------- Comment From [email protected] 2020-11-03 13:56 EDT------- Hello Patricia, We have this script(mpe.py) which will detect if a vmlinux has the alignment issue or not. We ran it against 16.04, 18.04, 20.04 and 21.04 kernels, and we only found the misalignment in 20.04 and 21.04. 16.04's kernel doesn't have the p9_hmi_special_emu().
16.04: user@ltc-zz9:/tmp/test/boot$ ~/mpe.py vmlinux-4.4.0-193-generic System.map-4.4.0-193-generic Couldn't find p9_hmi_special_emu in objdump output Error: couldn't find stvx! 18.04: user@ltc-zz9:/tmp/test/boot$ ~/mpe.py vmlinux-4.15.0-122-generic System.map-4.15.0-122-generic Couldn't find p9_hmi_special_emu in objdump output stvx found using register r25: c00000000002988c: ce c9 00 7c stvx v0,0,r25 addi found using offset 32: c000000000029884: 20 00 21 3b addi r25,r1,32 OK - offset is aligned 20.04: user@ltc-zz9:/tmp/test/boot$ ~/mpe.py vmlinux-5.4.0-52-generic System.map-5.4.0-52-generic stvx found using register r28: c00000000002cbec: ce e1 00 7c stvx v0,0,r28 addi found using offset 40: c00000000002cbe4: 28 00 81 3b addi r28,r1,40 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !! Offset is misaligned - bug present !! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 20.10: user@ltc-zz9:/tmp/test/boot$ ~/mpe.py vmlinux-5.8.0-26-generic System.map-5.8.0-26-generic stvx found using register r9: c000000000025a78: ce 49 00 7c stvx v0,0,r9 addi found using offset 40: c000000000025a70: 28 00 21 39 addi r9,r1,40 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !! Offset is misaligned - bug present !! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I will attach the mpe.py script. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1902694 Title: Ubuntu 20.10- Undetected Data corruption in MPI workloads that use VSX for reductions on POWER9 DD2.1 systems Status in The Ubuntu-power-systems project: New Status in linux package in Ubuntu: New Bug description: == Comment: #0 - Waiki Wright <[email protected]> - 2020-11-02 17:00:07 == ---Problem Description--- A data integrity issue was observed with the Ubuntu 20.04 - 5.4.0-52 and 20.10 - 5.8.0-26 kernel on Power 9. The root cause is found in the compiling of p9_hmi_special_emu(). When doing a VMX store (in __get_user_atomic_128_aligned()) to a buffer (vbuf), the buffer is not 128 bit aligned. The fixes of this bug are accepted upstream: 1. https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=fixes&id=1da4a0272c5469169f78cd76cf175ff984f52f06 ("powerpc: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation") 2. https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=fixes&id=d1781f23704707d350b8c9006e2bdf5394bf91b2 ("selftests/powerpc: Make alignment handler test P9N DD2.1 vector CI load workaround") To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1902694/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
