objtool: Validate disassembler headers in libopcodes probegrafted

commit 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
tested for libopcodes availability by linking a test snippet with a forward
declaration of disassemble_init_for_target().

However, testing symbol linkage with an extern declaration only verifies
the presence of the library (.so/.a) and bypasses checking for development
headers (binutils-dev). On systems where libopcodes is present without
development headers installed, the probe succeeds, enabling BUILD_DISAS.
Subsequent compilation of objtool then fails:

  fatal error: 'bfd.h' file not found
    113 | #include <bfd.h>

Additionally, the probe invokes $(HOSTCC) without $(HOSTCFLAGS), ignoring
any sysroot or include flags specified for the host compiler.

Fix this by including <bfd.h> and <dis-asm.h> directly in the test snippet,
passing $(HOSTCFLAGS) so host compiler options are respected, and defining
PACKAGE="objtool" to satisfy the configuration check in <bfd.h>.

Fixes: 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
Fixes: 436326bc525d ("objtool: fix build failure due to missing libopcodes check")
Reported-by: Alice Ryhl <aliceryhl@google.com>
Assisted-by: Antigravity:Gemini-Next
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
Link: https://patch.msgid.link/20260904150710.2997558-1-umendez@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/Documentation/driver-api/hw-recoverable-errors.rst b/Documentation/driver-api/hw-recoverable-errors.rst
new file mode 100644
index 000000000..fc526c345
--- /dev/null
+++ b/Documentation/driver-api/hw-recoverable-errors.rst
@@ -0,0 +1,60 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================================
+Recoverable Hardware Error Tracking in vmcoreinfo
+=================================================
+
+Overview
+--------
+
+This feature provides a generic infrastructure within the Linux kernel to track
+and log recoverable hardware errors. These are hardware recoverable errors
+visible that might not cause immediate panics but may influence health, mainly
+because new code path will be executed in the kernel.
+
+By recording counts and timestamps of recoverable errors into the vmcoreinfo
+crash dump notes, this infrastructure aids post-mortem crash analysis tools in
+correlating hardware events with kernel failures. This enables faster triage
+and better understanding of root causes, especially in large-scale cloud
+environments where hardware issues are common.
+
+Benefits
+--------
+
+- Facilitates correlation of hardware recoverable errors with kernel panics or
+  unusual code paths that lead to system crashes.
+- Provides operators and cloud providers quick insights, improving reliability
+  and reducing troubleshooting time.
+- Complements existing full hardware diagnostics without replacing them.
+
+Data Exposure and Consumption
+-----------------------------
+
+- The tracked error data consists of per-error-type counts and timestamps of
+  last occurrence.
+- This data is stored in the `hwerror_data` array, categorized by error source
+  types like CPU, memory, PCI, CXL, and others.
+- It is exposed via vmcoreinfo crash dump notes and can be read using tools
+  like `crash`, `drgn`, or other kernel crash analysis utilities.
+- There is no other way to read these data other than from crash dumps.
+- These errors are divided by area, which includes CPU, Memory, PCI, CXL and
+  others.
+
+Typical usage example (in drgn REPL):
+
+.. code-block:: python
+
+    >>> prog['hwerror_data']
+    (struct hwerror_info[HWERR_RECOV_MAX]){
+        {
+            .count = (int)844,
+            .timestamp = (time64_t)1752852018,
+        },
+        ...
+    }
+
+Enabling
+--------
+
+- This feature is enabled when CONFIG_VMCORE_INFO is set.
+