[Qemu-devel] [Bug 1673976] [NEW] core dump

[Qemu-devel] [Bug 1673976] [NEW] core dump

[l3iggs]

Public bug reported:

I'm running a command (locale-gen) inside of an armv7h chroot mounted on
my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
chroot file system and I get a core dump.

locale-gen
Generating locales...
  en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped
/usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

I've done this same thing successfully for years, but this breakage has
appeared some time in the last 3 or so months. Possibly with the update
to qemu version 2.8.

** Affects: qemu
     Importance: Undecided
         Status: New

** Description changed:

- I'm running a command command (locale-gen) inside of an armv7h chroot
- mounted on my x86_64 desktop by putting qemu-arm-static into /usr/bin/
- of the chroot file system and I get a core dump.
+ I'm running a command (locale-gen) inside of an armv7h chroot mounted on
+ my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
+ chroot file system and I get a core dump.
  
  locale-gen
  Generating locales...
-   en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
+   en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale
  
  I've done this same thing successfully for years, but this breakage has
  appeared some time in the last 3 or so months. Possibly with the update
  to qemu version 2.8.

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Title:
  core dump

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1673976] Re: core dump

[Matheus Izvekov]

I can confirm this. The ninja build system is also affected.

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Title:
  core dump

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Thomas Huth]

Could you please check whether the problem also occurs with QEMU v2.10?

** Changed in: qemu
       Status: New => Incomplete

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Title:
  core dump

Status in QEMU:
  Incomplete

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Alchemist]

Hi,

I can confirm it with QEMU 2.10.0 (running Gentoo Linux)

Portage 2.3.10 (python 2.7.14-final-0, default/linux/amd64/17.0/no-
multilib, gcc-7.2.0, glibc-2.25-r5, 4.13.4-gentoo x86_64)

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Title:
  core dump

Status in QEMU:
  Incomplete

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Alchemist]

# uname -a && locale-gen 
Linux **** 4.13.4-gentoo #1 SMP PREEMPT Thu Sep 28 09:41:30 CEST 2017 armv7l Intel(R) Celeron(R) 2957U @ 1.40GHz GNU/Linux
 * Generating 8 locales (this might take a while) with 2 jobs
 *  (2/8) Generating en_US.UTF-8 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (1/8) Generating en_US.ISO-8859-1 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (3/8) Generating fr_BE.ISO-8859-15@euro ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (4/8) Generating fr_BE.ISO-8859-1 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (5/8) Generating fr_BE.UTF-8 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (6/8) Generating fr_FR.ISO-8859-15@euro ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (7/8) Generating fr_FR.ISO-8859-1 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 *  (8/8) Generating fr_FR.UTF-8 ...
localedef: ../sysdeps/unix/sysv/linux/spawni.c:366: __spawnix: Assertion `ec >= 0' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped                                                                                                                                                                                  [ !! ]
 * Generation complete
 * Adding locales to archive ...
incomplete set of locale files in "//usr/lib/locale/en_US"
incomplete set of locale files in "//usr/lib/locale/en_US.utf8"
incomplete set of locale files in "//usr/lib/locale/fr_BE"
incomplete set of locale files in "//usr/lib/locale/fr_BE@euro"
incomplete set of locale files in "//usr/lib/locale/fr_BE.utf8"
incomplete set of locale files in "//usr/lib/locale/fr_FR"
incomplete set of locale files in "//usr/lib/locale/fr_FR@euro"
incomplete set of locale files in "//usr/lib/locale/fr_FR.utf8"                                                                                                                                                                         [ !! ]

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Title:
  core dump

Status in QEMU:
  Incomplete

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Thomas Huth]

** Changed in: qemu
       Status: Incomplete => New

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Title:
  core dump

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Dominique Belhachemi]

Looks like the __clone() call is failing for some reason:

https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/spawni.c;h=dea1650d08ded5fd848f263aebebe8748e703697;hb=HEAD#l362


Here is a workaround:

cd /usr/share/i18n/charmaps
gunzip --keep UTF-8.gz
locale-gen en_US.UTF-8

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Title:
  core dump

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: core dump

[Dominique Belhachemi]

It is possible to reproduce the issue with a simple clone example taken
from

   http://man7.org/linux/man-pages/man2/clone.2.html


# qemu-aarch64-static -strace  ./a.out testname
585 brk(NULL) = 0x0000004000013000
585 uname(0x4000812d08) = 0
585 faccessat(AT_FDCWD,"/etc/ld.so.nohwcap",F_OK,0x82e888) = -1 errno=2 (No such file or directory)
585 mmap(NULL,12288,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0) = 0x0000004000843000
585 faccessat(AT_FDCWD,"/etc/ld.so.preload",R_OK,AT_SYMLINK_NOFOLLOW|0x82d848) = -1 errno=2 (No such file or directory)
585 openat(AT_FDCWD,"/etc/ld.so.cache",O_RDONLY|O_CLOEXEC) = 3
585 fstat(3,0x0000004000812680) = 0
585 mmap(NULL,20645,PROT_READ,MAP_PRIVATE,3,0) = 0x0000004000846000
585 close(3) = 0
585 faccessat(AT_FDCWD,"/etc/ld.so.nohwcap",F_OK,0x82e888) = -1 errno=2 (No such file or directory)
585 openat(AT_FDCWD,"/lib/aarch64-linux-gnu/libc.so.6",O_RDONLY|O_CLOEXEC) = 3
585 read(3,0x812830,832) = 832
585 fstat(3,0x00000040008126d0) = 0
585 mmap(NULL,1393456,PROT_EXEC|PROT_READ,MAP_PRIVATE|MAP_DENYWRITE,3,0) = 0x000000400084c000
585 mprotect(0x0000004000987000,65536,PROT_NONE) = 0
585 mmap(0x0000004000997000,24576,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_DENYWRITE|MAP_FIXED,3,0x13b000) = 0x0000004000997000
585 mmap(0x000000400099d000,13104,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,-1,0) = 0x000000400099d000
585 close(3) = 0
585 mprotect(0x0000004000997000,16384,PROT_READ) = 0
585 mprotect(0x0000004000011000,4096,PROT_READ) = 0
585 mprotect(0x0000004000840000,4096,PROT_READ) = 0
585 munmap(0x0000004000846000,20645) = 0
585 brk(NULL) = 0x0000004000013000
585 brk(0x0000004000034000) = 0x0000004000013000
585 mmap(NULL,1048576,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0) = 0x00000040009a1000
585 mmap(NULL,1052672,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0) = 0x0000004000aa1000
585 clone(CLONE_NEWUTS|0x11,child_stack=0x0000004000ba1010,parent_tidptr=0x0000004000aa1010,tls=0x0000000000000000,child_tidptr=0x0000000000000000) = -1 errno=22 (Invalid argument)
585 dup(2,4222427270,274886578000,22,0,0) = 3
585 fcntl(3,F_GETFL) = 1026
585 fstat(3,0x0000004000812628) = 0
585 write(3,0x9a1490,24)clone: Invalid argument
 = 24
585 close(3) = 0
585 exit_group(1)


# strace ./a.out testname
qemu: Unsupported syscall: 117
qemu: Unsupported syscall: 117
/usr/bin/strace: ptrace(PTRACE_TRACEME, ...): Function not implemented
+++ exited with 1 +++

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Title:
  core dump

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: locale-gen dumps core run under arm-linux-user on x86-64 host

[Peter Maydell]

** Summary changed:

- core dump
+ locale-gen dumps core run under arm-linux-user on x86-64 host

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Title:
  locale-gen dumps core run under arm-linux-user on x86-64 host

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: locale-gen dumps core run under arm-linux-user on x86-64 host

[Peter Maydell]

** Tags added: linux-user

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Title:
  locale-gen dumps core run under arm-linux-user on x86-64 host

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: locale-gen dumps core run under arm-linux-user on x86-64 host

[Peter Maydell]

This happens because QEMU is now stricter about its checking of the
flags passed to clone() -- previously we would silently allow flags we
couldn't support and create new threads with the wrong behaviour. Now we
check and fail the clone() syscall if the requested behaviour is
something we can't implement. Unfortunately we don't have any way to
distinguish "guest program is asking for something odd that it doesn't
really need" from "guest program is asking for something odd that it
does need". So we err on the safe side and tell the guest we can't do
it.

It's particularly unfortunate that the glibc implementation of
posix_spawn() runs into this, though.


** Summary changed:

- locale-gen dumps core run under arm-linux-user on x86-64 host
+ linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[l3iggs]

Is there a way I can ask QEMU to not do this strict checking so that my
stuff stops breaking?

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

Not without messing with the QEMU source, no.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

OK, this can't be as simple as "posix_spawn() fails", because I've just
tried the test program from the posix_spawn manpage
(http://man7.org/linux/man-pages/man3/posix_spawn.3.html) and that works
fine for x86-64 guest, aarch64 guest and armhf guest. In the x86 and
armhf cases the libc I have seems to use the NR_vfork syscall, but for
aarch64 it uses clone(CLONE_VM | CLONE_VFORK | SIGCHLD, ...) which is
what the glibc sources linked in comment #5 do, and that all works fine.

And locale-gen runs fine for my xenial-armhf chroot using current head-
of-git QEMU:

root@e104462:/# locale-gen   
Generating locales (this might take a while)...
  en_GB.UTF-8... done
Generation complete.

So can I ask that people: (1) please try with current head of git (or
with 2.11-rc1, which is almost the same thing); (2) if there's still a
problem with localegen or with programs calling posix_spawn() or other
real-world code, please provide full repro instructions so I can try to
reproduce locally.

I don't think we can make clone() in general work, so oddball demo code
like the example program in the clone(2) manpage is out of scope, but
there may well be specific cases we can address.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[James Cowgill]

I can reproduce the bug in a mips64el chroot running current Debian
unstable - the posix_spawn example you mention fails there. I have
tested v2.11.0-rc2 and it fails there as well. I think you need glibc >=
2.25 to trigger the bug (artful / bionic chroot). I only noticed it due
to Debian updating to a newer glibc recently.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[James Cowgill]

I think I see the problem. This glibc commit rewrote the posix_spawn implementation on Linux:
https://sourceware.org/git/?p=glibc.git;a=commit;h=9ff72da471a509a8c19791efe469f47fa6977410

It now relies on the exact behavior of clone(CLONE_VM | CLONE_VFORK) - ie:
- That the parent will wait for the child to exec before continuing.
- Writes to memory in the child are later visible in the parent

QEMU emulates this clone using fork() which no longer works properly and
causes the assertion failure.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[James Cowgill]

Sorry, this is probably the commit that broke things (not the one above). I was added in glibc 2.25:
https://sourceware.org/git/?p=glibc.git;a=commit;h=4b4d4056bb154603f36c6f8845757c1012758158

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

Thanks for tracking down the glibc change; I will try to set up a chroot
with a more recent glibc to see whether we can do something that fixes
that posix_spawn implementation...

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[John Paul Adrian Glaubitz]

Interestingly, this also affects Microsoft Windows Services For Linux,
i.e. Microsoft's Linux emulation layer.

> https://github.com/Microsoft/WSL/issues/1878

** Bug watch added: github.com/Microsoft/WSL/issues #1878
   https://github.com/Microsoft/WSL/issues/1878

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[John Paul Adrian Glaubitz]

I have verified that this patch [1] in glibc_2.25 and glibc_2.26 fixes
the assert.

> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=22273

** Bug watch added: Sourceware.org Bugzilla #22273
   https://sourceware.org/bugzilla/show_bug.cgi?id=22273

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Éric Hoffman]

This should probably be put under 'glibc', since this is really an issue
with that package, which is fixed by the way since Oct 2017.

https://sourceware.org/git/?p=glibc.git;a=commit;h=fe05e1cb6d64dba6172249c79526f1e9af8f2bfd

This should also be backported to 17.10

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

That glibc change has caused the assert to go away, but QEMU's
spawn(CLONE_VFORK) still does not have the "always waits for child"
semantics that glibc has assumed since glibc commit 4b4d4056bb154. The
child and the parent will end up racing each other, and the child will
never be able to write to the parent's address space. I think that the
effect of that race will be that if the child fails (for instance if a
bad filename is passed and exec() fails) the parent will never notice
and will return a success code from the spawn function when it should
not.

So there remains a QEMU bug here; though it is also the case that I
can't see any way we can fix it.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Éric Hoffman]

Ok, thank you for clearing that up.

I'm noticing in 4b4d4056bb154 this comment:

"...we just make explicit use of the fact the the child and parent run
in the same VM, so the child can write an error code to a field of the
posix_spawn_args struct instead of sending it through a pipe.  To ensure
that this mechanism really works, the parent initializes the field to -1
and the child writes 0 before execing."

So, if the child fail to execute, that error code field of the
posix_spawn_args struct will remain -1.  Would this ensure that QEMU
return error in case of failing exec?

Best Regards,
Eric

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

Commit fe05e1cb6d64db changed that, so args.err is initialized to zero.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Éric Hoffman]

Ok, yes you are right...

I have looked a bit more on the source code, and indeed, I think
understand the issue with the VFORK with QEMU.  Please correct me if I'm
wrong...

- In the syscall trap handler, it has to use the fork() function to emulate the vfork() due to restriction of the vfork() function (as QEMU must continue to control the flow of instruction past the call to vfork(), and do a lot more things in the child thread before ending up performing a execve() or _exit())
- Also, it can not do a wait() for the emulated child, as this child will continue to exist even after it calls execve(), so the parent would stall.
- Then, I taught about doing condition signalling, like waiting for a pthread condition signal that the child would send once it come to the point of performing the _exit() or execve(), but the child would, for example, need to know if execve() was successful, or otherwise the child would continue and set an error flag and then call _exit().  We do need that error flag before continuing the execution on the parent.  So we can not signal back to the parent that the 'emulated vfork' is OK before calling execve(), but we can not wait after execve() because if the call is successful, there is no return from that function, and code goes outside the control of QEMU.

So, I taught of an idea...  What if, in the TARGET_NR_clone syscall trap, when we are called upon a CLONE_VFORK, we do:
- Do a regular fork, as it's currently done, with CLONE_VM flag (so the child share the same memory as the parent).  However, we also set a state flag that we are in this 'vfork emulation' mode just before the fork (more on that bellow...).
- Let the parent wait for the child to terminate (again, more on that bellow...).
- Let the child return normally and continue execution, as if the parent was waiting.

Then, eventually the child will eventually either end up in the TARGET_NR_execve or __NR_exit_group syscall trap.  At which point:
- The child check if it is in 'vfork emulation' mode.  If not, then there's nothing special, just continue the way the code is currently written.  If the flag is set, then follow on with the steps bellow...
- The child set a flag that tell where it is (TARGET_NR_execve or __NR_exit_group, and the arguments passed to that syscall), and that everything is ok (it has not simply died meanwhile).
- The child terminate, which resume the parent's execution.

The parent then:
- Clear the 'vfork emulation' flag.
- Look at where the child left (was it performing TARGET_NR_execve or __NR_exit_group syscall?  What was the arguments passed to the syscall?).  This is pretty easy since the child was writing to the parent's memory space the whole time (CLONE_VM).  The parent could even use a flag allocated on it's stack before the fork(), since the child will have run with it's own stack during that time (so the parent stack is still intact).
- Now that we know what the child wanted to do (what syscall and which parameters), the parent (which at his point has no more 'leftover' child), can then do a *real* vfork, or otherwise return the proper error code.

It's a bit far fetched, and I'm far from implying that I know much about
QEMU, but this is an idea :-)  Sound like it's pretty straightforward
though.  Basically we just wait for the code between the _clone()
function and the _execve/_exit function to complete, at which point we
take action and we are in measure to assess the status code (and do the
real vfork).

Regards,
Eric

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

Unfortunately that won't work, because if we do a clone(CLONE_VM) in
QEMU that will mean that parent and child share not just the guest
address space, but also all the QEMU data structures for the emulated
CPUs and also the host libc data structures. Then actions done by the
child will update those data structures and break execution of the
parent when it resumes.

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Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Éric Hoffman]

Ok, I taught that could be an issue, but as I said, I don't really know
all the internals of QEMU.

Another idea would be to fork the child, without CLONE_VM, on the
initial call to the clone syscall, like it's done right now, and then
wait for that child until he call execve or exit syscall.  Maybe using
some shared memory or IPC to pass the relevant status when the child
finally invoke those syscalls.

When the child finally call one of those, then after signalling the
parent about where it is (and the params to the syscall), the child
could exit and the parent actually take action.

Regards,
Eric

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

That way round the child doesn't have the shared memory with the parent,
so it can't update the parent's status variable. There's no easy way to
say "fork, and then share the guest memory mappings and only the guest
memory mappings with the child", because QEMU doesn't currently track
what memory the guest has mapped at all.

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Éric Hoffman]

Hello

Sorry for the delay...

Actually, you only need the parent to get the status from the child,
which can be passed in other way than through common memory.

The idea is to use pipefd to actually wait for the child to either
terminate or successfully call execve.  As follow:


When the TARGET_NR_clone syscall is trapped, you do:
- Call do_fork(), as currently done
- In do_fork(), at the beginning, if CLONE_VFORK flag is set, keep track of it (i.e. do not clear the flag, just clear the CLONE_VM, as currently done, to do a normal fork, i.e. the child have it's own copy of the memory segments).
- Just before the call to fork(), create a pipefd.
- The parent branch and then (if CLONE_VFORK is set) close the write end of the pipe (it's own copy), and start looping (could be indefinitely, but preferably some sort of timeout logic could be set) on the read fd, waiting continuously for status updates from the child.
- The child branch close the read-end of the pipe (it's own forked copy), set the write-end fd flag FD_CLOEXEC (with fnctl()), and put the write fd into it's QEMU state variables (parent vfork fd).
- The child then move on.

When the TARGET_NR_execve syscall is trapped (this is in child context), you do:
- Do everything as currently done, up to just before the safe_execve() call.
- Just before the call to safe_execve(), check if the QEMU state variable (parent vfork fd) is defined.  If so, tell the the parent (through the pipe), that we are good so far, and about to call execve().  Note that the parent just update the child status, but keep looping endlessly.
- Call the execve().
- If the above call return, an error occurred.  If this occur, check if the QEMU state variable (parent vfork fd) is defined.  If so, tell whatever error status you got to the parent (through the pipe).  The parent update it's child status, but again, continue to loop endlessly.
- Continue normally.

That's pretty much the bulk of the work done!  What will happen:
- Either the child will eventually call execve, which will succeed, at which point the write end of the pipe will be closed (because we set the pipe to close on execve, with the FD_CLOEXEC flag).
- The child could be playing on us, and try to re-call execve() multiple times (possibly with different arguments, executables path, etc.), but every time, the parent will just receive status update through the pipe.  And eventually, the above case will occur (success), and pipe will be closed.
- The child call _exit(), which will close the pipe again.
- The child get some horrible signal, get killed, or whatever else...  Pipe still get closed.

The parent, on it's side, just update the status endlessly, UNTIL the
other end of the pipe get closed.  At this point, the read() of the pipe
will get a 'broken pipe' error.  This signal the parent to move on, and
return whatever status the child last provided.

Note that this status could initially be set to an error state (in case
the child die or call _exit() before calling execve()).

The only thing that could make the parent hang is if the child hang (and
never call execve() or _exit() or die...).  But the beauty is that this
is perfectly fine, because that is exactly the required behavior when
CLONE_VFORK flag is set (parent wait for the child).


This is a lot of description, but should be relatively easy and straightforward to implement.  Could this work?

There are a few examples similar to this on the Web, using pipefd, fork
and execve, for different applications.  Here, we just pass the status.

Regards,
Eric

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Qemu-devel] [Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Peter Maydell]

> Actually, you only need the parent to get the status from the child,
which can be passed in other way than through common memory.

Certainly, it *can* be, but the glibc code we're trying to run in the
guest here doesn't do it in some other way, it uses common memory.
Having QEMU effectively pause the parent process until the child has
done its execve is certainly possible along the lines you suggest. But
that is only half the requirement -- the parent also has to be able to
see in its memory space the updates to the status variable that the
child has made.

If you're willing to change the guest code the problem is easy (for
instance you could just go back to the old glibc approach). But we need
to run the code as it stands.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Davide Palma]

any solution? trying to emulate a closed source amd64 app on my
raspberry and i'm getting this error with qemu 5.2.0-rc4 and glibc 2.27.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  New

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions

[Bug 1673976] Re: linux-user clone() can't handle glibc posix_spawn() (causes locale-gen to assert)

[Thomas Huth]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/140


** Changed in: qemu
       Status: New => Expired

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #140
   https://gitlab.com/qemu-project/qemu/-/issues/140

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1673976

Title:
  linux-user clone() can't handle glibc posix_spawn() (causes locale-gen
  to assert)

Status in QEMU:
  Expired

Bug description:
  I'm running a command (locale-gen) inside of an armv7h chroot mounted
  on my x86_64 desktop by putting qemu-arm-static into /usr/bin/ of the
  chroot file system and I get a core dump.

  locale-gen
  Generating locales...
    en_US.UTF-8...localedef: ../sysdeps/unix/sysv/linux/spawni.c:360: __spawnix: Assertion `ec >= 0' failed.
  qemu: uncaught target signal 6 (Aborted) - core dumped
  /usr/bin/locale-gen: line 41:    34 Aborted                 (core dumped) localedef -i $input -c -f $charset -A /usr/share/locale/locale.alias $locale

  I've done this same thing successfully for years, but this breakage
  has appeared some time in the last 3 or so months. Possibly with the
  update to qemu version 2.8.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1673976/+subscriptions