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0020b8a257
They are dead code already, but the verifier is still not happy. Don't assemble them at all. Looks like it has been like that for long. I don't know why it was ok. Maybe the verifier is now more picky? Fixes #19884. Change-Id: Ib806fb73ca469789dec56f52d484cf8baf7a245c Reviewed-on: https://go-review.googlesource.com/40111 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com> Reviewed-by: Dave Cheney <dave@cheney.net>
108 lines
3.4 KiB
ArmAsm
108 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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#else
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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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#endif
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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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#else
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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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#endif
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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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