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Date: Wed, 8 Mar 2017 12:16:16 -0800
From: Omar Sandoval <osandov@...ndov.com>
To: Matt Fleming <matt@...eblueprint.co.uk>,
Dave Young <dyoung@...hat.com>, Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org, kernel-team@...com
Subject: kexec regression since 4.9 caused by efi
Hi, everyone,
Since 4.9, kexec results in the following panic on some of our servers:
[ 0.001000] general protection fault: 0000 [#1] SMP
[ 0.001000] Modules linked in:
[ 0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc1 #53
[ 0.001000] Hardware name: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05 09/30/2016
[ 0.001000] task: ffffffff81e0e4c0 task.stack: ffffffff81e00000
[ 0.001000] RIP: 0010:virt_efi_set_variable+0x85/0x1a0
[ 0.001000] RSP: 0000:ffffffff81e03e18 EFLAGS: 00010202
[ 0.001000] RAX: afafafafafafafaf RBX: ffffffff81e3a4e0 RCX: 0000000000000007
[ 0.001000] RDX: ffffffff81e03e70 RSI: ffffffff81e3a4e0 RDI: ffff88407f8c2de0
[ 0.001000] RBP: ffffffff81e03e60 R08: 0000000000000000 R09: 0000000000000000
[ 0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff81e03e70
[ 0.001000] R13: 0000000000000007 R14: 0000000000000000 R15: 0000000000000000
[ 0.001000] FS: 0000000000000000(0000) GS:ffff881fff600000(0000) knlGS:0000000000000000
[ 0.001000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.001000] CR2: ffff88407f30f000 CR3: 0000001fff102000 CR4: 00000000000406b0
[ 0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 0.001000] Call Trace:
[ 0.001000] efi_delete_dummy_variable+0x7a/0x80
[ 0.001000] efi_enter_virtual_mode+0x3e2/0x494
[ 0.001000] start_kernel+0x392/0x418
[ 0.001000] ? set_init_arg+0x55/0x55
[ 0.001000] x86_64_start_reservations+0x2a/0x2c
[ 0.001000] x86_64_start_kernel+0xea/0xed
[ 0.001000] start_cpu+0x14/0x14
[ 0.001000] Code: 42 25 8d ff 80 3d 43 77 95 00 00 75 68 9c 8f 04 24 48 8b 05 3e 7d 7e 00 48 89 de 4d 89 f9 4d 89 f0 44 89 e9 4c 89 e2 48 8b 40 58 <48> 8b 78 58 31 c0 e8 90 e4 92 ff 48 8b 3c 24 48 c7 c6 2b 0a ca
[ 0.001000] RIP: virt_efi_set_variable+0x85/0x1a0 RSP: ffffffff81e03e18
[ 0.001000] ---[ end trace 0bd213e540e9b19f ]---
[ 0.001000] Kernel panic - not syncing: Fatal exception
[ 0.001000] ---[ end Kernel panic - not syncing: Fatal exception
Booting normally (i.e., not kexec) still works.
The decoded code is:
0: 42 25 8d ff 80 3d rex.X and $0x3d80ff8d,%eax
6: 43 77 95 rex.XB ja 0xffffffffffffff9e
9: 00 00 add %al,(%rax)
b: 75 68 jne 0x75
d: 9c pushfq
e: 8f 04 24 popq (%rsp)
11: 48 8b 05 3e 7d 7e 00 mov 0x7e7d3e(%rip),%rax # 0x7e7d56
18: 48 89 de mov %rbx,%rsi
1b: 4d 89 f9 mov %r15,%r9
1e: 4d 89 f0 mov %r14,%r8
21: 44 89 e9 mov %r13d,%ecx
24: 4c 89 e2 mov %r12,%rdx
27: 48 8b 40 58 mov 0x58(%rax),%rax
2b:* 48 8b 78 58 mov 0x58(%rax),%rdi <-- trapping instruction
2f: 31 c0 xor %eax,%eax
31: e8 90 e4 92 ff callq 0xffffffffff92e4c6
36: 48 8b 3c 24 mov (%rsp),%rdi
3a: 48 rex.W
3b: c7 .byte 0xc7
3c: c6 (bad)
3d: 2b 0a sub (%rdx),%ecx
3f: ca .byte 0xca
If I'm reading this correctly, efi.systab->runtime == 0xafafafafafafafaf,
and we're crashing when we try to dereference that.
Here is the output of efi=debug from before the crash:
[ 0.000000] Linux version 4.11.0-rc1 (osandov@...big561.prn1.facebook.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC) ) #53 SMP Wed Mar 8 12:07:16 PST 2017
[ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.6.7-34_fbk7_2504_g8275185 ro root=LABEL=/ ipv6.autoconf=0 erst_disable biosdevname=0 net.ifnames=0 fsck.repair=yes pcie_pme=nomsi netconsole=+6666@...1:db00:0011:b03e:face:0000:0009:0000/eth0,1514@...1:db00:eef0:a59::/02:90:fb:5b:b7:1e crashkernel=128M console=tty0 co
nsole=ttyS1,57600 efi=debug
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256
[ 0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format.
[ 0.000000] e820: BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000000100-0x000000000009ffff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000750bdfff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000750be000-0x0000000075ddbfff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000075ddc000-0x0000000075e32fff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x0000000075e33000-0x000000007642dfff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x000000007642e000-0x000000007bcd9fff] reserved
[ 0.000000] BIOS-e820: [mem 0x000000007bcda000-0x000000007bcdafff] usable
[ 0.000000] BIOS-e820: [mem 0x000000007bcdb000-0x000000007bd60fff] reserved
[ 0.000000] BIOS-e820: [mem 0x000000007bd61000-0x000000007bffffff] usable
[ 0.000000] BIOS-e820: [mem 0x000000007c000000-0x000000008fffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed44fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000407fffffff] usable
[ 0.000000] NX (Execute Disable) protection: active
[ 0.000000] extended physical RAM map:
[ 0.000000] reserve setup_data: [mem 0x0000000000000100-0x000000000009ffff] usable
[ 0.000000] reserve setup_data: [mem 0x0000000000100000-0x000000000010006f] usable
[ 0.000000] reserve setup_data: [mem 0x0000000000100070-0x00000000750bdfff] usable
[ 0.000000] reserve setup_data: [mem 0x00000000750be000-0x0000000075ddbfff] reserved
[ 0.000000] reserve setup_data: [mem 0x0000000075ddc000-0x0000000075e32fff] ACPI data
[ 0.000000] reserve setup_data: [mem 0x0000000075e33000-0x000000007642dfff] ACPI NVS
[ 0.000000] reserve setup_data: [mem 0x000000007642e000-0x000000007bcd9fff] reserved
[ 0.000000] reserve setup_data: [mem 0x000000007bcda000-0x000000007bcdafff] usable
[ 0.000000] reserve setup_data: [mem 0x000000007bcdb000-0x000000007bd60fff] reserved
[ 0.000000] reserve setup_data: [mem 0x000000007bd61000-0x000000007bffffff] usable
[ 0.000000] reserve setup_data: [mem 0x000000007c000000-0x000000008fffffff] reserved
[ 0.000000] reserve setup_data: [mem 0x00000000fed1c000-0x00000000fed44fff] reserved
[ 0.000000] reserve setup_data: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
[ 0.000000] reserve setup_data: [mem 0x0000000100000000-0x000000407fffffff] usable
[ 0.000000] efi: EFI v2.40 by American Megatrends
[ 0.000000] efi: ACPI=0x75f5c000 ACPI 2.0=0x75f5c000 ESRT=0x7bc4d018 SMBIOS=0xf05e0 SMBIOS 3.0=0x7bb2f000 MPS=0xfc9e0
[ 0.000000] efi: mem00: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007642e000-0x000000007bc50fff] (88MB)
[ 0.000000] efi: mem01: [Runtime Code |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007bc51000-0x000000007bcd9fff] (0MB)
[ 0.000000] efi: mem02: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000007bcdb000-0x000000007bd60fff] (0MB)
[ 0.000000] efi: mem03: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x0000000080000000-0x000000008fffffff] (256MB)
[ 0.000000] efi: mem04: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x00000000fed1c000-0x00000000fed44fff] (0MB)
[ 0.000000] efi: mem05: [Memory Mapped I/O |RUN| | | | | | | | | | |UC] range=[0x00000000ff000000-0x00000000ffffffff] (16MB)
[ 0.000000] SMBIOS 3.0.0 present.
[ 0.000000] DMI: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05 09/30/2016
[ 0.000000] e820: last_pfn = 0x4080000 max_arch_pfn = 0x400000000
[ 0.000000] x86/PAT: Configuration [0-7]: WB WC UC- UC WB WC UC- WT
[ 0.000000] x2apic: enabled by BIOS, switching to x2apic ops
[ 0.000000] e820: last_pfn = 0x7c000 max_arch_pfn = 0x400000000
[ 0.000000] esrt: Reserving ESRT space from 0x000000007bc4d018 to 0x000000007bc4d050.
Reverting commit 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and
avoid a kmalloc()") on top of v4.11-rc1 fixes the problem. Bisecting
this was interesting:
- Up until 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a
kmalloc()"), kexec worked.
- From 8e80632fb23f to 9d80448ac92b ("efi/arm64: Add debugfs node to
dump UEFI runtime page tables"), kexec just hung after the
"kexec_core: Starting new kernel" message.
- From 3dad6f7f6975 ("x86/efi: Defer efi_esrt_init until after
memblock_x86_fill") to 0a637ee61247 ("x86/efi: Allow invocation of
arbitrary boot services"), kexec hit the BUG_ON(!efi.systab) in
kexec_enter_virtual_mode().
- Finally, after 92dc33501bfb ("x86/efi: Round EFI memmap reservations
to EFI_PAGE_SIZE"), I get the panic described above.
Let me know if there is any more information I can provide.
Thanks!
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