On Thu, Jun 11, 2020 at 12:10:50PM -0700, Andy Lutomirski wrote:
On Thu, Jun 11, 2020 at 11:56 AM Naresh Kamboju naresh.kamboju@linaro.org wrote:
While running perf test and selftest x86 single_step_syscall_32 on i386 kernel linux next 5.7.0-next-20200610 kernel warning noticed.
steps to reproduce:
perf test and cd /opt/kselftests/default-in-kernel/x86 ./single_step_syscall_32
perf warning log:
[ 57.260865] ------------[ cut here ]------------ [ 57.266576] IRQs not disabled as expected [ 57.270583] WARNING: CPU: 1 PID: 500 at /usr/src/kernel/arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0 [ 57.281092] Modules linked in: x86_pkg_temp_thermal fuse [ 57.286406] CPU: 1 PID: 500 Comm: perf Not tainted 5.7.0-next-20200610 #1 [ 57.293190] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.2 05/23/2018 [ 57.300577] EIP: idtentry_exit_cond_rcu+0x92/0xc0 [ 57.305280] Code: 8b 89 d8 05 00 00 85 c9 74 ae 80 3d b1 64 2c d4 00 75 a5 68 94 2d fb d3 89 55 f8 89 45 fc c6 05 b1 64 2c d4 01 e8 8e f5 2b ff <0f> 0b 58 8b 55 f8 8b 45 fc eb 83 8d 76 00 e8 5b fd ff ff c9 c3 89 [ 57.324017] EAX: 0000001d EBX: 0d00022a ECX: 00000027 EDX: f5b9e14c [ 57.330274] ESI: f2a2ffb4 EDI: ffff0ff4 EBP: f2a2ff8c ESP: f2a2ff80 [ 57.336531] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010096 [ 57.343345] CR0: 80050033 CR2: 08700a58 CR3: 14ad7000 CR4: 003406d0 [ 57.349608] DR0: 080dfb80 DR1: 080dfc00 DR2: 08700a58 DR3: 00000000 [ 57.355866] DR6: fffe0ff0 DR7: 0d00062a [ 57.359697] Call Trace: [ 57.362143] exc_debug+0x84/0x1b0 [ 57.365487] ? exc_int3+0x1d0/0x1d0 [ 57.368981] handle_exception+0x145/0x145 [ 57.372991] EIP: 0x80dfbcd [ 57.375694] Code: Bad RIP value. [ 57.378918] EAX: 00000000 EBX: 00000005 ECX: 00002400 EDX: 00000000 [ 57.385175] ESI: 00000003 EDI: 00000004 EBP: bfd59798 ESP: bfd59770 [ 57.391431] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000246 [ 57.398215] irq event stamp: 1896
A regrettable property of the current entry code structure is that we lose any real indication of the vector. Presumably this is #DB, hence exc_debug. I don't know what perf has to do with it.
I'll bang on this after lunch if no one beats me to it.
Puzzling, CR3 seems to suggest this is !user_mode(), but either way #DB has either idtentry_enter_user() or nmi_enter().