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130 lines
3.7 KiB
ArmAsm
130 lines
3.7 KiB
ArmAsm
/* Copyright (C) 1996-2025 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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<https://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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#include <tcb-offsets.h>
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/* Non-thread code calls __clone with the following parameters:
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int clone(int (*fn)(void *arg),
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void *child_stack,
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int flags,
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void *arg)
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NPTL Code will call __clone with the following parameters:
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int clone(int (*fn)(void *arg),
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void *child_stack,
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int flags,
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void *arg,
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int *parent_tidptr,
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struct user_desc *newtls,
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int *child_pidptr)
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The code should not mangle the extra input registers.
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Syscall expects: Input to __clone:
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4(r25) - function pointer (r26, arg0)
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0(r25) - argument (r23, arg3)
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r26 - clone flags. (r24, arg2)
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r25+64 - user stack pointer. (r25, arg1)
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r24 - parent tid pointer. (stack - 52)
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r23 - struct user_desc newtls pointer. (stack - 56)
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r22 - child tid pointer. (stack - 60)
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r20 - clone syscall number (constant)
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Return:
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On success the thread ID of the child process is returned in
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the callers context.
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On error return -1, and set errno to the value returned by
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the syscall.
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*/
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.text
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ENTRY(__clone)
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/* Sanity check arguments. */
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comib,=,n 0,%arg0,.LerrorSanity /* no NULL function pointers */
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comib,=,n 0,%arg1,.LerrorSanity /* no NULL stack pointers */
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/* Ensure stack argument is 8-byte aligned. */
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ldo 7(%r25),%r25
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depi 0,31,3,%r25
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/* Save the function pointer, arg, and flags on the new stack. */
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stwm %r26, 64(%r25)
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stw %r23, -60(%r25)
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stw %r24, -56(%r25)
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/* Clone arguments are (int flags, void * child_stack) */
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copy %r24, %r26 /* flags are first */
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/* User stack pointer is in the correct register already */
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/* Load args from stack... */
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ldw -52(%sp), %r24 /* Load parent_tidptr */
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ldw -56(%sp), %r23 /* Load newtls */
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ldw -60(%sp), %r22 /* Load child_tidptr */
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/* Do the system call */
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ble 0x100(%sr2, %r0)
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ldi __NR_clone, %r20
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ldi -4096, %r1
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comb,<<,n %r1, %ret0, .LerrorRest /* Note: unsigned compare. */
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comib,=,n 0, %ret0, .LthreadStart
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bv,n %r0(%rp)
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.LerrorSanity:
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/* Sanity checks failed, set errno to EINVAL. */
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ldi -EINVAL, %ret0
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.LerrorRest:
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/* Something bad happened -- no child created -- need a frame */
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ldo 64(%sp),%sp
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.cfi_def_cfa_offset -64
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bl __syscall_error, %rp
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sub %r0, %ret0, %arg0
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ldw -84(%sp), %rp
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/* Return after setting errno, ret0 is set to -1 by __syscall_error. */
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bv %r0(%rp)
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ldo -64(%sp), %sp
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.LthreadStart:
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/* Load up the arguments. */
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ldw -60(%sp), %arg0
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ldw -64(%sp), %r22
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/* $$dyncall fixes child's PIC register */
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/* Call the user's function */
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bl $$dyncall, %r31
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copy %r31, %rp
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copy %r28, %r26
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ble 0x100(%sr2, %r0)
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ldi __NR_exit, %r20
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/* We should not return from exit.
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We do not restore the stack state. */
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iitlbp %r0, (%sr0, %r0)
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PSEUDO_END(__clone)
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libc_hidden_def (__clone)
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weak_alias (__clone, clone)
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