| // 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. |
| |
| // 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) 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 $GOMAXPROCS limit, |
| // and then unlocks g from m. |
| // |
| // The above description skipped over the possibility of the gcc-compiled |
| // function f calling back into Go. If that happens, we continue down |
| // the rabbit hole during the execution of f. |
| // |
| // To make it possible for gcc-compiled C code to call a Go function p.GoF, |
| // cgo writes a gcc-compiled function named GoF (not p.GoF, since gcc doesn't |
| // know about packages). The gcc-compiled C function f calls GoF. |
| // |
| // GoF initializes "frame", a structure containing all of its |
| // arguments and slots for p.GoF's results. It calls |
| // crosscall2(_cgoexp_GoF, frame, framesize, ctxt) using the gcc ABI. |
| // |
| // crosscall2 (in cgo/asm_$GOARCH.s) is a four-argument adapter from |
| // the gcc function call ABI to the gc function call ABI. At this |
| // point we're in the Go runtime, but we're still running on m.g0's |
| // stack and outside the $GOMAXPROCS limit. crosscall2 calls |
| // runtime.cgocallback(_cgoexp_GoF, frame, ctxt) using the gc ABI. |
| // (crosscall2's framesize argument is no longer used, but there's one |
| // case where SWIG calls crosscall2 directly and expects to pass this |
| // argument. See _cgo_panic.) |
| // |
| // runtime.cgocallback (in asm_$GOARCH.s) switches from m.g0's stack |
| // to the original g (m.curg)'s stack, on which it calls |
| // runtime.cgocallbackg(_cgoexp_GoF, frame, ctxt). 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. 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 _cgoexp_GoF(frame). |
| // |
| // _cgoexp_GoF, which was generated by cmd/cgo, unpacks the arguments |
| // from frame, calls p.GoF, writes the results back to frame, and |
| // returns. Now we start unwinding this whole process. |
| // |
| // runtime.cgocallbackg pops but does not execute the deferred |
| // function to unwind m.g0.sched.sp, 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 crosscall2. |
| // |
| // crosscall2 restores the callee-save registers for gcc and returns |
| // to GoF, which unpacks any result values and returns to f. |
| |
| package runtime |
| |
| import ( |
| "internal/abi" |
| "internal/goarch" |
| "internal/goexperiment" |
| "internal/runtime/sys" |
| "unsafe" |
| ) |
| |
| // Addresses collected in a cgo backtrace when crashing. |
| // Length must match arg.Max in x_cgo_callers in runtime/cgo/gcc_traceback.c. |
| type cgoCallers [32]uintptr |
| |
| // argset matches runtime/cgo/linux_syscall.c:argset_t |
| type argset struct { |
| args unsafe.Pointer |
| retval uintptr |
| } |
| |
| // wrapper for syscall package to call cgocall for libc (cgo) calls. |
| // |
| //go:linkname syscall_cgocaller syscall.cgocaller |
| //go:nosplit |
| //go:uintptrescapes |
| func syscall_cgocaller(fn unsafe.Pointer, args ...uintptr) uintptr { |
| as := argset{args: unsafe.Pointer(&args[0])} |
| cgocall(fn, unsafe.Pointer(&as)) |
| return as.retval |
| } |
| |
| var ncgocall uint64 // number of cgo calls in total for dead m |
| |
| // Call from Go to C. |
| // |
| // This must be nosplit because it's used for syscalls on some |
| // platforms. Syscalls may have untyped arguments on the stack, so |
| // it's not safe to grow or scan the stack. |
| // |
| // cgocall should be an internal detail, |
| // but widely used packages access it using linkname. |
| // Notable members of the hall of shame include: |
| // - github.com/ebitengine/purego |
| // |
| // Do not remove or change the type signature. |
| // See go.dev/issue/67401. |
| // |
| //go:linkname cgocall |
| //go:nosplit |
| func cgocall(fn, arg unsafe.Pointer) int32 { |
| if !iscgo && GOOS != "solaris" && GOOS != "illumos" && GOOS != "windows" { |
| throw("cgocall unavailable") |
| } |
| |
| if fn == nil { |
| throw("cgocall nil") |
| } |
| |
| if raceenabled { |
| racereleasemerge(unsafe.Pointer(&racecgosync)) |
| } |
| |
| mp := getg().m |
| mp.ncgocall++ |
| |
| // Reset traceback. |
| mp.cgoCallers[0] = 0 |
| |
| // 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 |
| // grow the stack and does not allocate memory, |
| // so it is safe to call while "in a system call", outside |
| // the $GOMAXPROCS accounting. |
| // |
| // fn may call back into Go code, in which case we'll exit the |
| // "system call", run the Go code (which may grow the stack), |
| // and then re-enter the "system call" reusing the PC and SP |
| // saved by entersyscall here. |
| entersyscall() |
| |
| // Tell asynchronous preemption that we're entering external |
| // code. We do this after entersyscall because this may block |
| // and cause an async preemption to fail, but at this point a |
| // sync preemption will succeed (though this is not a matter |
| // of correctness). |
| osPreemptExtEnter(mp) |
| |
| mp.incgo = true |
| // We use ncgo as a check during execution tracing for whether there is |
| // any C on the call stack, which there will be after this point. If |
| // there isn't, we can use frame pointer unwinding to collect call |
| // stacks efficiently. This will be the case for the first Go-to-C call |
| // on a stack, so it's preferable to update it here, after we emit a |
| // trace event in entersyscall above. |
| mp.ncgo++ |
| |
| errno := asmcgocall(fn, arg) |
| |
| // Update accounting before exitsyscall because exitsyscall may |
| // reschedule us on to a different M. |
| mp.incgo = false |
| mp.ncgo-- |
| |
| osPreemptExtExit(mp) |
| |
| // Save current syscall parameters, so m.winsyscall can be |
| // used again if callback decide to make syscall. |
| winsyscall := mp.winsyscall |
| |
| exitsyscall() |
| |
| getg().m.winsyscall = winsyscall |
| |
| // Note that raceacquire must be called only after exitsyscall has |
| // wired this M to a P. |
| if raceenabled { |
| raceacquire(unsafe.Pointer(&racecgosync)) |
| } |
| |
| // From the garbage collector's perspective, time can move |
| // backwards in the sequence above. If there's a callback into |
| // Go code, GC will see this function at the call to |
| // asmcgocall. When the Go call later returns to C, the |
| // syscall PC/SP is rolled back and the GC sees this function |
| // back at the call to entersyscall. Normally, fn and arg |
| // would be live at entersyscall and dead at asmcgocall, so if |
| // time moved backwards, GC would see these arguments as dead |
| // and then live. Prevent these undead arguments from crashing |
| // GC by forcing them to stay live across this time warp. |
| KeepAlive(fn) |
| KeepAlive(arg) |
| KeepAlive(mp) |
| |
| return errno |
| } |
| |
| // Set or reset the system stack bounds for a callback on sp. |
| // |
| // Must be nosplit because it is called by needm prior to fully initializing |
| // the M. |
| // |
| //go:nosplit |
| func callbackUpdateSystemStack(mp *m, sp uintptr, signal bool) { |
| g0 := mp.g0 |
| |
| inBound := sp > g0.stack.lo && sp <= g0.stack.hi |
| if mp.ncgo > 0 && !inBound { |
| // ncgo > 0 indicates that this M was in Go further up the stack |
| // (it called C and is now receiving a callback). |
| // |
| // !inBound indicates that we were called with SP outside the |
| // expected system stack bounds (C changed the stack out from |
| // under us between the cgocall and cgocallback?). |
| // |
| // It is not safe for the C call to change the stack out from |
| // under us, so throw. |
| |
| // Note that this case isn't possible for signal == true, as |
| // that is always passing a new M from needm. |
| |
| // Stack is bogus, but reset the bounds anyway so we can print. |
| hi := g0.stack.hi |
| lo := g0.stack.lo |
| g0.stack.hi = sp + 1024 |
| g0.stack.lo = sp - 32*1024 |
| g0.stackguard0 = g0.stack.lo + stackGuard |
| g0.stackguard1 = g0.stackguard0 |
| |
| print("M ", mp.id, " procid ", mp.procid, " runtime: cgocallback with sp=", hex(sp), " out of bounds [", hex(lo), ", ", hex(hi), "]") |
| print("\n") |
| exit(2) |
| } |
| |
| if !mp.isextra { |
| // We allocated the stack for standard Ms. Don't replace the |
| // stack bounds with estimated ones when we already initialized |
| // with the exact ones. |
| return |
| } |
| |
| // This M does not have Go further up the stack. However, it may have |
| // previously called into Go, initializing the stack bounds. Between |
| // that call returning and now the stack may have changed (perhaps the |
| // C thread is running a coroutine library). We need to update the |
| // stack bounds for this case. |
| // |
| // N.B. we need to update the stack bounds even if SP appears to |
| // already be in bounds. Our "bounds" may actually be estimated dummy |
| // bounds (below). The actual stack bounds could have shifted but still |
| // have partial overlap with our dummy bounds. If we failed to update |
| // in that case, we could find ourselves seemingly called near the |
| // bottom of the stack bounds, where we quickly run out of space. |
| |
| // Set the stack bounds to match the current stack. If we don't |
| // actually know how big the stack is, like we don't know how big any |
| // scheduling stack is, but we assume there's at least 32 kB. If we |
| // can get a more accurate stack bound from pthread, use that, provided |
| // it actually contains SP.. |
| g0.stack.hi = sp + 1024 |
| g0.stack.lo = sp - 32*1024 |
| if !signal && _cgo_getstackbound != nil { |
| // Don't adjust if called from the signal handler. |
| // We are on the signal stack, not the pthread stack. |
| // (We could get the stack bounds from sigaltstack, but |
| // we're getting out of the signal handler very soon |
| // anyway. Not worth it.) |
| var bounds [2]uintptr |
| asmcgocall(_cgo_getstackbound, unsafe.Pointer(&bounds)) |
| // getstackbound is an unsupported no-op on Windows. |
| // |
| // Don't use these bounds if they don't contain SP. Perhaps we |
| // were called by something not using the standard thread |
| // stack. |
| if bounds[0] != 0 && sp > bounds[0] && sp <= bounds[1] { |
| g0.stack.lo = bounds[0] |
| g0.stack.hi = bounds[1] |
| } |
| } |
| g0.stackguard0 = g0.stack.lo + stackGuard |
| g0.stackguard1 = g0.stackguard0 |
| } |
| |
| // Call from C back to Go. fn must point to an ABIInternal Go entry-point. |
| // |
| //go:nosplit |
| func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) { |
| gp := getg() |
| if gp != gp.m.curg { |
| println("runtime: bad g in cgocallback") |
| exit(2) |
| } |
| |
| sp := gp.m.g0.sched.sp // system sp saved by cgocallback. |
| callbackUpdateSystemStack(gp.m, sp, false) |
| |
| // The call from C is on gp.m's g0 stack, so we must ensure |
| // that we stay on that M. We have to do this before calling |
| // exitsyscall, since it would otherwise be free to move us to |
| // a different M. The call to unlockOSThread is in this function |
| // after cgocallbackg1, or in the case of panicking, in unwindm. |
| lockOSThread() |
| |
| checkm := gp.m |
| |
| // Save current syscall parameters, so m.winsyscall can be |
| // used again if callback decide to make syscall. |
| winsyscall := gp.m.winsyscall |
| |
| // 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. |
| // |
| // Note: savedsp and savedbp MUST be held in locals as an unsafe.Pointer. |
| // When we call into Go, the stack is free to be moved. If these locals |
| // aren't visible in the stack maps, they won't get updated properly, |
| // and will end up being stale when restored by reentersyscall. |
| savedsp := unsafe.Pointer(gp.syscallsp) |
| savedpc := gp.syscallpc |
| savedbp := unsafe.Pointer(gp.syscallbp) |
| exitsyscall() // coming out of cgo call |
| gp.m.incgo = false |
| if gp.m.isextra { |
| gp.m.isExtraInC = false |
| } |
| |
| osPreemptExtExit(gp.m) |
| |
| if gp.nocgocallback { |
| panic("runtime: function marked with #cgo nocallback called back into Go") |
| } |
| |
| cgocallbackg1(fn, frame, ctxt) |
| |
| // At this point we're about to call unlockOSThread. |
| // The following code must not change to a different m. |
| // This is enforced by checking incgo in the schedule function. |
| gp.m.incgo = true |
| unlockOSThread() |
| |
| if gp.m.isextra { |
| gp.m.isExtraInC = true |
| } |
| |
| if gp.m != checkm { |
| throw("m changed unexpectedly in cgocallbackg") |
| } |
| |
| osPreemptExtEnter(gp.m) |
| |
| // going back to cgo call |
| reentersyscall(savedpc, uintptr(savedsp), uintptr(savedbp)) |
| |
| gp.m.winsyscall = winsyscall |
| } |
| |
| func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) { |
| gp := getg() |
| |
| if gp.m.needextram || extraMWaiters.Load() > 0 { |
| gp.m.needextram = false |
| systemstack(newextram) |
| } |
| |
| if ctxt != 0 { |
| s := append(gp.cgoCtxt, ctxt) |
| |
| // Now we need to set gp.cgoCtxt = s, but we could get |
| // a SIGPROF signal while manipulating the slice, and |
| // the SIGPROF handler could pick up gp.cgoCtxt while |
| // tracing up the stack. We need to ensure that the |
| // handler always sees a valid slice, so set the |
| // values in an order such that it always does. |
| p := (*slice)(unsafe.Pointer(&gp.cgoCtxt)) |
| atomicstorep(unsafe.Pointer(&p.array), unsafe.Pointer(&s[0])) |
| p.cap = cap(s) |
| p.len = len(s) |
| |
| defer func(gp *g) { |
| // Decrease the length of the slice by one, safely. |
| p := (*slice)(unsafe.Pointer(&gp.cgoCtxt)) |
| p.len-- |
| }(gp) |
| } |
| |
| if gp.m.ncgo == 0 { |
| // The C call to Go came from a thread not currently running |
| // any Go. In the case of -buildmode=c-archive or c-shared, |
| // this call may be coming in before package initialization |
| // is complete. Wait until it is. |
| <-main_init_done |
| } |
| |
| // Check whether the profiler needs to be turned on or off; this route to |
| // run Go code does not use runtime.execute, so bypasses the check there. |
| hz := sched.profilehz |
| if gp.m.profilehz != hz { |
| setThreadCPUProfiler(hz) |
| } |
| |
| // Add entry to defer stack in case of panic. |
| restore := true |
| defer unwindm(&restore) |
| |
| if raceenabled { |
| raceacquire(unsafe.Pointer(&racecgosync)) |
| } |
| |
| // Invoke callback. This function is generated by cmd/cgo and |
| // will unpack the argument frame and call the Go function. |
| var cb func(frame unsafe.Pointer) |
| cbFV := funcval{uintptr(fn)} |
| *(*unsafe.Pointer)(unsafe.Pointer(&cb)) = noescape(unsafe.Pointer(&cbFV)) |
| cb(frame) |
| |
| if raceenabled { |
| racereleasemerge(unsafe.Pointer(&racecgosync)) |
| } |
| |
| // Do not unwind m->g0->sched.sp. |
| // Our caller, cgocallback, will do that. |
| restore = false |
| } |
| |
| func unwindm(restore *bool) { |
| if *restore { |
| // Restore sp saved by cgocallback during |
| // unwind of g's stack (see comment at top of file). |
| mp := acquirem() |
| sched := &mp.g0.sched |
| sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + alignUp(sys.MinFrameSize, sys.StackAlign))) |
| |
| // Do the accounting that cgocall will not have a chance to do |
| // during an unwind. |
| // |
| // In the case where a Go call originates from C, ncgo is 0 |
| // and there is no matching cgocall to end. |
| if mp.ncgo > 0 { |
| mp.incgo = false |
| mp.ncgo-- |
| osPreemptExtExit(mp) |
| } |
| |
| // Undo the call to lockOSThread in cgocallbackg, only on the |
| // panicking path. In normal return case cgocallbackg will call |
| // unlockOSThread, ensuring no preemption point after the unlock. |
| // Here we don't need to worry about preemption, because we're |
| // panicking out of the callback and unwinding the g0 stack, |
| // instead of reentering cgo (which requires the same thread). |
| unlockOSThread() |
| |
| releasem(mp) |
| } |
| } |
| |
| // called from assembly. |
| func badcgocallback() { |
| throw("misaligned stack in cgocallback") |
| } |
| |
| // called from (incomplete) assembly. |
| func cgounimpl() { |
| throw("cgo not implemented") |
| } |
| |
| var racecgosync uint64 // represents possible synchronization in C code |
| |
| // Pointer checking for cgo code. |
| |
| // We want to detect all cases where a program that does not use |
| // unsafe makes a cgo call passing a Go pointer to memory that |
| // contains an unpinned Go pointer. Here a Go pointer is defined as a |
| // pointer to memory allocated by the Go runtime. Programs that use |
| // unsafe can evade this restriction easily, so we don't try to catch |
| // them. The cgo program will rewrite all possibly bad pointer |
| // arguments to call cgoCheckPointer, where we can catch cases of a Go |
| // pointer pointing to an unpinned Go pointer. |
| |
| // Complicating matters, taking the address of a slice or array |
| // element permits the C program to access all elements of the slice |
| // or array. In that case we will see a pointer to a single element, |
| // but we need to check the entire data structure. |
| |
| // The cgoCheckPointer call takes additional arguments indicating that |
| // it was called on an address expression. An additional argument of |
| // true means that it only needs to check a single element. An |
| // additional argument of a slice or array means that it needs to |
| // check the entire slice/array, but nothing else. Otherwise, the |
| // pointer could be anything, and we check the entire heap object, |
| // which is conservative but safe. |
| |
| // When and if we implement a moving garbage collector, |
| // cgoCheckPointer will pin the pointer for the duration of the cgo |
| // call. (This is necessary but not sufficient; the cgo program will |
| // also have to change to pin Go pointers that cannot point to Go |
| // pointers.) |
| |
| // cgoCheckPointer checks if the argument contains a Go pointer that |
| // points to an unpinned Go pointer, and panics if it does. |
| func cgoCheckPointer(ptr any, arg any) { |
| if !goexperiment.CgoCheck2 && debug.cgocheck == 0 { |
| return |
| } |
| |
| ep := efaceOf(&ptr) |
| t := ep._type |
| |
| top := true |
| if arg != nil && (t.Kind_&abi.KindMask == abi.Pointer || t.Kind_&abi.KindMask == abi.UnsafePointer) { |
| p := ep.data |
| if t.Kind_&abi.KindDirectIface == 0 { |
| p = *(*unsafe.Pointer)(p) |
| } |
| if p == nil || !cgoIsGoPointer(p) { |
| return |
| } |
| aep := efaceOf(&arg) |
| switch aep._type.Kind_ & abi.KindMask { |
| case abi.Bool: |
| if t.Kind_&abi.KindMask == abi.UnsafePointer { |
| // We don't know the type of the element. |
| break |
| } |
| pt := (*ptrtype)(unsafe.Pointer(t)) |
| cgoCheckArg(pt.Elem, p, true, false, cgoCheckPointerFail) |
| return |
| case abi.Slice: |
| // Check the slice rather than the pointer. |
| ep = aep |
| t = ep._type |
| case abi.Array: |
| // Check the array rather than the pointer. |
| // Pass top as false since we have a pointer |
| // to the array. |
| ep = aep |
| t = ep._type |
| top = false |
| default: |
| throw("can't happen") |
| } |
| } |
| |
| cgoCheckArg(t, ep.data, t.Kind_&abi.KindDirectIface == 0, top, cgoCheckPointerFail) |
| } |
| |
| const cgoCheckPointerFail = "cgo argument has Go pointer to unpinned Go pointer" |
| const cgoResultFail = "cgo result is unpinned Go pointer or points to unpinned Go pointer" |
| |
| // cgoCheckArg is the real work of cgoCheckPointer. The argument p |
| // is either a pointer to the value (of type t), or the value itself, |
| // depending on indir. The top parameter is whether we are at the top |
| // level, where Go pointers are allowed. Go pointers to pinned objects are |
| // allowed as long as they don't reference other unpinned pointers. |
| func cgoCheckArg(t *_type, p unsafe.Pointer, indir, top bool, msg string) { |
| if !t.Pointers() || p == nil { |
| // If the type has no pointers there is nothing to do. |
| return |
| } |
| |
| switch t.Kind_ & abi.KindMask { |
| default: |
| throw("can't happen") |
| case abi.Array: |
| at := (*arraytype)(unsafe.Pointer(t)) |
| if !indir { |
| if at.Len != 1 { |
| throw("can't happen") |
| } |
| cgoCheckArg(at.Elem, p, at.Elem.Kind_&abi.KindDirectIface == 0, top, msg) |
| return |
| } |
| for i := uintptr(0); i < at.Len; i++ { |
| cgoCheckArg(at.Elem, p, true, top, msg) |
| p = add(p, at.Elem.Size_) |
| } |
| case abi.Chan, abi.Map: |
| // These types contain internal pointers that will |
| // always be allocated in the Go heap. It's never OK |
| // to pass them to C. |
| panic(errorString(msg)) |
| case abi.Func: |
| if indir { |
| p = *(*unsafe.Pointer)(p) |
| } |
| if !cgoIsGoPointer(p) { |
| return |
| } |
| panic(errorString(msg)) |
| case abi.Interface: |
| it := *(**_type)(p) |
| if it == nil { |
| return |
| } |
| // A type known at compile time is OK since it's |
| // constant. A type not known at compile time will be |
| // in the heap and will not be OK. |
| if inheap(uintptr(unsafe.Pointer(it))) { |
| panic(errorString(msg)) |
| } |
| p = *(*unsafe.Pointer)(add(p, goarch.PtrSize)) |
| if !cgoIsGoPointer(p) { |
| return |
| } |
| if !top && !isPinned(p) { |
| panic(errorString(msg)) |
| } |
| cgoCheckArg(it, p, it.Kind_&abi.KindDirectIface == 0, false, msg) |
| case abi.Slice: |
| st := (*slicetype)(unsafe.Pointer(t)) |
| s := (*slice)(p) |
| p = s.array |
| if p == nil || !cgoIsGoPointer(p) { |
| return |
| } |
| if !top && !isPinned(p) { |
| panic(errorString(msg)) |
| } |
| if !st.Elem.Pointers() { |
| return |
| } |
| for i := 0; i < s.cap; i++ { |
| cgoCheckArg(st.Elem, p, true, false, msg) |
| p = add(p, st.Elem.Size_) |
| } |
| case abi.String: |
| ss := (*stringStruct)(p) |
| if !cgoIsGoPointer(ss.str) { |
| return |
| } |
| if !top && !isPinned(ss.str) { |
| panic(errorString(msg)) |
| } |
| case abi.Struct: |
| st := (*structtype)(unsafe.Pointer(t)) |
| if !indir { |
| if len(st.Fields) != 1 { |
| throw("can't happen") |
| } |
| cgoCheckArg(st.Fields[0].Typ, p, st.Fields[0].Typ.Kind_&abi.KindDirectIface == 0, top, msg) |
| return |
| } |
| for _, f := range st.Fields { |
| if !f.Typ.Pointers() { |
| continue |
| } |
| cgoCheckArg(f.Typ, add(p, f.Offset), true, top, msg) |
| } |
| case abi.Pointer, abi.UnsafePointer: |
| if indir { |
| p = *(*unsafe.Pointer)(p) |
| if p == nil { |
| return |
| } |
| } |
| |
| if !cgoIsGoPointer(p) { |
| return |
| } |
| if !top && !isPinned(p) { |
| panic(errorString(msg)) |
| } |
| |
| cgoCheckUnknownPointer(p, msg) |
| } |
| } |
| |
| // cgoCheckUnknownPointer is called for an arbitrary pointer into Go |
| // memory. It checks whether that Go memory contains any other |
| // pointer into unpinned Go memory. If it does, we panic. |
| // The return values are unused but useful to see in panic tracebacks. |
| func cgoCheckUnknownPointer(p unsafe.Pointer, msg string) (base, i uintptr) { |
| if inheap(uintptr(p)) { |
| b, span, _ := findObject(uintptr(p), 0, 0) |
| base = b |
| if base == 0 { |
| return |
| } |
| tp := span.typePointersOfUnchecked(base) |
| for { |
| var addr uintptr |
| if tp, addr = tp.next(base + span.elemsize); addr == 0 { |
| break |
| } |
| pp := *(*unsafe.Pointer)(unsafe.Pointer(addr)) |
| if cgoIsGoPointer(pp) && !isPinned(pp) { |
| panic(errorString(msg)) |
| } |
| } |
| return |
| } |
| |
| for _, datap := range activeModules() { |
| if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) { |
| // We have no way to know the size of the object. |
| // We have to assume that it might contain a pointer. |
| panic(errorString(msg)) |
| } |
| // In the text or noptr sections, we know that the |
| // pointer does not point to a Go pointer. |
| } |
| |
| return |
| } |
| |
| // cgoIsGoPointer reports whether the pointer is a Go pointer--a |
| // pointer to Go memory. We only care about Go memory that might |
| // contain pointers. |
| // |
| //go:nosplit |
| //go:nowritebarrierrec |
| func cgoIsGoPointer(p unsafe.Pointer) bool { |
| if p == nil { |
| return false |
| } |
| |
| if inHeapOrStack(uintptr(p)) { |
| return true |
| } |
| |
| for _, datap := range activeModules() { |
| if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) { |
| return true |
| } |
| } |
| |
| return false |
| } |
| |
| // cgoInRange reports whether p is between start and end. |
| // |
| //go:nosplit |
| //go:nowritebarrierrec |
| func cgoInRange(p unsafe.Pointer, start, end uintptr) bool { |
| return start <= uintptr(p) && uintptr(p) < end |
| } |
| |
| // cgoCheckResult is called to check the result parameter of an |
| // exported Go function. It panics if the result is or contains any |
| // other pointer into unpinned Go memory. |
| func cgoCheckResult(val any) { |
| if !goexperiment.CgoCheck2 && debug.cgocheck == 0 { |
| return |
| } |
| |
| ep := efaceOf(&val) |
| t := ep._type |
| cgoCheckArg(t, ep.data, t.Kind_&abi.KindDirectIface == 0, false, cgoResultFail) |
| } |