cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size

The CXL r4.0 8.2.4.17.7 RAS Capability Structure has total length 0x58
bytes (CXL_RAS_CAPABILITY_LENGTH); the Header Log occupies the trailing
64 bytes at offset 0x18.  CXL_HEADERLOG_SIZE was defined as SZ_512,
eight times the actual on-device size.

header_log_copy() reads CXL_HEADERLOG_SIZE_U32 (128) dwords from the
RAS capability iomap, overrunning the 88-byte mapping by 448 bytes.
The cxl_aer_uncorrectable_error trace event memcpy()s CXL_HEADERLOG_SIZE
(512) bytes from its source.  For the CPER caller the source is
struct cxl_ras_capability_regs::header_log[16] (64 bytes) embedded in a
stack-local cxl_cper_prot_err_work_data, so the memcpy reads 448 bytes
of kernel stack into the trace event ring buffer where userspace can
read it via tracefs.

Set CXL_HEADERLOG_SIZE to 64 and derive CXL_HEADERLOG_SIZE_U32 from it,
bringing all iomap readers into agreement on 16 dwords.  Userspace tools
such as rasdaemon have grown a dependency on the buggy 512-byte (128 u32)
header_log layout in the cxl_aer_uncorrectable_error trace event.  Add
CXL_HEADERLOG_TRACE_SIZE_U32 = 128 and use it for the trace event
__array and its memcpy to preserve that ABI.  Both callers now pass a
zero-filled u32[CXL_HEADERLOG_TRACE_SIZE_U32] staging buffer with only
the first CXL_HEADERLOG_SIZE_U32 (16) entries populated from hardware;
the remaining 112 u32s are zero-padded, keeping the 512-byte trace ring
buffer layout intact.

[ dj: Replaced 64 with SZ_64 per RichardC ]

Fixes: 36f257e3b0ba ("acpi/ghes, cxl/pci: Process CXL CPER Protocol Errors")
Fixes: 2905cb5236cb ("cxl/pci: Add (hopeful) error handling support")
Cc: stable@vger.kernel.org
Reported-by: Sashiko
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ben Cheatham <benjamin.cheatham@amd.com>
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Link: https://patch.msgid.link/20260605180610.2249458-1-terry.bowman@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

0 files changed, 0 insertions, 0 deletions