This patch implements a new posix_spawn{p} implementation for Linux. The main
difference is it uses the clone syscall directly with CLONE_VM and CLONE_VFORK
flags and a direct allocated stack. The new stack and start function solves
most the vfork limitation (possible parent clobber due stack spilling). The
remaning issue are related to signal handling:
1. That no signal handlers must run in child context, to avoid corrupt
parent's state.
2. Child must synchronize with parent to enforce stack deallocation and
to possible return execv issues.
The first one is solved by blocking all signals in child, even NPTL-internal
ones (SIGCANCEL and SIGSETXID). The second issue is done by a stack allocation
in parent and a synchronization with using a pipe or waitpid (in case or error).
The pipe has the advantage of allowing the child signal an exec error (checked
with new tst-spawn2 test).
There is an inherent race condition in pipe2 usage for architectures that do not
support the syscall directly. In such cases the a pipe plus fctnl is used
instead and it may lead to file descriptor leak in parent (as decribed by fcntl
documentation).
The child process stack is allocate with a mmap with MAP_STACK flag using
default architecture stack size. Although it is slower than use a stack buffer
from parent, it allows some slack for the compatibility code to run scripts
with no shebang (which may use a buffer with size depending of argument list
count).
Performance should be similar to the vfork default posix implementation and
way faster than fork path (vfork on mostly linux ports are basically
clone with CLONE_VM plus CLONE_VFORK). The only difference is the syscalls
required for the stack allocation/deallocation.
It fixes BZ#10354, BZ#14750, and BZ#18433.
Tested on i386, x86_64, powerpc64le, and aarch64.
[BZ #14750]
[BZ #10354]
[BZ #18433]
* include/sched.h (__clone): Add hidden prototype.
(__clone2): Likewise.
* include/unistd.h (__dup): Likewise.
* posix/Makefile (tests): Add tst-spawn2.
* posix/tst-spawn2.c: New file.
* sysdeps/posix/dup.c (__dup): Add hidden definition.
* sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/m68k/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/microblaze/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone):
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/nptl-signals.h
(____nptl_is_internal_signal): New function.
* sysdeps/unix/sysv/linux/spawni.c: New file.
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.htmlhttp://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.
This is the first patch to support the new ELFv2 ABI in glibc.
As preparation, this patch simply refactors some of the powerpc64 assembler
code to move all code related to creating function descriptors (.opd section)
or using function descriptors (function pointer call) into a central place
in sysdep.h.
Note that most locations creating .opd entries were already using macros
in sysdep.h, this patch simply extends this to the remaining places.
No relevant change in generated code expected.
of non-volatile floating-point registers to the stack (fp14-fp31).
* sysdeps/powerpc/powerpc32/gprsave0.S: Add cfi_offset for spilling of
non-volatile general-purpose registers to the stack (gpr13-gpr31).
* sysdeps/powerpc/powerpc64/dl-trampoline.S: Add cfi_offset
for non-volatiles gpr30 - grp31 spilled to the stack.
* sysdeps/powerpc/powerpc64/memcpy.S: Add cfi_offset for non-volatile
gpr31 spill to the stack.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S:
Add cfi_offset for non-volatile gpr31 spill to the stack.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Add cfi_offset
for non-volatiles gpr28 - grp31 spilled to the stack.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/getcontext.S: Add
cfi_adjust_cfa_offset when a frame is stacked.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S:
(__novec_setcontext) : Add cfi_offset for non-volatile gpr31 spill
add LR saved to the stack. Add cfi_adjust_cfa_offset when frame is
stacked.
(__setcontext) : Add cfi_offset for non-volatile gpr31 spill to
the stack.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S:
(__novec_swapcontext) : Add cfi_offset for non-volatile gpr31 spill
add LR saved to the stack.
(__swapcontext) : Add cfi_offset for non-volatile gpr31 spill add LR
saved to the stack. Add cfi_adjust_cfa_offset when frame is stacked.
2004-12-15 Jakub Jelinek <jakub@redhat.com>
* nis/nis_domain_of_r.c (nis_domain_of_r): Use libnsl_hidden_def,
not libnsl_hidden_proto.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S (__clone): Add support
for NPTL where the PID is stored at userlevel and needs to be reset
when CLONE_THREAD is not used.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone): Save
and restore r2 around call to fn.
Ported to PowerPC64 running Linux.
* sysdeps/powerpc/powerpc64/Dist: New file.
* sysdeps/powerpc/powerpc64/Implies: New file.
* sysdeps/powerpc/powerpc64/Makefile: New file.
* sysdeps/powerpc/powerpc64/__longjmp.S: New file.
* sysdeps/powerpc/powerpc64/atomicity.h: New file.
* sysdeps/powerpc/powerpc64/backtrace.c: New file.
* sysdeps/powerpc/powerpc64/bp-asm.h: New file.
* sysdeps/powerpc/powerpc64/bsd-_setjmp.S: New file.
* sysdeps/powerpc/powerpc64/bsd-setjmp.S: New file.
* sysdeps/powerpc/powerpc64/dl-dtprocnum.h: New file.
* sysdeps/powerpc/powerpc64/dl-lookupcfg.h: New file.
* sysdeps/powerpc/powerpc64/dl-machine.c: New file.
* sysdeps/powerpc/powerpc64/dl-machine.h: New file.
* sysdeps/powerpc/powerpc64/memset.S: New file.
* sysdeps/powerpc/powerpc64/ppc-mcount.S: New file.
* sysdeps/powerpc/powerpc64/register-dump.h: New file.
* sysdeps/powerpc/powerpc64/setjmp.S: New file.
* sysdeps/powerpc/powerpc64/stpcpy.S: New file.
* sysdeps/powerpc/powerpc64/strchr.S: New file.
* sysdeps/powerpc/powerpc64/strcmp.S: New file.
* sysdeps/powerpc/powerpc64/strcpy.S: New file.
* sysdeps/powerpc/powerpc64/strlen.S: New file.
* sysdeps/powerpc/powerpc64/elf/bzero.S: New file.
* sysdeps/powerpc/powerpc64/elf/start.S: New file.
* sysdeps/powerpc/powerpc64/fpu/s_copysign.S: New file.
* sysdeps/powerpc/powerpc64/fpu/s_copysignf.S: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions: New File.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/brk.S: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/glob64.c: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/socket.S: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/syscalls.list: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h: New file.
