[PATCH v2 1/4] powerpc: Optimize register usage for esr register

[sxwjean]

From: Xiongwei Song <sxwjean@xxxxxxxxx>

Create an anonymous union for dsisr and esr regsiters, we can reference
esr to get the exception detail when CONFIG_4xx=y or CONFIG_BOOKE=y.
Otherwise, reference dsisr. This makes code more clear.

Signed-off-by: Xiongwei Song <sxwjean@xxxxxxxxx>
---
 arch/powerpc/include/asm/ptrace.h          | 5 ++++-
 arch/powerpc/kernel/process.c              | 2 +-
 arch/powerpc/kernel/ptrace/ptrace.c        | 2 ++
 arch/powerpc/kernel/traps.c                | 2 +-
 arch/powerpc/platforms/44x/machine_check.c | 4 ++--
 arch/powerpc/platforms/4xx/machine_check.c | 2 +-
 6 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 3e5d470a6155..c252d04b1206 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -44,7 +44,10 @@ struct pt_regs
 #endif
 			unsigned long trap;
 			unsigned long dar;
-			unsigned long dsisr;
+			union {
+				unsigned long dsisr;
+				unsigned long esr;
+			};
 			unsigned long result;
 		};
 	};
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 185beb290580..f74af8f9133c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1499,7 +1499,7 @@ static void __show_regs(struct pt_regs *regs)
 	    trap == INTERRUPT_DATA_STORAGE ||
 	    trap == INTERRUPT_ALIGNMENT) {
 		if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
-			pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar, regs->dsisr);
+			pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar, regs->esr);
 		else
 			pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
 	}
diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index 0a0a33eb0d28..a222fd4d6334 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c
@@ -375,6 +375,8 @@ void __init pt_regs_check(void)
 		     offsetof(struct user_pt_regs, dar));
 	BUILD_BUG_ON(offsetof(struct pt_regs, dsisr) !=
 		     offsetof(struct user_pt_regs, dsisr));
+	BUILD_BUG_ON(offsetof(struct pt_regs, esr) !=
+		     offsetof(struct user_pt_regs, dsisr));
 	BUILD_BUG_ON(offsetof(struct pt_regs, result) !=
 		     offsetof(struct user_pt_regs, result));
 
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index dfbce527c98e..2164f5705a0b 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -562,7 +562,7 @@ static inline int check_io_access(struct pt_regs *regs)
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 /* On 4xx, the reason for the machine check or program exception
    is in the ESR. */
-#define get_reason(regs)	((regs)->dsisr)
+#define get_reason(regs)	((regs)->esr)
 #define REASON_FP		ESR_FP
 #define REASON_ILLEGAL		(ESR_PIL | ESR_PUO)
 #define REASON_PRIVILEGED	ESR_PPR
diff --git a/arch/powerpc/platforms/44x/machine_check.c b/arch/powerpc/platforms/44x/machine_check.c
index a5c898bb9bab..5d19daacd78a 100644
--- a/arch/powerpc/platforms/44x/machine_check.c
+++ b/arch/powerpc/platforms/44x/machine_check.c
@@ -11,7 +11,7 @@
 
 int machine_check_440A(struct pt_regs *regs)
 {
-	unsigned long reason = regs->dsisr;
+	unsigned long reason = regs->esr;
 
 	printk("Machine check in kernel mode.\n");
 	if (reason & ESR_IMCP){
@@ -48,7 +48,7 @@ int machine_check_440A(struct pt_regs *regs)
 #ifdef CONFIG_PPC_47x
 int machine_check_47x(struct pt_regs *regs)
 {
-	unsigned long reason = regs->dsisr;
+	unsigned long reason = regs->esr;
 	u32 mcsr;
 
 	printk(KERN_ERR "Machine check in kernel mode.\n");
diff --git a/arch/powerpc/platforms/4xx/machine_check.c b/arch/powerpc/platforms/4xx/machine_check.c
index a71c29892a91..a905da1d6f41 100644
--- a/arch/powerpc/platforms/4xx/machine_check.c
+++ b/arch/powerpc/platforms/4xx/machine_check.c
@@ -10,7 +10,7 @@
 
 int machine_check_4xx(struct pt_regs *regs)
 {
-	unsigned long reason = regs->dsisr;
+	unsigned long reason = regs->esr;
 
 	if (reason & ESR_IMCP) {
 		printk("Instruction");
-- 
2.30.2