111 lines
4.0 KiB
Go
111 lines
4.0 KiB
Go
// Copyright 2021 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package checklinkname
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// knownLinknames is the set of the symbols for which we can do a rudimentary
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// type-check on.
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//
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// When analyzing the remote package (e.g., runtime), we verify the symbol
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// signature matches 'remote'. When analyzing local packages with //go:linkname
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// directives, we verify the symbol signature matches 'local'.
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//
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// Usually these are identical, but may differ slightly if equivalent
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// replacement types are used in the local packages, such as a copy of a struct
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// or uintptr instead of a pointer type.
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//
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// NOTE: It is the responsibility of the developer to verify the safety of the
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// signatures used here! This analyzer only checks that types match this map;
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// it does not verify compatibility of the entries themselves.
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//
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// //go:linkname directives with no corresponding entry here will trigger a
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// finding.
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//
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// We preform only rudimentary string-based type-checking due to limitations in
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// the analysis framework. Ideally, from the local package we'd lookup the
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// remote symbol's types.Object and perform robust type-checking.
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// Unfortunately, remote symbols are typically loaded from the remote package's
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// gcexportdata. Since //go:linkname targets are usually not exported symbols,
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// they are no included in gcexportdata and we cannot load their types.Object.
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//
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// TODO(b/165820485): Add option to specific per-version signatures.
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var knownLinknames = map[string]map[string]linknameSignatures{
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"runtime": map[string]linknameSignatures{
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"entersyscall": linknameSignatures{
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local: "func()",
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},
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"entersyscallblock": linknameSignatures{
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local: "func()",
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},
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"exitsyscall": linknameSignatures{
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local: "func()",
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},
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"fastrand": linknameSignatures{
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local: "func() uint32",
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},
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"gopark": linknameSignatures{
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// TODO(b/165820485): add verification of waitReason
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// size and reason and traceEv values.
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local: "func(unlockf func(uintptr, unsafe.Pointer) bool, lock unsafe.Pointer, reason uint8, traceEv byte, traceskip int)",
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remote: "func(unlockf func(*runtime.g, unsafe.Pointer) bool, lock unsafe.Pointer, reason runtime.waitReason, traceEv byte, traceskip int)",
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},
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"goready": linknameSignatures{
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local: "func(gp uintptr, traceskip int)",
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remote: "func(gp *runtime.g, traceskip int)",
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},
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"goyield": linknameSignatures{
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local: "func()",
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},
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"memmove": linknameSignatures{
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local: "func(to unsafe.Pointer, from unsafe.Pointer, n uintptr)",
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},
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"throw": linknameSignatures{
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local: "func(s string)",
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},
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},
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"sync": map[string]linknameSignatures{
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"runtime_canSpin": linknameSignatures{
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local: "func(i int) bool",
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},
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"runtime_doSpin": linknameSignatures{
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local: "func()",
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},
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"runtime_Semacquire": linknameSignatures{
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// The only difference here is the parameter names. We
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// can't just change our local use to match remote, as
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// the stdlib runtime and sync packages also disagree
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// on the name, and the analyzer checks that use as
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// well.
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local: "func(addr *uint32)",
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remote: "func(s *uint32)",
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},
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"runtime_Semrelease": linknameSignatures{
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// See above.
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local: "func(addr *uint32, handoff bool, skipframes int)",
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remote: "func(s *uint32, handoff bool, skipframes int)",
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},
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},
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"syscall": map[string]linknameSignatures{
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"runtime_BeforeFork": linknameSignatures{
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local: "func()",
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},
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"runtime_AfterFork": linknameSignatures{
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local: "func()",
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},
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"runtime_AfterForkInChild": linknameSignatures{
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local: "func()",
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},
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},
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}
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