1efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// Copyright 2014 The Go Authors. All rights reserved. 2efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// Use of this source code is governed by a BSD-style 3efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// license that can be found in the LICENSE file. 4efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 5efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#include "go_asm.h" 6efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#include "go_tls.h" 7efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#include "funcdata.h" 8efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#include "textflag.h" 9efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 10efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// We have to resort to TLS variable to save g(R10). 11efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// One reason is that external code might trigger 12efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// SIGSEGV, and our runtime.sigtramp don't even know we 13efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// are in external code, and will continue to use R10, 14efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// this might as well result in another SIGSEGV. 15efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// Note: both functions will clobber R0 and R11 and 16efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// can be called from 5c ABI code. 17efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 18efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// On android and darwin, runtime.tls_g is a normal variable. 19efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// TLS offset is computed in x_cgo_inittls. 20efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef GOOS_android 21efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#define TLSG_IS_VARIABLE 22efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 23efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef GOOS_darwin 24efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#define TLSG_IS_VARIABLE 25efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 26efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 27efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// save_g saves the g register into pthread-provided 28efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// thread-local memory, so that we can call externally compiled 29efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// ARM code that will overwrite those registers. 30efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// NOTE: runtime.gogo assumes that R1 is preserved by this function. 31efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// runtime.mcall assumes this function only clobbers R0 and R11. 32efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// Returns with g in R0. 33efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenTEXT runtime·save_g(SB),NOSPLIT,$-4 34efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef GOOS_nacl 35efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // nothing to do as nacl/arm does not use TLS at all. 36efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW g, R0 // preserve R0 across call to setg<> 37efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen RET 38efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 39efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // If the host does not support MRC the linker will replace it with 40efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // a call to runtime.read_tls_fallback which jumps to __kuser_get_tls. 41efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // The replacement function saves LR in R11 over the call to read_tls_fallback. 42efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer 43efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen BIC $3, R0 // Darwin/ARM might return unaligned pointer 44efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW runtime·tls_g(SB), R11 45efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen ADD R11, R0 46efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW g, 0(R0) 47efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW g, R0 // preserve R0 across call to setg<> 48efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen RET 49efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 50efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// load_g loads the g register from pthread-provided 51efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// thread-local memory, for use after calling externally compiled 52efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// ARM code that overwrote those registers. 53efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenTEXT runtime·load_g(SB),NOSPLIT,$0 54efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef GOOS_nacl 55efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // nothing to do as nacl/arm does not use TLS at all. 56efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen RET 57efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 58efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // See save_g 59efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer 60efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen BIC $3, R0 // Darwin/ARM might return unaligned pointer 61efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW runtime·tls_g(SB), R11 62efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen ADD R11, R0 63efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW 0(R0), g 64efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen RET 65efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 66efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// This is called from rt0_go, which runs on the system stack 67efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// using the initial stack allocated by the OS. 68efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// It calls back into standard C using the BL (R4) below. 69efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// To do that, the stack pointer must be 8-byte-aligned 70efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// on some systems, notably FreeBSD. 71efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// The ARM ABI says the stack pointer must be 8-byte-aligned 72efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// on entry to any function, but only FreeBSD's C library seems to care. 73efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// The caller was 8-byte aligned, but we push an LR. 74efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// Declare a dummy word ($4, not $0) to make sure the 75efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// frame is 8 bytes and stays 8-byte-aligned. 76efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenTEXT runtime·_initcgo(SB),NOSPLIT,$4 77efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifndef GOOS_nacl 78efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen // if there is an _cgo_init, call it. 79efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW _cgo_init(SB), R4 80efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen CMP $0, R4 81efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen B.EQ nocgo 82efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MRC 15, 0, R0, C13, C0, 3 // load TLS base pointer 83efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW R0, R3 // arg 3: TLS base pointer 84efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef TLSG_IS_VARIABLE 85efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW $runtime·tls_g(SB), R2 // arg 2: &tls_g 86efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#else 87efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW $0, R2 // arg 2: not used when using platform tls 88efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 89efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW $setg_gcc<>(SB), R1 // arg 1: setg 90efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW g, R0 // arg 0: G 91efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen BL (R4) // will clobber R0-R3 92efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 93efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsennocgo: 94efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen RET 95efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 96efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen// void setg_gcc(G*); set g called from gcc. 97efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenTEXT setg_gcc<>(SB),NOSPLIT,$0 98efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen MOVW R0, g 99efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen B runtime·save_g(SB) 100efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen 101efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#ifdef TLSG_IS_VARIABLE 102efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenGLOBL runtime·tls_g+0(SB), NOPTR, $4 103efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#else 104efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan WillemsenGLOBL runtime·tls_g+0(SB), TLSBSS, $4 105efea46b87b2dcc66da02dfbf66fd901d24c7a09Dan Willemsen#endif 106