Re: [PATCH 1/4] x86/percpu: Use explicit segment registers in lib/cmpxchg{8,16}b_emu.S
From: Uros Bizjak
Date: Thu Oct 26 2023 - 03:16:29 EST
On Thu, Oct 26, 2023 at 9:01 AM kernel test robot <oliver.sang@xxxxxxxxx> wrote:
>
>
>
> Hello,
>
> kernel test robot noticed "general_protection_fault:#[##]" on:
>
> commit: 33c7952d925e905f7af1fb7628e48e03f59885da ("[PATCH 1/4] x86/percpu: Use explicit segment registers in lib/cmpxchg{8,16}b_emu.S")
> url: https://github.com/intel-lab-lkp/linux/commits/Uros-Bizjak/x86-percpu-Use-explicit-segment-registers-in-lib-cmpxchg-8-16-b_emu-S/20231017-111304
> base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 92fe9bb77b0c9fade150350fdb0629a662f0923f
> patch link: https://lore.kernel.org/all/20231012161237.114733-2-ubizjak@xxxxxxxxx/
> patch subject: [PATCH 1/4] x86/percpu: Use explicit segment registers in lib/cmpxchg{8,16}b_emu.S
>
> in testcase: boot
>
> compiler: gcc-12
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
This problem was fixed in a -v3 version of the patch [1], that was
committed to the tip/percpu branch and later merged into tip/master.
[1] https://lore.kernel.org/lkml/20231017162811.200569-3-ubizjak@xxxxxxxxx/
Thanks,
Uros.
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
> +------------------------------------------+------------+------------+
> | | 92fe9bb77b | 33c7952d92 |
> +------------------------------------------+------------+------------+
> | boot_successes | 7 | 0 |
> | boot_failures | 0 | 7 |
> | general_protection_fault:#[##] | 0 | 7 |
> | EIP:this_cpu_cmpxchg8b_emu | 0 | 7 |
> | Kernel_panic-not_syncing:Fatal_exception | 0 | 7 |
> +------------------------------------------+------------+------------+
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-lkp/202310261417.b269d37e-oliver.sang@xxxxxxxxx
>
>
> [ 0.186570][ T0] stackdepot hash table entries: 65536 (order: 6, 262144 bytes, linear)
> [ 0.187499][ T0] Initializing HighMem for node 0 (0002ebfe:000bffe0)
> [ 1.727965][ T0] Initializing Movable for node 0 (00000000:00000000)
> [ 1.943274][ T0] Checking if this processor honours the WP bit even in supervisor mode...Ok.
> [ 1.944313][ T0] Memory: 2896220K/3145208K available (16182K kernel code, 5537K rwdata, 11756K rodata, 816K init, 9720K bss, 248988K reserved, 0K cma-reserved, 2379656K highmem)
> [ 1.947172][ T0] general protection fault: 0000 [#1] PREEMPT
> [ 1.947900][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc1-00024-g33c7952d925e #1 8d4b014f9a0a85cc9a3f6a52ed8e88f1e431f74e
> [ 1.949317][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 1.950480][ T0] EIP: this_cpu_cmpxchg8b_emu (kbuild/src/consumer/arch/x86/lib/cmpxchg8b_emu.S:73)
> [ 1.951093][ T0] Code: ff ff ff 8d b4 26 00 00 00 00 66 90 83 c6 01 3c 3d 0f 95 c0 0f b6 c0 83 c0 01 e9 56 ff ff ff bf ff ff ff ff eb a6 cc cc 9c fa <64> 3b 06 75 13 64 3b 56 04 75 0d 64 89 1e 64 89 4e 04 83 0c 24 40
> All code
> ========
> 0: ff (bad)
> 1: ff (bad)
> 2: ff 8d b4 26 00 00 decl 0x26b4(%rbp)
> 8: 00 00 add %al,(%rax)
> a: 66 90 xchg %ax,%ax
> c: 83 c6 01 add $0x1,%esi
> f: 3c 3d cmp $0x3d,%al
> 11: 0f 95 c0 setne %al
> 14: 0f b6 c0 movzbl %al,%eax
> 17: 83 c0 01 add $0x1,%eax
> 1a: e9 56 ff ff ff jmp 0xffffffffffffff75
> 1f: bf ff ff ff ff mov $0xffffffff,%edi
> 24: eb a6 jmp 0xffffffffffffffcc
> 26: cc int3
> 27: cc int3
> 28: 9c pushf
> 29: fa cli
> 2a:* 64 3b 06 cmp %fs:(%rsi),%eax <-- trapping instruction
> 2d: 75 13 jne 0x42
> 2f: 64 3b 56 04 cmp %fs:0x4(%rsi),%edx
> 33: 75 0d jne 0x42
> 35: 64 89 1e mov %ebx,%fs:(%rsi)
> 38: 64 89 4e 04 mov %ecx,%fs:0x4(%rsi)
> 3c: 83 0c 24 40 orl $0x40,(%rsp)
>
> Code starting with the faulting instruction
> ===========================================
> 0: 64 3b 06 cmp %fs:(%rsi),%eax
> 3: 75 13 jne 0x18
> 5: 64 3b 56 04 cmp %fs:0x4(%rsi),%edx
> 9: 75 0d jne 0x18
> b: 64 89 1e mov %ebx,%fs:(%rsi)
> e: 64 89 4e 04 mov %ecx,%fs:0x4(%rsi)
> 12: 83 0c 24 40 orl $0x40,(%rsp)
> [ 1.953397][ T0] EAX: c3c01100 EBX: c3c01180 ECX: 00000004 EDX: 00000003
> [ 1.954231][ T0] ESI: e52cd090 EDI: e52cd090 EBP: c2b4bf00 ESP: c2b4bec4
> [ 1.955060][ T0] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00210082
> [ 1.955949][ T0] CR0: 80050033 CR2: ffdeb000 CR3: 031b5000 CR4: 00000090
> [ 1.956783][ T0] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
> [ 1.957641][ T0] DR6: fffe0ff0 DR7: 00000400
> [ 1.958190][ T0] Call Trace:
> [ 1.958554][ T0] ? show_regs (kbuild/src/consumer/arch/x86/kernel/dumpstack.c:479)
> [ 1.959026][ T0] ? die_addr (kbuild/src/consumer/arch/x86/kernel/dumpstack.c:421 kbuild/src/consumer/arch/x86/kernel/dumpstack.c:460)
> [ 1.959480][ T0] ? exc_general_protection (kbuild/src/consumer/arch/x86/kernel/traps.c:697 kbuild/src/consumer/arch/x86/kernel/traps.c:642)
> [ 1.960101][ T0] ? exc_bounds (kbuild/src/consumer/arch/x86/kernel/traps.c:642)
> [ 1.960579][ T0] ? handle_exception (kbuild/src/consumer/arch/x86/entry/entry_32.S:1049)
>
>
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20231026/202310261417.b269d37e-oliver.sang@xxxxxxxxx
>
>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>