xtensa: clean up exception handling structure

Instead of using flat array of longs use normal C structure and generate
EXC_TABLE_* constants in the asm-offsets.c
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/ptrace.h

@@ -39,18 +39,6 @@
  *		+-----------------------+ --------
  */
 
-/*  Offsets for exception_handlers[] (3 x 64-entries x 4-byte tables). */
-
-#define EXC_TABLE_KSTK		0x004	/* Kernel Stack */
-#define EXC_TABLE_DOUBLE_SAVE	0x008	/* Double exception save area for a0 */
-#define EXC_TABLE_FIXUP		0x00c	/* Fixup handler */
-#define EXC_TABLE_PARAM		0x010	/* For passing a parameter to fixup */
-#define EXC_TABLE_SYSCALL_SAVE	0x014	/* For fast syscall handler */
-#define EXC_TABLE_FAST_USER	0x100	/* Fast user exception handler */
-#define EXC_TABLE_FAST_KERNEL	0x200	/* Fast kernel exception handler */
-#define EXC_TABLE_DEFAULT	0x300	/* Default C-Handler */
-#define EXC_TABLE_SIZE		0x400
-
 #ifndef __ASSEMBLY__
 
 #include <asm/coprocessor.h>

arch/xtensa/include/asm/regs.h

@@ -76,6 +76,7 @@
 #define EXCCAUSE_COPROCESSOR5_DISABLED		37
 #define EXCCAUSE_COPROCESSOR6_DISABLED		38
 #define EXCCAUSE_COPROCESSOR7_DISABLED		39
+#define EXCCAUSE_N				64
 
 /*  PS register fields.  */
 

arch/xtensa/include/asm/traps.h

@@ -12,6 +12,29 @@
 
 #include <asm/ptrace.h>
 
+/*
+ * Per-CPU exception handling data structure.
+ * EXCSAVE1 points to it.
+ */
+struct exc_table {
+	/* Kernel Stack */
+	void *kstk;
+	/* Double exception save area for a0 */
+	unsigned long double_save;
+	/* Fixup handler */
+	void *fixup;
+	/* For passing a parameter to fixup */
+	void *fixup_param;
+	/* For fast syscall handler */
+	unsigned long syscall_save;
+	/* Fast user exception handlers */
+	void *fast_user_handler[EXCCAUSE_N];
+	/* Fast kernel exception handlers */
+	void *fast_kernel_handler[EXCCAUSE_N];
+	/* Default C-Handlers */
+	void *default_handler[EXCCAUSE_N];
+};
+
 /*
  * handler must be either of the following:
  *  void (*)(struct pt_regs *regs);

arch/xtensa/kernel/asm-offsets.c

@@ -132,5 +132,18 @@ int main(void)
 	       offsetof(struct debug_table, icount_level_save));
 #endif
 
+	/* struct exc_table */
+	DEFINE(EXC_TABLE_KSTK, offsetof(struct exc_table, kstk));
+	DEFINE(EXC_TABLE_DOUBLE_SAVE, offsetof(struct exc_table, double_save));
+	DEFINE(EXC_TABLE_FIXUP, offsetof(struct exc_table, fixup));
+	DEFINE(EXC_TABLE_PARAM, offsetof(struct exc_table, fixup_param));
+	DEFINE(EXC_TABLE_SYSCALL_SAVE,
+	       offsetof(struct exc_table, syscall_save));
+	DEFINE(EXC_TABLE_FAST_USER,
+	       offsetof(struct exc_table, fast_user_handler));
+	DEFINE(EXC_TABLE_FAST_KERNEL,
+	       offsetof(struct exc_table, fast_kernel_handler));
+	DEFINE(EXC_TABLE_DEFAULT, offsetof(struct exc_table, default_handler));
+
 	return 0;
 }

arch/xtensa/kernel/traps.c

@@ -159,8 +159,7 @@ COPROCESSOR(7),
  * 2. it is a temporary memory buffer for the exception handlers.
  */
 
-DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
-
+DEFINE_PER_CPU(struct exc_table, exc_table);
 DEFINE_PER_CPU(struct debug_table, debug_table);
 
 void die(const char*, struct pt_regs*, long);
@@ -368,28 +367,28 @@ do_debug(struct pt_regs *regs)
 }
 
 
-static void set_handler(int idx, void *handler)
-{
-	unsigned int cpu;
-
-	for_each_possible_cpu(cpu)
-		per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
-}
+#define set_handler(type, cause, handler)				\
+	do {								\
+		unsigned int cpu;					\
+									\
+		for_each_possible_cpu(cpu)				\
+			per_cpu(exc_table, cpu).type[cause] = (handler);\
+	} while (0)
 
 /* Set exception C handler - for temporary use when probing exceptions */
 
 void * __init trap_set_handler(int cause, void *handler)
 {
-	void *previous = (void *)per_cpu(exc_table, 0)[
-		EXC_TABLE_DEFAULT / 4 + cause];
-	set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
+	void *previous = per_cpu(exc_table, 0).default_handler[cause];
+
+	set_handler(default_handler, cause, handler);
 	return previous;
 }
 
 
 static void trap_init_excsave(void)
 {
-	unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
+	unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
 	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 }
 
@@ -421,10 +420,10 @@ void __init trap_init(void)
 
 	/* Setup default vectors. */
 
-	for(i = 0; i < 64; i++) {
-		set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
-		set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
-		set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
+	for (i = 0; i < EXCCAUSE_N; i++) {
+		set_handler(fast_user_handler, i, user_exception);
+		set_handler(fast_kernel_handler, i, kernel_exception);
+		set_handler(default_handler, i, do_unhandled);
 	}
 
 	/* Setup specific handlers. */
@@ -436,11 +435,11 @@ void __init trap_init(void)
 		void *handler = dispatch_init_table[i].handler;
 
 		if (fast == 0)
-			set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
+			set_handler(default_handler, cause, handler);
 		if (fast && fast & USER)
-			set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
+			set_handler(fast_user_handler, cause, handler);
 		if (fast && fast & KRNL)
-			set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
+			set_handler(fast_kernel_handler, cause, handler);
 	}
 
 	/* Initialize EXCSAVE_1 to hold the address of the exception table. */