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55668624cf
For arm this makes no difference--the result is bit-for-bit identical; for thumb this results in smaller encodings. Perhaps it ought not and this is in fact an assembler bug, but I also think it's clearer.
106 lines
2.5 KiB
ArmAsm
106 lines
2.5 KiB
ArmAsm
/* Copyright (C) 1996-2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Pat Beirne <patb@corelcomputer.com>
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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 0x00000100
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#define CLONE_THREAD 0x00010000
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/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
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pid_t *ptid, struct user_desc *tls, pid_t *ctid); */
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.text
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ENTRY(__clone)
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@ sanity check args
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cmp r0, #0
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ite ne
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cmpne r1, #0
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moveq r0, #-EINVAL
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beq PLTJMP(syscall_error)
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@ insert the args onto the new stack
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str r3, [r1, #-4]!
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str r0, [r1, #-4]!
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@ do the system call
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@ get flags
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mov r0, r2
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#ifdef RESET_PID
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mov ip, r2
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#endif
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@ new sp is already in r1
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push {r4, r7}
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cfi_adjust_cfa_offset (8)
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cfi_rel_offset (r4, 0)
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cfi_rel_offset (r7, 4)
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ldr r2, [sp, #8]
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ldr r3, [sp, #12]
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ldr r4, [sp, #16]
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ldr r7, =SYS_ify(clone)
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swi 0x0
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cfi_endproc
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cmp r0, #0
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beq 1f
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pop {r4, r7}
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blt PLTJMP(C_SYMBOL_NAME(__syscall_error))
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RETINSTR(, lr)
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cfi_startproc
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PSEUDO_END (__clone)
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1:
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.fnstart
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.cantunwind
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#ifdef RESET_PID
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tst ip, #CLONE_THREAD
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bne 3f
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GET_TLS (lr)
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mov r1, r0
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tst ip, #CLONE_VM
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ldr r7, =SYS_ify(getpid)
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ite ne
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movne r0, #-1
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swieq 0x0
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NEGOFF_ADJ_BASE (r1, TID_OFFSET)
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str r0, NEGOFF_OFF1 (r1, TID_OFFSET)
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str r0, NEGOFF_OFF2 (r1, PID_OFFSET, TID_OFFSET)
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3:
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#endif
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@ pick the function arg and call address off the stack and execute
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ldr r0, [sp, #4]
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#if defined(__ARM_ARCH_4T__) && defined(__THUMB_INTERWORK__)
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ldr ip, [sp], #8
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mov lr, pc
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bx ip
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#else
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mov lr, pc
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ldr pc, [sp], #8
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#endif
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@ and we are done, passing the return value through r0
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b PLTJMP(HIDDEN_JUMPTARGET(_exit))
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.fnend
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weak_alias (__clone, clone)
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