• Elias Naur's avatar
    runtime: preserve darwin/arm{,64} callee-save registers · ea4b785a
    Elias Naur authored
    CL 14603 attempted to preserve the callee-save registers for
    the darwin/arm runtime initialization routine, but I believe it
    wasn't sufficient and resulted in the crash reported in issue
    
    Saving and restoring the registers on the stack the same way
    linux/arm does seems more obvious and fixes #14778, so do that.
    
    Even though #14778 is not reproducible on darwin/arm64, I applied
    a similar change there, and to linux/arm64 which obeys the same
    calling convention.
    
    Finally, this CL is a candidate for a 1.6 minor release for the same
    reason CL 14603 was in a 1.5 minor release (as CL 16968). It is
    small and only touches the iOS platforms and gomobile on darwin/arm
    is currently useless without it.
    
    Fixes #14778
    Fixes #12590 (again)
    
    Change-Id: I7401daf0bbd7c579a7e84761384a7b763651752a
    Reviewed-on: https://go-review.googlesource.com/20621Reviewed-by: default avatarDavid Crawshaw <crawshaw@golang.org>
    Run-TryBot: Elias Naur <elias.naur@gmail.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    ea4b785a
rt0_darwin_arm.s 2 KB
// 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.

#include "textflag.h"

TEXT _rt0_arm_darwin(SB),7,$-4
	// prepare arguments for main (_rt0_go)
	MOVW	(R13), R0	// argc
	MOVW	$4(R13), R1		// argv
	MOVW	$main(SB), R4
	B		(R4)

// When linking with -buildmode=c-archive or -buildmode=c-shared,
// this symbol is called from a global initialization function.
//
// Note that all currently shipping darwin/arm platforms require
// cgo and do not support c-shared.
TEXT _rt0_arm_darwin_lib(SB),NOSPLIT,$32
	// Preserve callee-save registers.
	MOVW    R4, 12(R13)
	MOVW    R5, 16(R13)
	MOVW    R6, 20(R13)
	MOVW    R7, 24(R13)
	MOVW    R8, 28(R13)
	MOVW    R11, 32(R13)

	MOVW  R0, _rt0_arm_darwin_lib_argc<>(SB)
	MOVW  R1, _rt0_arm_darwin_lib_argv<>(SB)

	// Synchronous initialization.
	MOVW	$runtime·libpreinit(SB), R3
	CALL	(R3)

	// Create a new thread to do the runtime initialization and return.
	MOVW  _cgo_sys_thread_create(SB), R3
	CMP   $0, R3
	B.EQ  nocgo
	MOVW  $_rt0_arm_darwin_lib_go(SB), R0
	MOVW  $0, R1
	BL    (R3)
	B rr
nocgo:
	MOVW  $0x400000, R0
	MOVW  R0, (R13) // stacksize
	MOVW  $_rt0_arm_darwin_lib_go(SB), R0
	MOVW  R0, 4(R13) // fn
	MOVW  $0, R0
	MOVW  R0, 8(R13) // fnarg
	MOVW  $runtime·newosproc0(SB), R3
	BL    (R3)
rr:
	// Restore callee-save registers and return.
	MOVW    12(R13), R4
	MOVW    16(R13), R5
	MOVW    20(R13), R6
	MOVW    24(R13), R7
	MOVW    28(R13), R8
	MOVW    32(R13), R11
	RET


TEXT _rt0_arm_darwin_lib_go(SB),NOSPLIT,$0
	MOVW  _rt0_arm_darwin_lib_argc<>(SB), R0
	MOVW  _rt0_arm_darwin_lib_argv<>(SB), R1
	MOVW  R0,  (R13)
	MOVW  R1, 4(R13)
	MOVW  $runtime·rt0_go(SB), R4
	B     (R4)

DATA  _rt0_arm_darwin_lib_argc<>(SB)/4, $0
GLOBL _rt0_arm_darwin_lib_argc<>(SB),NOPTR, $4
DATA  _rt0_arm_darwin_lib_argv<>(SB)/4, $0
GLOBL _rt0_arm_darwin_lib_argv<>(SB),NOPTR, $4

TEXT main(SB),NOSPLIT,$-8
	// save argc and argv onto stack
	MOVM.DB.W [R0-R1], (R13)
	MOVW	$runtime·rt0_go(SB), R4
	B		(R4)