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83d641efd1
With this change we properly set up the frame first, and tear it down last, doing argument checking only when the frame is set up.
223 lines
5.2 KiB
ArmAsm
223 lines
5.2 KiB
ArmAsm
/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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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 it's 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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#include <asm/unistd.h>
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#include <arch/abi.h>
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#include <tls.h>
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#include <linux/sched.h>
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/* What we save where in the stack frame; must include all callee-saves. */
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#define FRAME_NEXT_LR (0 * REGSIZE) /* reserved by ABI; not used here */
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#define FRAME_SP (1 * REGSIZE)
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#define FRAME_R30 (2 * REGSIZE)
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#define FRAME_R31 (3 * REGSIZE)
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#define FRAME_R32 (4 * REGSIZE)
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#define FRAME_SIZE (5 * REGSIZE)
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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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/* Create a stack frame so we can pass callee-saves to new task. */
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{
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move r10, sp
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ST sp, lr
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ADDI_PTR sp, sp, -FRAME_SIZE
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}
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cfi_offset (lr, 0)
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cfi_def_cfa_offset (FRAME_SIZE)
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ADDI_PTR r11, sp, FRAME_SP
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{
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ST r11, r10
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ADDI_PTR r11, sp, FRAME_R30
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}
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{
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ST r11, r30
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ADDI_PTR r11, sp, FRAME_R31
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}
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cfi_offset (r30, FRAME_R30 - FRAME_SIZE)
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{
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ST r11, r31
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ADDI_PTR r11, sp, FRAME_R32
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}
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cfi_offset (r31, FRAME_R31 - FRAME_SIZE)
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ST r11, r32
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cfi_offset (r32, FRAME_R32 - FRAME_SIZE)
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/* sanity check arguments */
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BEQZ r0, .Linvalid
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BEQZ r1, .Linvalid
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/* Make sure child stack is properly aligned, and set up the
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top frame so that we can call out of it immediately in the
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child. Setting it up here means we fault in the parent if
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it's bogus, which is probably cleaner than faulting first
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thing in the child. */
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ADDI_PTR r1, r1, -C_ABI_SAVE_AREA_SIZE
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andi r1, r1, -C_ABI_SAVE_AREA_SIZE
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ADDI_PTR r9, r1, REGSIZE /* sp of this frame on entry, i.e. zero */
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ST r9, zero
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/* We need to switch the argument convention around from
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libc to kernel:
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libc:
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r0 fn
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r1 child_stack
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r2 flags
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r3 arg
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r4 ptid
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r5 tls
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r6 ctid
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kernel:
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r0 flags
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r1 child_stack [same as libc]
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r2 ptid
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r3 ctid
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r4 tls
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Plus the callee-saves as described at .Lthread_start, below. */
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{
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move r32, r0
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move r0, r2
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}
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{
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move r31, r3
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move r3, r6
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}
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{
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move r30, r2
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move r2, r4
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}
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{
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move r4, r5
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moveli TREG_SYSCALL_NR_NAME, __NR_clone
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}
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swint1
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BEQZ r0, .Lthread_start /* If in child task. */
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.Ldone:
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/* Restore the callee-saved registers and return. */
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ADDLI_PTR lr, sp, FRAME_SIZE
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{
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LD lr, lr
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ADDLI_PTR r30, sp, FRAME_R30
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}
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{
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LD r30, r30
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ADDLI_PTR r31, sp, FRAME_R31
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}
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{
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LD r31, r31
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ADDLI_PTR r32, sp, FRAME_R32
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}
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{
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LD r32, r32
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ADDI_PTR sp, sp, FRAME_SIZE
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}
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cfi_def_cfa_offset (0)
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BNEZ r1, .Lerror
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jrp lr
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.Lerror:
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j SYSCALL_ERROR_NAME
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.Linvalid:
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{
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movei r1, EINVAL
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j .Ldone
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}
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/* This function expects to receive:
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sp: the top of a valid stack area
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r30: clone() flags
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r31: the argument to pass to the user function
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r32: the user function pointer */
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.Lthread_start:
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cfi_def_cfa_offset (FRAME_SIZE)
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cfi_undefined (lr)
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/* Check and see if we need to reset the PID, which we do if
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CLONE_THREAD isn't set, i.e. we're not staying in the thread group.
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If CLONE_VM is set, we're doing some kind of thread-like clone,
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so we set the tid/pid to -1 to disable using the cached values
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in getpid(). Otherwise (if CLONE_VM isn't set), it's a
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fork-like clone, and we go ahead and write the cached values
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from the true system pid (retrieved via __NR_getpid syscall). */
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#ifdef __tilegx__
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{
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moveli r0, hw1_last(CLONE_VM)
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moveli r1, hw1_last(CLONE_THREAD)
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}
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{
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shl16insli r0, r0, hw0(CLONE_VM)
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shl16insli r1, r1, hw0(CLONE_THREAD)
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}
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#else
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{
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moveli r0, lo16(CLONE_VM)
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moveli r1, lo16(CLONE_THREAD)
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}
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{
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auli r0, r0, ha16(CLONE_VM)
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auli r1, r1, ha16(CLONE_THREAD)
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}
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#endif
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{
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and r0, r30, r0
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and r1, r30, r1
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}
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BNEZ r1, .Lno_reset_pid /* CLONE_THREAD is set */
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{
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movei r0, -1
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BNEZ r0, .Lgotpid /* CLONE_VM is set */
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}
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moveli TREG_SYSCALL_NR_NAME, __NR_getpid
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swint1
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.Lgotpid:
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ADDLI_PTR r2, tp, PID_OFFSET
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{
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ST4 r2, r0
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ADDLI_PTR r2, tp, TID_OFFSET
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}
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ST4 r2, r0
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.Lno_reset_pid:
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{
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/* Invoke user function with specified argument. */
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move r0, r31
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jalr r32
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}
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{
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j HIDDEN_JUMPTARGET(_exit)
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info INFO_OP_CANNOT_BACKTRACE /* Notify backtracer to stop. */
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}
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PSEUDO_END (__clone)
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weak_alias (__clone, clone)
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