[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, 87 insertions, 15 deletions

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 0473953f6a37..60e852f2f8e5 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -14,14 +14,32 @@
  *      2 of the License, or (at your option) any later version.
  */
 
+#undef DEBUG
+
 #include <linux/config.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>
 #include <asm/mmu_context.h>
 #include <asm/paca.h>
 #include <asm/cputable.h>
+#include <asm/cacheflush.h>
+
+#ifdef DEBUG
+#define DBG(fmt...) udbg_printf(fmt)
+#else
+#define DBG(fmt...)
+#endif
 
-extern void slb_allocate(unsigned long ea);
+extern void slb_allocate_realmode(unsigned long ea);
+extern void slb_allocate_user(unsigned long ea);
+
+static void slb_allocate(unsigned long ea)
+{
+        /* Currently, we do real mode for all SLBs including user, but
+         * that will change if we bring back dynamic VSIDs
+         */
+        slb_allocate_realmode(ea);
+}
 
 static inline unsigned long mk_esid_data(unsigned long ea, unsigned long slot)
 {
@@ -46,13 +64,15 @@ static void slb_flush_and_rebolt(void)
 {
         /* If you change this make sure you change SLB_NUM_BOLTED
          * appropriately too. */
-        unsigned long ksp_flags = SLB_VSID_KERNEL;
+        unsigned long linear_llp, virtual_llp, lflags, vflags;
         unsigned long ksp_esid_data;
 
         WARN_ON(!irqs_disabled());
 
-        if (cpu_has_feature(CPU_FTR_16M_PAGE))
-                ksp_flags |= SLB_VSID_L;
+        linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
+        virtual_llp = mmu_psize_defs[mmu_virtual_psize].sllp;
+        lflags = SLB_VSID_KERNEL | linear_llp;
+        vflags = SLB_VSID_KERNEL | virtual_llp;
 
         ksp_esid_data = mk_esid_data(get_paca()->kstack, 2);
         if ((ksp_esid_data & ESID_MASK) == KERNELBASE)
@@ -67,9 +87,9 @@ static void slb_flush_and_rebolt(void)
                      /* Slot 2 - kernel stack */
                      "slbmte    %2,%3\n"
                      "isync"
-                     :: "r"(mk_vsid_data(VMALLOCBASE, SLB_VSID_KERNEL)),
+                     :: "r"(mk_vsid_data(VMALLOCBASE, vflags)),
                         "r"(mk_esid_data(VMALLOCBASE, 1)),
-                        "r"(mk_vsid_data(ksp_esid_data, ksp_flags)),
+                        "r"(mk_vsid_data(ksp_esid_data, lflags)),
                         "r"(ksp_esid_data)
                      : "memory");
 }
@@ -102,6 +122,9 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
 
         get_paca()->slb_cache_ptr = 0;
         get_paca()->context = mm->context;
+#ifdef CONFIG_PPC_64K_PAGES
+        get_paca()->pgdir = mm->pgd;
+#endif /* CONFIG_PPC_64K_PAGES */
 
         /*
          * preload some userspace segments into the SLB.
@@ -131,28 +154,77 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
         slb_allocate(unmapped_base);
 }
 
+static inline void patch_slb_encoding(unsigned int *insn_addr,
+                                      unsigned int immed)
+{
+        /* Assume the instruction had a "0" immediate value, just
+         * "or" in the new value
+         */
+        *insn_addr |= immed;
+        flush_icache_range((unsigned long)insn_addr, 4+
+                           (unsigned long)insn_addr);
+}
+
 void slb_initialize(void)
 {
+        unsigned long linear_llp, virtual_llp;
+        static int slb_encoding_inited;
+        extern unsigned int *slb_miss_kernel_load_linear;
+        extern unsigned int *slb_miss_kernel_load_virtual;
+        extern unsigned int *slb_miss_user_load_normal;
+#ifdef CONFIG_HUGETLB_PAGE
+        extern unsigned int *slb_miss_user_load_huge;
+        unsigned long huge_llp;
+
+        huge_llp = mmu_psize_defs[mmu_huge_psize].sllp;
+#endif
+
+        /* Prepare our SLB miss handler based on our page size */
+        linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
+        virtual_llp = mmu_psize_defs[mmu_virtual_psize].sllp;
+        if (!slb_encoding_inited) {
+                slb_encoding_inited = 1;
+                patch_slb_encoding(slb_miss_kernel_load_linear,
+                                   SLB_VSID_KERNEL | linear_llp);
+                patch_slb_encoding(slb_miss_kernel_load_virtual,
+                                   SLB_VSID_KERNEL | virtual_llp);
+                patch_slb_encoding(slb_miss_user_load_normal,
+                                   SLB_VSID_USER | virtual_llp);
+
+                DBG("SLB: linear  LLP = %04x\n", linear_llp);
+                DBG("SLB: virtual LLP = %04x\n", virtual_llp);
+#ifdef CONFIG_HUGETLB_PAGE
+                patch_slb_encoding(slb_miss_user_load_huge,
+                                   SLB_VSID_USER | huge_llp);
+                DBG("SLB: huge    LLP = %04x\n", huge_llp);
+#endif
+        }
+
         /* On iSeries the bolted entries have already been set up by
          * the hypervisor from the lparMap data in head.S */
 #ifndef CONFIG_PPC_ISERIES
-        unsigned long flags = SLB_VSID_KERNEL;
+ {
+        unsigned long lflags, vflags;
 
-        /* Invalidate the entire SLB (even slot 0) & all the ERATS */
-        if (cpu_has_feature(CPU_FTR_16M_PAGE))
-                flags |= SLB_VSID_L;
+        lflags = SLB_VSID_KERNEL | linear_llp;
+        vflags = SLB_VSID_KERNEL | virtual_llp;
 
-        asm volatile("isync":::"memory");
-        asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
+        /* Invalidate the entire SLB (even slot 0) & all the ERATS */
+        asm volatile("isync":::"memory");
+        asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
         asm volatile("isync; slbia; isync":::"memory");
-        create_slbe(KERNELBASE, flags, 0);
-        create_slbe(VMALLOCBASE, SLB_VSID_KERNEL, 1);
+        create_slbe(KERNELBASE, lflags, 0);
+
+        /* VMALLOC space has 4K pages always for now */
+        create_slbe(VMALLOCBASE, vflags, 1);
+
         /* We don't bolt the stack for the time being - we're in boot,
          * so the stack is in the bolted segment.  By the time it goes
          * elsewhere, we'll call _switch() which will bolt in the new
          * one. */
         asm volatile("isync":::"memory");
-#endif
+ }
+#endif /* CONFIG_PPC_ISERIES */
 
         get_paca()->stab_rr = SLB_NUM_BOLTED;
 }