tracing: Add the ::ppin field to the mce_record tracepoint

Machine Check Error information from 'struct mce' is exposed to userspace
through the mce_record tracepoint.

Currently, however, the PPIN (Protected Processor Inventory Number) field
of 'struct mce' is not exposed.

Add a PPIN field to the tracepoint as it provides a unique identifier for
the system (or socket in case of multi-socket systems) on which the MCE
has been received.

Also, add a comment explaining the kind of information that can be and
should be added to the tracepoint.
Signed-off-by: Avadhut Naik <avadhut.naik@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20240401171455.1737976-2-avadhut.naik@amd.com

include/trace/events/mce.h

@@ -9,6 +9,14 @@
 #include <linux/tracepoint.h>
 #include <asm/mce.h>
 
+/*
+ * MCE Event Record.
+ *
+ * Only very relevant and transient information which cannot be
+ * gathered from a system by any other means or which can only be
+ * acquired arduously should be added to this record.
+ */
+
 TRACE_EVENT(mce_record,
 
 	TP_PROTO(struct mce *m),
@@ -25,6 +33,7 @@ TRACE_EVENT(mce_record,
 		__field(	u64,		ipid		)
 		__field(	u64,		ip		)
 		__field(	u64,		tsc		)
+		__field(	u64,		ppin		)
 		__field(	u64,		walltime	)
 		__field(	u32,		cpu		)
 		__field(	u32,		cpuid		)
@@ -45,6 +54,7 @@ TRACE_EVENT(mce_record,
 		__entry->ipid		= m->ipid;
 		__entry->ip		= m->ip;
 		__entry->tsc		= m->tsc;
+		__entry->ppin		= m->ppin;
 		__entry->walltime	= m->time;
 		__entry->cpu		= m->extcpu;
 		__entry->cpuid		= m->cpuid;
@@ -55,7 +65,7 @@ TRACE_EVENT(mce_record,
 		__entry->cpuvendor	= m->cpuvendor;
 	),
 
-	TP_printk("CPU: %d, MCGc/s: %llx/%llx, MC%d: %016Lx, IPID: %016Lx, ADDR: %016Lx, MISC: %016Lx, SYND: %016Lx, RIP: %02x:<%016Lx>, TSC: %llx, vendor: %u, CPUID: %x, time: %llu, socket: %u, APIC: %x",
+	TP_printk("CPU: %d, MCGc/s: %llx/%llx, MC%d: %016Lx, IPID: %016Lx, ADDR: %016Lx, MISC: %016Lx, SYND: %016Lx, RIP: %02x:<%016Lx>, TSC: %llx, PPIN: %llx, vendor: %u, CPUID: %x, time: %llu, socket: %u, APIC: %x",
 		__entry->cpu,
 		__entry->mcgcap, __entry->mcgstatus,
 		__entry->bank, __entry->status,
@@ -65,6 +75,7 @@ TRACE_EVENT(mce_record,
 		__entry->synd,
 		__entry->cs, __entry->ip,
 		__entry->tsc,
+		__entry->ppin,
 		__entry->cpuvendor,
 		__entry->cpuid,
 		__entry->walltime,