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From:   Lukasz Majczak <lma@semihalf.com>
Date:   Wed, 2 Jun 2021 17:51:01 +0200
Message-ID: <CAFJ_xbq06nfaEWtVNLtg7XCJrQeQ9wCs4Zsoi5Y_HP3Dx0iTRA@mail.gmail.com>
Subject: Re: [PATCH v3 16/16] objtool,x86: Rewrite retpoline thunk calls
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Josh Poimboeuf <jpoimboe@redhat.com>, x86@kernel.org,
        jgross@suse.com, mbenes@suse.com, linux-kernel@vger.kernel.org,
        upstream@semihalf.com,
        =?UTF-8?Q?Rados=C5=82aw_Biernacki?= <rad@semihalf.com>,
        =?UTF-8?Q?=C5=81ukasz_Bartosik?= <lb@semihalf.com>,
        Guenter Roeck <groeck@google.com>
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Precedence: bulk

Hi Peter,

This patch seems to crash on Tigerlake platform (Chromebook delbin), I
got the following error:

[    2.103054] pcieport 0000:00:1c.0: PME: Signaling with IRQ 122
[    2.110148] pcieport 0000:00:1c.0: pciehp: Slot #7 AttnBtn-
PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+ Interlock- NoCompl+
IbPresDis- LLActRep+
[    2.126754] pcieport 0000:00:1d.0: PME: Signaling with IRQ 123
[    2.133946] ACPI: \_SB_.CP00: Found 3 idle states
[    2.139708] BUG: kernel NULL pointer dereference, address: 000000000000012b
[    2.140704] #PF: supervisor read access in kernel mode
[    2.140704] #PF: error_code(0x0000) - not-present page
[    2.140704] PGD 0 P4D 0
[    2.140704] Oops: 0000 [#1] PREEMPT SMP NOPTI
[    2.140704] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G     U
  5.13.0-rc1 #31
[    2.140704] Hardware name: Google Delbin/Delbin, BIOS
Google_Delbin.13672.156.3 05/14/2021
[    2.140704] RIP: 0010:cpuidle_poll_time+0x9/0x6a
[    2.140704] Code: 44 00 00 85 f6 78 19 55 48 89 e5 48 8b 05 16 44
44 01 4c 8b 58 40 4d 85 db 5d 41 ff d3 66 90 00 c3 0f 1f 44 00 00 55
48 89 e5 <48> 8b 46 20 48 85 c0 75 56 4c 63 87 28 04 00 00 b8 24 f49
[    2.140704] RSP: 0000:ffffffff9cc03ea8 EFLAGS: 00010282
[    2.140704] RAX: 0000000000008e7d RBX: ffffffff9cc1c5fd RCX: 000000007f894e5a
[    2.140704] RDX: 000000007f894d4f RSI: 000000000000010b RDI: 0000000002fa1cf6
[    2.140704] RBP: ffffffff9cc03ea8 R08: 0000000000000000 R09: 00000000ca948246
[    2.140704] R10: 0000000000000000 R11: ffffffff9bf132cb R12: 0000000000000003
[    2.140704] R13: ffffbbfdffc21960 R14: 0000000000000000 R15: ffffffff9cdba638
[    2.140704] FS:  0000000000000000(0000) GS:ffff928280000000(0000)
knlGS:0000000000000000
[    2.140704] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.140704] CR2: 000000000000012b CR3: 000000027e414001 CR4: 0000000000770ef0
[    2.140704] PKRU: 55555554
[    2.140704] Call Trace:
[    2.140704]  do_idle+0x175/0x1f6
[    2.140704]  cpu_startup_entry+0x1d/0x1f
[    2.140704]  start_kernel+0x3be/0x420
[    2.140704]  secondary_startup_64_no_verify+0xb0/0xbb
[    2.140704] Modules linked in:
[    2.140704] CR2: 000000000000012b
[    2.140704] ---[ end trace d15839e2bd509f00 ]---
[    2.140704] RIP: 0010:cpuidle_poll_time+0x9/0x6a
[    2.140704] Code: 44 00 00 85 f6 78 19 55 48 89 e5 48 8b 05 16 44
44 01 4c 8b 58 40 4d 85 db 5d 41 ff d3 66 90 00 c3 0f 1f 44 00 00 55
48 89 e5 <48> 8b 46 20 48 85 c0 75 56 4c 63 87 28 04 00 00 b8 24 f49
[    2.140704] RSP: 0000:ffffffff9cc03ea8 EFLAGS: 00010282
[    2.140704] RAX: 0000000000008e7d RBX: ffffffff9cc1c5fd RCX: 000000007f894e5a
[    2.140704] RDX: 000000007f894d4f RSI: 000000000000010b RDI: 0000000002fa1cf6
[    2.140704] RBP: ffffffff9cc03ea8 R08: 0000000000000000 R09: 00000000ca948246
[    2.140704] R10: 0000000000000000 R11: ffffffff9bf132cb R12: 0000000000000003
[    2.140704] R13: ffffbbfdffc21960 R14: 0000000000000000 R15: ffffffff9cdba638
[    2.140704] FS:  0000000000000000(0000) GS:ffff928280000000(0000)
knlGS:0000000000000000
[    2.140704] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.140704] CR2: 000000000000012b CR3: 000000027e414001 CR4: 0000000000770ef0
[    2.140704] PKRU: 55555554
[    2.140704] Kernel panic - not syncing: Fatal exception
[    2.140704] Kernel Offset: 0x1a600000 from 0xffffffff81000000
(relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[    2.140704] ACPI MEMORY or I/O RESET_REG.

Git bisect pointed to this commit:

9bc0bb50727c8ac69fbb33fb937431cf3518ff37 is the first bad commit
commit 9bc0bb50727c8ac69fbb33fb937431cf3518ff37
Author: Peter Zijlstra <peterz@infradead.org>
Date:   Fri Mar 26 16:12:15 2021 +0100

    objtool/x86: Rewrite retpoline thunk calls

If there is anything I could do to help debug this issue (additional
debugs, logs etc.), please let me know.
Best regards,
Lukasz