[PATCH] ppc64: support 64k pages

Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel
base page size to 64K.  The resulting kernel still boots on any
hardware.  On current machines with 4K pages support only, the kernel
will maintain 16 "subpages" for each 64K page transparently.

Note that while real 64K capable HW has been tested, the current patch
will not enable it yet as such hardware is not released yet, and I'm
still verifying with the firmware architects the proper to get the
information from the newer hypervisors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 15 deletions

diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
index 1b83f002bf27..fa325dbf98fc 100644
--- a/arch/powerpc/mm/stab.c
+++ b/arch/powerpc/mm/stab.c
@@ -26,7 +26,6 @@ struct stab_entry {
         unsigned long vsid_data;
 };
 
-/* Both the segment table and SLB code uses the following cache */
 #define NR_STAB_CACHE_ENTRIES 8
 DEFINE_PER_CPU(long, stab_cache_ptr);
 DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
@@ -186,7 +185,7 @@ void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
                 /* Never flush the first entry. */
                 ste += 1;
                 for (entry = 1;
-                     entry < (PAGE_SIZE / sizeof(struct stab_entry));
+                     entry < (HW_PAGE_SIZE / sizeof(struct stab_entry));
                      entry++, ste++) {
                         unsigned long ea;
                         ea = ste->esid_data & ESID_MASK;
@@ -200,6 +199,10 @@ void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
 
         __get_cpu_var(stab_cache_ptr) = 0;
 
+#ifdef CONFIG_PPC_64K_PAGES
+        get_paca()->pgdir = mm->pgd;
+#endif /* CONFIG_PPC_64K_PAGES */
+
         /* Now preload some entries for the new task */
         if (test_tsk_thread_flag(tsk, TIF_32BIT))
                 unmapped_base = TASK_UNMAPPED_BASE_USER32;
@@ -223,8 +226,6 @@ void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
         asm volatile("sync" : : : "memory");
 }
 
-extern void slb_initialize(void);
-
 /*
  * Allocate segment tables for secondary CPUs.  These must all go in
  * the first (bolted) segment, so that do_stab_bolted won't get a
@@ -243,18 +244,21 @@ void stabs_alloc(void)
                 if (cpu == 0)
                         continue; /* stab for CPU 0 is statically allocated */
 
-                newstab = lmb_alloc_base(PAGE_SIZE, PAGE_SIZE, 1<<SID_SHIFT);
+                newstab = lmb_alloc_base(HW_PAGE_SIZE, HW_PAGE_SIZE,
+                                         1<<SID_SHIFT);
                 if (! newstab)
                         panic("Unable to allocate segment table for CPU %d.\n",
                               cpu);
 
                 newstab += KERNELBASE;
 
-                memset((void *)newstab, 0, PAGE_SIZE);
+                memset((void *)newstab, 0, HW_PAGE_SIZE);
 
                 paca[cpu].stab_addr = newstab;
                 paca[cpu].stab_real = virt_to_abs(newstab);
-                printk(KERN_DEBUG "Segment table for CPU %d at 0x%lx virtual, 0x%lx absolute\n", cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
+                printk(KERN_DEBUG "Segment table for CPU %d at 0x%lx "
+                       "virtual, 0x%lx absolute\n",
+                       cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
         }
 }
 
@@ -267,13 +271,9 @@ void stab_initialize(unsigned long stab)
 {
         unsigned long vsid = get_kernel_vsid(KERNELBASE);
 
-        if (cpu_has_feature(CPU_FTR_SLB)) {
-                slb_initialize();
-        } else {
-                asm volatile("isync; slbia; isync":::"memory");
-                make_ste(stab, GET_ESID(KERNELBASE), vsid);
+        asm volatile("isync; slbia; isync":::"memory");
+        make_ste(stab, GET_ESID(KERNELBASE), vsid);
 
-                /* Order update */
-                asm volatile("sync":::"memory");
-        }
+        /* Order update */
+        asm volatile("sync":::"memory");
 }