Merge master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6

* master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6: (108 commits)
  sh: Fix occasional flush_cache_4096() stack corruption.
  sh: Calculate shm alignment at runtime.
  sh: dma-mapping compile fixes.
  sh: Initial vsyscall page support.
  sh: Clean up PAGE_SIZE definition for assembly use.
  sh: Selective flush_cache_mm() flushing.
  sh: More intelligent entry_mask/way_size calculation.
  sh: Support for L2 cache on newer SH-4A CPUs.
  sh: Update kexec support for API changes.
  sh: Optimized readsl()/writesl() support.
  sh: Report movli.l/movco.l capabilities.
  sh: CPU flags in AT_HWCAP in ELF auxvt.
  sh: Add support for 4K stacks.
  sh: Enable /proc/kcore support.
  sh: stack debugging support.
  sh: select CONFIG_EMBEDDED.
  sh: machvec rework.
  sh: Solution Engine SH7343 board support.
  sh: SH7710VoIPGW board support.
  sh: Enable verbose BUG() support.
  ...

1 files changed, 548 insertions, 137 deletions

diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index 524cea5b47f..e48cc22724d 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -2,49 +2,120 @@
  * arch/sh/mm/cache-sh4.c
  *
  * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
- * Copyright (C) 2001, 2002, 2003, 2004  Paul Mundt
+ * Copyright (C) 2001 - 2006  Paul Mundt
  * Copyright (C) 2003  Richard Curnow
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  */
-
 #include <linux/init.h>
-#include <linux/mman.h>
 #include <linux/mm.h>
-#include <linux/threads.h>
 #include <asm/addrspace.h>
-#include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/cache.h>
 #include <asm/io.h>
-#include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
-extern void __flush_cache_4096_all(unsigned long start);
-static void __flush_cache_4096_all_ex(unsigned long start);
-extern void __flush_dcache_all(void);
-static void __flush_dcache_all_ex(void);
+/*
+ * The maximum number of pages we support up to when doing ranged dcache
+ * flushing. Anything exceeding this will simply flush the dcache in its
+ * entirety.
+ */
+#define MAX_DCACHE_PAGES	64	/* XXX: Tune for ways */
+
+static void __flush_dcache_segment_1way(unsigned long start,
+					unsigned long extent);
+static void __flush_dcache_segment_2way(unsigned long start,
+					unsigned long extent);
+static void __flush_dcache_segment_4way(unsigned long start,
+					unsigned long extent);
+
+static void __flush_cache_4096(unsigned long addr, unsigned long phys,
+			       unsigned long exec_offset);
+
+/*
+ * This is initialised here to ensure that it is not placed in the BSS.  If
+ * that were to happen, note that cache_init gets called before the BSS is
+ * cleared, so this would get nulled out which would be hopeless.
+ */
+static void (*__flush_dcache_segment_fn)(unsigned long, unsigned long) =
+	(void (*)(unsigned long, unsigned long))0xdeadbeef;
+
+static void compute_alias(struct cache_info *c)
+{
+	c->alias_mask = ((c->sets - 1) << c->entry_shift) & ~(PAGE_SIZE - 1);
+	c->n_aliases = (c->alias_mask >> PAGE_SHIFT) + 1;
+}
+
+static void __init emit_cache_params(void)
+{
+	printk("PVR=%08x CVR=%08x PRR=%08x\n",
+		ctrl_inl(CCN_PVR),
+		ctrl_inl(CCN_CVR),
+		ctrl_inl(CCN_PRR));
+	printk("I-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+		cpu_data->icache.ways,
+		cpu_data->icache.sets,
+		cpu_data->icache.way_incr);
+	printk("I-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+		cpu_data->icache.entry_mask,
+		cpu_data->icache.alias_mask,
+		cpu_data->icache.n_aliases);
+	printk("D-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+		cpu_data->dcache.ways,
+		cpu_data->dcache.sets,
+		cpu_data->dcache.way_incr);
+	printk("D-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+		cpu_data->dcache.entry_mask,
+		cpu_data->dcache.alias_mask,
+		cpu_data->dcache.n_aliases);
+
+	if (!__flush_dcache_segment_fn)
+		panic("unknown number of cache ways\n");
+}
 
 /*
  * SH-4 has virtually indexed and physically tagged cache.
  */
 
-struct semaphore p3map_sem[4];
+/* Worst case assumed to be 64k cache, direct-mapped i.e. 4 synonym bits. */
+#define MAX_P3_SEMAPHORES 16
+
+struct semaphore p3map_sem[MAX_P3_SEMAPHORES];
 
 void __init p3_cache_init(void)
 {
-	if (remap_area_pages(P3SEG, 0, PAGE_SIZE*4, _PAGE_CACHABLE))
+	int i;
+
+	compute_alias(&cpu_data->icache);
+	compute_alias(&cpu_data->dcache);
+
+	switch (cpu_data->dcache.ways) {
+	case 1:
+		__flush_dcache_segment_fn = __flush_dcache_segment_1way;
+		break;
+	case 2:
+		__flush_dcache_segment_fn = __flush_dcache_segment_2way;
+		break;
+	case 4:
+		__flush_dcache_segment_fn = __flush_dcache_segment_4way;
+		break;
+	default:
+		__flush_dcache_segment_fn = NULL;
+		break;
+	}
+
+	emit_cache_params();
+
+	if (remap_area_pages(P3SEG, 0, PAGE_SIZE * 4, _PAGE_CACHABLE))
 		panic("%s failed.", __FUNCTION__);
 
-	sema_init (&p3map_sem[0], 1);
-	sema_init (&p3map_sem[1], 1);
-	sema_init (&p3map_sem[2], 1);
-	sema_init (&p3map_sem[3], 1);
+	for (i = 0; i < cpu_data->dcache.n_aliases; i++)
+		sema_init(&p3map_sem[i], 1);
 }
 
 /*
@@ -89,7 +160,6 @@ void __flush_purge_region(void *start, int size)
 	}
 }
 
-
 /*
  * No write back please
  */
@@ -108,40 +178,6 @@ void __flush_invalidate_region(void *start, int size)
 	}
 }
 
-static void __flush_dcache_all_ex(void)
-{
-	unsigned long addr, end_addr, entry_offset;
-
-	end_addr = CACHE_OC_ADDRESS_ARRAY + (cpu_data->dcache.sets << cpu_data->dcache.entry_shift) * cpu_data->dcache.ways;
-	entry_offset = 1 << cpu_data->dcache.entry_shift;
-	for (addr = CACHE_OC_ADDRESS_ARRAY; addr < end_addr; addr += entry_offset) {
-		ctrl_outl(0, addr);
-	}
-}
-
-static void __flush_cache_4096_all_ex(unsigned long start)
-{
-	unsigned long addr, entry_offset;
-	int i;
-
-	entry_offset = 1 << cpu_data->dcache.entry_shift;
-	for (i = 0; i < cpu_data->dcache.ways; i++, start += cpu_data->dcache.way_incr) {
-		for (addr = CACHE_OC_ADDRESS_ARRAY + start;
-		     addr < CACHE_OC_ADDRESS_ARRAY + 4096 + start;
-		     addr += entry_offset) {
-			ctrl_outl(0, addr);
-		}
-	}
-}
-
-void flush_cache_4096_all(unsigned long start)
-{
-	if (cpu_data->dcache.ways == 1)
-		__flush_cache_4096_all(start);
-	else
-		__flush_cache_4096_all_ex(start);
-}
-
 /*
  * Write back the range of D-cache, and purge the I-cache.
  *
@@ -153,14 +189,14 @@ void flush_icache_range(unsigned long start, unsigned long end)
 }
 
 /*
- * Write back the D-cache and purge the I-cache for signal trampoline. 
+ * Write back the D-cache and purge the I-cache for signal trampoline.
  * .. which happens to be the same behavior as flush_icache_range().
  * So, we simply flush out a line.
  */
 void flush_cache_sigtramp(unsigned long addr)
 {
 	unsigned long v, index;
-	unsigned long flags; 
+	unsigned long flags;
 	int i;
 
 	v = addr & ~(L1_CACHE_BYTES-1);
@@ -172,30 +208,33 @@ void flush_cache_sigtramp(unsigned long addr)
 
 	local_irq_save(flags);
 	jump_to_P2();
-	for(i = 0; i < cpu_data->icache.ways; i++, index += cpu_data->icache.way_incr)
+
+	for (i = 0; i < cpu_data->icache.ways;
+	     i++, index += cpu_data->icache.way_incr)
 		ctrl_outl(0, index);	/* Clear out Valid-bit */
+
 	back_to_P1();
+	wmb();
 	local_irq_restore(flags);
 }
 
 static inline void flush_cache_4096(unsigned long start,
 				    unsigned long phys)
 {
-	unsigned long flags; 
-	extern void __flush_cache_4096(unsigned long addr, unsigned long phys, unsigned long exec_offset);
+	unsigned long flags, exec_offset = 0;
 
 	/*
-	 * SH7751, SH7751R, and ST40 have no restriction to handle cache.
-	 * (While SH7750 must do that at P2 area.)
+	 * All types of SH-4 require PC to be in P2 to operate on the I-cache.
+	 * Some types of SH-4 require PC to be in P2 to operate on the D-cache.
 	 */
-	if ((cpu_data->flags & CPU_HAS_P2_FLUSH_BUG)
-	   || start < CACHE_OC_ADDRESS_ARRAY) {
-		local_irq_save(flags);
-		__flush_cache_4096(start | SH_CACHE_ASSOC, P1SEGADDR(phys), 0x20000000);
-		local_irq_restore(flags);
-	} else {
-		__flush_cache_4096(start | SH_CACHE_ASSOC, P1SEGADDR(phys), 0);
-	}
+	if ((cpu_data->flags & CPU_HAS_P2_FLUSH_BUG) ||
+	    (start < CACHE_OC_ADDRESS_ARRAY))
+	    	exec_offset = 0x20000000;
+
+	local_irq_save(flags);
+	__flush_cache_4096(start | SH_CACHE_ASSOC,
+			   P1SEGADDR(phys), exec_offset);
+	local_irq_restore(flags);
 }
 
 /*
@@ -206,15 +245,19 @@ void flush_dcache_page(struct page *page)
 {
 	if (test_bit(PG_mapped, &page->flags)) {
 		unsigned long phys = PHYSADDR(page_address(page));
+		unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
+		int i, n;
 
 		/* Loop all the D-cache */
-		flush_cache_4096(CACHE_OC_ADDRESS_ARRAY,          phys);
-		flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x1000, phys);
-		flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x2000, phys);
-		flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x3000, phys);
+		n = cpu_data->dcache.n_aliases;
+		for (i = 0; i < n; i++, addr += PAGE_SIZE)
+			flush_cache_4096(addr, phys);
 	}
+
+	wmb();
 }
 
+/* TODO: Selective icache invalidation through IC address array.. */
 static inline void flush_icache_all(void)
 {
 	unsigned long flags, ccr;
@@ -227,34 +270,142 @@ static inline void flush_icache_all(void)
 	ccr |= CCR_CACHE_ICI;
 	ctrl_outl(ccr, CCR);
 
+	/*
+	 * back_to_P1() will take care of the barrier for us, don't add
+	 * another one!
+	 */
+
 	back_to_P1();
 	local_irq_restore(flags);
 }
 
+void flush_dcache_all(void)
+{
+	(*__flush_dcache_segment_fn)(0UL, cpu_data->dcache.way_size);
+	wmb();
+}
+
 void flush_cache_all(void)
 {
-	if (cpu_data->dcache.ways == 1)
-		__flush_dcache_all();
-	else
-		__flush_dcache_all_ex();
+	flush_dcache_all();
 	flush_icache_all();
 }
 
+static void __flush_cache_mm(struct mm_struct *mm, unsigned long start,
+			     unsigned long end)
+{
+	unsigned long d = 0, p = start & PAGE_MASK;
+	unsigned long alias_mask = cpu_data->dcache.alias_mask;
+	unsigned long n_aliases = cpu_data->dcache.n_aliases;
+	unsigned long select_bit;
+	unsigned long all_aliases_mask;
+	unsigned long addr_offset;
+	pgd_t *dir;
+	pmd_t *pmd;
+	pud_t *pud;
+	pte_t *pte;
+	int i;
+
+	dir = pgd_offset(mm, p);
+	pud = pud_offset(dir, p);
+	pmd = pmd_offset(pud, p);
+	end = PAGE_ALIGN(end);
+
+	all_aliases_mask = (1 << n_aliases) - 1;
+
+	do {
+		if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) {
+			p &= PMD_MASK;
+			p += PMD_SIZE;
+			pmd++;
+
+			continue;
+		}
+
+		pte = pte_offset_kernel(pmd, p);
+
+		do {
+			unsigned long phys;
+			pte_t entry = *pte;
+
+			if (!(pte_val(entry) & _PAGE_PRESENT)) {
+				pte++;
+				p += PAGE_SIZE;
+				continue;
+			}
+
+			phys = pte_val(entry) & PTE_PHYS_MASK;
+
+			if ((p ^ phys) & alias_mask) {
+				d |= 1 << ((p & alias_mask) >> PAGE_SHIFT);
+				d |= 1 << ((phys & alias_mask) >> PAGE_SHIFT);
+
+				if (d == all_aliases_mask)
+					goto loop_exit;
+			}
+
+			pte++;
+			p += PAGE_SIZE;
+		} while (p < end && ((unsigned long)pte & ~PAGE_MASK));
+		pmd++;
+	} while (p < end);
+
+loop_exit:
+	addr_offset = 0;
+	select_bit = 1;
+
+	for (i = 0; i < n_aliases; i++) {
+		if (d & select_bit) {
+			(*__flush_dcache_segment_fn)(addr_offset, PAGE_SIZE);
+			wmb();
+		}
+
+		select_bit <<= 1;
+		addr_offset += PAGE_SIZE;
+	}
+}
+
+/*
+ * Note : (RPC) since the caches are physically tagged, the only point
+ * of flush_cache_mm for SH-4 is to get rid of aliases from the
+ * D-cache.  The assumption elsewhere, e.g. flush_cache_range, is that
+ * lines can stay resident so long as the virtual address they were
+ * accessed with (hence cache set) is in accord with the physical
+ * address (i.e. tag).  It's no different here.  So I reckon we don't
+ * need to flush the I-cache, since aliases don't matter for that.  We
+ * should try that.
+ *
+ * Caller takes mm->mmap_sem.
+ */
 void flush_cache_mm(struct mm_struct *mm)
 {
-	/* Is there any good way? */
-	/* XXX: possibly call flush_cache_range for each vm area */
-	/* 
-	 * FIXME: Really, the optimal solution here would be able to flush out
-	 * individual lines created by the specified context, but this isn't
-	 * feasible for a number of architectures (such as MIPS, and some
-	 * SPARC) .. is this possible for SuperH?
-	 *
-	 * In the meantime, we'll just flush all of the caches.. this
-	 * seems to be the simplest way to avoid at least a few wasted
-	 * cache flushes. -Lethal
+	/*
+	 * If cache is only 4k-per-way, there are never any 'aliases'.  Since
+	 * the cache is physically tagged, the data can just be left in there.
 	 */
-	flush_cache_all();
+	if (cpu_data->dcache.n_aliases == 0)
+		return;
+
+	/*
+	 * Don't bother groveling around the dcache for the VMA ranges
+	 * if there are too many PTEs to make it worthwhile.
+	 */
+	if (mm->nr_ptes >= MAX_DCACHE_PAGES)
+		flush_dcache_all();
+	else {
+		struct vm_area_struct *vma;
+
+		/*
+		 * In this case there are reasonably sized ranges to flush,
+		 * iterate through the VMA list and take care of any aliases.
+		 */
+		for (vma = mm->mmap; vma; vma = vma->vm_next)
+			__flush_cache_mm(mm, vma->vm_start, vma->vm_end);
+	}
+
+	/* Only touch the icache if one of the VMAs has VM_EXEC set. */
+	if (mm->exec_vm)
+		flush_icache_all();
 }
 
 /*
@@ -263,27 +414,40 @@ void flush_cache_mm(struct mm_struct *mm)
  * ADDR: Virtual Address (U0 address)
  * PFN: Physical page number
  */
-void flush_cache_page(struct vm_area_struct *vma, unsigned long address, unsigned long pfn)
+void flush_cache_page(struct vm_area_struct *vma, unsigned long address,
+		      unsigned long pfn)
 {
 	unsigned long phys = pfn << PAGE_SHIFT;
+	unsigned int alias_mask;
+
+	alias_mask = cpu_data->dcache.alias_mask;
 
 	/* We only need to flush D-cache when we have alias */
-	if ((address^phys) & CACHE_ALIAS) {
+	if ((address^phys) & alias_mask) {
 		/* Loop 4K of the D-cache */
 		flush_cache_4096(
-			CACHE_OC_ADDRESS_ARRAY | (address & CACHE_ALIAS),
+			CACHE_OC_ADDRESS_ARRAY | (address & alias_mask),
 			phys);
 		/* Loop another 4K of the D-cache */
 		flush_cache_4096(
-			CACHE_OC_ADDRESS_ARRAY | (phys & CACHE_ALIAS),
+			CACHE_OC_ADDRESS_ARRAY | (phys & alias_mask),
 			phys);
 	}
 
-	if (vma->vm_flags & VM_EXEC)
-		/* Loop 4K (half) of the I-cache */
+	alias_mask = cpu_data->icache.alias_mask;
+	if (vma->vm_flags & VM_EXEC) {
+		/*
+		 * Evict entries from the portion of the cache from which code
+		 * may have been executed at this address (virtual).  There's
+		 * no need to evict from the portion corresponding to the
+		 * physical address as for the D-cache, because we know the
+		 * kernel has never executed the code through its identity
+		 * translation.
+		 */
 		flush_cache_4096(
-			CACHE_IC_ADDRESS_ARRAY | (address & 0x1000),
+			CACHE_IC_ADDRESS_ARRAY | (address & alias_mask),
 			phys);
+	}
 }
 
 /*
@@ -298,52 +462,31 @@ void flush_cache_page(struct vm_area_struct *vma, unsigned long address, unsigne
 void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
 		       unsigned long end)
 {
-	unsigned long p = start & PAGE_MASK;
-	pgd_t *dir;
-	pmd_t *pmd;
-	pte_t *pte;
-	pte_t entry;
-	unsigned long phys;
-	unsigned long d = 0;
-
-	dir = pgd_offset(vma->vm_mm, p);
-	pmd = pmd_offset(dir, p);
+	/*
+	 * If cache is only 4k-per-way, there are never any 'aliases'.  Since
+	 * the cache is physically tagged, the data can just be left in there.
+	 */
+	if (cpu_data->dcache.n_aliases == 0)
+		return;
 
-	do {
-		if (pmd_none(*pmd) || pmd_bad(*pmd)) {
-			p &= ~((1 << PMD_SHIFT) -1);
-			p += (1 << PMD_SHIFT);
-			pmd++;
-			continue;
-		}
-		pte = pte_offset_kernel(pmd, p);
-		do {
-			entry = *pte;
-			if ((pte_val(entry) & _PAGE_PRESENT)) {
-				phys = pte_val(entry)&PTE_PHYS_MASK;
-				if ((p^phys) & CACHE_ALIAS) {
-					d |= 1 << ((p & CACHE_ALIAS)>>12); 
-					d |= 1 << ((phys & CACHE_ALIAS)>>12);
-					if (d == 0x0f)
-						goto loop_exit;
-				}
-			}
-			pte++;
-			p += PAGE_SIZE;
-		} while (p < end && ((unsigned long)pte & ~PAGE_MASK));
-		pmd++;
-	} while (p < end);
- loop_exit:
-	if (d & 1)
-		flush_cache_4096_all(0);
-	if (d & 2)
-		flush_cache_4096_all(0x1000);
-	if (d & 4)
-		flush_cache_4096_all(0x2000);
-	if (d & 8)
-		flush_cache_4096_all(0x3000);
-	if (vma->vm_flags & VM_EXEC)
+	/*
+	 * Don't bother with the lookup and alias check if we have a
+	 * wide range to cover, just blow away the dcache in its
+	 * entirety instead. -- PFM.
+	 */
+	if (((end - start) >> PAGE_SHIFT) >= MAX_DCACHE_PAGES)
+		flush_dcache_all();
+	else
+		__flush_cache_mm(vma->vm_mm, start, end);
+
+	if (vma->vm_flags & VM_EXEC) {
+		/*
+		 * TODO: Is this required???  Need to look at how I-cache
+		 * coherency is assured when new programs are loaded to see if
+		 * this matters.
+		 */
 		flush_icache_all();
+	}
 }
 
 /*
@@ -357,5 +500,273 @@ void flush_icache_user_range(struct vm_area_struct *vma,
 			     struct page *page, unsigned long addr, int len)
 {
 	flush_cache_page(vma, addr, page_to_pfn(page));
+	mb();
+}
+
+/**
+ * __flush_cache_4096
+ *
+ * @addr:  address in memory mapped cache array
+ * @phys:  P1 address to flush (has to match tags if addr has 'A' bit
+ *         set i.e. associative write)
+ * @exec_offset: set to 0x20000000 if flush has to be executed from P2
+ *               region else 0x0
+ *
+ * The offset into the cache array implied by 'addr' selects the
+ * 'colour' of the virtual address range that will be flushed.  The
+ * operation (purge/write-back) is selected by the lower 2 bits of
+ * 'phys'.
+ */
+static void __flush_cache_4096(unsigned long addr, unsigned long phys,
+			       unsigned long exec_offset)
+{
+	int way_count;
+	unsigned long base_addr = addr;
+	struct cache_info *dcache;
+	unsigned long way_incr;
+	unsigned long a, ea, p;
+	unsigned long temp_pc;
+
+	dcache = &cpu_data->dcache;
+	/* Write this way for better assembly. */
+	way_count = dcache->ways;
+	way_incr = dcache->way_incr;
+
+	/*
+	 * Apply exec_offset (i.e. branch to P2 if required.).
+	 *
+	 * FIXME:
+	 *
+	 *	If I write "=r" for the (temp_pc), it puts this in r6 hence
+	 *	trashing exec_offset before it's been added on - why?  Hence
+	 *	"=&r" as a 'workaround'
+	 */
+	asm volatile("mov.l 1f, %0\n\t"
+		     "add   %1, %0\n\t"
+		     "jmp   @%0\n\t"
+		     "nop\n\t"
+		     ".balign 4\n\t"
+		     "1:  .long 2f\n\t"
+		     "2:\n" : "=&r" (temp_pc) : "r" (exec_offset));
+
+	/*
+	 * We know there will be >=1 iteration, so write as do-while to avoid
+	 * pointless nead-of-loop check for 0 iterations.
+	 */
+	do {
+		ea = base_addr + PAGE_SIZE;
+		a = base_addr;
+		p = phys;
+
+		do {
+			*(volatile unsigned long *)a = p;
+			/*
+			 * Next line: intentionally not p+32, saves an add, p
+			 * will do since only the cache tag bits need to
+			 * match.
+			 */
+			*(volatile unsigned long *)(a+32) = p;
+			a += 64;
+			p += 64;
+		} while (a < ea);
+
+		base_addr += way_incr;
+	} while (--way_count != 0);
 }
 
+/*
+ * Break the 1, 2 and 4 way variants of this out into separate functions to
+ * avoid nearly all the overhead of having the conditional stuff in the function
+ * bodies (+ the 1 and 2 way cases avoid saving any registers too).
+ */
+static void __flush_dcache_segment_1way(unsigned long start,
+					unsigned long extent_per_way)
+{
+	unsigned long orig_sr, sr_with_bl;
+	unsigned long base_addr;
+	unsigned long way_incr, linesz, way_size;
+	struct cache_info *dcache;
+	register unsigned long a0, a0e;
+
+	asm volatile("stc sr, %0" : "=r" (orig_sr));
+	sr_with_bl = orig_sr | (1<<28);
+	base_addr = ((unsigned long)&empty_zero_page[0]);
+
+	/*
+	 * The previous code aligned base_addr to 16k, i.e. the way_size of all
+	 * existing SH-4 D-caches.  Whilst I don't see a need to have this
+	 * aligned to any better than the cache line size (which it will be
+	 * anyway by construction), let's align it to at least the way_size of
+	 * any existing or conceivable SH-4 D-cache.  -- RPC
+	 */
+	base_addr = ((base_addr >> 16) << 16);
+	base_addr |= start;
+
+	dcache = &cpu_data->dcache;
+	linesz = dcache->linesz;
+	way_incr = dcache->way_incr;
+	way_size = dcache->way_size;
+
+	a0 = base_addr;
+	a0e = base_addr + extent_per_way;
+	do {
+		asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+		asm volatile("movca.l r0, @%0\n\t"
+			     "ocbi @%0" : : "r" (a0));
+		a0 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "ocbi @%0" : : "r" (a0));
+		a0 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "ocbi @%0" : : "r" (a0));
+		a0 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "ocbi @%0" : : "r" (a0));
+		asm volatile("ldc %0, sr" : : "r" (orig_sr));
+		a0 += linesz;
+	} while (a0 < a0e);
+}
+
+static void __flush_dcache_segment_2way(unsigned long start,
+					unsigned long extent_per_way)
+{
+	unsigned long orig_sr, sr_with_bl;
+	unsigned long base_addr;
+	unsigned long way_incr, linesz, way_size;
+	struct cache_info *dcache;
+	register unsigned long a0, a1, a0e;
+
+	asm volatile("stc sr, %0" : "=r" (orig_sr));
+	sr_with_bl = orig_sr | (1<<28);
+	base_addr = ((unsigned long)&empty_zero_page[0]);
+
+	/* See comment under 1-way above */
+	base_addr = ((base_addr >> 16) << 16);
+	base_addr |= start;
+
+	dcache = &cpu_data->dcache;
+	linesz = dcache->linesz;
+	way_incr = dcache->way_incr;
+	way_size = dcache->way_size;
+
+	a0 = base_addr;
+	a1 = a0 + way_incr;
+	a0e = base_addr + extent_per_way;
+	do {
+		asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1" : :
+			     "r" (a0), "r" (a1));
+		a0 += linesz;
+		a1 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1" : :
+			     "r" (a0), "r" (a1));
+		a0 += linesz;
+		a1 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1" : :
+			     "r" (a0), "r" (a1));
+		a0 += linesz;
+		a1 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1" : :
+			     "r" (a0), "r" (a1));
+		asm volatile("ldc %0, sr" : : "r" (orig_sr));
+		a0 += linesz;
+		a1 += linesz;
+	} while (a0 < a0e);
+}
+
+static void __flush_dcache_segment_4way(unsigned long start,
+					unsigned long extent_per_way)
+{
+	unsigned long orig_sr, sr_with_bl;
+	unsigned long base_addr;
+	unsigned long way_incr, linesz, way_size;
+	struct cache_info *dcache;
+	register unsigned long a0, a1, a2, a3, a0e;
+
+	asm volatile("stc sr, %0" : "=r" (orig_sr));
+	sr_with_bl = orig_sr | (1<<28);
+	base_addr = ((unsigned long)&empty_zero_page[0]);
+
+	/* See comment under 1-way above */
+	base_addr = ((base_addr >> 16) << 16);
+	base_addr |= start;
+
+	dcache = &cpu_data->dcache;
+	linesz = dcache->linesz;
+	way_incr = dcache->way_incr;
+	way_size = dcache->way_size;
+
+	a0 = base_addr;
+	a1 = a0 + way_incr;
+	a2 = a1 + way_incr;
+	a3 = a2 + way_incr;
+	a0e = base_addr + extent_per_way;
+	do {
+		asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "movca.l r0, @%2\n\t"
+			     "movca.l r0, @%3\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1\n\t"
+			     "ocbi @%2\n\t"
+			     "ocbi @%3\n\t" : :
+			     "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+		a0 += linesz;
+		a1 += linesz;
+		a2 += linesz;
+		a3 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "movca.l r0, @%2\n\t"
+			     "movca.l r0, @%3\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1\n\t"
+			     "ocbi @%2\n\t"
+			     "ocbi @%3\n\t" : :
+			     "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+		a0 += linesz;
+		a1 += linesz;
+		a2 += linesz;
+		a3 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "movca.l r0, @%2\n\t"
+			     "movca.l r0, @%3\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1\n\t"
+			     "ocbi @%2\n\t"
+			     "ocbi @%3\n\t" : :
+			     "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+		a0 += linesz;
+		a1 += linesz;
+		a2 += linesz;
+		a3 += linesz;
+		asm volatile("movca.l r0, @%0\n\t"
+			     "movca.l r0, @%1\n\t"
+			     "movca.l r0, @%2\n\t"
+			     "movca.l r0, @%3\n\t"
+			     "ocbi @%0\n\t"
+			     "ocbi @%1\n\t"
+			     "ocbi @%2\n\t"
+			     "ocbi @%3\n\t" : :
+			     "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+		asm volatile("ldc %0, sr" : : "r" (orig_sr));
+		a0 += linesz;
+		a1 += linesz;
+		a2 += linesz;
+		a3 += linesz;
+	} while (a0 < a0e);
+}