| // Copyright 2014 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. |
| |
| package runtime |
| |
| import "unsafe" |
| |
| // Should be a built-in for unsafe.Pointer? |
| //go:nosplit |
| func add(p unsafe.Pointer, x uintptr) unsafe.Pointer { |
| return unsafe.Pointer(uintptr(p) + x) |
| } |
| |
| // getg returns the pointer to the current g. |
| // The compiler rewrites calls to this function into instructions |
| // that fetch the g directly (from TLS or from the dedicated register). |
| func getg() *g |
| |
| // mcall switches from the g to the g0 stack and invokes fn(g), |
| // where g is the goroutine that made the call. |
| // mcall saves g's current PC/SP in g->sched so that it can be restored later. |
| // It is up to fn to arrange for that later execution, typically by recording |
| // g in a data structure, causing something to call ready(g) later. |
| // mcall returns to the original goroutine g later, when g has been rescheduled. |
| // fn must not return at all; typically it ends by calling schedule, to let the m |
| // run other goroutines. |
| // |
| // mcall can only be called from g stacks (not g0, not gsignal). |
| // |
| // This must NOT be go:noescape: if fn is a stack-allocated closure, |
| // fn puts g on a run queue, and g executes before fn returns, the |
| // closure will be invalidated while it is still executing. |
| func mcall(fn func(*g)) |
| |
| // systemstack runs fn on a system stack. |
| // If systemstack is called from the per-OS-thread (g0) stack, or |
| // if systemstack is called from the signal handling (gsignal) stack, |
| // systemstack calls fn directly and returns. |
| // Otherwise, systemstack is being called from the limited stack |
| // of an ordinary goroutine. In this case, systemstack switches |
| // to the per-OS-thread stack, calls fn, and switches back. |
| // It is common to use a func literal as the argument, in order |
| // to share inputs and outputs with the code around the call |
| // to system stack: |
| // |
| // ... set up y ... |
| // systemstack(func() { |
| // x = bigcall(y) |
| // }) |
| // ... use x ... |
| // |
| //go:noescape |
| func systemstack(fn func()) |
| |
| var badsystemstackMsg = "fatal: systemstack called from unexpected goroutine" |
| |
| //go:nosplit |
| //go:nowritebarrierrec |
| func badsystemstack() { |
| sp := stringStructOf(&badsystemstackMsg) |
| write(2, sp.str, int32(sp.len)) |
| } |
| |
| // memclrNoHeapPointers clears n bytes starting at ptr. |
| // |
| // Usually you should use typedmemclr. memclrNoHeapPointers should be |
| // used only when the caller knows that *ptr contains no heap pointers |
| // because either: |
| // |
| // *ptr is initialized memory and its type is pointer-free, or |
| // |
| // *ptr is uninitialized memory (e.g., memory that's being reused |
| // for a new allocation) and hence contains only "junk". |
| // |
| // The (CPU-specific) implementations of this function are in memclr_*.s. |
| //go:noescape |
| func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) |
| |
| //go:linkname reflect_memclrNoHeapPointers reflect.memclrNoHeapPointers |
| func reflect_memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) { |
| memclrNoHeapPointers(ptr, n) |
| } |
| |
| // memmove copies n bytes from "from" to "to". |
| // |
| // memmove ensures that any pointer in "from" is written to "to" with |
| // an indivisible write, so that racy reads cannot observe a |
| // half-written pointer. This is necessary to prevent the garbage |
| // collector from observing invalid pointers, and differs from memmove |
| // in unmanaged languages. However, memmove is only required to do |
| // this if "from" and "to" may contain pointers, which can only be the |
| // case if "from", "to", and "n" are all be word-aligned. |
| // |
| // Implementations are in memmove_*.s. |
| // |
| //go:noescape |
| func memmove(to, from unsafe.Pointer, n uintptr) |
| |
| //go:linkname reflect_memmove reflect.memmove |
| func reflect_memmove(to, from unsafe.Pointer, n uintptr) { |
| memmove(to, from, n) |
| } |
| |
| // exported value for testing |
| var hashLoad = float32(loadFactorNum) / float32(loadFactorDen) |
| |
| //go:nosplit |
| func fastrand() uint32 { |
| mp := getg().m |
| // Implement xorshift64+: 2 32-bit xorshift sequences added together. |
| // Shift triplet [17,7,16] was calculated as indicated in Marsaglia's |
| // Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf |
| // This generator passes the SmallCrush suite, part of TestU01 framework: |
| // http://simul.iro.umontreal.ca/testu01/tu01.html |
| s1, s0 := mp.fastrand[0], mp.fastrand[1] |
| s1 ^= s1 << 17 |
| s1 = s1 ^ s0 ^ s1>>7 ^ s0>>16 |
| mp.fastrand[0], mp.fastrand[1] = s0, s1 |
| return s0 + s1 |
| } |
| |
| //go:nosplit |
| func fastrandn(n uint32) uint32 { |
| // This is similar to fastrand() % n, but faster. |
| // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ |
| return uint32(uint64(fastrand()) * uint64(n) >> 32) |
| } |
| |
| //go:linkname sync_fastrand sync.fastrand |
| func sync_fastrand() uint32 { return fastrand() } |
| |
| //go:linkname net_fastrand net.fastrand |
| func net_fastrand() uint32 { return fastrand() } |
| |
| //go:linkname os_fastrand os.fastrand |
| func os_fastrand() uint32 { return fastrand() } |
| |
| // in internal/bytealg/equal_*.s |
| //go:noescape |
| func memequal(a, b unsafe.Pointer, size uintptr) bool |
| |
| // noescape hides a pointer from escape analysis. noescape is |
| // the identity function but escape analysis doesn't think the |
| // output depends on the input. noescape is inlined and currently |
| // compiles down to zero instructions. |
| // USE CAREFULLY! |
| //go:nosplit |
| func noescape(p unsafe.Pointer) unsafe.Pointer { |
| x := uintptr(p) |
| return unsafe.Pointer(x ^ 0) |
| } |
| |
| // Not all cgocallback frames are actually cgocallback, |
| // so not all have these arguments. Mark them uintptr so that the GC |
| // does not misinterpret memory when the arguments are not present. |
| // cgocallback is not called from Go, only from crosscall2. |
| // This in turn calls cgocallbackg, which is where we'll find |
| // pointer-declared arguments. |
| func cgocallback(fn, frame, ctxt uintptr) |
| func gogo(buf *gobuf) |
| func gosave(buf *gobuf) |
| |
| //go:noescape |
| func jmpdefer(fv *funcval, argp uintptr) |
| func asminit() |
| func setg(gg *g) |
| func breakpoint() |
| |
| // reflectcall calls fn with a copy of the n argument bytes pointed at by arg. |
| // After fn returns, reflectcall copies n-retoffset result bytes |
| // back into arg+retoffset before returning. If copying result bytes back, |
| // the caller should pass the argument frame type as argtype, so that |
| // call can execute appropriate write barriers during the copy. |
| // |
| // Package reflect always passes a frame type. In package runtime, |
| // Windows callbacks are the only use of this that copies results |
| // back, and those cannot have pointers in their results, so runtime |
| // passes nil for the frame type. |
| // |
| // Package reflect accesses this symbol through a linkname. |
| func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32) |
| |
| func procyield(cycles uint32) |
| |
| type neverCallThisFunction struct{} |
| |
| // goexit is the return stub at the top of every goroutine call stack. |
| // Each goroutine stack is constructed as if goexit called the |
| // goroutine's entry point function, so that when the entry point |
| // function returns, it will return to goexit, which will call goexit1 |
| // to perform the actual exit. |
| // |
| // This function must never be called directly. Call goexit1 instead. |
| // gentraceback assumes that goexit terminates the stack. A direct |
| // call on the stack will cause gentraceback to stop walking the stack |
| // prematurely and if there is leftover state it may panic. |
| func goexit(neverCallThisFunction) |
| |
| // publicationBarrier performs a store/store barrier (a "publication" |
| // or "export" barrier). Some form of synchronization is required |
| // between initializing an object and making that object accessible to |
| // another processor. Without synchronization, the initialization |
| // writes and the "publication" write may be reordered, allowing the |
| // other processor to follow the pointer and observe an uninitialized |
| // object. In general, higher-level synchronization should be used, |
| // such as locking or an atomic pointer write. publicationBarrier is |
| // for when those aren't an option, such as in the implementation of |
| // the memory manager. |
| // |
| // There's no corresponding barrier for the read side because the read |
| // side naturally has a data dependency order. All architectures that |
| // Go supports or seems likely to ever support automatically enforce |
| // data dependency ordering. |
| func publicationBarrier() |
| |
| // getcallerpc returns the program counter (PC) of its caller's caller. |
| // getcallersp returns the stack pointer (SP) of its caller's caller. |
| // The implementation may be a compiler intrinsic; there is not |
| // necessarily code implementing this on every platform. |
| // |
| // For example: |
| // |
| // func f(arg1, arg2, arg3 int) { |
| // pc := getcallerpc() |
| // sp := getcallersp() |
| // } |
| // |
| // These two lines find the PC and SP immediately following |
| // the call to f (where f will return). |
| // |
| // The call to getcallerpc and getcallersp must be done in the |
| // frame being asked about. |
| // |
| // The result of getcallersp is correct at the time of the return, |
| // but it may be invalidated by any subsequent call to a function |
| // that might relocate the stack in order to grow or shrink it. |
| // A general rule is that the result of getcallersp should be used |
| // immediately and can only be passed to nosplit functions. |
| |
| //go:noescape |
| func getcallerpc() uintptr |
| |
| //go:noescape |
| func getcallersp() uintptr // implemented as an intrinsic on all platforms |
| |
| // getclosureptr returns the pointer to the current closure. |
| // getclosureptr can only be used in an assignment statement |
| // at the entry of a function. Moreover, go:nosplit directive |
| // must be specified at the declaration of caller function, |
| // so that the function prolog does not clobber the closure register. |
| // for example: |
| // |
| // //go:nosplit |
| // func f(arg1, arg2, arg3 int) { |
| // dx := getclosureptr() |
| // } |
| // |
| // The compiler rewrites calls to this function into instructions that fetch the |
| // pointer from a well-known register (DX on x86 architecture, etc.) directly. |
| func getclosureptr() uintptr |
| |
| //go:noescape |
| func asmcgocall(fn, arg unsafe.Pointer) int32 |
| |
| func morestack() |
| func morestack_noctxt() |
| func rt0_go() |
| |
| // return0 is a stub used to return 0 from deferproc. |
| // It is called at the very end of deferproc to signal |
| // the calling Go function that it should not jump |
| // to deferreturn. |
| // in asm_*.s |
| func return0() |
| |
| // in asm_*.s |
| // not called directly; definitions here supply type information for traceback. |
| func call16(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call32(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call64(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call128(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call256(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call512(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call1024(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call2048(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call4096(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call8192(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call16384(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call32768(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call65536(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call131072(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call262144(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call524288(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call1048576(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call2097152(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call4194304(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call8388608(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call16777216(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call33554432(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call67108864(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call134217728(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call268435456(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call536870912(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| func call1073741824(typ, fn, arg unsafe.Pointer, n, retoffset uint32) |
| |
| func systemstack_switch() |
| |
| // alignUp rounds n up to a multiple of a. a must be a power of 2. |
| func alignUp(n, a uintptr) uintptr { |
| return (n + a - 1) &^ (a - 1) |
| } |
| |
| // alignDown rounds n down to a multiple of a. a must be a power of 2. |
| func alignDown(n, a uintptr) uintptr { |
| return n &^ (a - 1) |
| } |
| |
| // divRoundUp returns ceil(n / a). |
| func divRoundUp(n, a uintptr) uintptr { |
| // a is generally a power of two. This will get inlined and |
| // the compiler will optimize the division. |
| return (n + a - 1) / a |
| } |
| |
| // checkASM reports whether assembly runtime checks have passed. |
| func checkASM() bool |
| |
| func memequal_varlen(a, b unsafe.Pointer) bool |
| |
| // bool2int returns 0 if x is false or 1 if x is true. |
| func bool2int(x bool) int { |
| // Avoid branches. In the SSA compiler, this compiles to |
| // exactly what you would want it to. |
| return int(uint8(*(*uint8)(unsafe.Pointer(&x)))) |
| } |
| |
| // abort crashes the runtime in situations where even throw might not |
| // work. In general it should do something a debugger will recognize |
| // (e.g., an INT3 on x86). A crash in abort is recognized by the |
| // signal handler, which will attempt to tear down the runtime |
| // immediately. |
| func abort() |
| |
| // Called from compiled code; declared for vet; do NOT call from Go. |
| func gcWriteBarrier() |
| func duffzero() |
| func duffcopy() |
| |
| // Called from linker-generated .initarray; declared for go vet; do NOT call from Go. |
| func addmoduledata() |