diff options
Diffstat (limited to 'src/syscall/syscall_linux.go')
| -rw-r--r-- | src/syscall/syscall_linux.go | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/src/syscall/syscall_linux.go b/src/syscall/syscall_linux.go index a9a8ecbefd..999ca5bb7f 100644 --- a/src/syscall/syscall_linux.go +++ b/src/syscall/syscall_linux.go @@ -16,7 +16,6 @@ import ( "unsafe" ) -func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) // N.B. RawSyscall6 is provided via linkname by runtime/internal/syscall. @@ -26,6 +25,18 @@ func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) +// Pull in entersyscall/exitsyscall for Syscall/Syscall6. +// +// Note that this can't be a push linkname because the runtime already has a +// nameless linkname to export to assembly here and in x/sys. Additionally, +// entersyscall fetches the caller PC and SP and thus can't have a wrapper +// inbetween. + +//go:linkname runtime_entersyscall runtime.entersyscall +func runtime_entersyscall() +//go:linkname runtime_exitsyscall runtime.exitsyscall +func runtime_exitsyscall() + // N.B. For the Syscall functions below: // // //go:uintptrkeepalive because the uintptr argument may be converted pointers @@ -47,6 +58,28 @@ func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) { return RawSyscall6(trap, a1, a2, a3, 0, 0, 0) } +//go:uintptrkeepalive +//go:nosplit +//go:linkname Syscall +func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) { + runtime_entersyscall() + // N.B. Calling RawSyscall here is unsafe with atomic coverage + // instrumentation and race mode. + // + // Coverage instrumentation will add a sync/atomic call to RawSyscall. + // Race mode will add race instrumentation to sync/atomic. Race + // instrumentation requires a P, which we no longer have. + // + // RawSyscall6 is fine because it is implemented in assembly and thus + // has no coverage instrumentation. + // + // This is typically not a problem in the runtime because cmd/go avoids + // adding coverage instrumentation to the runtime in race mode. + r1, r2, err = RawSyscall6(trap, a1, a2, a3, 0, 0, 0) + runtime_exitsyscall() + return +} + func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr) /* |