it possible for gcc-compiled C code to call a Go function p.GoF, -// cgo writes a gcc-compiled function named GoF (not p.GoF, since gcc doesn't -// know about packages). The gcc-compiled C function f calls GoF. -// -// GoF calls crosscall2(_cgoexp_GoF, frame, framesize). Crosscall2 -// (in cgo/gcc_$GOARCH.S, a gcc-compiled assembly file) is a two-argument -// adapter from the gcc function call ABI to the 6c function call ABI. -// It is called from gcc to call 6c functions. In this case it calls -// _cgoexp_GoF(frame, framesize), still running on m->g0's stack -// and outside the $GOMAXPROCS limit. Thus, this code cannot yet -// call arbitrary Go code directly and must be careful not to allocate -// memory or use up m->g0's stack. -// -// _cgoexp_GoF calls runtime.cgocallback(p.GoF, frame, framesize). -// (The reason for having _cgoexp_GoF instead of writing a crosscall3 -// to make this call directly is that _cgoexp_GoF, because it is compiled -// with 6c instead of gcc, can refer to dotted names like -// runtime.cgocallback and p.GoF.) -// -// runtime.cgocallback (in asm_$GOARCH.s) switches from m->g0's -// stack to the original g (m->curg)'s stack, on which it calls -// runtime.cgocallbackg(p.GoF, frame, framesize). -// As part of the stack switch, runtime.cgocallback saves the current -// SP as m->g0->sched.sp, so that any use of m->g0's stack during the -// execution of the callback will be done below the existing stack frames. -// Before overwriting m->g0->sched.sp, it pushes the old value on the -// m->g0 stack, so that it can be restored later. -// -// runtime.cgocallbackg (below) is now running on a real goroutine -// stack (not an m->g0 stack). First it calls runtime.exitsyscall, which will -// block until the $GOMAXPROCS limit allows running this goroutine. -// Once exitsyscall has returned, it is safe to do things like call the memory -// allocator or invoke the Go callback function p.GoF. runtime.cgocallbackg -// first defers a function to unwind m->g0.sched.sp, so that if p.GoF -// panics, m->g0.sched.sp will be restored to its old value: the m->g0 stack -// and the m->curg stack will be unwound in lock step. -// Then it calls p.GoF. Finally it pops but does not execute the deferred -// function, calls runtime.entersyscall, and returns to runtime.cgocallback. -// -// After it regains control, runtime.cgocallback switches back to -// m->g0's stack (the pointer is still in m->g0.sched.sp), restores the old -// m->g0.sched.sp value from the stack, and returns to _cgoexp_GoF. -// -// _cgoexp_GoF immediately returns to crosscall2, which restores the -// callee-save registers for gcc and returns to GoF, which returns to f. - -void *_cgo_init; /* filled in by dynamic linker when Cgo is available */ -static int64 cgosync; /* represents possible synchronization in C code */ - -static void unwindm(void); - -// Call from Go to C. - -static void endcgo(void); -static FuncVal endcgoV = { endcgo }; - -void -runtime·cgocall(void (*fn)(void*), void *arg) -{ - Defer d; - - if(!runtime·iscgo && !Solaris && !Windows) - runtime·throw("cgocall unavailable"); - - if(fn == 0) - runtime·throw("cgocall nil"); - - if(raceenabled) - runtime·racereleasemerge(&cgosync); - - // Create an extra M for callbacks on threads not created by Go on first cgo call. - if(runtime·needextram && runtime·cas(&runtime·needextram, 1, 0)) - runtime·newextram(); - - m->ncgocall++; - - /* - * Lock g to m to ensure we stay on the same stack if we do a - * cgo callback. Add entry to defer stack in case of panic. - */ - runtime·lockOSThread(); - d.fn = &endcgoV; - d.siz = 0; - d.link = g->defer; - d.argp = NoArgs; - d.special = true; - g->defer = &d; - - m->ncgo++; - - /* - * Announce we are entering a system call - * so that the scheduler knows to create another - * M to run goroutines while we are in the - * foreign code. - * - * The call to asmcgocall is guaranteed not to - * split the stack and does not allocate memory, - * so it is safe to call while "in a system call", outside - * the $GOMAXPROCS accounting. - */ - runtime·entersyscall(); - runtime·asmcgocall(fn, arg); - runtime·exitsyscall(); - - if(g->defer != &d || d.fn != &endcgoV) - runtime·throw("runtime: bad defer entry in cgocallback"); - g->defer = d.link; - endcgo(); -} - -static void -endcgo(void) -{ - runtime·unlockOSThread(); - m->ncgo--; - if(m->ncgo == 0) { - // We are going back to Go and are not in a recursive - // call. Let the GC collect any memory allocated via - // _cgo_allocate that is no longer referenced. - m->cgomal = nil; - } - - if(raceenabled) - runtime·raceacquire(&cgosync); -} - -// Helper functions for cgo code. - -void (*_cgo_malloc)(void*); -void (*_cgo_free)(void*); - -void* -runtime·cmalloc(uintptr n) -{ - struct { - uint64 n; - void *ret; - } a; - - a.n = n; - a.ret = nil; - runtime·cgocall(_cgo_malloc, &a); - if(a.ret == nil) - runtime·throw("runtime: C malloc failed"); - return a.ret; -} - -void -runtime·cfree(void *p) -{ - runtime·cgocall(_cgo_free, p); -} - -// Call from C back to Go. - -static FuncVal unwindmf = {unwindm}; - -typedef struct CallbackArgs CallbackArgs; -struct CallbackArgs -{ - FuncVal *fn; - void *arg; - uintptr argsize; -}; - -// Location of callback arguments depends on stack frame layout -// and size of stack frame of cgocallback_gofunc. - -// On arm, stack frame is two words and there's a saved LR between -// SP and the stack frame and between the stack frame and the arguments. -#ifdef GOARCH_arm -#define CBARGS (CallbackArgs*)((byte*)m->g0->sched.sp+4*sizeof(void*)) -#endif - -// On amd64, stack frame is one word, plus caller PC. -#ifdef GOARCH_amd64 -#define CBARGS (CallbackArgs*)((byte*)m->g0->sched.sp+2*sizeof(void*)) -#endif - -// Unimplemented on amd64p32 -#ifdef GOARCH_amd64p32 -#define CBARGS (CallbackArgs*)(nil) -#endif - -// On 386, stack frame is three words, plus caller PC. -#ifdef GOARCH_386 -#define CBARGS (CallbackArgs*)((byte*)m->g0->sched.sp+4*sizeof(void*)) -#endif - -void runtime·cgocallbackg1(void); - -#pragma textflag NOSPLIT -void -runtime·cgocallbackg(void) -{ - uintptr pc, sp; - - if(g != m->curg) { - runtime·prints("runtime: bad g in cgocallback"); - runtime·exit(2); - } - - pc = g->syscallpc; - sp = g->syscallsp; - runtime·exitsyscall(); // coming out of cgo call - runtime·cgocallbackg1(); - runtime·reentersyscall((void*)pc, sp); // going back to cgo call -} - -void -runtime·cgocallbackg1(void) -{ - CallbackArgs *cb; - Defer d; - - if(m->needextram) { - m->needextram = 0; - runtime·newextram(); - } - - // Add entry to defer stack in case of panic. - d.fn = &unwindmf; - d.siz = 0; - d.link = g->defer; - d.argp = NoArgs; - d.special = true; - g->defer = &d; - - if(raceenabled) - runtime·raceacquire(&cgosync); - - // Invoke callback. - cb = CBARGS; - runtime·newstackcall(cb->fn, cb->arg, cb->argsize); - - if(raceenabled) - runtime·racereleasemerge(&cgosync); - - // Pop defer. - // Do not unwind m->g0->sched.sp. - // Our caller, cgocallback, will do that. - if(g->defer != &d || d.fn != &unwindmf) - runtime·throw("runtime: bad defer entry in cgocallback"); - g->defer = d.link; -} - -static void -unwindm(void) -{ - // Restore sp saved by cgocallback during - // unwind of g's stack (see comment at top of file). - switch(thechar){ - default: - runtime·throw("runtime: unwindm not implemented"); - case '8': - case '6': - m->g0->sched.sp = *(uintptr*)m->g0->sched.sp; - break; - case '5': - m->g0->sched.sp = *(uintptr*)((byte*)m->g0->sched.sp + 4); - break; - } -} - -void -runtime·badcgocallback(void) // called from assembly -{ - runtime·throw("runtime: misaligned stack in cgocallback"); -} - -void -runtime·cgounimpl(void) // called from (incomplete) assembly -{ - runtime·throw("runtime: cgo not implemented"); -} - -// For cgo-using programs with external linking, -// export "main" (defined in assembly) so that libc can handle basic -// C runtime startup and call the Go program as if it were -// the C main function. -#pragma cgo_export_static main |