| // 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. |
| |
| // +build ppc64 ppc64le |
| |
| #include "go_asm.h" |
| #include "go_tls.h" |
| #include "funcdata.h" |
| #include "textflag.h" |
| |
| // We have to resort to TLS variable to save g (R30). |
| // One reason is that external code might trigger |
| // SIGSEGV, and our runtime.sigtramp don't even know we |
| // are in external code, and will continue to use R30, |
| // this might well result in another SIGSEGV. |
| |
| // save_g saves the g register into pthread-provided |
| // thread-local memory, so that we can call externally compiled |
| // ppc64 code that will overwrite this register. |
| // |
| // If !iscgo, this is a no-op. |
| // |
| // NOTE: setg_gcc<> assume this clobbers only R31. |
| TEXT runtime·save_g(SB),NOSPLIT,$-8-0 |
| MOVB runtime·iscgo(SB), R31 |
| CMP R31, $0 |
| BEQ nocgo |
| |
| // $runtime.tlsg(SB) is a special linker symbol. |
| // It is the offset from the start of TLS to our |
| // thread-local storage for g. |
| MOVD $runtime·tlsg(SB), R31 |
| ADD R13, R31 |
| // The actual TLS base is 0x7000 below R13 |
| SUB $0x7000, R31 |
| |
| // Store g in TLS |
| MOVD g, 0(R31) |
| |
| nocgo: |
| RET |
| |
| // load_g loads the g register from pthread-provided |
| // thread-local memory, for use after calling externally compiled |
| // ppc64 code that overwrote those registers. |
| // |
| // This is never called directly from C code (it doesn't have to |
| // follow the C ABI), but it may be called from a C context, where the |
| // usual Go registers aren't set up. |
| // |
| // NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31. |
| TEXT runtime·load_g(SB),NOSPLIT,$-8-0 |
| MOVD $runtime·tlsg(SB), R31 |
| // R13 is the C ABI TLS base pointer + 0x7000 |
| ADD R13, R31 |
| SUB $0x7000, R31 |
| |
| MOVD 0(R31), g |
| RET |
