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111cc71489
At the same time, rely on non-clobbered registers across syscall so that we eliminate the stack frame that we previously ignored in the unwind info.
97 lines
2.5 KiB
ArmAsm
97 lines
2.5 KiB
ArmAsm
/* Copyright (C) 1996-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* clone() is even more special than fork() as it mucks with stacks
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and invokes a function in the right context after its all over. */
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#include <sysdep.h>
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#define _ERRNO_H 1
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#include <bits/errno.h>
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#define CLONE_VM_BIT 8
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#define CLONE_VM (1 << CLONE_VM_BIT)
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#define CLONE_THREAD_BIT 16
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#define CLONE_THREAD (1 << CLONE_THREAD_BIT)
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/* int clone(int (*fn)(void *arg), x0
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void *child_stack, x1
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int flags, x2
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void *arg, x3
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pid_t *ptid, x4
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struct user_desc *tls, x5
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pid_t *ctid); x6
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*/
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.text
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ENTRY(__clone)
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/* Save args for the child. */
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mov x10, x0
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mov x11, x2
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mov x12, x3
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/* Sanity check args. */
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mov x0, #-EINVAL
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cbz x10, .Lsyscall_error
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cbz x1, .Lsyscall_error
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/* Do the system call. */
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/* X0:flags, x1:newsp, x2:parenttidptr, x3:newtls, x4:childtid. */
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mov x0, x2 /* flags */
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/* New sp is already in x1. */
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mov x2, x4 /* ptid */
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mov x3, x5 /* tls */
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mov x4, x6 /* ctid */
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mov x8, #SYS_ify(clone)
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svc 0x0
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cmp x0, #0
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beq thread_start
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blt .Lsyscall_error
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RET
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PSEUDO_END (__clone)
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.align 4
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.type thread_start, %function
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thread_start:
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cfi_startproc
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cfi_undefined (x30)
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mov x29, 0
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tbnz x11, #CLONE_THREAD_BIT, 3f
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mov x0, #-1
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tbnz x11, #CLONE_VM_BIT, 2f
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mov x8, #SYS_ify(getpid)
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svc 0x0
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2:
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mrs x1, tpidr_el0
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sub x1, x1, #PTHREAD_SIZEOF
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str w0, [x1, #PTHREAD_PID_OFFSET]
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str w0, [x1, #PTHREAD_TID_OFFSET]
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3:
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/* Pick the function arg and execute. */
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mov x0, x12
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blr x10
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/* We are done, pass the return value through x0. */
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b HIDDEN_JUMPTARGET(_exit)
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cfi_endproc
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.size thread_start, .-thread_start
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weak_alias (__clone, clone)
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