On Wed, Sep 14, 2022 at 08:03:47AM +0200, Christian Borntraeger wrote: > Am 13.09.22 um 19:34 schrieb Nathan Chancellor: > > Hi all, > > > > Recently, Fedora moved their baseline from CONFIG_MARCH_ZEC12 to > > CONFIG_MARCH_Z13: > > > > https://src.fedoraproject.org/rpms/kernel/c/aff6e8acdaa437e9f06ef4166ca2209071223f8d > > > > Unfortunately, this causes clang built kernels to have an "illegal > > operation" panic when booting in QEMU. This is trivially reproducible on > > mainline with the versions of clang that s390 supports. > > > > # Switch from CONFIG_MARCH_ZEC12 to CONFIG_MARCH_Z13 > > $ make -skj"$(nproc)" ARCH=s390 CC=clang CROSS_COMPILE=s390x-linux-gnu- defconfig menuconfig bzImage > > > > $ qemu-system-s390x \ > > -M s390-ccw-virtio \ > > -kernel arch/s390/boot/bzImage \ > > -display none \ > > -initrd .../boot-utils/images/s390/rootfs.cpio \ > > -m 512m \ > > -nodefaults \ > > -no-reboot \ > > -serial mon:stdio > > ... > > [ 0.558817] Linux version 6.0.0-rc5-00017-gd1221cea11fc (nathan@distrobox-oTN5YGrt3J.thelio-3990X) (clang version 14.0.5 (Fedora 14.0.5-7.fc38), GNU ld version 2.38-4.fc37) #1 SMP Tue Sep 13 08:35:38 MST 2022 > > ... > > [ 1.675787] illegal operation: 0001 ilc:3 [#1] SMP > > [ 1.675888] Modules linked in: > > [ 1.676044] CPU: 0 PID: 59 Comm: modprobe Not tainted 6.0.0-rc5-00017-gd1221cea11fc #1 > > [ 1.676134] Hardware name: QEMU 8561 QEMU (KVM/Linux) > > What qemu version is that and what command line did you use (any cpu model?) I was able to reproduce this with QEMU 6.0.0 through 7.1.0, which are the versions that can boot a clang built kernel. I don't think we specify a cpu model, you can see the full command above. If there is something we should be doing differently, please let us know! > > [ 1.676202] Krnl PSW : 0704d00180000000 0000000000579fbc (load_elf_binary+0x31c/0x11c0) > > [ 1.676459] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 RI:0 EA:3 > > [ 1.676489] Krnl GPRS: 0000000000000001 00000000044f0000 0000000000000000 0000000000000000 > > [ 1.676506] 8000000000000080 0000000000000000 0000000000000000 00000000035fa900 > > [ 1.676522] 0000000000000001 000000000353ce00 0000000000000001 00000000044693c0 > > [ 1.676538] 000000000276fa00 000000000446a000 0000000000579f9e 00000380002ebc78 > > [ 1.677128] Krnl Code: 0000000000579fac: a7f405b8 brc 15,000000000057ab1c > > [ 1.677128] 0000000000579fb0: e31003400004 lg %r1,832 > > [ 1.677128] #0000000000579fb6: e3001780003b lzrf %r0,1920(%r1) > > QEMU does support lzrf as far asI can tell as soon as you have S390_FEAT_STFLE_53 which is part > of the qemu_V4_1 cpu model. > > > [ 1.677128] >0000000000579fbc: 50001780 st %r0,1920(%r1) > > [ 1.677128] 0000000000579fc0: e31003400004 lg %r1,832 > > [ 1.677128] 0000000000579fc6: c40800aa99a9 lgrl %r0,0000000001acd318 > > [ 1.677128] 0000000000579fcc: e3001d400124 stg %r0,7488(%r1) > > [ 1.677128] 0000000000579fd2: e31003400004 lg %r1,832 > > [ 1.677343] Call Trace: > > [ 1.677564] [<0000000000579fbc>] load_elf_binary+0x31c/0x11c0 > > [ 1.677635] ([<0000000000579f9e>] load_elf_binary+0x2fe/0x11c0) > > [ 1.677652] [<00000000004e1ae6>] bprm_execve+0x4f6/0x7b0 > > [ 1.677671] [<00000000004e1256>] kernel_execve+0x3b6/0x3d0 > > [ 1.677687] [<000000000017e1c8>] call_usermodehelper_exec_async+0x158/0x1d0 > > [ 1.677706] [<0000000000103a9a>] __ret_from_fork+0x3a/0x60 > > [ 1.677719] [<0000000000f8562a>] ret_from_fork+0xa/0x40 > > [ 1.677748] Last Breaking-Event-Address: > > [ 1.677757] [<0000000000579fa2>] load_elf_binary+0x302/0x11c0 > > [ 1.678012] Kernel panic - not syncing: Fatal exception: panic_on_oops > > > > The rootfs image is available in our boot-utils repo [1], should it be > > necessary for reproducing this issue. I do not see any problems with > > booting a CONFIG_MARCH_Z13 kernel compiled with GCC 12.2.1 from Fedora > > but it is possible that clang and GCC generate different code. I am not > > sure if this is a compiler problem or an emulation one, which is where I > > was looking for some input from you all. > > > > [1]: https://github.com/ClangBuiltLinux/boot-utils > > > > Cheers, > > Nathan
