[SPARC64]: Move away from virtual page tables, part 1.

We now use the TSB hardware assist features of the UltraSPARC
MMUs.

SMP is currently knowingly broken, we need to find another place
to store the per-cpu base pointers.  We hid them away in the TSB
base register, and that obviously will not work any more :-)

Another known broken case is non-8KB base page size.

Also noticed that flush_tlb_all() is not referenced anywhere, only
the internal __flush_tlb_all() (local cpu only) is used by the
sparc64 port, so we can get rid of flush_tlb_all().

The kernel gets it's own 8KB TSB (swapper_tsb) and each address space
gets it's own private 8K TSB.  Later we can add code to dynamically
increase the size of per-process TSB as the RSS grows.  An 8KB TSB is
good enough for up to about a 4MB RSS, after which the TSB starts to
incur many capacity and conflict misses.

We even accumulate OBP translations into the kernel TSB.

Another area for refinement is large page size support.  We could use
a secondary address space TSB to handle those.

Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 204 insertions, 57 deletions

diff --git a/include/asm-sparc64/mmu.h b/include/asm-sparc64/mmu.h
index 8627eed..36384cf 100644
--- a/include/asm-sparc64/mmu.h
+++ b/include/asm-sparc64/mmu.h
@@ -92,6 +92,7 @@
 
 typedef struct {
 	unsigned long	sparc64_ctx_val;
+	unsigned long	*sparc64_tsb;
 } mm_context_t;
 
 #endif /* !__ASSEMBLY__ */
diff --git a/include/asm-sparc64/mmu_context.h b/include/asm-sparc64/mmu_context.h
index 57ee7b3..34640a3 100644
--- a/include/asm-sparc64/mmu_context.h
+++ b/include/asm-sparc64/mmu_context.h
@@ -25,7 +25,13 @@ extern void get_new_mmu_context(struct mm_struct *mm);
  * This just needs to set mm->context to an invalid context.
  */
 #define init_new_context(__tsk, __mm)	\
-	(((__mm)->context.sparc64_ctx_val = 0UL), 0)
+({	unsigned long __pg = get_zeroed_page(GFP_KERNEL); \
+	(__mm)->context.sparc64_ctx_val = 0UL; \
+	(__mm)->context.sparc64_tsb = \
+	  (unsigned long *) __pg; \
+	(__pg ? 0 : -ENOMEM); \
+})
+
 
 /* Destroy a dead context.  This occurs when mmput drops the
  * mm_users count to zero, the mmaps have been released, and
@@ -35,7 +41,8 @@ extern void get_new_mmu_context(struct mm_struct *mm);
  * this task if valid.
  */
 #define destroy_context(__mm)					\
-do {	spin_lock(&ctx_alloc_lock);				\
+do {	free_page((unsigned long)(__mm)->context.sparc64_tsb);	\
+	spin_lock(&ctx_alloc_lock);				\
 	if (CTX_VALID((__mm)->context)) {			\
 		unsigned long nr = CTX_NRBITS((__mm)->context);	\
 		mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));	\
@@ -43,35 +50,7 @@ do {	spin_lock(&ctx_alloc_lock);				\
 	spin_unlock(&ctx_alloc_lock);				\
 } while(0)
 
-/* Reload the two core values used by TLB miss handler
- * processing on sparc64.  They are:
- * 1) The physical address of mm->pgd, when full page
- *    table walks are necessary, this is where the
- *    search begins.
- * 2) A "PGD cache".  For 32-bit tasks only pgd[0] is
- *    ever used since that maps the entire low 4GB
- *    completely.  To speed up TLB miss processing we
- *    make this value available to the handlers.  This
- *    decreases the amount of memory traffic incurred.
- */
-#define reload_tlbmiss_state(__tsk, __mm) \
-do { \
-	register unsigned long paddr asm("o5"); \
-	register unsigned long pgd_cache asm("o4"); \
-	paddr = __pa((__mm)->pgd); \
-	pgd_cache = 0UL; \
-	if (task_thread_info(__tsk)->flags & _TIF_32BIT) \
-		pgd_cache = get_pgd_cache((__mm)->pgd); \
-	__asm__ __volatile__("wrpr	%%g0, 0x494, %%pstate\n\t" \
-			     "mov	%3, %%g4\n\t" \
-			     "mov	%0, %%g7\n\t" \
-			     "stxa	%1, [%%g4] %2\n\t" \
-			     "membar	#Sync\n\t" \
-			     "wrpr	%%g0, 0x096, %%pstate" \
-			     : /* no outputs */ \
-			     : "r" (paddr), "r" (pgd_cache),\
-			       "i" (ASI_DMMU), "i" (TSB_REG)); \
-} while(0)
+extern unsigned long tsb_context_switch(unsigned long pgd_pa, unsigned long *tsb);
 
 /* Set MMU context in the actual hardware. */
 #define load_secondary_context(__mm) \
@@ -101,7 +80,8 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str
 
 	if (!ctx_valid || (old_mm != mm)) {
 		load_secondary_context(mm);
-		reload_tlbmiss_state(tsk, mm);
+		tsb_context_switch(__pa(mm->pgd),
+				   mm->context.sparc64_tsb);
 	}
 
 	/* Even if (mm == old_mm) we _must_ check
@@ -139,7 +119,7 @@ static inline void activate_mm(struct mm_struct *active_mm, struct mm_struct *mm
 
 	load_secondary_context(mm);
 	__flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT);
-	reload_tlbmiss_state(current, mm);
+	tsb_context_switch(__pa(mm->pgd), mm->context.sparc64_tsb);
 }
 
 #endif /* !(__ASSEMBLY__) */
diff --git a/include/asm-sparc64/pgalloc.h b/include/asm-sparc64/pgalloc.h
index a96067c..baf59c0 100644
--- a/include/asm-sparc64/pgalloc.h
+++ b/include/asm-sparc64/pgalloc.h
@@ -61,6 +61,7 @@ static __inline__ void free_pgd_slow(pgd_t *pgd)
 	free_page((unsigned long)pgd);
 }
 
+/* XXX This crap can die, no longer using virtual page tables... */
 #ifdef DCACHE_ALIASING_POSSIBLE
 #define VPTE_COLOR(address)		(((address) >> (PAGE_SHIFT + 10)) & 1UL)
 #define DCACHE_COLOR(address)		(((address) >> PAGE_SHIFT) & 1UL)
diff --git a/include/asm-sparc64/pgtable.h b/include/asm-sparc64/pgtable.h
index f0a9b44..f3ba1e0 100644
--- a/include/asm-sparc64/pgtable.h
+++ b/include/asm-sparc64/pgtable.h
@@ -25,7 +25,8 @@
 #include <asm/const.h>
 
 /* The kernel image occupies 0x4000000 to 0x1000000 (4MB --> 32MB).
- * The page copy blockops can use 0x2000000 to 0x10000000.
+ * The page copy blockops can use 0x2000000 to 0x4000000.
+ * The TSB is mapped in the 0x4000000 to 0x6000000 range.
  * The PROM resides in an area spanning 0xf0000000 to 0x100000000.
  * The vmalloc area spans 0x100000000 to 0x200000000.
  * Since modules need to be in the lowest 32-bits of the address space,
@@ -34,6 +35,7 @@
  * 0x400000000.
  */
 #define	TLBTEMP_BASE		_AC(0x0000000002000000,UL)
+#define	TSBMAP_BASE		_AC(0x0000000004000000,UL)
 #define MODULES_VADDR		_AC(0x0000000010000000,UL)
 #define MODULES_LEN		_AC(0x00000000e0000000,UL)
 #define MODULES_END		_AC(0x00000000f0000000,UL)
@@ -296,11 +298,6 @@ static inline pte_t pte_modify(pte_t orig_pte, pgprot_t new_prot)
 /* to find an entry in a kernel page-table-directory */
 #define pgd_offset_k(address) pgd_offset(&init_mm, address)
 
-/* extract the pgd cache used for optimizing the tlb miss
- * slow path when executing 32-bit compat processes
- */
-#define get_pgd_cache(pgd)	((unsigned long) pgd_val(*pgd) << 11)
-
 /* Find an entry in the second-level page table.. */
 #define pmd_offset(pudp, address)	\
 	((pmd_t *) pud_page(*(pudp)) + \
diff --git a/include/asm-sparc64/processor.h b/include/asm-sparc64/processor.h
index cd8d9b4..b3889f3 100644
--- a/include/asm-sparc64/processor.h
+++ b/include/asm-sparc64/processor.h
@@ -28,6 +28,8 @@
  * User lives in his very own context, and cannot reference us. Note
  * that TASK_SIZE is a misnomer, it really gives maximum user virtual 
  * address that the kernel will allocate out.
+ *
+ * XXX No longer using virtual page tables, kill this upper limit...
  */
 #define VA_BITS		44
 #ifndef __ASSEMBLY__
@@ -37,18 +39,6 @@
 #endif
 #define TASK_SIZE	((unsigned long)-VPTE_SIZE)
 
-/*
- * The vpte base must be able to hold the entire vpte, half
- * of which lives above, and half below, the base. And it
- * is placed as close to the highest address range as possible.
- */
-#define VPTE_BASE_SPITFIRE	(-(VPTE_SIZE/2))
-#if 1
-#define VPTE_BASE_CHEETAH	VPTE_BASE_SPITFIRE
-#else
-#define VPTE_BASE_CHEETAH	0xffe0000000000000
-#endif
-
 #ifndef __ASSEMBLY__
 
 typedef struct {
diff --git a/include/asm-sparc64/tlbflush.h b/include/asm-sparc64/tlbflush.h
index 3ef9909..9ad5d9c 100644
--- a/include/asm-sparc64/tlbflush.h
+++ b/include/asm-sparc64/tlbflush.h
@@ -5,6 +5,11 @@
 #include <linux/mm.h>
 #include <asm/mmu_context.h>
 
+/* TSB flush operations. */
+struct mmu_gather;
+extern void flush_tsb_kernel_range(unsigned long start, unsigned long end);
+extern void flush_tsb_user(struct mmu_gather *mp);
+
 /* TLB flush operations. */
 
 extern void flush_tlb_pending(void);
@@ -14,28 +19,36 @@ extern void flush_tlb_pending(void);
 #define flush_tlb_page(vma,addr)	flush_tlb_pending()
 #define flush_tlb_mm(mm)		flush_tlb_pending()
 
+/* Local cpu only.  */
 extern void __flush_tlb_all(void);
+
 extern void __flush_tlb_page(unsigned long context, unsigned long page, unsigned long r);
 
 extern void __flush_tlb_kernel_range(unsigned long start, unsigned long end);
 
 #ifndef CONFIG_SMP
 
-#define flush_tlb_all()		__flush_tlb_all()
 #define flush_tlb_kernel_range(start,end) \
-	__flush_tlb_kernel_range(start,end)
+do {	flush_tsb_kernel_range(start,end); \
+	__flush_tlb_kernel_range(start,end); \
+} while (0)
 
 #else /* CONFIG_SMP */
 
-extern void smp_flush_tlb_all(void);
 extern void smp_flush_tlb_kernel_range(unsigned long start, unsigned long end);
 
-#define flush_tlb_all()		smp_flush_tlb_all()
 #define flush_tlb_kernel_range(start, end) \
-	smp_flush_tlb_kernel_range(start, end)
+do {	flush_tsb_kernel_range(start,end); \
+	smp_flush_tlb_kernel_range(start, end); \
+} while (0)
 
 #endif /* ! CONFIG_SMP */
 
-extern void flush_tlb_pgtables(struct mm_struct *, unsigned long, unsigned long);
+static inline void flush_tlb_pgtables(struct mm_struct *mm, unsigned long start, unsigned long end)
+{
+	/* We don't use virtual page tables for TLB miss processing
+	 * any more.  Nowadays we use the TSB.
+	 */
+}
 
 #endif /* _SPARC64_TLBFLUSH_H */
diff --git a/include/asm-sparc64/tsb.h b/include/asm-sparc64/tsb.h
new file mode 100644
index 0000000..03d272e
--- /dev/null
+++ b/include/asm-sparc64/tsb.h
@@ -0,0 +1,165 @@
+#ifndef _SPARC64_TSB_H
+#define _SPARC64_TSB_H
+
+/* The sparc64 TSB is similar to the powerpc hashtables.  It's a
+ * power-of-2 sized table of TAG/PTE pairs.  The cpu precomputes
+ * pointers into this table for 8K and 64K page sizes, and also a
+ * comparison TAG based upon the virtual address and context which
+ * faults.
+ *
+ * TLB miss trap handler software does the actual lookup via something
+ * of the form:
+ *
+ * 	ldxa		[%g0] ASI_{D,I}MMU_TSB_8KB_PTR, %g1
+ * 	ldxa		[%g0] ASI_{D,I}MMU, %g6
+ * 	ldda		[%g1] ASI_NUCLEUS_QUAD_LDD, %g4
+ * 	cmp		%g4, %g6
+ * 	bne,pn	%xcc, tsb_miss_{d,i}tlb
+ * 	 mov		FAULT_CODE_{D,I}TLB, %g3
+ * 	stxa		%g5, [%g0] ASI_{D,I}TLB_DATA_IN
+ * 	retry
+ *
+
+ * Each 16-byte slot of the TSB is the 8-byte tag and then the 8-byte
+ * PTE.  The TAG is of the same layout as the TLB TAG TARGET mmu
+ * register which is:
+ *
+ * -------------------------------------------------
+ * |  -  |  CONTEXT |  -  |    VADDR bits 63:22    |
+ * -------------------------------------------------
+ *  63 61 60      48 47 42 41                     0
+ *
+ * Like the powerpc hashtables we need to use locking in order to
+ * synchronize while we update the entries.  PTE updates need locking
+ * as well.
+ *
+ * We need to carefully choose a lock bits for the TSB entry.  We
+ * choose to use bit 47 in the tag.  Also, since we never map anything
+ * at page zero in context zero, we use zero as an invalid tag entry.
+ * When the lock bit is set, this forces a tag comparison failure.
+ *
+ * Currently, we allocate an 8K TSB per-process and we use it for both
+ * I-TLB and D-TLB misses.  Perhaps at some point we'll add code that
+ * monitors the number of active pages in the process as we get
+ * major/minor faults, and grow the TSB in response.  The only trick
+ * in implementing that is synchronizing the freeing of the old TSB
+ * wrt.  parallel TSB updates occuring on other processors.  On
+ * possible solution is to use RCU for the freeing of the TSB.
+ */
+
+#define TSB_TAG_LOCK	(1 << (47 - 32))
+
+#define TSB_MEMBAR	membar	#StoreStore
+
+#define TSB_LOCK_TAG(TSB, REG1, REG2)	\
+99:	lduwa	[TSB] ASI_N, REG1;	\
+	sethi	%hi(TSB_TAG_LOCK), REG2;\
+	andcc	REG1, REG2, %g0;	\
+	bne,pn	%icc, 99b;		\
+	 nop;				\
+	casa	[TSB] ASI_N, REG1, REG2;\
+	cmp	REG1, REG2;		\
+	bne,pn	%icc, 99b;		\
+	 nop;				\
+	TSB_MEMBAR
+
+#define TSB_WRITE(TSB, TTE, TAG)	   \
+	stx		TTE, [TSB + 0x08]; \
+	TSB_MEMBAR;			   \
+	stx		TAG, [TSB + 0x00];
+
+	/* Do a kernel page table walk.  Leaves physical PTE pointer in
+	 * REG1.  Jumps to FAIL_LABEL on early page table walk termination.
+	 * VADDR will not be clobbered, but REG2 will.
+	 */
+#define KERN_PGTABLE_WALK(VADDR, REG1, REG2, FAIL_LABEL)	\
+	sethi		%hi(swapper_pg_dir), REG1; \
+	or		REG1, %lo(swapper_pg_dir), REG1; \
+	sllx		VADDR, 64 - (PGDIR_SHIFT + PGDIR_BITS), REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	andn		REG2, 0x3, REG2; \
+	lduw		[REG1 + REG2], REG1; \
+	brz,pn		REG1, FAIL_LABEL; \
+	 sllx		VADDR, 64 - (PMD_SHIFT + PMD_BITS), REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	sllx		REG1, 11, REG1; \
+	andn		REG2, 0x3, REG2; \
+	lduwa		[REG1 + REG2] ASI_PHYS_USE_EC, REG1; \
+	brz,pn		REG1, FAIL_LABEL; \
+	 sllx		VADDR, 64 - PMD_SHIFT, REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	sllx		REG1, 11, REG1; \
+	andn		REG2, 0x7, REG2; \
+	add		REG1, REG2, REG1;
+
+	/* Do a user page table walk in MMU globals.  Leaves physical PTE
+	 * pointer in REG1.  Jumps to FAIL_LABEL on early page table walk
+	 * termination.  Physical base of page tables is in PHYS_PGD which
+	 * will not be modified.
+	 *
+	 * VADDR will not be clobbered, but REG1 and REG2 will.
+	 */
+#define USER_PGTABLE_WALK_TL1(VADDR, PHYS_PGD, REG1, REG2, FAIL_LABEL)	\
+	sllx		VADDR, 64 - (PGDIR_SHIFT + PGDIR_BITS), REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	andn		REG2, 0x3, REG2; \
+	lduwa		[PHYS_PGD + REG2] ASI_PHYS_USE_EC, REG1; \
+	brz,pn		REG1, FAIL_LABEL; \
+	 sllx		VADDR, 64 - (PMD_SHIFT + PMD_BITS), REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	sllx		REG1, 11, REG1; \
+	andn		REG2, 0x3, REG2; \
+	lduwa		[REG1 + REG2] ASI_PHYS_USE_EC, REG1; \
+	brz,pn		REG1, FAIL_LABEL; \
+	 sllx		VADDR, 64 - PMD_SHIFT, REG2; \
+	srlx		REG2, 64 - PAGE_SHIFT, REG2; \
+	sllx		REG1, 11, REG1; \
+	andn		REG2, 0x7, REG2; \
+	add		REG1, REG2, REG1;
+
+/* Lookup a OBP mapping on VADDR in the prom_trans[] table at TL>0.
+ * If no entry is found, FAIL_LABEL will be branched to.  On success
+ * the resulting PTE value will be left in REG1.  VADDR is preserved
+ * by this routine.
+ */
+#define OBP_TRANS_LOOKUP(VADDR, REG1, REG2, REG3, FAIL_LABEL) \
+	sethi		%hi(prom_trans), REG1; \
+	or		REG1, %lo(prom_trans), REG1; \
+97:	ldx		[REG1 + 0x00], REG2; \
+	brz,pn		REG2, FAIL_LABEL; \
+	 nop; \
+	ldx		[REG1 + 0x08], REG3; \
+	add		REG2, REG3, REG3; \
+	cmp		REG2, VADDR; \
+	bgu,pt		%xcc, 98f; \
+	 cmp		VADDR, REG3; \
+	bgeu,pt		%xcc, 98f; \
+	 ldx		[REG1 + 0x10], REG3; \
+	sub		VADDR, REG2, REG2; \
+	ba,pt		%xcc, 99f; \
+	 add		REG3, REG2, REG1; \
+98:	ba,pt		%xcc, 97b; \
+	 add		REG1, (3 * 8), REG1; \
+99:
+
+	/* Do a kernel TSB lookup at tl>0 on VADDR+TAG, branch to OK_LABEL
+	 * on TSB hit.  REG1, REG2, REG3, and REG4 are used as temporaries
+	 * and the found TTE will be left in REG1.  REG3 and REG4 must
+	 * be an even/odd pair of registers.
+	 *
+	 * VADDR and TAG will be preserved and not clobbered by this macro.
+	 */
+	/* XXX non-8K base page size support... */
+#define KERN_TSB_LOOKUP_TL1(VADDR, TAG, REG1, REG2, REG3, REG4, OK_LABEL) \
+	sethi		%hi(swapper_tsb), REG1; \
+	or		REG1, %lo(swapper_tsb), REG1; \
+	srlx		VADDR, 13, REG2; \
+	and		REG2, (512 - 1), REG2; \
+	sllx		REG2, 4, REG2; \
+	add		REG1, REG2, REG2; \
+	ldda		[REG2] ASI_NUCLEUS_QUAD_LDD, REG3; \
+	cmp		REG3, TAG; \
+	be,a,pt		%xcc, OK_LABEL; \
+	 mov		REG4, REG1;
+
+#endif /* !(_SPARC64_TSB_H) */