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https://github.com/golang/go
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63 lines
2.0 KiB
ArmAsm
63 lines
2.0 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 "zasm_GOOS_GOARCH.h"
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#include "funcdata.h"
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#include "../../cmd/ld/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, runtime.tlsg is a normal variable.
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// TLS offset is computed in x_cgo_inittls.
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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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TEXT runtime·save_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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MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
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// $runtime.tlsg(SB) is a special linker symbol.
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// It is the offset from the TLS base pointer to our
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// thread-local storage for g.
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#ifdef GOOS_android
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MOVW runtime·tlsg(SB), R11
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#else
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MOVW $runtime·tlsg(SB), R11
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#endif
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ADD R11, R0
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MOVW g, 0(R0)
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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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MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer
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// $runtime.tlsg(SB) is a special linker symbol.
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// It is the offset from the TLS base pointer to our
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// thread-local storage for g.
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#ifdef GOOS_android
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MOVW runtime·tlsg(SB), R11
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#else
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MOVW $runtime·tlsg(SB), R11
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#endif
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ADD R11, R0
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MOVW 0(R0), g
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RET
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