Kselftest test case mov_ss_trap_64 is causing kernel panic on qemu-system-x86_64 and PASS on real x86_64 hardware.

Test code snippet, main() { <> printf("[RUN]\tMOV SS; CS CS INT3\n"); asm volatile ("mov %[ss], %%ss; .byte 0x2e, 0x2e; int3" :: [ss] "m" (ss)); <> }

Linux version 4.17.3-rc1 (buildslave@lkft-01) (gcc version 6.2.1 20161016 (Linaro GCC 6.2-2016.11)) #1 SMP Thu Jun 21 02:19:19 UTC 2018

This test was good on kernel 4.17.2 good git commit: 3816828a8cd06c5e0a0a9e0456013d61d979d975

Bad on 4.17.3-rc1 (and stable-rc 4.14.52-rc1) Bad git commit: 894caab83aab21f120cde83eb5b969b99fcf8696

git repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git

qemu-system-x86_64 version 2.12.0

steps to reproduce and test log, + cd tools/testing/selftests/x86 + ./mov_ss_trap_64

SS = 0x2b, &SS = 0x0x604188 Set up a watchpoint DR0 = 604188, DR1 = 400a19, DR7 = 7000a [RUN] Read from watched memory (should get SIGTRAP) Got SIGTRAP with RIP=4008ea, EFLAGS.RF=0 [RUN] MOV SS; INT3 Got SIGTRAP with RIP=4008fb, EFLAGS.RF=0 [RUN] MOV SS; INT 3 Got SIGTRAP with RIP=40090d, EFLAGS.RF=0 [RUN] M[ 20.305426] PANIC: double fault, error_code: 0x0 OV SS; CS CS INT3 Got SIGTRAP with RIP=400920,[ 20.308317] CPU: 3 PID: 2471 Comm: mov_ss_trap_64 Not tainted 4.17.3-rc1 #1 EFLAGS.RF=0 [RUN] MOV SS; CSx14 INT3 [ 20.311664] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 20.314738] RIP: 0010:error_entry+0x32/0x100 <trim> [ 20.336649] Call Trace: [ 20.337523] <ENTRY_TRAMPOLINE> [ 20.338507] ? native_iret+0x7/0x7 [ 20.339611] ? page_fault+0x8/0x30 [ 20.340693] ? error_entry+0x86/0x100 [ 20.341871] ? trace_hardirqs_off_caller+0x7/0xa0 [ 20.343212] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 20.344554] ? native_iret+0x7/0x7 [ 20.345647] ? page_fault+0x8/0x30 [ 20.346716] ? error_entry+0x86/0x100 [ 20.347853] ? page_fault+0x8/0x30 [ 20.348920] ? ist_enter+0x6/0xa0 [ 20.349961] ? do_int3+0x34/0x120 [ 20.351095] ? int3+0x14/0x20 [ 20.352047] </ENTRY_TRAMPOLINE> [ 20.353060] Code: 48 89 7c 24 08 52 31 d2 51 31 c9 50 41 50 45 31 c0 41 51 45 31 c9 41 52 45 31 d2 41 53 45 31 db 53 31 db 55 31 ed 41 54 45 31 e4 <41> 55 45 31 ed 41 56 45 31 f6 41 57 45 31 ff 56 48 8d 6c 24 09 [ 20.357895] Kernel panic - not syncing: Machine halted.

Bug ink, https://bugs.linaro.org/show_bug.cgi?id=3916

Test case link, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree...

Best regards Naresh Kamboju -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html