[POWERPC] Use SLB size from the device tree

Currently we hardwire the number of SLBs to 64, but PAPR says we
should use the ibm,slb-size property to obtain the number of SLB
entries.  This uses this property instead of assuming 64.  If no
property is found, we assume 64 entries as before.

This soft patches the SLB handler, so it shouldn't change performance
at all.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

6 files changed, 25 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index acc0d24..6c2d883 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -583,6 +583,20 @@ static void __init check_cpu_pa_features(unsigned long node)
 		      ibm_pa_features, ARRAY_SIZE(ibm_pa_features));
 }
 
+#ifdef CONFIG_PPC64
+static void __init check_cpu_slb_size(unsigned long node)
+{
+	u32 *slb_size_ptr;
+
+	slb_size_ptr = of_get_flat_dt_prop(node, "ibm,slb-size", NULL);
+	if (slb_size_ptr != NULL) {
+		mmu_slb_size = *slb_size_ptr;
+	}
+}
+#else
+#define check_cpu_slb_size(node) do { } while(0)
+#endif
+
 static struct feature_property {
 	const char *name;
 	u32 min_value;
@@ -713,6 +727,7 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
 
 	check_cpu_feature_properties(node);
 	check_cpu_pa_features(node);
+	check_cpu_slb_size(node);
 
 #ifdef CONFIG_PPC_PSERIES
 	if (nthreads > 1)
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index f09730b..cbbd8b0 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -96,6 +96,7 @@ int mmu_vmalloc_psize = MMU_PAGE_4K;
 int mmu_io_psize = MMU_PAGE_4K;
 int mmu_kernel_ssize = MMU_SEGSIZE_256M;
 int mmu_highuser_ssize = MMU_SEGSIZE_256M;
+u16 mmu_slb_size = 64;
 #ifdef CONFIG_HUGETLB_PAGE
 int mmu_huge_psize = MMU_PAGE_16M;
 unsigned int HPAGE_SHIFT;
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 27922df..3cf0802 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -256,6 +256,7 @@ void slb_initialize(void)
 	static int slb_encoding_inited;
 	extern unsigned int *slb_miss_kernel_load_linear;
 	extern unsigned int *slb_miss_kernel_load_io;
+	extern unsigned int *slb_compare_rr_to_size;
 
 	/* Prepare our SLB miss handler based on our page size */
 	linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
@@ -269,6 +270,8 @@ void slb_initialize(void)
 				   SLB_VSID_KERNEL | linear_llp);
 		patch_slb_encoding(slb_miss_kernel_load_io,
 				   SLB_VSID_KERNEL | io_llp);
+		patch_slb_encoding(slb_compare_rr_to_size,
+				   mmu_slb_size);
 
 		DBG("SLB: linear  LLP = %04x\n", linear_llp);
 		DBG("SLB: io      LLP = %04x\n", io_llp);
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index 1328a81..657f6b3 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -227,8 +227,9 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
 
 7:	ld	r10,PACASTABRR(r13)
 	addi	r10,r10,1
-	/* use a cpu feature mask if we ever change our slb size */
-	cmpldi	r10,SLB_NUM_ENTRIES
+	/* This gets soft patched on boot. */
+_GLOBAL(slb_compare_rr_to_size)
+	cmpldi	r10,0
 
 	blt+	4f
 	li	r10,SLB_NUM_BOLTED
diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
index 5748194..6d7d068 100644
--- a/arch/powerpc/platforms/pasemi/setup.c
+++ b/arch/powerpc/platforms/pasemi/setup.c
@@ -36,6 +36,7 @@
 #include <asm/mpic.h>
 #include <asm/smp.h>
 #include <asm/time.h>
+#include <asm/mmu.h>
 
 #include <pcmcia/ss.h>
 #include <pcmcia/cistpl.h>
@@ -302,7 +303,7 @@ static int pas_machine_check_handler(struct pt_regs *regs)
 		int i;
 
 		printk(KERN_ERR "slb contents:\n");
-		for (i = 0; i < SLB_NUM_ENTRIES; i++) {
+		for (i = 0; i < mmu_slb_size; i++) {
 			asm volatile("slbmfee  %0,%1" : "=r" (e) : "r" (i));
 			asm volatile("slbmfev  %0,%1" : "=r" (v) : "r" (i));
 			printk(KERN_ERR "%02d %016lx %016lx\n", i, e, v);
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 381d467..c60d123 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -2543,7 +2543,7 @@ static void dump_slb(void)
 
 	printf("SLB contents of cpu %x\n", smp_processor_id());
 
-	for (i = 0; i < SLB_NUM_ENTRIES; i++) {
+	for (i = 0; i < mmu_slb_size; i++) {
 		asm volatile("slbmfee  %0,%1" : "=r" (tmp) : "r" (i));
 		printf("%02d %016lx ", i, tmp);