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519474451a
This is a subset of https://golang.org/cl/20022 with only the copyright header lines, so the next CL will be smaller and more reviewable. Go policy has been single space after periods in comments for some time. The copyright header template at: https://golang.org/doc/contribute.html#copyright also uses a single space. Make them all consistent. Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0 Reviewed-on: https://go-review.googlesource.com/20111 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
106 lines
3.4 KiB
ArmAsm
106 lines
3.4 KiB
ArmAsm
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "go_asm.h"
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#include "go_tls.h"
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#include "funcdata.h"
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#include "textflag.h"
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// We have to resort to TLS variable to save g(R10).
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// One reason is that external code might trigger
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// SIGSEGV, and our runtime.sigtramp don't even know we
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// are in external code, and will continue to use R10,
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// this might as well result in another SIGSEGV.
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// Note: both functions will clobber R0 and R11 and
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// can be called from 5c ABI code.
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// On android and darwin, runtime.tls_g is a normal variable.
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// TLS offset is computed in x_cgo_inittls.
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#ifdef GOOS_android
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#define TLSG_IS_VARIABLE
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#endif
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#ifdef GOOS_darwin
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#define TLSG_IS_VARIABLE
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#endif
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// save_g saves the g register into pthread-provided
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// thread-local memory, so that we can call externally compiled
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// ARM code that will overwrite those registers.
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// NOTE: runtime.gogo assumes that R1 is preserved by this function.
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// runtime.mcall assumes this function only clobbers R0 and R11.
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// Returns with g in R0.
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TEXT runtime·save_g(SB),NOSPLIT,$-4
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#ifdef GOOS_nacl
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// nothing to do as nacl/arm does not use TLS at all.
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MOVW g, R0 // preserve R0 across call to setg<>
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RET
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#endif
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// If the host does not support MRC the linker will replace it with
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// a call to runtime.read_tls_fallback which jumps to __kuser_get_tls.
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// The replacement function saves LR in R11 over the call to read_tls_fallback.
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MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
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BIC $3, R0 // Darwin/ARM might return unaligned pointer
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MOVW runtime·tls_g(SB), R11
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ADD R11, R0
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MOVW g, 0(R0)
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MOVW g, R0 // preserve R0 across call to setg<>
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RET
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// load_g loads the g register from pthread-provided
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// thread-local memory, for use after calling externally compiled
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// ARM code that overwrote those registers.
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TEXT runtime·load_g(SB),NOSPLIT,$0
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#ifdef GOOS_nacl
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// nothing to do as nacl/arm does not use TLS at all.
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RET
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#endif
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// See save_g
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MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
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BIC $3, R0 // Darwin/ARM might return unaligned pointer
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MOVW runtime·tls_g(SB), R11
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ADD R11, R0
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MOVW 0(R0), g
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RET
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// This is called from rt0_go, which runs on the system stack
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// using the initial stack allocated by the OS.
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// It calls back into standard C using the BL (R4) below.
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// To do that, the stack pointer must be 8-byte-aligned
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// on some systems, notably FreeBSD.
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// The ARM ABI says the stack pointer must be 8-byte-aligned
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// on entry to any function, but only FreeBSD's C library seems to care.
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// The caller was 8-byte aligned, but we push an LR.
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// Declare a dummy word ($4, not $0) to make sure the
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// frame is 8 bytes and stays 8-byte-aligned.
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TEXT runtime·_initcgo(SB),NOSPLIT,$4
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#ifndef GOOS_nacl
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// if there is an _cgo_init, call it.
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MOVW _cgo_init(SB), R4
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CMP $0, R4
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B.EQ nocgo
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MRC 15, 0, R0, C13, C0, 3 // load TLS base pointer
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MOVW R0, R3 // arg 3: TLS base pointer
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#ifdef TLSG_IS_VARIABLE
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MOVW $runtime·tls_g(SB), R2 // arg 2: &tls_g
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#else
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MOVW $0, R2 // arg 2: not used when using platform tls
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#endif
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MOVW $setg_gcc<>(SB), R1 // arg 1: setg
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MOVW g, R0 // arg 0: G
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BL (R4) // will clobber R0-R3
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#endif
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nocgo:
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RET
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// void setg_gcc(G*); set g called from gcc.
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TEXT setg_gcc<>(SB),NOSPLIT,$0
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MOVW R0, g
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B runtime·save_g(SB)
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#ifdef TLSG_IS_VARIABLE
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GLOBL runtime·tls_g+0(SB), NOPTR, $4
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#else
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GLOBL runtime·tls_g+0(SB), TLSBSS, $4
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#endif
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