1 // Copyright 2016 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 #include "go_asm.h" 6 #include "go_tls.h" 7 #include "funcdata.h" 8 #include "textflag.h" 9 10 // We have to resort to TLS variable to save g (R13). 11 // One reason is that external code might trigger 12 // SIGSEGV, and our runtime.sigtramp don't even know we 13 // are in external code, and will continue to use R13, 14 // this might well result in another SIGSEGV. 15 16 // save_g saves the g register into pthread-provided 17 // thread-local memory, so that we can call externally compiled 18 // s390x code that will overwrite this register. 19 // 20 // If !iscgo, this is a no-op. 21 // 22 // NOTE: setg_gcc<> assume this clobbers only R10 and R11. 23 TEXT runtimesave_g(SB),NOSPLIT|NOFRAME,$0-0 24 MOVB runtimeiscgo(SB), R10 25 CMPBEQ R10, $0, nocgo 26 MOVW AR0, R11 27 SLD $32, R11 28 MOVW AR1, R11 29 MOVD runtimetls_g(SB), R10 30 MOVD g, 0(R10)(R11*1) 31 nocgo: 32 RET 33 34 // load_g loads the g register from pthread-provided 35 // thread-local memory, for use after calling externally compiled 36 // s390x code that overwrote those registers. 37 // 38 // This is never called directly from C code (it doesn't have to 39 // follow the C ABI), but it may be called from a C context, where the 40 // usual Go registers aren't set up. 41 // 42 // NOTE: _cgo_topofstack assumes this only clobbers g (R13), R10 and R11. 43 TEXT runtimeload_g(SB),NOSPLIT|NOFRAME,$0-0 44 MOVW AR0, R11 45 SLD $32, R11 46 MOVW AR1, R11 47 MOVD runtimetls_g(SB), R10 48 MOVD 0(R10)(R11*1), g 49 RET 50 51 GLOBL runtimetls_g+0(SB),TLSBSS,$8 52
