// 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 !windows
|
|
#include "go_asm.h"
|
#include "go_tls.h"
|
#include "funcdata.h"
|
#include "textflag.h"
|
|
// We have to resort to TLS variable to save g(R10).
|
// 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 R10,
|
// this might as well result in another SIGSEGV.
|
// Note: both functions will clobber R0 and R11 and
|
// can be called from 5c ABI code.
|
|
// On android and darwin, runtime.tls_g is a normal variable.
|
// TLS offset is computed in x_cgo_inittls.
|
#ifdef GOOS_android
|
#define TLSG_IS_VARIABLE
|
#endif
|
#ifdef GOOS_darwin
|
#define TLSG_IS_VARIABLE
|
#endif
|
|
// save_g saves the g register into pthread-provided
|
// thread-local memory, so that we can call externally compiled
|
// ARM code that will overwrite those registers.
|
// NOTE: runtime.gogo assumes that R1 is preserved by this function.
|
// runtime.mcall assumes this function only clobbers R0 and R11.
|
// Returns with g in R0.
|
TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0
|
#ifdef GOOS_nacl
|
// nothing to do as nacl/arm does not use TLS at all.
|
MOVW g, R0 // preserve R0 across call to setg<>
|
RET
|
#else
|
// If the host does not support MRC the linker will replace it with
|
// a call to runtime.read_tls_fallback which jumps to __kuser_get_tls.
|
// The replacement function saves LR in R11 over the call to read_tls_fallback.
|
MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
|
BIC $3, R0 // Darwin/ARM might return unaligned pointer
|
MOVW runtime·tls_g(SB), R11
|
ADD R11, R0
|
MOVW g, 0(R0)
|
MOVW g, R0 // preserve R0 across call to setg<>
|
RET
|
#endif
|
|
// load_g loads the g register from pthread-provided
|
// thread-local memory, for use after calling externally compiled
|
// ARM code that overwrote those registers.
|
TEXT runtime·load_g(SB),NOSPLIT,$0
|
#ifdef GOOS_nacl
|
// nothing to do as nacl/arm does not use TLS at all.
|
RET
|
#else
|
// See save_g
|
MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
|
BIC $3, R0 // Darwin/ARM might return unaligned pointer
|
MOVW runtime·tls_g(SB), R11
|
ADD R11, R0
|
MOVW 0(R0), g
|
RET
|
#endif
|
|
// This is called from rt0_go, which runs on the system stack
|
// using the initial stack allocated by the OS.
|
// It calls back into standard C using the BL (R4) below.
|
// To do that, the stack pointer must be 8-byte-aligned
|
// on some systems, notably FreeBSD.
|
// The ARM ABI says the stack pointer must be 8-byte-aligned
|
// on entry to any function, but only FreeBSD's C library seems to care.
|
// The caller was 8-byte aligned, but we push an LR.
|
// Declare a dummy word ($4, not $0) to make sure the
|
// frame is 8 bytes and stays 8-byte-aligned.
|
TEXT runtime·_initcgo(SB),NOSPLIT,$4
|
#ifndef GOOS_nacl
|
// if there is an _cgo_init, call it.
|
MOVW _cgo_init(SB), R4
|
CMP $0, R4
|
B.EQ nocgo
|
MRC 15, 0, R0, C13, C0, 3 // load TLS base pointer
|
MOVW R0, R3 // arg 3: TLS base pointer
|
#ifdef TLSG_IS_VARIABLE
|
MOVW $runtime·tls_g(SB), R2 // arg 2: &tls_g
|
#else
|
MOVW $0, R2 // arg 2: not used when using platform tls
|
#endif
|
MOVW $setg_gcc<>(SB), R1 // arg 1: setg
|
MOVW g, R0 // arg 0: G
|
BL (R4) // will clobber R0-R3
|
#endif
|
nocgo:
|
RET
|
|
// void setg_gcc(G*); set g called from gcc.
|
TEXT setg_gcc<>(SB),NOSPLIT,$0
|
MOVW R0, g
|
B runtime·save_g(SB)
|
|
#ifdef TLSG_IS_VARIABLE
|
GLOBL runtime·tls_g+0(SB), NOPTR, $4
|
#else
|
GLOBL runtime·tls_g+0(SB), TLSBSS, $4
|
#endif
|
