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https://github.com/linuxkit/linuxkit.git
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81 lines
4.1 KiB
Diff
81 lines
4.1 KiB
Diff
From 207fa9a93a6708071fecec462915570a52641c78 Mon Sep 17 00:00:00 2001
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From: Rolf Neugebauer <rolf.neugebauer@gmail.com>
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Date: Tue, 6 Feb 2018 13:02:57 +0000
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Subject: [PATCH 13/13] x86/microcode/intel: Avoid division by zero
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The backport of 7e702d17ed1 ("x86/microcode/intel: Extend BDW
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late-loading further with LLC size check") introduced a division
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by zero panic on some platforms, specifically on machine types
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with one vCPU on Google Cloud (e.g., g1-small and n1-standard-1):
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[ 1.591435] divide error: 0000 [#1] SMP
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[ 1.591961] Modules linked in:
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[ 1.592546] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.79-linuxkit #1
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[ 1.593461] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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[ 1.595135] task: ffffa01b2b63c040 task.stack: ffffb24f40010000
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[ 1.596683] RIP: 0010:[<ffffffffb7d88ce3>] [<ffffffffb7d88ce3>] init_intel_microcode+0x49/0x5a
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[ 1.598018] RSP: 0000:ffffb24f40013e48 EFLAGS: 00010206
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[ 1.599016] RAX: 0000000001400000 RBX: 00000000ffffffea RCX: 0000000000000000
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[ 1.600093] RDX: 0000000000000000 RSI: ffffa01b2fffa9a8 RDI: ffffffffb7d8888b
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[ 1.601222] RBP: 00000000ffffffff R08: ffffa01b2fffa9a1 R09: 000000000000005f
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[ 1.602330] R10: 0000000000000067 R11: ffffa01b22164177 R12: 0000000000000000
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[ 1.603291] R13: ffffffffb7d787b6 R14: 0000000000000000 R15: 0000000000000000
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[ 1.604406] FS: 0000000000000000(0000) GS:ffffa01b2fc00000(0000) knlGS:0000000000000000
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[ 1.606154] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
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[ 1.607493] CR2: 0000000000000000 CR3: 000000002ac0a000 CR4: 0000000000040630
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[ 1.609310] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
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[ 1.611122] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
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[ 1.613008] Stack:
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[ 1.613445] ffffffffb7d888c1 0000000000000000 ffffffffb7d1ba40 0000000000000000
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[ 1.615423] 0000000000000000 ffffffffb7d787b6 0000000000000000 0000000000000000
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[ 1.617049] ffffffffb74fed89 00000000fffffff4 00000000ffffffff 4eae7bc133547c47
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[ 1.617904] Call Trace:
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[ 1.618198] [<ffffffffb7d888c1>] ? microcode_init+0x36/0x1de
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[ 1.619264] [<ffffffffb7d787b6>] ? set_debug_rodata+0xc/0xc
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[ 1.620143] [<ffffffffb74fed89>] ? driver_register+0xaf/0xb4
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[ 1.621841] [<ffffffffb7d8888b>] ? save_microcode_in_initrd+0x3c/0x3c
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[ 1.623424] [<ffffffffb70021b7>] ? do_one_initcall+0x98/0x130
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[ 1.624659] [<ffffffffb7d787b6>] ? set_debug_rodata+0xc/0xc
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[ 1.626303] [<ffffffffb7d79091>] ? kernel_init_freeable+0x166/0x1e7
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[ 1.627674] [<ffffffffb77ce3d7>] ? rest_init+0x6e/0x6e
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[ 1.628942] [<ffffffffb77ce3e1>] ? kernel_init+0xa/0xe6
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[ 1.630243] [<ffffffffb77d8587>] ? ret_from_fork+0x57/0x70
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[ 1.631592] Code: 16 0f b6 35 a0 ac fb ff 48 c7 c7 c4 ea 99 b7 e8 82 3e 41 ff 31 c0 c3 8b 05 3b ad fb ff 0f b7 0d 54 ad fb ff 31 d2 c1 e0 0a 48 98 <48> f7 f1 89 05 f4 6a 14 00 48 c7 c0 00 d8 c2 b7 c3 4c 8d 54 24
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[ 1.638875] RIP [<ffffffffb7d88ce3>] init_intel_microcode+0x49/0x5a
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[ 1.640382] RSP <ffffb24f40013e48>
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[ 1.641320] ---[ end trace e88ef332e19594b9 ]---
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[ 1.642418] Kernel panic - not syncing: Fatal exception
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[ 1.644581] Kernel Offset: 0x36000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
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[ 1.647312] ---[ end Kernel panic - not syncing: Fatal exception
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On these platforms x86_max_cores is 0:
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[ 0.227977] ftrace: allocating 35563 entries in 139 pages
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[ 0.273941] smpboot: x86_max_cores == zero !?!?
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[ 0.274645] smpboot: Max logical packages: 1
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Here, we check x86_max_core before calculating the llc_size.
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Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
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---
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arch/x86/kernel/cpu/microcode/intel.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
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index f90f17610f62..a5dd9e5db4ce 100644
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--- a/arch/x86/kernel/cpu/microcode/intel.c
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+++ b/arch/x86/kernel/cpu/microcode/intel.c
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@@ -1134,6 +1134,9 @@ static int __init calc_llc_size_per_core(struct cpuinfo_x86 *c)
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{
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u64 llc_size = c->x86_cache_size * 1024;
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+ if (!c->x86_max_cores)
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+ return 0;
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+
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do_div(llc_size, c->x86_max_cores);
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return (int)llc_size;
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--
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2.16.0
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