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/tools/testing/selftests/x86/mov_ss_trap.c?h=linux-4.17.y
Best regards
Naresh Kamboju
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