powerpc/slb: Define an enum for the bolted indexes

This patch defines macros for the three bolted SLB indexes we use.
Switch the functions that take the indexes as an argument to use the
enum.

Signed-off-by: Anshuman Khandual <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/mm/slb.c

···
 #include <asm/udbg.h>
 #include <asm/code-patching.h>
 
+enum slb_index {
+	LINEAR_INDEX	= 0, /* Kernel linear map  (0xc000000000000000) */
+	VMALLOC_INDEX	= 1, /* Kernel virtual map (0xd000000000000000) */
+	KSTACK_INDEX	= 2, /* Kernel stack map */
+};
 
 extern void slb_allocate_realmode(unsigned long ea);
 extern void slb_allocate_user(unsigned long ea);
···
 	(((ssize) == MMU_SEGSIZE_256M)? ESID_MASK: ESID_MASK_1T)
 
 static inline unsigned long mk_esid_data(unsigned long ea, int ssize,
-					 unsigned long entry)
+					 enum slb_index index)
 {
-	return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | entry;
+	return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | index;
 }
 
 static inline unsigned long mk_vsid_data(unsigned long ea, int ssize,
···
 
 static inline void slb_shadow_update(unsigned long ea, int ssize,
 				     unsigned long flags,
-				     unsigned long entry)
+				     enum slb_index index)
 {
 	/*
 	 * Clear the ESID first so the entry is not valid while we are
 	 * updating it.  No write barriers are needed here, provided
 	 * we only update the current CPU's SLB shadow buffer.
 	 */
-	get_slb_shadow()->save_area[entry].esid = 0;
-	get_slb_shadow()->save_area[entry].vsid =
+	get_slb_shadow()->save_area[index].esid = 0;
+	get_slb_shadow()->save_area[index].vsid =
 				cpu_to_be64(mk_vsid_data(ea, ssize, flags));
-	get_slb_shadow()->save_area[entry].esid =
-				cpu_to_be64(mk_esid_data(ea, ssize, entry));
+	get_slb_shadow()->save_area[index].esid =
+				cpu_to_be64(mk_esid_data(ea, ssize, index));
 }
 
-static inline void slb_shadow_clear(unsigned long entry)
+static inline void slb_shadow_clear(enum slb_index index)
 {
-	get_slb_shadow()->save_area[entry].esid = 0;
+	get_slb_shadow()->save_area[index].esid = 0;
 }
 
 static inline void create_shadowed_slbe(unsigned long ea, int ssize,
 					unsigned long flags,
-					unsigned long entry)
+					enum slb_index index)
 {
 	/*
 	 * Updating the shadow buffer before writing the SLB ensures
 	 * we don't get a stale entry here if we get preempted by PHYP
 	 * between these two statements.
 	 */
-	slb_shadow_update(ea, ssize, flags, entry);
+	slb_shadow_update(ea, ssize, flags, index);
 
 	asm volatile("slbmte  %0,%1" :
 		     : "r" (mk_vsid_data(ea, ssize, flags)),
-		       "r" (mk_esid_data(ea, ssize, entry))
+		       "r" (mk_esid_data(ea, ssize, index))
 		     : "memory" );
 }
 
···
 	lflags = SLB_VSID_KERNEL | linear_llp;
 	vflags = SLB_VSID_KERNEL | vmalloc_llp;
 
-	ksp_esid_data = mk_esid_data(get_paca()->kstack, mmu_kernel_ssize, 2);
+	ksp_esid_data = mk_esid_data(get_paca()->kstack, mmu_kernel_ssize, KSTACK_INDEX);
 	if ((ksp_esid_data & ~0xfffffffUL) <= PAGE_OFFSET) {
 		ksp_esid_data &= ~SLB_ESID_V;
 		ksp_vsid_data = 0;
-		slb_shadow_clear(2);
+		slb_shadow_clear(KSTACK_INDEX);
 	} else {
 		/* Update stack entry; others don't change */
-		slb_shadow_update(get_paca()->kstack, mmu_kernel_ssize, lflags, 2);
+		slb_shadow_update(get_paca()->kstack, mmu_kernel_ssize, lflags, KSTACK_INDEX);
 		ksp_vsid_data =
-			be64_to_cpu(get_slb_shadow()->save_area[2].vsid);
+			be64_to_cpu(get_slb_shadow()->save_area[KSTACK_INDEX].vsid);
 	}
 
 	/* We need to do this all in asm, so we're sure we don't touch
···
 	unsigned long vflags;
 
 	vflags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmalloc_psize].sllp;
-	slb_shadow_update(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
+	slb_shadow_update(VMALLOC_START, mmu_kernel_ssize, vflags, VMALLOC_INDEX);
 	slb_flush_and_rebolt();
 }
 
···
 	asm volatile("isync":::"memory");
 	asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
 	asm volatile("isync; slbia; isync":::"memory");
-	create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, 0);
-	create_shadowed_slbe(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
+	create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, LINEAR_INDEX);
+	create_shadowed_slbe(VMALLOC_START, mmu_kernel_ssize, vflags, VMALLOC_INDEX);
 
 	/* For the boot cpu, we're running on the stack in init_thread_union,
 	 * which is in the first segment of the linear mapping, and also
 	 * get_paca()->kstack hasn't been initialized yet.
 	 * For secondary cpus, we need to bolt the kernel stack entry now.
 	 */
-	slb_shadow_clear(2);
+	slb_shadow_clear(KSTACK_INDEX);
 	if (raw_smp_processor_id() != boot_cpuid &&
 	    (get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) > PAGE_OFFSET)
 		create_shadowed_slbe(get_paca()->kstack,
-				     mmu_kernel_ssize, lflags, 2);
+				     mmu_kernel_ssize, lflags, KSTACK_INDEX);
 
 	asm volatile("isync":::"memory");
 }