glibc/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
Ulrich Weigand 8b8a692cfd PowerPC64 ELFv2 ABI 4/6: Stack frame layout changes
This updates glibc for the changes in the ELFv2 relating to the
stack frame layout.  These are described in more detail here:
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01149.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01146.html

Specifically, the "compiler and linker doublewords" were removed,
which has the effect that the save slot for the TOC register is
now at offset 24 rather than 40 to the stack pointer.

In addition, a function may now no longer necessarily assume that
its caller has set up a 64-byte register save area its use.

To address the first change, the patch goes through all assembler
files and replaces immediate offsets in instructions accessing the
ABI-defined stack slots by symbolic offsets.  Those already were
defined in ucontext_i.sym and used in some of the context routines,
but that doesn't really seem like the right place for those defines.

The patch instead defines those symbolic offsets in sysdeps.h,
in two variants for the old and new ABI, and uses them systematically
in all assembler files, not just the context routines.

The second change only affected a few assembler files that used
the save area to temporarily store some registers.  In those
cases where this happens within a leaf function, this patch
changes the code to store those registers to the "red zone"
below the stack pointer.  Otherwise, the functions already allocate
a stack frame, and the patch changes them to add extra space in
these frames as temporary space for the ELFv2 ABI.
2013-12-04 07:41:39 -06:00

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3.4 KiB
ArmAsm

/* Wrapper around clone system call. PowerPC64 version.
Copyright (C) 1997-2013 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
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#define CLONE_VM 0x00000100
#define CLONE_THREAD 0x00010000
/* This is the only really unusual system call in PPC linux, but not
because of any weirdness in the system call itself; because of
all the freaky stuff we have to do to make the call useful. */
/* int [r3] clone(int (*fn)(void *arg) [r3], void *child_stack [r4],
int flags [r5], void *arg [r6], void *parent_tid [r7],
void *tls [r8], void *child_tid [r9]); */
ENTRY (__clone)
CALL_MCOUNT 7
/* Check for child_stack == NULL || fn == NULL. */
cmpdi cr0,r4,0
cmpdi cr1,r3,0
cror cr0*4+eq,cr1*4+eq,cr0*4+eq
beq- cr0,L(badargs)
/* Save some regs in the "red zone". */
#ifdef RESET_PID
std r29,-24(r1)
#endif
std r30,-16(r1)
std r31,-8(r1)
#ifdef RESET_PID
cfi_offset(r29,-24)
#endif
cfi_offset(r30,-16)
cfi_offset(r31,-8)
/* Set up stack frame for child. */
clrrdi r4,r4,4
li r0,0
stdu r0,-FRAME_MIN_SIZE_PARM(r4)
/* Save fn, args, stack across syscall. */
mr r30,r3 /* Function in r30. */
#ifdef RESET_PID
mr r29,r5 /* Flags in r29. */
#endif
mr r31,r6 /* Argument in r31. */
/* 'flags' argument is first parameter to clone syscall.
Second is the stack pointer, already in r4. */
mr r3,r5
/* Move the parent_tid, child_tid and tls arguments. */
mr r5,r7
mr r6,r8
mr r7,r9
/* End FDE now, because in the child the unwind info will be
wrong. */
cfi_endproc
/* Do the call. */
DO_CALL(SYS_ify(clone))
/* Check for child process. */
cmpdi cr1,r3,0
crandc cr1*4+eq,cr1*4+eq,cr0*4+so
bne- cr1,L(parent) /* The '-' is to minimise the race. */
#ifdef RESET_PID
andis. r0,r29,CLONE_THREAD>>16
bne+ cr0,L(oldpid)
andi. r0,r29,CLONE_VM
li r3,-1
bne- cr0,L(nomoregetpid)
DO_CALL(SYS_ify(getpid))
L(nomoregetpid):
stw r3,TID(r13)
stw r3,PID(r13)
L(oldpid):
#endif
std r2,FRAME_TOC_SAVE(r1)
/* Call procedure. */
PPC64_LOAD_FUNCPTR r30
mr r3,r31
bctrl
ld r2,FRAME_TOC_SAVE(r1)
/* Call _exit with result from procedure. */
#ifdef SHARED
b JUMPTARGET(__GI__exit)
#else
b JUMPTARGET(_exit)
/* We won't ever get here but provide a nop so that the linker
will insert a toc adjusting stub if necessary. */
nop
#endif
L(badargs):
cfi_startproc
li r3,EINVAL
TAIL_CALL_SYSCALL_ERROR
L(parent):
/* Parent. Restore registers & return. */
#ifdef RESET_PID
cfi_offset(r29,-24)
#endif
cfi_offset(r30,-16)
cfi_offset(r31,-8)
#ifdef RESET_PID
ld r29,-24(r1)
#endif
ld r30,-16(r1)
ld r31,-8(r1)
#ifdef RESET_PID
cfi_restore(r29)
#endif
cfi_restore(r30)
cfi_restore(r31)
PSEUDO_RET
END (__clone)
weak_alias (__clone, clone)