linux-kernel - [PATCH 2/3] x86/MCE: Cleanup and complete struct mce fields definitions

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Date:   Tue,  6 Mar 2018 15:21:42 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     Tony Luck <tony.luck@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/3] x86/MCE: Cleanup and complete struct mce fields definitions

From: Borislav Petkov <bp@...e.de>

Struct is part of the uapi, document that fact and all fields properly
and fix formatting.

No functionality change.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/uapi/asm/mce.h | 52 ++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/uapi/asm/mce.h b/arch/x86/include/uapi/asm/mce.h
index 435db58a7bad..955c2a2e1cf9 100644
--- a/arch/x86/include/uapi/asm/mce.h
+++ b/arch/x86/include/uapi/asm/mce.h
@@ -5,32 +5,36 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 
-/* Fields are zero when not available */
+/*
+ * Fields are zero when not available. Also, this struct is shared with
+ * userspace mcelog and thus must keep existing fields at current offsets.
+ * Only add new fields to the end of the structure
+ */
 struct mce {
-	__u64 status;
-	__u64 misc;
-	__u64 addr;
-	__u64 mcgstatus;
-	__u64 ip;
-	__u64 tsc;	/* cpu time stamp counter */
-	__u64 time;	/* wall time_t when error was detected */
-	__u8  cpuvendor;	/* cpu vendor as encoded in system.h */
-	__u8  inject_flags;	/* software inject flags */
-	__u8  severity;
+	__u64 status;		/* Bank's MCi_STATUS MSR */
+	__u64 misc;		/* Bank's MCi_MISC MSR */
+	__u64 addr;		/* Bank's MCi_ADDR MSR */
+	__u64 mcgstatus;	/* Machine Check Global Status MSR */
+	__u64 ip;		/* Instruction Pointer when the error happened */
+	__u64 tsc;		/* CPU time stamp counter */
+	__u64 time;		/* Wall time_t when error was detected */
+	__u8  cpuvendor;	/* Kernel's X86_VENDOR enum */
+	__u8  inject_flags;	/* Software inject flags */
+	__u8  severity;		/* Error severity */
 	__u8  pad;
-	__u32 cpuid;	/* CPUID 1 EAX */
-	__u8  cs;		/* code segment */
-	__u8  bank;	/* machine check bank */
-	__u8  cpu;	/* cpu number; obsolete; use extcpu now */
-	__u8  finished;   /* entry is valid */
-	__u32 extcpu;	/* linux cpu number that detected the error */
-	__u32 socketid;	/* CPU socket ID */
-	__u32 apicid;	/* CPU initial apic ID */
-	__u64 mcgcap;	/* MCGCAP MSR: machine check capabilities of CPU */
-	__u64 synd;	/* MCA_SYND MSR: only valid on SMCA systems */
-	__u64 ipid;	/* MCA_IPID MSR: only valid on SMCA systems */
-	__u64 ppin;	/* Protected Processor Inventory Number */
-	__u32 microcode;/* Microcode revision */
+	__u32 cpuid;		/* CPUID 1 EAX */
+	__u8  cs;		/* Code segment */
+	__u8  bank;		/* Machine check bank reporting the error */
+	__u8  cpu;		/* CPU number; obsoleted by extcpu */
+	__u8  finished;		/* Entry is valid */
+	__u32 extcpu;		/* Linux CPU number that detected the error */
+	__u32 socketid;		/* CPU socket ID */
+	__u32 apicid;		/* CPU initial APIC ID */
+	__u64 mcgcap;		/* MCGCAP MSR: machine check capabilities of CPU */
+	__u64 synd;		/* MCA_SYND MSR: only valid on SMCA systems */
+	__u64 ipid;		/* MCA_IPID MSR: only valid on SMCA systems */
+	__u64 ppin;		/* Protected Processor Inventory Number */
+	__u32 microcode;	/* Microcode revision */
 };
 
 #define MCE_GET_RECORD_LEN   _IOR('M', 1, int)
-- 
2.13.0