On May 22, 2019 3:50 PM, "Cornelia Huck" <coh...@redhat.com> wrote: > > On Wed, 22 May 2019 15:22:23 +0200 > Aleksandar Markovic <aleksandar.m.m...@gmail.com> wrote: > > > On May 22, 2019 2:24 PM, "Cornelia Huck" <coh...@redhat.com> wrote: > > > > > > On Wed, 22 May 2019 14:10:39 +0200 > > > Laurent Vivier <laur...@vivier.eu> wrote: > > > > > > > On 22/05/2019 14:07, Cornelia Huck wrote: > > > > > On Wed, 22 May 2019 13:47:25 +0200 > > > > > Philippe Mathieu-Daudé <phi...@redhat.com> wrote: > > > > > > > > > >> On 5/21/19 5:28 PM, Cornelia Huck wrote: > > > > >>> commit a188339ca5a396acc588e5851ed7e19f66b0ebd9 > > > > >>> > > > > >>> Signed-off-by: Cornelia Huck <coh...@redhat.com> > > > > >>> --- > > > > >> [...] > > > > >>> #define __NR_mq_notify 184 > > > > >>> __SC_COMP(__NR_mq_notify, sys_mq_notify, compat_sys_mq_notify) > > > > >>> #define __NR_mq_getsetattr 185 > > > > >>> @@ -536,8 +567,10 @@ __SC_COMP(__NR_msgsnd, sys_msgsnd, > > compat_sys_msgsnd) > > > > >>> __SYSCALL(__NR_semget, sys_semget) > > > > >>> #define __NR_semctl 191 > > > > >>> __SC_COMP(__NR_semctl, sys_semctl, compat_sys_semctl) > > > > >>> +#if defined(__ARCH_WANT_TIME32_SYSCALLS) || __BITS_PER_LONG != 32 > > > > > > > > > > Eww. It seems only aarch64 sets __ARCH_WANT_TIME32_SYSCALLS, and the > > > > > second condition probably catches others but not mipsel. > > > > > > > > > >>> #define __NR_semtimedop 192 > > > > >>> -__SC_COMP(__NR_semtimedop, sys_semtimedop, compat_sys_semtimedop) > > > > >>> +__SC_COMP(__NR_semtimedop, sys_semtimedop, sys_semtimedop_time32) > > > > >>> +#endif > > > > >>> #define __NR_semop 193 > > > > >>> __SYSCALL(__NR_semop, sys_semop) > > > > >> [...] > > > > >> > > > > >> https://app.shippable.com/github/qemu/qemu/runs/1703/summary/console > > > > >> > > > > >> It seems this commit introduce a regression on mips32: > > > > >> > > > > >> CC mipsel-linux-user/linux-user/syscall.o > > > > >> ./linux-user/syscall.c: In function 'safe_semtimedop': > > > > >> ./linux-user/syscall.c:697:25: error: '__NR_semtimedop' undeclared > > > > >> (first use in this function) > > > > >> return safe_syscall(__NR_##name, arg1, arg2, arg3, arg4); \ > > > > > > > > > > So, we unconditionally deal with this syscall, i.e. we assume it is > > > > > always present? (I'm not sure of the logic in linux-user code.) > > > > > > > > > > > > > linux-user assumes it is present if __NR_msgsnd is present. > > > > > > Hm. The kernel change seems to break that assumption. Does anyone with > > > mips knowledge have an idea whether that was intentional (and the > > > linux-user code needs to be changed), or whether that's an issue on the > > > kernel side? > > > > > > > Hi, Cornelia. > > > > Thanks for your involving into this issue! > > > > It could be that (not-originating-from-MIPS) kernel commit: > > > > https://github.com/torvalds/linux/commit/1a787fc5ba18ac767e635c58d06a0b46876184e3 > > > > made a mess with system call availability for MIPS (I will forward this to > > MIPS kernel maintainer Paul Burton). My impression is that this was not > > intentional, and is a temporary instability of kernel interface. > > I don't think that's the problematic commit; that one seems to be a > follow-up on c8ce48f06503 ("asm-generic: Make time32 syscall numbers > optional") for tools usage (we sync from the 'normal' headers). > > The stated intention of the asm-generic commit is to keep 32 bit > architectures working as before via defining > __ARCH_WANT_TIME32_SYSCALLS, but it seems that was not done for mips > (but it should, right?) > > > However, I think that QEMU nevertheless should not make the assumption that > > if __NR_MSGSND, than semtimedop() is present. It could be true, but it is > > still just self-imposed belief in QEMU, kernel never guarantied such things. > > I'm not too familiar with that family of syscalls; is there a better > way to check for syscall availability here? > > > The alternative way of invoking via IPCV6 (else part of “ifdef > > __NR_MSGSND”) should work for MIPS in the present stage of headers and > > kernel. > > If my assumption above (mips skipped by accident) is correct, we need > to fix the kernel headers instead :/ -- unless we want to add a > temporary build fix. > > > As a side note, perhaps we shoul update kernel headers only off of stable > > kernel releases. > > In the past, we have even updated the kernel headers against > non-mainline (kvm) versions :) > > Breakage here seems to be rare (and if this is a real kernel interface > bug, it'd be a good thing that we caught it);
Definitely a good thing. I think it is fair to say that you found three or even more bugs, in two separate software projects, and all of this using a single patch only. :-o Perhaps you should do it more often. ;) > I believe getting support > for new features into QEMU quicker makes that a good trade-off.
