[Bug 1856837] [NEW] qemu 4.2.0 arm segmentation fault with gcc 9.2

[Fabian Godehardt]

Public bug reported:

As discussed with f4bug yesterday on IRC here comes the bug description.

I'm building/configured qemu-4.2.0 on an x86_64 (gcc (Debian
6.3.0-18+deb9u1) 6.3.0 20170516) with target-list "arm-softmmu,arm-
linux-user" and debug enabled. I use the arm-linux-user variant, "qemu-
arm".

Then i'm trying to cross-compile (arm gcc) an old version of googles v8
(as i need this version of the lib for binary compatibility) which uses
qemu during build.

It worked with gcc 5.4.0 but not with 9.2.0. I also tried with 6.5.0,
7.4.0 and 8.3.0 but those are also causing the same segmentation fault.

The executed command wich breaks qemu is:

 qemu-arm /tmp/build/out/arm.release/mksnapshot.arm --log-snapshot-
positions --logfile
/tmp/build/out/arm.release/obj.host/v8_snapshot/geni/snapshot.log
--random-seed 314159265 /tmp/build/out/arm.release/obj.host/v8_snap

The printed error message is:

ARMv7=1 VFP3=1 VFP32DREGS=1 NEON=0 SUDIV=0 UNALIGNED_ACCESSES=1 
MOVW_MOVT_IMMEDIATE_LOADS=0 USE_EABI_HARDFLOAT=1
qemu: uncaught target signal 11 (Segmentation fault) - core dumped

Calling qemu with gdb gives the following information:

 Thread 1 "qemu-arm" received signal SIGSEGV, Segmentation fault.
 0x0000555555d63d11 in static_code_gen_buffer ()

and

 (gdb) bt
 #0  0x0000555555d63d11 in static_code_gen_buffer ()
 #1  0x0000555555628d58 in cpu_tb_exec (itb=<optimized out>, 
cpu=0x555557c33930) at 
 /tmp/build/qemu/accel/tcg/cpu-exec.c:172
 #2  cpu_loop_exec_tb (tb_exit=<synthetic pointer>, last_tb=<synthetic 
pointer>, tb=<optimized out>, 
 cpu=0x555557c33930) at /tmp/build/qemu/accel/tcg/cpu-exec.c:618
 #3  cpu_exec (cpu=cpu@entry=0x555557c2b660) at 
/tmp/build/qemu/accel/tcg/cpu-exec.c:731
 #4  0x0000555555661578 in cpu_loop (env=0x555557c33930) at 
/tmp/build/qemu/linux-user/arm/cpu_loop.c:219
#5  0x00005555555d6d76 in main (argc=<optimized out>, argv=<optimized out>, 
envp=<optimized out>) at /tmp/build/qemu/linux-user/main.c:865

Calling qemu-arm with debug switch "-d in_asm,int,op_opt" shows the log
in the attached file.

Thanks for any hints!
Fabian

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: gcc9.2 segfault

** Attachment added: "Debug with in_asm,int,op_opt"
   
https://bugs.launchpad.net/bugs/1856837/+attachment/5313610/+files/log-in_asm-int-op_opt

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https://bugs.launchpad.net/bugs/1856837

Title:
  qemu 4.2.0 arm  segmentation fault with gcc 9.2

Status in QEMU:
  New

Bug description:
  As discussed with f4bug yesterday on IRC here comes the bug
  description.

  I'm building/configured qemu-4.2.0 on an x86_64 (gcc (Debian
  6.3.0-18+deb9u1) 6.3.0 20170516) with target-list "arm-softmmu,arm-
  linux-user" and debug enabled. I use the arm-linux-user variant,
  "qemu-arm".

  Then i'm trying to cross-compile (arm gcc) an old version of googles
  v8 (as i need this version of the lib for binary compatibility) which
  uses qemu during build.

  It worked with gcc 5.4.0 but not with 9.2.0. I also tried with 6.5.0,
  7.4.0 and 8.3.0 but those are also causing the same segmentation
  fault.

  The executed command wich breaks qemu is:

   qemu-arm /tmp/build/out/arm.release/mksnapshot.arm --log-snapshot-
  positions --logfile
  /tmp/build/out/arm.release/obj.host/v8_snapshot/geni/snapshot.log
  --random-seed 314159265 /tmp/build/out/arm.release/obj.host/v8_snap

  The printed error message is:

  ARMv7=1 VFP3=1 VFP32DREGS=1 NEON=0 SUDIV=0 UNALIGNED_ACCESSES=1 
MOVW_MOVT_IMMEDIATE_LOADS=0 USE_EABI_HARDFLOAT=1
  qemu: uncaught target signal 11 (Segmentation fault) - core dumped

  Calling qemu with gdb gives the following information:

   Thread 1 "qemu-arm" received signal SIGSEGV, Segmentation fault.
   0x0000555555d63d11 in static_code_gen_buffer ()

  and

   (gdb) bt
   #0  0x0000555555d63d11 in static_code_gen_buffer ()
   #1  0x0000555555628d58 in cpu_tb_exec (itb=<optimized out>, 
cpu=0x555557c33930) at 
   /tmp/build/qemu/accel/tcg/cpu-exec.c:172
   #2  cpu_loop_exec_tb (tb_exit=<synthetic pointer>, last_tb=<synthetic 
pointer>, tb=<optimized out>, 
   cpu=0x555557c33930) at /tmp/build/qemu/accel/tcg/cpu-exec.c:618
   #3  cpu_exec (cpu=cpu@entry=0x555557c2b660) at 
/tmp/build/qemu/accel/tcg/cpu-exec.c:731
   #4  0x0000555555661578 in cpu_loop (env=0x555557c33930) at 
/tmp/build/qemu/linux-user/arm/cpu_loop.c:219
  #5  0x00005555555d6d76 in main (argc=<optimized out>, argv=<optimized out>, 
envp=<optimized out>) at /tmp/build/qemu/linux-user/main.c:865

  Calling qemu-arm with debug switch "-d in_asm,int,op_opt" shows the
  log in the attached file.

  Thanks for any hints!
  Fabian

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