Doing this only for aarch64 targets seems like a bad idea to me -- this isn't an aarch64 specific issue. QEMU needs SIGSEGV to go to its own handler (so we can unprotect pages we've marked as read-only in order to catch guest writes to them so we can throw away invalidated translated code), and that's true for all targets. It probably just happens more often on the aarch64 target than others you've tested because aarch64 has a signal-return trampoline on the stack frame, so we'll often see that page get translated and thrown away again. (Other targets with a trampoline include sparc, cris, openrisc and ppc.)
PS: the comment "this is not required for qemu to work" just means that QEMU will work fine whether we tell the guest a lie about what's going on with SIGSEGV in one way (saying "it's blocked") or the other (saying "it's not blocked"). -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1285363 Title: qemu-aarch64-static segfaults Status in QEMU: New Status in “qemu” package in Ubuntu: Confirmed Bug description: I've found a couple conditions that causes qemu-user-static to core dump fairly reliably - same with upstream git - while a binary built from suse's aarch64-1.6 branch seems to consistently work fine. Testing suggests they are resolved by the sigprocmask wrapper patches included in suse's tree. 1) dh_fixperms is a script that commonly runs at the end of a package build. Its basically doing a `find | xargs chmod`. 2) debootstrap --second-stage This is used to configure an arm64 chroot that was built using debootstrap on a non-native host. It is basically invoking a bunch of shell scripts (postinst, etc). When it blows up, the stack consistently looks like this: Core was generated by `/usr/bin/qemu-aarch64-static /bin/sh -e /debootstrap/debootstrap --second-stage'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x0000000060058e55 in memcpy (__len=8, __src=0x7fff62ae34e0, __dest=0x400082c330) at /usr/include/x86_64-linux-gnu/bits/string3.h:51 51 return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest)); (gdb) bt #0 0x0000000060058e55 in memcpy (__len=8, __src=0x7fff62ae34e0, __dest=0x400082c330) at /usr/include/x86_64-linux-gnu/bits/string3.h:51 #1 stq_p (v=274886476624, ptr=0x400082c330) at /mnt/qemu.upstream/include/qemu/bswap.h:280 #2 stq_le_p (v=274886476624, ptr=0x400082c330) at /mnt/qemu.upstream/include/qemu/bswap.h:315 #3 target_setup_sigframe (set=0x7fff62ae3530, env=0x62d9c678, sf=0x400082b0d0) at /mnt/qemu.upstream/linux-user/signal.c:1167 #4 target_setup_frame (usig=usig@entry=17, ka=ka@entry=0x604ec1e0 <sigact_table+512>, info=info@entry=0x0, set=set@entry=0x7fff62ae3530, env=env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/signal.c:1286 #5 0x0000000060059f46 in setup_frame (env=0x62d9c678, set=0x7fff62ae3530, ka=0x604ec1e0 <sigact_table+512>, sig=17) at /mnt/qemu.upstream/linux-user/signal.c:1322 #6 process_pending_signals (cpu_env=cpu_env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/signal.c:5747 #7 0x0000000060056e60 in cpu_loop (env=env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/main.c:1082 #8 0x0000000060005079 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at /mnt/qemu.upstream/linux-user/main.c:4374 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1285363/+subscriptions
