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Author SHA1 Message Date
Tony Luck
3006381013 x86/mce: Decode a kernel instruction to determine if it is copying from user
All instructions copying data between kernel and user memory
are tagged with either _ASM_EXTABLE_UA or _ASM_EXTABLE_CPY
entries in the exception table. ex_fault_handler_type() returns
EX_HANDLER_UACCESS for both of these.

Recovery is only possible when the machine check was triggered
on a read from user memory. In this case the same strategy for
recovery applies as if the user had made the access in ring3. If
the fault was in kernel memory while copying to user there is no
current recovery plan.

For MOV and MOVZ instructions a full decode of the instruction
is done to find the source address. For MOVS instructions
the source address is in the %rsi register. The function
fault_in_kernel_space() determines whether the source address is
kernel or user, upgrade it from "static" so it can be used here.

Co-developed-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201006210910.21062-7-tony.luck@intel.com
2020-10-07 11:32:40 +02:00
Tony Luck
a05d54c41e x86/mce: Provide method to find out the type of an exception handler
Avoid a proliferation of ex_has_*_handler() functions by having just
one function that returns the type of the handler (if any).

Drop the __visible attribute for this function. It is not called
from assembler so the attribute is not necessary.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201006210910.21062-3-tony.luck@intel.com
2020-10-07 11:08:59 +02:00
Youquan Song
41ce0564bf x86/mce: Pass pointer to saved pt_regs to severity calculation routines
New recovery features require additional information about processor
state when a machine check occurred. Pass pt_regs down to the routines
that need it.

No functional change.

Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201006210910.21062-2-tony.luck@intel.com
2020-10-07 10:51:42 +02:00
Tony Luck
ed9705e4ad x86/mce: Drop AMD-specific "DEFERRED" case from Intel severity rule list
Way back in v3.19 Intel and AMD shared the same machine check severity
grading code. So it made sense to add a case for AMD DEFERRED errors in
commit

  e3480271f5 ("x86, mce, severity: Extend the the mce_severity mechanism to handle UCNA/DEFERRED error")

But later in v4.2 AMD switched to a separate grading function in
commit

  bf80bbd7dc ("x86/mce: Add an AMD severities-grading function")

Belatedly drop the DEFERRED case from the Intel rule list.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200930021313.31810-3-tony.luck@intel.com
2020-09-30 07:49:58 +02:00
Borislav Petkov
fd258dc444 x86/mce: Add Skylake quirk for patrol scrub reported errors
The patrol scrubber in Skylake and Cascade Lake systems can be configured
to report uncorrected errors using a special signature in the machine
check bank and to signal using CMCI instead of machine check.

Update the severity calculation mechanism to allow specifying the model,
minimum stepping and range of machine check bank numbers.

Add a new rule to detect the special signature (on model 0x55, stepping
>=4 in any of the memory controller banks).

 [ bp: Rewrite it.
   aegl: Productize it. ]

Suggested-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200930021313.31810-2-tony.luck@intel.com
2020-09-30 07:43:56 +02:00
Borislav Petkov
1df73b2131 x86/mce: Fixup exception only for the correct MCEs
The severity grading code returns IN_KERNEL_RECOV error context for
errors which have happened in kernel space but from which the kernel can
recover. Whether the recovery can happen is determined by the exception
table entry having as handler ex_handler_fault() and which has been
declared at build time using _ASM_EXTABLE_FAULT().

IN_KERNEL_RECOV is used in mce_severity_intel() to lookup the
corresponding error severity in the severities table.

However, the mapping back from error severity to whether the error is
IN_KERNEL_RECOV is ambiguous and in the very paranoid case - which
might not be possible right now - but be better safe than sorry later,
an exception fixup could be attempted for another MCE whose address
is in the exception table and has the proper severity. Which would be
unfortunate, to say the least.

Therefore, mark such MCEs explicitly as MCE_IN_KERNEL_RECOV so that the
recovery attempt is done only for them.

Document the whole handling, while at it, as it is not trivial.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200407163414.18058-10-bp@alien8.de
2020-04-14 16:01:49 +02:00
Tony Luck
aaefca8e30 x86/mce: Don't check for the overflow bit on action optional machine checks
We currently do not process SRAO (Software Recoverable Action Optional)
machine checks if they are logged with the overflow bit set to 1 in the
machine check bank status register. This is overly conservative.

There are two cases where we could end up with an SRAO+OVER log based
on the SDM volume 3 overwrite rules in "Table 15-8. Overwrite Rules for
UC, CE, and UCR Errors"

1) First a corrected error is logged, then the SRAO error overwrites.
   The second error overwrites the first because uncorrected errors
   have a higher severity than corrected errors.
2) The SRAO error was logged first, followed by a correcetd error.
   In this case the first error is retained in the bank.

So in either case the machine check bank will contain the address
of the SRAO error. So we can process that even if the overflow bit
was set.

Reported-by: Yongkai Wu <yongkaiwu@tencent.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190718182920.32621-1-tony.luck@intel.com
2019-08-05 09:34:02 +02:00
Linus Torvalds
090bc5a2a9 Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RAS updates from Ingo Molnar:
 "Boris is on vacation so I'm sending the RAS bits this time. The main
  changes were:

   - Various RAS/CEC improvements and fixes by Borislav Petkov:
       - error insertion fixes
       - offlining latency fix
       - memory leak fix
       - additional sanity checks
       - cleanups
       - debug output improvements

   - More SMCA enhancements by Yazen Ghannam:
       - make banks truly per-CPU which they are in the hardware
       - don't over-cache certain registers
       - make the number of MCA banks per-CPU variable

     The long term goal with these changes is to support future
     heterogenous SMCA extensions.

   - Misc fixes and improvements"

* 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Do not check return value of debugfs_create functions
  x86/MCE: Determine MCA banks' init state properly
  x86/MCE: Make the number of MCA banks a per-CPU variable
  x86/MCE/AMD: Don't cache block addresses on SMCA systems
  x86/MCE: Make mce_banks a per-CPU array
  x86/MCE: Make struct mce_banks[] static
  RAS/CEC: Add copyright
  RAS/CEC: Add CONFIG_RAS_CEC_DEBUG and move CEC debug features there
  RAS/CEC: Dump the different array element sections
  RAS/CEC: Rename count_threshold to action_threshold
  RAS/CEC: Sanity-check array on every insertion
  RAS/CEC: Fix potential memory leak
  RAS/CEC: Do not set decay value on error
  RAS/CEC: Check count_threshold unconditionally
  RAS/CEC: Fix pfn insertion
2019-07-08 16:31:06 -07:00
Greg Kroah-Hartman
6e4f929ea8 x86/mce: Do not check return value of debugfs_create functions
When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.

The only way this can fail is if:

 * debugfs superblock can not be pinned - something really went wrong with the
 vfs layer.
 * file is created with same name - the caller's fault.
 * new_inode() fails - happens if memory is exhausted.

so failing to clean up debugfs properly is the least of the system's
sproblems in uch a situation.

 [ bp: Extend commit message, remove unused err var in inject_init(). ]

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190612151531.GA16278@kroah.com
2019-06-14 16:04:21 +02:00
Thomas Gleixner
b886d83c5b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 315 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:37:17 +02:00
Tony Luck
41f035a86b x86/mce: Improve error message when kernel cannot recover, p2
In

  c7d606f560 ("x86/mce: Improve error message when kernel cannot recover")

a case was added for a machine check caused by a DATA access to poison
memory from the kernel. A case should have been added also for an
uncorrectable error during an instruction fetch in the kernel.

Add that extra case so the error message now reads:

  mce: [Hardware Error]: Machine check: Instruction fetch error in kernel

Fixes: c7d606f560 ("x86/mce: Improve error message when kernel cannot recover")
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Pu Wen <puwen@hygon.cn>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190225205940.15226-1-tony.luck@intel.com
2019-02-25 23:21:35 +01:00
Borislav Petkov
21afaf1813 x86/mce: Streamline MCE subsystem's naming
Rename the containing folder to "mce" which is the most widespread name.
Drop the "mce[-_]" filename prefix of some compilation units (while
others don't have it).

This unifies the file naming in the MCE subsystem:

mce/
|-- amd.c
|-- apei.c
|-- core.c
|-- dev-mcelog.c
|-- genpool.c
|-- inject.c
|-- intel.c
|-- internal.h
|-- Makefile
|-- p5.c
|-- severity.c
|-- therm_throt.c
|-- threshold.c
`-- winchip.c

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20181205141323.14995-1-bp@alien8.de
2018-12-05 18:00:29 +01:00
Renamed from arch/x86/kernel/cpu/mcheck/mce-severity.c (Browse further)