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SubjectRe: [PATCH v2 03/18] x86/dumpstack: Add get_stack_info() support for the SYSENTER stack
On Tue, Nov 21, 2017 at 08:43:58PM -0800, Andy Lutomirski wrote:
> get_stack_info() doesn't currently know about the SYSENTER stack, so
> unwinding will fail if we entered the kernel on the SYSENTER stack
> and haven't fully switched off. Teach get_stack_info() about the
> SYSENTER stack.
>
> With future patches applied that run part of the entry code on the
> SYSENTER stack and introduce an intentional BUG(), I would get:
>
> [ 3.962218] PANIC: double fault, error_code: 0x0
> ...
> [ 3.963998] task: ffff88001aa18000 task.stack: ffff88001aa20000
> [ 3.964526] RIP: 0010:do_error_trap+0x33/0x1c0
> [ 3.964947] RSP: 0000:ffffffffff1b8f78 EFLAGS: 00010096
> [ 3.965439] RAX: dffffc0000000000 RBX: ffffffffff1b8f90 RCX: 0000000000000006
> [ 3.966067] RDX: ffffffff82048b20 RSI: 0000000000000000 RDI: ffffffffff1b9110
> [ 3.966696] RBP: ffffffffff1b9088 R08: 0000000000000004 R09: 0000000000000000
> [ 3.967316] R10: 0000000000000000 R11: fffffbffffe3723f R12: 0000000000000006
> [ 3.967939] R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000000
> [ 3.968565] FS: 0000000000000000(0000) GS:ffff88001ae00000(0000) knlGS:0000000000000000
> [ 3.969272] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 3.969776] CR2: ffffffffff1b8f68 CR3: 0000000019308002 CR4: 00000000003606f0
> [ 3.970406] Call Trace:
> [ 3.970632] Code: ...
>
> With this patch, I get:
>
> [ 4.211553] PANIC: double fault, error_code: 0x0
> ...
> [ 4.213536] task: ffff88001aa18000 task.stack: ffff88001aa20000
> [ 4.214059] RIP: 0010:do_error_trap+0x33/0x1c0
> [ 4.214449] RSP: 0000:ffffffffff1b8f78 EFLAGS: 00010096
> [ 4.214934] RAX: dffffc0000000000 RBX: ffffffffff1b8f90 RCX: 0000000000000006
> [ 4.215554] RDX: ffffffff82048b20 RSI: 0000000000000000 RDI: ffffffffff1b9110
> [ 4.216176] RBP: ffffffffff1b9088 R08: 0000000000000004 R09: 0000000000000000
> [ 4.216793] R10: 0000000000000000 R11: fffffbffffe3723f R12: 0000000000000006
> [ 4.217419] R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000000
> [ 4.218046] FS: 0000000000000000(0000) GS:ffff88001ae00000(0000) knlGS:0000000000000000
> [ 4.218775] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 4.219280] CR2: ffffffffff1b8f68 CR3: 00000000193da002 CR4: 00000000003606f0
> [ 4.219931] Call Trace:
> [ 4.220156] <SYSENTER>
> [ 4.220383] ? async_page_fault+0x36/0x60
> [ 4.220768] ? invalid_op+0x22/0x40
> [ 4.221087] ? async_page_fault+0x36/0x60
> [ 4.221442] ? sync_regs+0x3c/0x40
> [ 4.221745] ? sync_regs+0x2e/0x40
> [ 4.222051] ? error_entry+0x6c/0xd0
> [ 4.222395] ? async_page_fault+0x36/0x60
> [ 4.222748] </SYSENTER>
> [ 4.223014] Code: ...

Please clean up those oopses: remove the timestamps, registers and the
offsets from the symbol names - they only clutter the text and have no
meaning.

>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> arch/x86/include/asm/stacktrace.h | 3 +++
> arch/x86/kernel/dumpstack.c | 19 +++++++++++++++++++
> arch/x86/kernel/dumpstack_32.c | 6 ++++++
> arch/x86/kernel/dumpstack_64.c | 6 ++++++
> 4 files changed, 34 insertions(+)

With that:

Reviewed-by: Borislav Petkov <bp@suse.de>

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--

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