[Qemu-devel] [Bug 1727737] Re: qemu-arm stalls on a GCC sanitizer test since qemu-2.7

[Christophe Lyon]

I looked a bit more at the sanitizers source code, to understand the
differences between arm and aarch64. And it turns out that on aarch64,
we have:

sanitizer_common/sanitizer_syscall_linux_aarch64.inc:
133     // Helper function used to avoid cobbler errno.
134     bool internal_iserror(uptr retval, int *rverrno) {
135       if (retval >= (uptr)-4095) {

but on arm, in the GCC version, we use:

sanitizer_common/sanitizer_syscall_generic.inc:
54      bool internal_iserror(uptr retval, int *rverrno) {
55        if (retval == (uptr)-1) {

But recently (Nov 8th), the upstream sanitizer repo got a new file:

sanitizer_common/sanitizer_syscall_linux_arm.inc
133     // Helper function used to avoid cobbler errno.
134     bool internal_iserror(uptr retval, int *rverrno) {
135       if (retval >= (uptr)-4095) {

With that change, I now observe the same behaviour with qemu-aarch64 and
qemu-arm.

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https://bugs.launchpad.net/bugs/1727737

Title:
  qemu-arm stalls on a GCC sanitizer test since qemu-2.7

Status in QEMU:
  Incomplete

Bug description:
  Hi,

  I have noticed that several GCC/sanitizer tests fail with timeout when
  executed under QEMU.

  After a bit of investigation, I have noticed that this worked with
  qemu-2.7, and started failing with qemu-2.8, and still fails with
  qemu-2.10.1

  I'm attaching a tarball containing:
  alloca_instruments_all_paddings.exe : the testcase, and the needed libs:
  lib/librt.so.1
  lib/libdl.so.2
  lib/ld-linux-armhf.so.3
  lib/libasan.so.5
  lib/libc.so.6
  lib/libgcc_s.so.1
  lib/libpthread.so.0
  lib/libm.so.6

  To reproduce the problem:
  $ qemu-arm -cpu any -R 0 -L $PWD $PWD/alloca_instruments_all_paddings.exe
  returns in less than a second with qemu-2.7, and never with qemu-2.8

  Using -d in_asm suggests that the program "almost" completes and qemu seems 
to stall on:
  0x40b6eb44: e08f4004 add r4, pc, r4

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