[PATCH v5 0/4] fix CPER issues related to UEFI 2.9A Errata

[PATCH v5 0/4] fix CPER issues related to UEFI 2.9A Errata

[Mauro Carvalho Chehab]

The UEFI 2.9A errata makes clear how ARM processor type encoding should
be done: it is meant to be equal to Generic processor, using a bitmask.

The current code assumes, for both generic and ARM processor types
that this is an integer, which is an incorrect assumption.

Fix it. While here, also fix a compilation issue when using W=1.

After the change, Kernel will properly decode receiving two errors at the same
message, as defined at UEFI spec:

[   75.282430] Memory failure: 0x5cdfd: recovery action for free buddy page: Recovered
[   94.973081] {2}[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1
[   94.973770] {2}[Hardware Error]: event severity: recoverable
[   94.974334] {2}[Hardware Error]:  Error 0, type: recoverable
[   94.974962] {2}[Hardware Error]:   section_type: ARM processor error
[   94.975586] {2}[Hardware Error]:   MIDR: 0x000000000000cd24
[   94.976202] {2}[Hardware Error]:   Multiprocessor Affinity Register (MPIDR): 0x000000000000ab12
[   94.977011] {2}[Hardware Error]:   error affinity level: 2
[   94.977593] {2}[Hardware Error]:   running state: 0x1
[   94.978135] {2}[Hardware Error]:   Power State Coordination Interface state: 4660
[   94.978884] {2}[Hardware Error]:   Error info structure 0:
[   94.979463] {2}[Hardware Error]:   num errors: 3
[   94.979971] {2}[Hardware Error]:    first error captured
[   94.980523] {2}[Hardware Error]:    propagated error captured
[   94.981110] {2}[Hardware Error]:    overflow occurred, error info is incomplete
[   94.981893] {2}[Hardware Error]:    error_type: 0x0006: cache error|TLB error
[   94.982606] {2}[Hardware Error]:    error_info: 0x000000000091000f
[   94.983249] {2}[Hardware Error]:     transaction type: Data Access
[   94.983891] {2}[Hardware Error]:     cache error, operation type: Data write
[   94.984559] {2}[Hardware Error]:     TLB error, operation type: Data write
[   94.985215] {2}[Hardware Error]:     cache level: 2
[   94.985749] {2}[Hardware Error]:     TLB level: 2
[   94.986277] {2}[Hardware Error]:     processor context not corrupted

And the error code is properly decoded according with table N.17 from UEFI 2.10
spec:

	[   94.981893] {2}[Hardware Error]:    error_type: 0x0006: cache error|TLB error

The error injection logic was checked via QEMU using this patch:
https://lore.kernel.org/all/20240621165115.336-1-shiju.jose@huawei.com/

v5:
- Do some cleanups and minor fixes as suggested by Jonathan and Tony:
  - check errors at strscpy();
  - simplify cper_bits_to_str() function;
  - use FIELD_GET() and for_each_set_bit();
  - use ARRAY_SIZE() on infofx to let it clear that it should be size of newpfx + 1;
  - fix kernel-doc warning with W=1;
  - use kernel-doc for two exported functions at cper.c.

v4:
- The print function had some bugs on it, which was discovered with
  the help of an error injection tool I'm now using.

v3:
- It adds a helper function to produce a buffer describing the
  error bits at cper's printk and ghes pr_warn_bitrated. It also
  fixes a W=1 error while building cper.

v2:
- It fixes the way printks are handled on both cper_arm and ghes
  drivers.

v1: 
- (tagged as RFC) was mostly to give a heads up that the current 
  implementation is not following the spec. It also touches
  only cper code.




Mauro Carvalho Chehab (4):
  efi/cper: Adjust infopfx size to accept an extra space
  efi/cper: Add a new helper function to print bitmasks
  efi/cper: align ARM CPER type with UEFI 2.9A/2.10 specs
  docs: efi: add CPER functions to driver-api

 .../driver-api/firmware/efi/index.rst         | 11 ++--
 drivers/acpi/apei/ghes.c                      | 15 +++---
 drivers/firmware/efi/cper-arm.c               | 52 +++++++++----------
 drivers/firmware/efi/cper.c                   | 41 ++++++++++++++-
 include/linux/cper.h                          | 12 +++--
 5 files changed, 89 insertions(+), 42 deletions(-)

-- 
2.45.2

[PATCH v5 4/4] docs: efi: add CPER functions to driver-api

[Mauro Carvalho Chehab]

There are two kernel-doc like descriptions at cper, which is used
by other parts of cper and on ghes driver. They both have kernel-doc
like descriptions.

Change the tags for them to be actual kernel-doc tags and add them
to the driver-api documentaion at the UEFI section.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 Documentation/driver-api/firmware/efi/index.rst | 11 ++++++++---
 drivers/firmware/efi/cper.c                     | 10 ++++------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/Documentation/driver-api/firmware/efi/index.rst b/Documentation/driver-api/firmware/efi/index.rst
index 4fe8abba9fc6..5a6b6229592c 100644
--- a/Documentation/driver-api/firmware/efi/index.rst
+++ b/Documentation/driver-api/firmware/efi/index.rst
@@ -1,11 +1,16 @@
 .. SPDX-License-Identifier: GPL-2.0
 
-============
-UEFI Support
-============
+====================================================
+Unified Extensible Firmware Interface (UEFI) Support
+====================================================
 
 UEFI stub library functions
 ===========================
 
 .. kernel-doc:: drivers/firmware/efi/libstub/mem.c
    :internal:
+
+UEFI Common Platform Error Record (CPER) functions
+==================================================
+
+.. kernel-doc:: drivers/firmware/efi/cper.c
diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index 4cf56657afde..c8a432c5cb5d 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -69,7 +69,7 @@ const char *cper_severity_str(unsigned int severity)
 }
 EXPORT_SYMBOL_GPL(cper_severity_str);
 
-/*
+/**
  * cper_print_bits - print strings for set bits
  * @pfx: prefix for each line, including log level and prefix string
  * @bits: bit mask
@@ -106,18 +106,16 @@ void cper_print_bits(const char *pfx, unsigned int bits,
 		printk("%s\n", buf);
 }
 
-/*
+/**
  * cper_bits_to_str - return a string for set bits
  * @buf: buffer to store the output string
  * @buf_size: size of the output string buffer
  * @bits: bit mask
  * @strs: string array, indexed by bit position
  * @strs_size: size of the string array: @strs
- * @mask: a continuous bitmask used to detect the first valid bit of the
- *        bitmap.
  *
- * Add to @buf the bitmask in hexadecimal. Then, for each set bit in @bits
- * mask, add the corresponding string describing the bit in @strs to @buf.
+ * Add to @buf the bitmask in hexadecimal. Then, for each set bit in @bits,
+ * add the corresponding string describing the bit in @strs to @buf.
  */
 char *cper_bits_to_str(char *buf, int buf_size, unsigned long bits,
 		       const char * const strs[], unsigned int strs_size)
-- 
2.45.2