[apple/dyld.git] / src / dyldStartup.s

/*
 * Copyright (c) 1999-2011 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * C runtime startup for interface to the dynamic linker.
 * This is the same as the entry point in crt0.o with the addition of the
 * address of the mach header passed as the an extra first argument.
 *
 * Kernel sets up stack frame to look like:
 *
 *	| STRING AREA |
 *	+-------------+
 *	|      0      |	
*	+-------------+
 *	|  apple[n]   |
 *	+-------------+
 *	       :
 *	+-------------+
 *	|  apple[0]   | 
 *	+-------------+ 
 *	|      0      |
 *	+-------------+
 *	|    env[n]   |
 *	+-------------+
 *	       :
 *	       :
 *	+-------------+
 *	|    env[0]   |
 *	+-------------+
 *	|      0      |
 *	+-------------+
 *	| arg[argc-1] |
 *	+-------------+
 *	       :
 *	       :
 *	+-------------+
 *	|    arg[0]   |
 *	+-------------+
 *	|     argc    |
 *	+-------------+
 * sp->	|      mh     | address of where the a.out's file offset 0 is in memory
 *	+-------------+
 *
 *	Where arg[i] and env[i] point into the STRING AREA
 */


#include <TargetConditionals.h>

	.globl __dyld_start

#ifdef __i386__

#if !TARGET_IPHONE_SIMULATOR
	.text
	.align	4, 0x90
	.globl __dyld_start
__dyld_start:
	popl	%edx		# edx = mh of app
	pushl	$0		# push a zero for debugger end of frames marker
	movl	%esp,%ebp	# pointer to base of kernel frame
	andl    $-16,%esp       # force SSE alignment
	subl	$32,%esp	# room for locals and outgoing parameters
	
	call    L__dyld_start_picbase
L__dyld_start_picbase:	
	popl	%ebx		# set %ebx to runtime value of picbase

   	movl	Lmh-L__dyld_start_picbase(%ebx), %ecx # ecx = prefered load address
   	movl	__dyld_start_static_picbase-L__dyld_start_picbase(%ebx), %eax
	subl    %eax, %ebx      # ebx = slide = L__dyld_start_picbase - [__dyld_start_static_picbase]
	addl	%ebx, %ecx	# ecx = actual load address
	# call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	movl	%edx,(%esp)	# param1 = app_mh
	movl	4(%ebp),%eax	
	movl	%eax,4(%esp)	# param2 = argc
	lea     8(%ebp),%eax	
	movl	%eax,8(%esp)	# param3 = argv
	movl	%ebx,12(%esp)	# param4 = slide
	movl	%ecx,16(%esp)	# param5 = actual load address
	lea	28(%esp),%eax
	movl	%eax,20(%esp)	# param6 = &startGlue
	call	__ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm	
	movl	28(%esp),%edx
	cmpl	$0,%edx
	jne	Lnew

    	# clean up stack and jump to "start" in main executable
	movl	%ebp,%esp	# restore the unaligned stack pointer
	addl	$4,%esp		# remove debugger end frame marker
	movl	$0,%ebp		# restore ebp back to zero
	jmp	*%eax		# jump to the entry point

	# LC_MAIN case, set up stack for call to main() 
Lnew:	movl	4(%ebp),%ebx
	movl	%ebx,(%esp)	# main param1 = argc
	leal	8(%ebp),%ecx
	movl	%ecx,4(%esp)	# main param2 = argv
	leal	0x4(%ecx,%ebx,4),%ebx
	movl	%ebx,8(%esp)	# main param3 = env
Lapple:	movl	(%ebx),%ecx	# look for NULL ending env[] array
	add	$4,%ebx
	testl	%ecx,%ecx
	jne	Lapple		# once found, next pointer is "apple" parameter now in %ebx
	movl	%ebx,12(%esp)	# main param4 = apple
	pushl	%edx		# simulate return address into _start in libdyld
	jmp	*%eax		# jump to main(argc,argv,env,apple) with return address set to _start
#endif	

#if !TARGET_IPHONE_SIMULATOR
	.data
__dyld_start_static_picbase: 
	.long   L__dyld_start_picbase
Lmh:	.long	___dso_handle
#endif


#endif /* __i386__ */


#if __x86_64__
#if !TARGET_IPHONE_SIMULATOR
	.data
	.align 3
__dyld_start_static: 
	.quad   __dyld_start
#endif


#if !TARGET_IPHONE_SIMULATOR
	.text
	.align 2,0x90
	.globl __dyld_start
__dyld_start:
	popq	%rdi		# param1 = mh of app
	pushq	$0		# push a zero for debugger end of frames marker
	movq	%rsp,%rbp	# pointer to base of kernel frame
	andq    $-16,%rsp       # force SSE alignment
	subq	$16,%rsp	# room for local variables
	
	# call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	movl	8(%rbp),%esi	# param2 = argc into %esi
	leaq	16(%rbp),%rdx	# param3 = &argv[0] into %rdx
	movq	__dyld_start_static(%rip), %r8
	leaq	__dyld_start(%rip), %rcx
	subq	 %r8, %rcx	# param4 = slide into %rcx
	leaq	___dso_handle(%rip),%r8 # param5 = dyldsMachHeader
	leaq	-8(%rbp),%r9
	call	__ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	movq	-8(%rbp),%rdi
	cmpq	$0,%rdi
	jne	Lnew

    	# clean up stack and jump to "start" in main executable
	movq	%rbp,%rsp	# restore the unaligned stack pointer
	addq	$8,%rsp 	# remove the mh argument, and debugger end frame marker
	movq	$0,%rbp		# restore ebp back to zero
	jmp	*%rax		# jump to the entry point
	
	# LC_MAIN case, set up stack for call to main() 
Lnew:	addq	$16,%rsp	# remove local variables
	pushq	%rdi		# simulate return address into _start in libdyld
	movq	8(%rbp),%rdi	# main param1 = argc into %rdi
	leaq	16(%rbp),%rsi	# main param2 = &argv[0] into %rsi
	leaq	0x8(%rsi,%rdi,8),%rdx # main param3 = &env[0] into %rdx
 	movq	%rdx,%rcx
Lapple: movq	(%rcx),%r8
	add	$8,%rcx
	testq	%r8,%r8		# look for NULL ending env[] array
	jne	Lapple		# main param4 = apple into %rcx
	jmp	*%rax		# jump to main(argc,argv,env,apple) with return address set to _start

#endif /* TARGET_IPHONE_SIMULATOR */
#endif /* __x86_64__ */


#if __arm__
	.syntax unified
	.data
	.align 2
__dyld_start_static_picbase: 
	.long	L__dyld_start_picbase

    
	// Hack to make ___dso_handle work
	// Without this local symbol, assembler will error out about in subtraction expression
	// The real ___dso_handle (non-weak) sythesized by the linker
	// Since this one is weak, the linker will throw this one away and use the real one instead.
	.data
	.globl ___dso_handle
	.weak_definition ___dso_handle
___dso_handle:	.long 0

	.text
	.align 2
__dyld_start:
	mov	r8, sp		// save stack pointer
	sub	sp, #16		// make room for outgoing parameters
	bic     sp, sp, #7	// force 8-byte alignment

	// call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)

	ldr	r3, L__dyld_start_picbase_ptr
L__dyld_start_picbase:
	sub	r0, pc, #8	// load actual PC
	ldr	r3, [r0, r3]	// load expected PC
	sub	r3, r0, r3	// r3 = slide

	ldr	r0, [r8]	// r0 = mach_header
	ldr	r1, [r8, #4]	// r1 = argc
	add	r2, r8, #8	// r2 = argv

	ldr	r4, Lmh
L3:	add	r4, r4, pc	
	str	r4, [sp, #0]	// [sp] = dyld_mh
	add	r4, sp, #12
	str	r4, [sp, #4]	// [sp+4] = &startGlue
       
	bl	__ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	ldr	r5, [sp, #12]
	cmp	r5, #0
	bne	Lnew
	
	// traditional case, clean up stack and jump to result
	add	sp, r8, #4	// remove the mach_header argument.
	bx	r0		// jump to the program's entry point

	// LC_MAIN case, set up stack for call to main()
Lnew:	mov	lr, r5		    // simulate return address into _start in libdyld
	mov	r5, r0		    // save address of main() for later use
	ldr	r0, [r8, #4]	    // main param1 = argc
	add	r1, r8, #8	    // main param2 = argv
	add	r2, r1, r0, lsl #2  
	add	r2, r2, #4	    // main param3 = &env[0]
	mov	r3, r2
Lapple:	ldr	r4, [r3]
	add	r3, #4
	cmp	r4, #0
	bne	Lapple		    // main param4 = apple
	bx	r5

	.align 2
L__dyld_start_picbase_ptr:
	.long	__dyld_start_static_picbase-L__dyld_start_picbase
Lmh:	.long   ___dso_handle-L3-8

#endif /* __arm__ */


#if __arm64__
	.data
	.align 3
__dso_static: 
	.quad   ___dso_handle

	.text
	.align 2
	.globl __dyld_start
__dyld_start:
	mov 	x28, sp
	and     sp, x28, #~15		// force 16-byte alignment of stack
	mov	x0, #0
	mov	x1, #0
	stp	x1, x0, [sp, #-16]!	// make aligned terminating frame
	mov	fp, sp			// set up fp to point to terminating frame
	sub	sp, sp, #16             // make room for local variables
	ldr     x0, [x28]		// get app's mh into x0
 	ldr     x1, [x28, #8]           // get argc into x1 (kernel passes 32-bit int argc as 64-bits on stack to keep alignment)
	add     x2, x28, #16		// get argv into x2
	adrp	x4,___dso_handle@page
	add 	x4,x4,___dso_handle@pageoff // get dyld's mh in to x4
	adrp	x3,__dso_static@page
	ldr 	x3,[x3,__dso_static@pageoff] // get unslid start of dyld
	sub 	x3,x4,x3		// x3 now has slide of dyld
	mov	x5,sp                   // x5 has &startGlue
	
	// call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	bl	__ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	mov	x16,x0                  // save entry point address in x16
	ldr     x1, [sp]
	cmp	x1, #0
	b.ne	Lnew

	// LC_UNIXTHREAD way, clean up stack and jump to result
	add	sp, x28, #8		// restore unaligned stack pointer without app mh
	br	x16			// jump to the program's entry point

	// LC_MAIN case, set up stack for call to main()
Lnew:	mov	lr, x1		    // simulate return address into _start in libdyld.dylib
	ldr     x0, [x28, #8] 	    // main param1 = argc
	add     x1, x28, #16	    // main param2 = argv
	add	x2, x1, x0, lsl #3  
	add	x2, x2, #8	    // main param3 = &env[0]
	mov	x3, x2
Lapple:	ldr	x4, [x3]
	add	x3, x3, #8
	cmp	x4, #0
	b.ne	Lapple		    // main param4 = apple
	br	x16

#endif // __arm64__


/*
 * dyld calls this function to terminate a process.
 * It has a label so that CrashReporter can distinguish this
 * termination from a random crash.  rdar://problem/4764143
 */
	.text
	.align 2
	.globl	_dyld_fatal_error
_dyld_fatal_error:
#if __arm__
    trap
    nop
#elif __x86_64__ || __i386__
    int3
    nop
#elif __arm64__
    brk	#3
#else
    #error unknown architecture
#endif

#if __arm__
	// work around for:  <rdar://problem/6530727> gdb-1109: notifier in dyld does not work if it is in thumb
 	.text
	.align 2
	.globl	_gdb_image_notifier
	.private_extern _gdb_image_notifier
_gdb_image_notifier:
	bx  lr
#endif
Commit	Line	Data
0959b6d4	1	/*
832b6fce	2	* Copyright (c) 1999-2011 Apple Inc. All rights reserved.
0959b6d4 A	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. Please obtain a copy of the License at
	10	* http://www.opensource.apple.com/apsl/ and read it before using this
	11	* file.
	12	*
	13	* The Original Code and all software distributed under the License are
	14	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	15	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	16	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	17	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	18	* Please see the License for the specific language governing rights and
	19	* limitations under the License.
	20	*
	21	* @APPLE_LICENSE_HEADER_END@
	22	*/
	23	/*
832b6fce	24	* C runtime startup for interface to the dynamic linker.
0959b6d4 A	25	* This is the same as the entry point in crt0.o with the addition of the
	26	* address of the mach header passed as the an extra first argument.
	27	*
	28	* Kernel sets up stack frame to look like:
	29	*
	30	* \| STRING AREA \|
	31	* +-------------+
	32	* \| 0 \|
	33	* +-------------+
	34	* \| apple[n] \|
	35	* +-------------+
	36	* :
	37	* +-------------+
	38	* \| apple[0] \|
	39	* +-------------+
	40	* \| 0 \|
	41	* +-------------+
	42	* \| env[n] \|
	43	* +-------------+
	44	* :
	45	* :
	46	* +-------------+
	47	* \| env[0] \|
	48	* +-------------+
	49	* \| 0 \|
	50	* +-------------+
	51	* \| arg[argc-1] \|
	52	* +-------------+
	53	* :
	54	* :
	55	* +-------------+
	56	* \| arg[0] \|
	57	* +-------------+
	58	* \| argc \|
	59	* +-------------+
	60	* sp-> \| mh \| address of where the a.out's file offset 0 is in memory
	61	* +-------------+
	62	*
	63	* Where arg[i] and env[i] point into the STRING AREA
	64	*/
	65
0959b6d4	66
2fd3f4e8	67	#include <TargetConditionals.h>
39a8cd10 A	68
	69	.globl __dyld_start
	70
0959b6d4	71	#ifdef __i386__
0959b6d4	72
2fd3f4e8	73	#if !TARGET_IPHONE_SIMULATOR
0959b6d4 A	74	.text
	75	.align 4, 0x90
	76	.globl __dyld_start
	77	__dyld_start:
832b6fce	78	popl %edx # edx = mh of app
0959b6d4 A	79	pushl $0 # push a zero for debugger end of frames marker
	80	movl %esp,%ebp # pointer to base of kernel frame
	81	andl $-16,%esp # force SSE alignment
832b6fce	82	subl $32,%esp # room for locals and outgoing parameters
0959b6d4	83
0959b6d4 A	84	call L__dyld_start_picbase
	85	L__dyld_start_picbase:
	86	popl %ebx # set %ebx to runtime value of picbase
832b6fce	87
412ebb8e A	88	movl Lmh-L__dyld_start_picbase(%ebx), %ecx # ecx = prefered load address
	89	movl __dyld_start_static_picbase-L__dyld_start_picbase(%ebx), %eax
	90	subl %eax, %ebx # ebx = slide = L__dyld_start_picbase - [__dyld_start_static_picbase]
	91	addl %ebx, %ecx # ecx = actual load address
832b6fce A	92	# call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	93	movl %edx,(%esp) # param1 = app_mh
	94	movl 4(%ebp),%eax
	95	movl %eax,4(%esp) # param2 = argc
	96	lea 8(%ebp),%eax
	97	movl %eax,8(%esp) # param3 = argv
	98	movl %ebx,12(%esp) # param4 = slide
	99	movl %ecx,16(%esp) # param5 = actual load address
	100	lea 28(%esp),%eax
	101	movl %eax,20(%esp) # param6 = &startGlue
	102	call __ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	103	movl 28(%esp),%edx
	104	cmpl $0,%edx
	105	jne Lnew
	106
	107	# clean up stack and jump to "start" in main executable
0959b6d4	108	movl %ebp,%esp # restore the unaligned stack pointer
832b6fce	109	addl $4,%esp # remove debugger end frame marker
0959b6d4	110	movl $0,%ebp # restore ebp back to zero
bac542e6	111	jmp *%eax # jump to the entry point
0959b6d4	112
832b6fce A	113	# LC_MAIN case, set up stack for call to main()
	114	Lnew: movl 4(%ebp),%ebx
	115	movl %ebx,(%esp) # main param1 = argc
	116	leal 8(%ebp),%ecx
	117	movl %ecx,4(%esp) # main param2 = argv
	118	leal 0x4(%ecx,%ebx,4),%ebx
	119	movl %ebx,8(%esp) # main param3 = env
	120	Lapple: movl (%ebx),%ecx # look for NULL ending env[] array
	121	add $4,%ebx
	122	testl %ecx,%ecx
	123	jne Lapple # once found, next pointer is "apple" parameter now in %ebx
	124	movl %ebx,12(%esp) # main param4 = apple
	125	pushl %edx # simulate return address into _start in libdyld
	126	jmp *%eax # jump to main(argc,argv,env,apple) with return address set to _start
2fd3f4e8	127	#endif
19894a12 A	128
	129	#if !TARGET_IPHONE_SIMULATOR
	130	.data
	131	__dyld_start_static_picbase:
	132	.long L__dyld_start_picbase
	133	Lmh: .long ___dso_handle
	134	#endif
	135
	136
0959b6d4 A	137	#endif /* __i386__ */
0959b6d4 A	138
3d7c199a	139
39a8cd10	140
8bc9f0af	141	#if __x86_64__
2fd3f4e8	142	#if !TARGET_IPHONE_SIMULATOR
8bc9f0af A	143	.data
	144	.align 3
	145	__dyld_start_static:
	146	.quad __dyld_start
2fd3f4e8	147	#endif
8bc9f0af	148
8bc9f0af	149
2fd3f4e8	150	#if !TARGET_IPHONE_SIMULATOR
8bc9f0af A	151	.text
	152	.align 2,0x90
	153	.globl __dyld_start
	154	__dyld_start:
832b6fce	155	popq %rdi # param1 = mh of app
8bc9f0af A	156	pushq $0 # push a zero for debugger end of frames marker
	157	movq %rsp,%rbp # pointer to base of kernel frame
	158	andq $-16,%rsp # force SSE alignment
832b6fce	159	subq $16,%rsp # room for local variables
8bc9f0af	160
832b6fce A	161	# call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	162	movl 8(%rbp),%esi # param2 = argc into %esi
	163	leaq 16(%rbp),%rdx # param3 = &argv[0] into %rdx
8bc9f0af A	164	movq __dyld_start_static(%rip), %r8
	165	leaq __dyld_start(%rip), %rcx
	166	subq %r8, %rcx # param4 = slide into %rcx
412ebb8e	167	leaq ___dso_handle(%rip),%r8 # param5 = dyldsMachHeader
832b6fce A	168	leaq -8(%rbp),%r9
	169	call __ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	170	movq -8(%rbp),%rdi
	171	cmpq $0,%rdi
	172	jne Lnew
8bc9f0af	173
832b6fce	174	# clean up stack and jump to "start" in main executable
8bc9f0af	175	movq %rbp,%rsp # restore the unaligned stack pointer
832b6fce	176	addq $8,%rsp # remove the mh argument, and debugger end frame marker
8bc9f0af A	177	movq $0,%rbp # restore ebp back to zero
8bc9f0af A	178	jmp *%rax # jump to the entry point
bac542e6	179
832b6fce A	180	# LC_MAIN case, set up stack for call to main()
	181	Lnew: addq $16,%rsp # remove local variables
	182	pushq %rdi # simulate return address into _start in libdyld
	183	movq 8(%rbp),%rdi # main param1 = argc into %rdi
	184	leaq 16(%rbp),%rsi # main param2 = &argv[0] into %rsi
	185	leaq 0x8(%rsi,%rdi,8),%rdx # main param3 = &env[0] into %rdx
	186	movq %rdx,%rcx
	187	Lapple: movq (%rcx),%r8
	188	add $8,%rcx
	189	testq %r8,%r8 # look for NULL ending env[] array
	190	jne Lapple # main param4 = apple into %rcx
	191	jmp *%rax # jump to main(argc,argv,env,apple) with return address set to _start
2fd3f4e8 A	192
2fd3f4e8 A	193	#endif /* TARGET_IPHONE_SIMULATOR */
8bc9f0af	194	#endif /* __x86_64__ */
3d7c199a	195
2de2b37b	196
0959b6d4	197
39a8cd10	198	#if __arm__
832b6fce	199	.syntax unified
39a8cd10 A	200	.data
	201	.align 2
	202	__dyld_start_static_picbase:
	203	.long L__dyld_start_picbase
	204
39a8cd10	205
412ebb8e A	206	// Hack to make ___dso_handle work
	207	// Without this local symbol, assembler will error out about in subtraction expression
	208	// The real ___dso_handle (non-weak) sythesized by the linker
	209	// Since this one is weak, the linker will throw this one away and use the real one instead.
	210	.data
	211	.globl ___dso_handle
	212	.weak_definition ___dso_handle
	213	___dso_handle: .long 0
	214
39a8cd10 A	215	.text
	216	.align 2
	217	__dyld_start:
412ebb8e	218	mov r8, sp // save stack pointer
832b6fce	219	sub sp, #16 // make room for outgoing parameters
412ebb8e A	220	bic sp, sp, #7 // force 8-byte alignment
412ebb8e A	221
832b6fce	222	// call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
39a8cd10 A	223
	224	ldr r3, L__dyld_start_picbase_ptr
	225	L__dyld_start_picbase:
	226	sub r0, pc, #8 // load actual PC
	227	ldr r3, [r0, r3] // load expected PC
	228	sub r3, r0, r3 // r3 = slide
	229
412ebb8e A	230	ldr r0, [r8] // r0 = mach_header
	231	ldr r1, [r8, #4] // r1 = argc
	232	add r2, r8, #8 // r2 = argv
39a8cd10	233
412ebb8e	234	ldr r4, Lmh
832b6fce A	235	L3: add r4, r4, pc
	236	str r4, [sp, #0] // [sp] = dyld_mh
	237	add r4, sp, #12
	238	str r4, [sp, #4] // [sp+4] = &startGlue
39a8cd10	239
832b6fce A	240	bl __ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	241	ldr r5, [sp, #12]
	242	cmp r5, #0
	243	bne Lnew
	244
	245	// traditional case, clean up stack and jump to result
39a8cd10 A	246	add sp, r8, #4 // remove the mach_header argument.
	247	bx r0 // jump to the program's entry point
	248
832b6fce A	249	// LC_MAIN case, set up stack for call to main()
	250	Lnew: mov lr, r5 // simulate return address into _start in libdyld
	251	mov r5, r0 // save address of main() for later use
	252	ldr r0, [r8, #4] // main param1 = argc
	253	add r1, r8, #8 // main param2 = argv
	254	add r2, r1, r0, lsl #2
	255	add r2, r2, #4 // main param3 = &env[0]
	256	mov r3, r2
	257	Lapple: ldr r4, [r3]
	258	add r3, #4
	259	cmp r4, #0
	260	bne Lapple // main param4 = apple
	261	bx r5
412ebb8e	262
39a8cd10 A	263	.align 2
	264	L__dyld_start_picbase_ptr:
	265	.long __dyld_start_static_picbase-L__dyld_start_picbase
412ebb8e	266	Lmh: .long ___dso_handle-L3-8
19894a12 A	267
	268	#endif /* __arm__ */
	269
	270
	271
	272
	273	#if __arm64__
	274	.data
	275	.align 3
	276	__dso_static:
	277	.quad ___dso_handle
	278
39a8cd10 A	279	.text
39a8cd10 A	280	.align 2
19894a12 A	281	.globl __dyld_start
	282	__dyld_start:
	283	mov x28, sp
	284	and sp, x28, #~15 // force 16-byte alignment of stack
	285	mov x0, #0
	286	mov x1, #0
	287	stp x1, x0, [sp, #-16]! // make aligned terminating frame
	288	mov fp, sp // set up fp to point to terminating frame
	289	sub sp, sp, #16 // make room for local variables
	290	ldr x0, [x28] // get app's mh into x0
	291	ldr x1, [x28, #8] // get argc into x1 (kernel passes 32-bit int argc as 64-bits on stack to keep alignment)
	292	add x2, x28, #16 // get argv into x2
	293	adrp x4,___dso_handle@page
	294	add x4,x4,___dso_handle@pageoff // get dyld's mh in to x4
	295	adrp x3,__dso_static@page
	296	ldr x3,[x3,__dso_static@pageoff] // get unslid start of dyld
	297	sub x3,x4,x3 // x3 now has slide of dyld
	298	mov x5,sp // x5 has &startGlue
39a8cd10	299
19894a12 A	300	// call dyldbootstrap::start(app_mh, argc, argv, slide, dyld_mh, &startGlue)
	301	bl __ZN13dyldbootstrap5startEPK12macho_headeriPPKclS2_Pm
	302	mov x16,x0 // save entry point address in x16
	303	ldr x1, [sp]
	304	cmp x1, #0
	305	b.ne Lnew
	306
	307	// LC_UNIXTHREAD way, clean up stack and jump to result
	308	add sp, x28, #8 // restore unaligned stack pointer without app mh
	309	br x16 // jump to the program's entry point
	310
	311	// LC_MAIN case, set up stack for call to main()
	312	Lnew: mov lr, x1 // simulate return address into _start in libdyld.dylib
	313	ldr x0, [x28, #8] // main param1 = argc
	314	add x1, x28, #16 // main param2 = argv
	315	add x2, x1, x0, lsl #3
	316	add x2, x2, #8 // main param3 = &env[0]
	317	mov x3, x2
	318	Lapple: ldr x4, [x3]
	319	add x3, x3, #8
	320	cmp x4, #0
	321	b.ne Lapple // main param4 = apple
	322	br x16
	323
	324	#endif // __arm64__
39a8cd10	325
0959b6d4	326
bac542e6 A	327	/*
	328	* dyld calls this function to terminate a process.
	329	* It has a label so that CrashReporter can distinguish this
	330	* termination from a random crash. rdar://problem/4764143
	331	*/
	332	.text
	333	.align 2
	334	.globl _dyld_fatal_error
	335	_dyld_fatal_error:
832b6fce	336	#if __arm__
bac542e6	337	trap
39a8cd10	338	nop
bac542e6 A	339	#elif __x86_64__ \|\| __i386__
bac542e6 A	340	int3
39a8cd10	341	nop
19894a12 A	342	#elif __arm64__
19894a12 A	343	brk #3
bac542e6 A	344	#else
	345	#error unknown architecture
	346	#endif
	347
412ebb8e A	348	#if __arm__
	349	// work around for: <rdar://problem/6530727> gdb-1109: notifier in dyld does not work if it is in thumb
	350	.text
	351	.align 2
	352	.globl _gdb_image_notifier
	353	.private_extern _gdb_image_notifier
	354	_gdb_image_notifier:
	355	bx lr
	356	#endif
	357
	358
bac542e6 A	359
bac542e6 A	360