[Qemu-devel] [Bug 1221966] Re: SIGSEGV in static_code_gen_buffer

[Peter Maydell]

SIGSEGVs from qemu-linux-user are expected -- this is how we track self-
modifying code in the guest binary. We catch the SIGSEGV and handle it
appropriately. In particular, SPARC binaries do this a lot because their
dynamic-linking mechanism involves self-modifying code.

If you don't run the program under a debugger (or if you tell gdb to
pass SIGSEGV through to the target rather than stopping), what does it
do?

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https://bugs.launchpad.net/bugs/1221966

Title:
  SIGSEGV in static_code_gen_buffer

Status in QEMU:
  New

Bug description:
  Trying to run 'ls' (or, anything else as far as I can tell) from a
  SunOS 5.8 box under RHEL 6.4 linux, I get a segfault.  I've tried
  qemu-1.5.3, qemu-1.6.0, and I fetched git://git.qemu-
  project.org/qemu.git.  I've also tried a statically linked sh from
  /sbin/ and it also segfaulted.

  address@hidden</home/anotheruvula/qemu>$ gdb bin/qemu-sparc
  GNU gdb (GDB) Red Hat Enterprise Linux (7.2-60.el6_4.1)
  Copyright (C) 2010 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
  and "show warranty" for details.
  This GDB was configured as "x86_64-redhat-linux-gnu".
  For bug reporting instructions, please see:
  <http://www.gnu.org/software/gdb/bugs/>...
  Reading symbols from /home/anotheruvula/qemu/bin/qemu-sparc...done.
  (gdb) run ../sparc/ls
  Starting program: /home/anotheruvula/qemu/bin/qemu-sparc ../sparc/ls
  [Thread debugging using libthread_db enabled]

  Program received signal SIGSEGV, Segmentation fault.
  0x00007ffff8259116 in static_code_gen_buffer ()
  Missing separate debuginfos, use: debuginfo-install glib2-2.22.5-7.el6.x86_64 
glibc-2.12-1.107.el6_4.4.x86_64
  (gdb) where
  #0  0x00007ffff8259116 in static_code_gen_buffer ()
  #1  0x00007ffff7f570cd in cpu_tb_exec (cpu=0x7ffffa2b1210, tb_ptr=
      0x7ffff82590d0 "A\213n \205í\017\205Í")
      at /home/anotheruvula/qemu-devel/cpu-exec.c:56
  #2  0x00007ffff7f57b2d in cpu_sparc_exec (env=0x7ffffa2b1348)
      at /home/anotheruvula/qemu-devel/cpu-exec.c:631
  #3  0x00007ffff7f77f36 in cpu_loop (env=0x7ffffa2b1348)
      at /home/anotheruvula/qemu-devel/linux-user/main.c:1089
  #4  0x00007ffff7f798ff in main (argc=2, argv=0x7fffffffdfc8, envp=
      0x7fffffffdfe0) at /home/anotheruvula/qemu-devel/linux-user/main.c:4083
  (gdb)

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