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Re: [PATCH] Call exit directly in clone (BZ #21512)
- From: Carlos O'Donell <carlos at redhat dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, libc-alpha at sourceware dot org
- Date: Fri, 23 Jun 2017 08:55:03 -0400
- Subject: Re: [PATCH] Call exit directly in clone (BZ #21512)
- Authentication-results: sourceware.org; auth=none
- References: <1498221450-8381-1-git-send-email-adhemerval.zanella@linaro.org>
On 06/23/2017 08:37 AM, Adhemerval Zanella wrote:
> On aarch64, alpha, arm, hppa, mips, nios2, powerpc, s390, sh,
> sparch, tile, and x86_64 the clone syscall jumps to _exit after
> the child execution and the function ends the process execution by
> calling exit_group. This behavior have a small issue where
> threads created with CLONE_THREAD using clone syscall directly
> will eventually exit the whole group altogether instead of just
> the thread created. Also, microblaze, ia64, i386, and m68k
> differs by calling exit syscall directly.
>
> This patch changes all architectures to call the exit syscall
> directly, as for microblaze, ia64, i386, and m68k. This do not
> have change glibc internal behavior in any sort, since the only
> usage of clone implementation in posix_spawn calls _exit directly
> in the created child (fork uses a direct call to clone).
>
> Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
> powerpc-linux-gnu, powerpc64le-linux-gnu, sparc64-linux-gnu,
> and sparcv9-linux-gnu.
How is it that this doesn't break threading completely on the existing
architectures that call _exit? Is it because NPTL calls the clone syscall
directly instead of calling the clone() function and nobody uses clone()
because of all the other problems it has?
I admit that only an explicit call to _exit() or exit() should terminate
every thread in the thread group, *and* looking at the kernel side code
I see it does try to terminate every thread in the group (zap_other_threads()).
The patch looks good to me, but I just want some clarification about my
question "Why haven't we noticed?" :-)
> [BZ #21512]
> * sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Call exit
> syscall instead of jump to _exit.
> (CLONE_VM_BIT): Remove unused define.
> (CLONE_VM): Likewise.
> (CLONE_THREAD_BIT): Likewise.
> (CLONE_THREAD): Likewise.
> * sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> * sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> (CLONE_THREAD): Likewise.
> * sysdeps/unix/sysv/linux/i386/clone.S (CLONE_VM): Likewise.
> * sysdeps/unix/sysv/linux/ia64/clone2.S (__clone2): Call exit
> syscall instead of jump to _exit.
> * sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise.
> * sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> (CLONE_THREAD): Likewise.
> * sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> * sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone):
> Likewise.
> (CLONE_VM): Remove unused define.
> (CLONE_THREAD): Likewise.
> * sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone):
> Likewise.
> (CLONE_VM): Remove unused define.
> (CLONE_THREAD): 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.
> (CLONE_VM): Remove unused define.
> * sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> * sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise.
> * sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise.
> (CLONE_VM): Remove unused define.
> * sysdeps/unix/sysv/linux/Makefile (tests): Add tst-clone3.
> * sysdeps/unix/sysv/linux/tst-clone3.c: New file.
> ---
> sysdeps/unix/sysv/linux/Makefile | 4 +-
> sysdeps/unix/sysv/linux/aarch64/clone.S | 9 +--
> sysdeps/unix/sysv/linux/alpha/clone.S | 11 +--
> sysdeps/unix/sysv/linux/arm/clone.S | 6 +-
> sysdeps/unix/sysv/linux/hppa/clone.S | 6 +-
> sysdeps/unix/sysv/linux/i386/clone.S | 2 -
> sysdeps/unix/sysv/linux/ia64/clone2.S | 8 +-
> sysdeps/unix/sysv/linux/m68k/clone.S | 2 -
> sysdeps/unix/sysv/linux/mips/clone.S | 12 +--
> sysdeps/unix/sysv/linux/nios2/clone.S | 17 +---
> sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S | 7 +-
> sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S | 11 +--
> sysdeps/unix/sysv/linux/s390/s390-32/clone.S | 2 +-
> sysdeps/unix/sysv/linux/s390/s390-64/clone.S | 2 +-
> sysdeps/unix/sysv/linux/sh/clone.S | 21 +----
> sysdeps/unix/sysv/linux/sparc/sparc32/clone.S | 5 +-
> sysdeps/unix/sysv/linux/sparc/sparc64/clone.S | 5 +-
> sysdeps/unix/sysv/linux/tile/clone.S | 6 +-
> sysdeps/unix/sysv/linux/tst-clone3.c | 95 +++++++++++++++++++++++
> sysdeps/unix/sysv/linux/x86_64/clone.S | 5 +-
> 20 files changed, 130 insertions(+), 106 deletions(-)
> create mode 100644 sysdeps/unix/sysv/linux/tst-clone3.c
>
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 8b340d4..9d6a2de 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -49,8 +49,8 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
> bits/mman-linux.h \
> bits/siginfo-arch.h bits/siginfo-consts-arch.h
>
> -tests += tst-clone tst-clone2 tst-fanotify tst-personality tst-quota \
> - tst-sync_file_range test-errno-linux
> +tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
> + tst-quota tst-sync_file_range test-errno-linux
>
> # Generate the list of SYS_* macros for the system calls (__NR_* macros).
>
> diff --git a/sysdeps/unix/sysv/linux/aarch64/clone.S b/sysdeps/unix/sysv/linux/aarch64/clone.S
> index 259ec07..905915a 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/clone.S
> +++ b/sysdeps/unix/sysv/linux/aarch64/clone.S
> @@ -23,12 +23,6 @@
> #define _ERRNO_H 1
> #include <bits/errno.h>
>
> -#define CLONE_VM_BIT 8
> -#define CLONE_VM (1 << CLONE_VM_BIT)
> -
> -#define CLONE_THREAD_BIT 16
> -#define CLONE_THREAD (1 << CLONE_THREAD_BIT)
> -
> /* int clone(int (*fn)(void *arg), x0
> void *child_stack, x1
> int flags, x2
> @@ -84,7 +78,8 @@ thread_start:
> blr x10
>
> /* We are done, pass the return value through x0. */
> - b HIDDEN_JUMPTARGET(_exit)
> + mov x8, #SYS_ify(exit)
> + svc 0x0
> cfi_endproc
> .size thread_start, .-thread_start
>
> diff --git a/sysdeps/unix/sysv/linux/alpha/clone.S b/sysdeps/unix/sysv/linux/alpha/clone.S
> index 20ae361..550461f 100644
> --- a/sysdeps/unix/sysv/linux/alpha/clone.S
> +++ b/sysdeps/unix/sysv/linux/alpha/clone.S
> @@ -23,8 +23,6 @@
> #define _ERRNO_H 1
> #include <bits/errno.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags,
> void *arg, pid_t *ptid, void *tls, pid_t *ctid);
>
> @@ -100,13 +98,8 @@ thread_start:
> jsr ra, (pv)
> ldgp gp, 0(ra)
>
> - /* Call _exit rather than doing it inline for breakpoint purposes. */
> - mov v0, a0
> -#ifdef PIC
> - bsr ra, HIDDEN_JUMPTARGET(_exit) !samegp
> -#else
> - jsr ra, HIDDEN_JUMPTARGET(_exit)
> -#endif
> + ldiq v0, __NR_exit
> + call_pal PAL_callsys
>
> /* Die horribly. */
> .align 4
> diff --git a/sysdeps/unix/sysv/linux/arm/clone.S b/sysdeps/unix/sysv/linux/arm/clone.S
> index a309add..f01968a 100644
> --- a/sysdeps/unix/sysv/linux/arm/clone.S
> +++ b/sysdeps/unix/sysv/linux/arm/clone.S
> @@ -24,9 +24,6 @@
> #define _ERRNO_H 1
> #include <bits/errno.h>
>
> -#define CLONE_VM 0x00000100
> -#define CLONE_THREAD 0x00010000
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> pid_t *ptid, struct user_desc *tls, pid_t *ctid); */
>
> @@ -76,7 +73,8 @@ PSEUDO_END (__clone)
> BLX (ip)
>
> @ and we are done, passing the return value through r0
> - b PLTJMP(HIDDEN_JUMPTARGET(_exit))
> + ldr r7, =SYS_ify(clone)
> + swi 0x0
>
> .fnend
>
> diff --git a/sysdeps/unix/sysv/linux/hppa/clone.S b/sysdeps/unix/sysv/linux/hppa/clone.S
> index d36b302..8c43944 100644
> --- a/sysdeps/unix/sysv/linux/hppa/clone.S
> +++ b/sysdeps/unix/sysv/linux/hppa/clone.S
> @@ -148,10 +148,10 @@ ENTRY(__clone)
> copy %r4, %r19
> #endif
> /* The call to _exit needs saved r19. */
> - bl _exit, %rp
> - copy %ret0, %arg0
> + ble 0x100(%sr2, %r0)
> + ldi __NR_exit, %r20
>
> - /* We should not return from _exit.
> + /* We should not return from exit.
> We do not restore r4, or the stack state. */
> iitlbp %r0, (%sr0, %r0)
>
> diff --git a/sysdeps/unix/sysv/linux/i386/clone.S b/sysdeps/unix/sysv/linux/i386/clone.S
> index a4ba3e2..49c82d9 100644
> --- a/sysdeps/unix/sysv/linux/i386/clone.S
> +++ b/sysdeps/unix/sysv/linux/i386/clone.S
> @@ -39,8 +39,6 @@
> #define __NR_clone 120
> #define SYS_clone 120
>
> -#define CLONE_VM 0x00000100
> -
> .text
> ENTRY (__clone)
> /* Sanity check arguments. */
> diff --git a/sysdeps/unix/sysv/linux/ia64/clone2.S b/sysdeps/unix/sysv/linux/ia64/clone2.S
> index 9b59473..3157ce9 100644
> --- a/sysdeps/unix/sysv/linux/ia64/clone2.S
> +++ b/sysdeps/unix/sysv/linux/ia64/clone2.S
> @@ -74,11 +74,11 @@ ENTRY(__clone2)
> mov b6=out1
> br.call.dptk.many rp=b6 /* Call fn(arg) in the child */
> ;;
> - mov out0=r8 /* Argument to _exit */
> + mov out0=r8 /* Argument to exit */
> mov gp=loc0
> - .globl HIDDEN_JUMPTARGET(_exit)
> - br.call.dpnt.many rp=HIDDEN_JUMPTARGET(_exit)
> - /* call _exit with result from fn. */
> + mov r15=SYS_ify (exit)
> + .save rp, r0
> + break __BREAK_SYSCALL
> ret /* Not reached. */
> PSEUDO_END(__clone2)
>
> diff --git a/sysdeps/unix/sysv/linux/m68k/clone.S b/sysdeps/unix/sysv/linux/m68k/clone.S
> index a680191..0894b2a 100644
> --- a/sysdeps/unix/sysv/linux/m68k/clone.S
> +++ b/sysdeps/unix/sysv/linux/m68k/clone.S
> @@ -24,8 +24,6 @@
> #include <bits/errno.h>
> #include <tls.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> void *parent_tidptr, void *tls, void *child_tidptr) */
>
> diff --git a/sysdeps/unix/sysv/linux/mips/clone.S b/sysdeps/unix/sysv/linux/mips/clone.S
> index 8b79457..855f972 100644
> --- a/sysdeps/unix/sysv/linux/mips/clone.S
> +++ b/sysdeps/unix/sysv/linux/mips/clone.S
> @@ -25,9 +25,6 @@
> #include <bits/errno.h>
> #include <tls.h>
>
> -#define CLONE_VM 0x00000100
> -#define CLONE_THREAD 0x00010000
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> void *parent_tidptr, void *tls, void *child_tidptr) */
>
> @@ -137,14 +134,9 @@ L(thread_start):
> /* Call the user's function. */
> jal t9
>
> - /* Call _exit rather than doing it inline for breakpoint purposes. */
> move a0,v0
> -#ifdef __PIC__
> - PTR_LA t9,_exit
> - jalr t9
> -#else
> - jal _exit
> -#endif
> + li v0,__NR_clone
> + syscall
>
> END(__thread_start)
>
> diff --git a/sysdeps/unix/sysv/linux/nios2/clone.S b/sysdeps/unix/sysv/linux/nios2/clone.S
> index 7929dfa..2ba8258 100644
> --- a/sysdeps/unix/sysv/linux/nios2/clone.S
> +++ b/sysdeps/unix/sysv/linux/nios2/clone.S
> @@ -25,8 +25,6 @@
> #include <bits/errno.h>
> #include <tcb-offsets.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> void *parent_tidptr, void *tls, void *child_tidptr) */
>
> @@ -75,18 +73,9 @@ thread_start:
> /* Call the user's function. */
> callr r5
>
> - /* _exit with the result. */
> - mov r4, r2
> -#ifdef PIC
> - nextpc r22
> -1: movhi r8, %hiadj(_gp_got - 1b)
> - addi r8, r8, %lo(_gp_got - 1b)
> - add r22, r22, r8
> - ldw r8, %call(HIDDEN_JUMPTARGET(_exit))(r22)
> - jmp r8
> -#else
> - jmpi _exit
> -#endif
> + /* exit with the result. */
> + movi r2, SYS_ify (exit)
> + trap
> cfi_endproc
>
> cfi_startproc
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
> index a07b7d3..e48cc5f 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
> @@ -20,10 +20,6 @@
> #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. */
> @@ -80,8 +76,7 @@ ENTRY (__clone)
> mtctr r30
> mr r3,r31
> bctrl
> - /* Call _exit with result from procedure. */
> - b HIDDEN_JUMPTARGET(_exit)
> + DO_CALL(SYS_ify(exit))
>
> L(parent):
> /* Parent. Restore registers & return. */
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
> index 9e5bfd2..78c353a 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
> @@ -20,9 +20,6 @@
> #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. */
> @@ -84,15 +81,11 @@ ENTRY (__clone)
> mr r3,r31
> bctrl
> ld r2,FRAME_TOC_SAVE(r1)
> - /* Call _exit with result from procedure. */
> -#ifdef SHARED
> - b JUMPTARGET(__GI__exit)
> -#else
> - bl JUMPTARGET(_exit)
> +
> + DO_CALL(SYS_ify(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
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
> index a8b4dbc..1588e5f 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
> +++ b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
> @@ -59,7 +59,7 @@ thread_start:
> ahi %r15,-96 /* make room on the stack for the save area */
> xc 0(4,%r15),0(%r15)
> basr %r14,%r1 /* jump to fn */
> - DO_CALL (exit, 1)
> + svc SYS_ify(exit)
>
> libc_hidden_def (__clone)
> weak_alias (__clone, clone)
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
> index daf8a58..5843188 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
> +++ b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
> @@ -60,7 +60,7 @@ thread_start:
> aghi %r15,-160 /* make room on the stack for the save area */
> xc 0(8,%r15),0(%r15)
> basr %r14,%r1 /* jump to fn */
> - DO_CALL (exit, 1)
> + svc SYS_ify(exit)
>
> libc_hidden_def (__clone)
> weak_alias (__clone, clone)
> diff --git a/sysdeps/unix/sysv/linux/sh/clone.S b/sysdeps/unix/sysv/linux/sh/clone.S
> index 9063b21..b13a64b 100644
> --- a/sysdeps/unix/sysv/linux/sh/clone.S
> +++ b/sysdeps/unix/sysv/linux/sh/clone.S
> @@ -73,25 +73,8 @@ ENTRY(__clone)
> mov.l @(4,r15), r4
>
> /* we are done, passing the return value through r0 */
> - mov.l .L3, r1
> -#ifdef SHARED
> - mov.l r12, @-r15
> - sts.l pr, @-r15
> - mov r0, r4
> - mova .LG, r0
> - mov.l .LG, r12
> - add r0, r12
> - mova .L3, r0
> - add r0, r1
> - jsr @r1
> - nop
> - lds.l @r15+, pr
> - rts
> - mov.l @r15+, r12
> -#else
> - jmp @r1
> - mov r0, r4
> -#endif
> + mov #+SYS_ify(exit), r3
> + trapa #0x15
> .align 2
> .LG:
> .long _GLOBAL_OFFSET_TABLE_
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
> index 6d2f5bd..1afa26e 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
> @@ -24,8 +24,6 @@
> #include <tcb-offsets.h>
> #include <sysdep.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> pid_t *ptid, void *tls, pid_t *ctid); */
>
> @@ -81,7 +79,8 @@ __thread_start:
> mov %g0, %fp /* terminate backtrace */
> call %g2
> mov %g3,%o0
> - call HIDDEN_JUMPTARGET(_exit),0
> + set __NR_exit, %g1
> + ta 0x10
> nop
>
> .size __thread_start, .-__thread_start
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
> index fc28539..785ccd1 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
> @@ -24,8 +24,6 @@
> #include <tcb-offsets.h>
> #include <sysdep.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
> pid_t *ptid, void *tls, pid_t *ctid); */
>
> @@ -78,7 +76,8 @@ __thread_start:
> mov %g0, %fp /* terminate backtrace */
> call %g2
> mov %g3,%o0
> - call HIDDEN_JUMPTARGET(_exit),0
> + set __NR_exit, %g1
> + ta 0x6d
> nop
>
> .size __thread_start, .-__thread_start
> diff --git a/sysdeps/unix/sysv/linux/tile/clone.S b/sysdeps/unix/sysv/linux/tile/clone.S
> index d7d2a3b..9610acd 100644
> --- a/sysdeps/unix/sysv/linux/tile/clone.S
> +++ b/sysdeps/unix/sysv/linux/tile/clone.S
> @@ -168,10 +168,8 @@ ENTRY (__clone)
> move r0, r31
> jalr r32
> }
> - {
> - j HIDDEN_JUMPTARGET(_exit)
> - info INFO_OP_CANNOT_BACKTRACE /* Notify backtracer to stop. */
> - }
> + moveli TREG_SYSCALL_NR_NAME, __NR_exit
> + swint1
> PSEUDO_END (__clone)
>
> libc_hidden_def (__clone)
> diff --git a/sysdeps/unix/sysv/linux/tst-clone3.c b/sysdeps/unix/sysv/linux/tst-clone3.c
> new file mode 100644
> index 0000000..e893e4d
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-clone3.c
> @@ -0,0 +1,95 @@
> +/* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512)
> + Copyright (C) 2017 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 <string.h>
> +#include <sched.h>
> +#include <signal.h>
> +#include <unistd.h>
> +#include <sys/syscall.h>
> +#include <sys/wait.h>
> +#include <sys/types.h>
> +#include <linux/futex.h>
> +
> +#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
> +#include <support/check.h>
> +
> +/* Test if clone call with CLONE_THREAD does not call exit_group. The 'f'
> + function returns '1', which will be used by clone thread to call the
> + 'exit' syscall directly. If _exit is used instead, exit_group will be
> + used and thus the thread group will finish with return value of '1'
> + (where '2' from main thread is expected. */
s/(where/where/g
> +
> +static int
> +f (void *a)
> +{
> + return 1;
> +}
> +
> +/* Futex wait for TID argument, similar to pthread_join internal
> + implementation. */
> +#define wait_tid(tid) \
> + do { \
> + __typeof (tid) __tid; \
> + while ((__tid = (tid)) != 0) \
> + futex_wait (&(tid), __tid); \
> + } while (0)
> +
> +static inline int
> +futex_wait (int *futexp, int val)
> +{
> + return syscall (__NR_futex, futexp, FUTEX_WAIT, val);
> +}
> +
> +static int
> +do_test (void)
> +{
> + char st[1024] __attribute__ ((aligned));
> + int clone_flags = CLONE_THREAD;
> + /* Minimum required flags to used along with CLONE_THREAD. */
> + clone_flags |= CLONE_VM | CLONE_SIGHAND;
> + /* We will used ctid to call on futex to wait for thread exit. */
> + clone_flags |= CLONE_CHILD_CLEARTID;
> + pid_t ctid, tid;
> +
> +#ifdef __ia64__
> + extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
> + size_t __child_stack_size, int __flags,
> + void *__arg, ...);
> + tid = __clone2 (f, st, sizeof (st), clone_flags, NULL, /* ptid */ NULL,
> + /* tls */ NULL, &ctid);
> +#else
> +#if _STACK_GROWS_DOWN
> + tid = clone (f, st + sizeof (st), clone_flags, NULL, /* ptid */ NULL,
> + /* tls */ NULL, &ctid);
> +#elif _STACK_GROWS_UP
> + tid = clone (f, st, clone_flags, NULL, /* ptid */ NULL, /* tls */ NULL,
> + &ctid);
> +#else
> +#error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
> +#endif
> +#endif
> + if (tid == -1)
> + FAIL_EXIT1 ("clone failed: %m");
> +
> + wait_tid (ctid);
> +
> + return 2;
> +}
> +
> +#define EXPECTED_STATUS 2
> +#include <support/test-driver.c>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/clone.S b/sysdeps/unix/sysv/linux/x86_64/clone.S
> index d5c2d07..b10fc29 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/clone.S
> +++ b/sysdeps/unix/sysv/linux/x86_64/clone.S
> @@ -23,8 +23,6 @@
> #include <bits/errno.h>
> #include <asm-syntax.h>
>
> -#define CLONE_VM 0x00000100
> -
> /* The userland implementation is:
> int clone (int (*fn)(void *arg), void *child_stack, int flags, void *arg),
> the kernel entry is:
> @@ -97,7 +95,8 @@ L(thread_start):
> call *%rax
> /* Call exit with return value from function call. */
> movq %rax, %rdi
> - call HIDDEN_JUMPTARGET (_exit)
> + movl $SYS_ify(exit), %eax
> + syscall
> cfi_endproc;
>
> cfi_startproc;
>
--
Cheers,
Carlos.