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Re: [PATCH] Call exit directly in clone (BZ #21512)
> On 23 Jun 2017, at 09:55, Carlos O'Donell <carlos@redhat.com> wrote:
>
>> 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?
For thread creation within GLIBC the clone is called using the ARCH_FORK macro which issues a direct syscall. Sometime ago I tried to see if it were worth a cleanup to use clone symbol instead, but I got stuck with an issue I don't quite remind the details.
>
> 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?" :-)
Basically because we never used the clone symbol internally and when we did (new posix_spawn implementation) we call an explicit _exit (spawni). I also think no one really tried to use clone along with CLONE_THREAD.
>
>> [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.