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/* The clone3 syscall wrapper. Linux/powerpc64 version.
Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
/* The userland implementation is:
int clone3 (struct clone_args *cl_args, size_t size,
int (*func)(void *arg), void *arg);
the kernel entry is:
int clone3 (struct clone_args *cl_args, size_t size);
The parameters are passed in registers from userland:
r3: cl_args
r4: size
r5: func
r6: arg */
#ifdef USE_PPC_SCV
/* This is equivalent to DO_CALL_SCV, but we cannot use the macro here
because it uses CFI directives and we just called cfi_endproc. */
# define DO_CLONE3_SVC_CALL(jumpfalse) \
CHECK_SCV_SUPPORT r28 jumpfalse; \
mflr r9; \
std r9, FRAME_LR_SAVE(r1); \
.machine "push"; \
.machine "power9"; \
scv 0; \
.machine "pop"; \
ld r9, FRAME_LR_SAVE(r1); \
mtlr r9; \
/* With scv an, an error is a value -4095 <= x < 0. */ \
cmpdi cr1, r3, 0; \
b 1f;
#else
# define DO_CLONE3_SVC_CALL(fail_branch)
#endif
.text
ENTRY(__clone3)
CALL_MCOUNT 4
/* Sanity checks args. */
cmpdi cr0, r3, 0
cmpdi cr1, r5, 0
cror cr0*4+eq, cr1*4+eq, cr0*4+eq
beq cr0,L(badargs)
/* Save some regs in the "red zone". */
#ifdef USE_PPC_SCV
std r28, -24(r1)
cfi_offset (r28, -24)
#endif
std r29, -16(r1)
std r30, -8(r1)
cfi_offset (r29, -16)
cfi_offset (r30, -8)
/* Save func and arg across syscall. */
mr r30, r5 /* Function in r30. */
mr r29, r6 /* Argument in r29. */
/* End FDE now, because in the child the unwind info will be
wrong. */
cfi_endproc
/* Setup a minimum stack frame for child. It needs to first calculate
the effective stack address, write the start empty backchain pointer,
and update the frame size in the input cl_args. */
ld r7, 40(r3) /* Load stack value. */
ld r8, 48(r3) /* Load stack_size value. */
li r10, 0
add r7, r7, r8 /* Calculate effective stack address. */
std r10, -FRAME_MIN_SIZE_PARM(r7)
addi r8, r8, -FRAME_MIN_SIZE_PARM
std r8, 48(r3)
/* Do the system call, the kernel expects:
r0: system call numer
r3: cl_args
r4: size */
li r0, SYS_ify(clone3)
DO_CLONE3_SVC_CALL (0f)
0: DO_CALL_SC
/* With sc, error is indicated by cr0.SO. */
cmpdi cr1, r3, 0
crandc cr1*4+eq, cr1*4+eq, cr0*4+so
1: bne- cr1,L(parent)
/* Child, load the function and arguments. */
std r2, FRAME_TOC_SAVE(r1)
PPC64_LOAD_FUNCPTR r30
mr r3, r29
bctrl
ld r2, FRAME_TOC_SAVE(r1)
li r0, SYS_ify(exit)
DO_CLONE3_SVC_CALL (2f)
2: DO_CALL_SC
/* We won't ever get here but provide a nop so that the linker
will insert a toc adjusting stub if necessary. */
nop
L(badargs):
cfi_startproc
li r3, EINVAL
TAIL_CALL_SYSCALL_ERROR
L(parent):
/* Check if scv is available. */
cmpdi cr1, r28, 0
/* Parent. Restore registers & return. */
#ifdef USE_PPC_SCV
cfi_offset (r28, -24)
ld r28, -24(r1)
cfi_restore (r28)
#endif
cfi_offset (r29,-16)
cfi_offset (r30,-8)
ld r29, -16(r1)
ld r30, -8(r1)
cfi_restore (r29)
cfi_restore (r30)
#ifdef USE_PPC_SCV
beq cr1, 0f
RET_SCV
b 1f
#endif
0: RET_SC
1: TAIL_CALL_SYSCALL_ERROR
PSEUDO_END (__clone3)
libc_hidden_def (__clone3)
weak_alias (__clone3, clone3)
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