[PATCH 1/2] panic: add taint flag for recoverable hardware errors

[Breno Leitao]

This change introduces a new taint flag, bit 20 ('H'), to indicate when
the kernel has identified recoverable hardware failures during runtime.

The flag is documented in tainted-kernels.rst, defined in panic.h, added
to the taint_flags array in panic.c, and supported in the
kernel-chktaint debugging tool.

Marking kernels that have encountered recoverable hardware errors helps
correlate future issues with hardware events, improving diagnostics and
support for affected systems

Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
---
 Documentation/admin-guide/tainted-kernels.rst | 7 ++++++-
 include/linux/panic.h                         | 3 ++-
 kernel/panic.c                                | 1 +
 tools/debugging/kernel-chktaint               | 8 ++++++++
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
index a0cc017e44246..28185e9c0e039 100644
--- a/Documentation/admin-guide/tainted-kernels.rst
+++ b/Documentation/admin-guide/tainted-kernels.rst
@@ -102,7 +102,8 @@ Bit  Log  Number  Reason that got the kernel tainted
  17  _/T  131072  kernel was built with the struct randomization plugin
  18  _/N  262144  an in-kernel test has been run
  19  _/J  524288  userspace used a mutating debug operation in fwctl
-===  ===  ======  ========================================================
+ 20  _/H 1048576  hardware recoverable failures identified
+===  === =======  ========================================================
 
 Note: The character ``_`` is representing a blank in this table to make reading
 easier.
@@ -189,3 +190,7 @@ More detailed explanation for tainting
  19) ``J`` if userpace opened /dev/fwctl/* and performed a FWTCL_RPC_DEBUG_WRITE
      to use the devices debugging features. Device debugging features could
      cause the device to malfunction in undefined ways.
+
+ 20) ``H`` if the kernel identified any recoverable hardware failure earlier
+     during its operation. This helps to correlate possible future issues to
+     the fact that the hardware got a recoverable error.
diff --git a/include/linux/panic.h b/include/linux/panic.h
index 4adc657669354..d8241a052d69a 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -73,7 +73,8 @@ static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 #define TAINT_RANDSTRUCT		17
 #define TAINT_TEST			18
 #define TAINT_FWCTL			19
-#define TAINT_FLAGS_COUNT		20
+#define TAINT_HW_ERROR_RECOVERED	20
+#define TAINT_FLAGS_COUNT		21
 #define TAINT_FLAGS_MAX			((1UL << TAINT_FLAGS_COUNT) - 1)
 
 struct taint_flag {
diff --git a/kernel/panic.c b/kernel/panic.c
index b0b9a8bf4560d..fd13baf5d94bc 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -540,6 +540,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
 	TAINT_FLAG(RANDSTRUCT,			'T', ' ', true),
 	TAINT_FLAG(TEST,			'N', ' ', true),
 	TAINT_FLAG(FWCTL,			'J', ' ', true),
+	TAINT_FLAG(HW_ERROR_RECOVERED,		'H', ' ', false),
 };
 
 #undef TAINT_FLAG
diff --git a/tools/debugging/kernel-chktaint b/tools/debugging/kernel-chktaint
index e7da0909d0970..b2099155a820c 100755
--- a/tools/debugging/kernel-chktaint
+++ b/tools/debugging/kernel-chktaint
@@ -212,6 +212,14 @@ else
 	echo " * fwctl's mutating debug interface was used (#19)"
 fi
 
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+	addout " "
+else
+	addout "H"
+	echo " * the kernel identified recoverable hardware errors (#20)"
+fi
+
 echo "For a more detailed explanation of the various taint flags see"
 echo " Documentation/admin-guide/tainted-kernels.rst in the Linux kernel sources"
 echo " or https://kernel.org/doc/html/latest/admin-guide/tainted-kernels.html";

-- 
2.47.1