From 62ea5c0a2212b9827f093551fc3da166facb9f0b Mon Sep 17 00:00:00 2001 From: Michael Pratt Date: Fri, 30 Jul 2021 13:39:18 -0700 Subject: checklinkname: rudimentary type-checking of linkname directives This CL introduces a 'checklinkname' analyzer, which provides rudimentary type-checking that verifies that function signatures on the local and remote sides of //go:linkname directives match expected values. If the Go standard library changes the definitions of any of these function, checklinkname will flag the change as a finding, providing an error informing the gVisor team to adapt to the upstream changes. This allows us to eliminate the majority of gVisor's forward-looking negative build tags, as we can catch mismatches in testing [1]. The remaining forward-looking negative build tags are covering shared struct definitions, which I hope to add to checklinkname in a future CL. [1] Of course, semantics/requirements can change without the signature changing, so we still must be careful, but this covers the common case. PiperOrigin-RevId: 387873847 --- pkg/sync/runtime_unsafe.go | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'pkg/sync/runtime_unsafe.go') diff --git a/pkg/sync/runtime_unsafe.go b/pkg/sync/runtime_unsafe.go index 1d9cf304e..49d4109a9 100644 --- a/pkg/sync/runtime_unsafe.go +++ b/pkg/sync/runtime_unsafe.go @@ -6,8 +6,13 @@ //go:build go1.13 && !go1.18 // +build go1.13,!go1.18 -// Check go:linkname function signatures, type definitions, and constants when -// updating Go version. +// //go:linkname directives type-checked by checklinkname. Any other +// non-linkname assumptions outside the Go 1 compatibility guarantee should +// have an accompanied vet check or version guard build tag. + +// Check type definitions and constants when updating Go version. +// +// TODO(b/165820485): add these checks to checklinkname. package sync @@ -109,10 +114,10 @@ type maptype struct { // These functions are only used within the sync package. //go:linkname semacquire sync.runtime_Semacquire -func semacquire(s *uint32) +func semacquire(addr *uint32) //go:linkname semrelease sync.runtime_Semrelease -func semrelease(s *uint32, handoff bool, skipframes int) +func semrelease(addr *uint32, handoff bool, skipframes int) //go:linkname canSpin sync.runtime_canSpin func canSpin(i int) bool -- cgit v1.2.3