github.com/comwrg/go/src@v0.0.0-20220319063731-c238d0440370/runtime/tls_ppc64x.s (about) 1 // Copyright 2014 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:build ppc64 || ppc64le 6 // +build ppc64 ppc64le 7 8 #include "go_asm.h" 9 #include "go_tls.h" 10 #include "funcdata.h" 11 #include "textflag.h" 12 13 // We have to resort to TLS variable to save g (R30). 14 // One reason is that external code might trigger 15 // SIGSEGV, and our runtime.sigtramp don't even know we 16 // are in external code, and will continue to use R30, 17 // this might well result in another SIGSEGV. 18 19 // save_g saves the g register into pthread-provided 20 // thread-local memory, so that we can call externally compiled 21 // ppc64 code that will overwrite this register. 22 // 23 // If !iscgo, this is a no-op. 24 // 25 // NOTE: setg_gcc<> assume this clobbers only R31. 26 TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0-0 27 #ifndef GOOS_aix 28 MOVBZ runtime·iscgo(SB), R31 29 CMP R31, $0 30 BEQ nocgo 31 #endif 32 MOVD runtime·tls_g(SB), R31 33 MOVD g, 0(R31) 34 35 nocgo: 36 RET 37 38 // load_g loads the g register from pthread-provided 39 // thread-local memory, for use after calling externally compiled 40 // ppc64 code that overwrote those registers. 41 // 42 // This is never called directly from C code (it doesn't have to 43 // follow the C ABI), but it may be called from a C context, where the 44 // usual Go registers aren't set up. 45 // 46 // NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31. 47 TEXT runtime·load_g(SB),NOSPLIT|NOFRAME,$0-0 48 MOVD runtime·tls_g(SB), R31 49 MOVD 0(R31), g 50 RET 51 52 GLOBL runtime·tls_g+0(SB), TLSBSS+DUPOK, $8