[PARISC] parisc specific kmap API implementation for pa8800

This patch fixes the pa8800 at a gross level (there are still other
subtle incoherency issues which can still cause crashes and HPMCs).

What it does is try to force eject inequivalent aliases before they
become visible to the L2 cache (which is where we get the incoherence
problems).

A new function (parisc_requires_coherency) is introduced in
asm/processor.h to identify the pa8x00 processors (8800 and 8900)
which have the issue.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

arch/parisc/kernel/cache.c

@@ -91,7 +91,8 @@ update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t pte)
 
 		flush_kernel_dcache_page(page);
 		clear_bit(PG_dcache_dirty, &page->flags);
-	}
+	} else if (parisc_requires_coherency())
+		flush_kernel_dcache_page(page);
 }
 
 void
@@ -370,3 +371,45 @@ void parisc_setup_cache_timing(void)
 
 	printk(KERN_INFO "Setting cache flush threshold to %x (%d CPUs online)\n", parisc_cache_flush_threshold, num_online_cpus());
 }
+
+extern void purge_kernel_dcache_page(unsigned long);
+extern void clear_user_page_asm(void *page, unsigned long vaddr);
+
+void
+clear_user_page(void *page, unsigned long vaddr, struct page *pg)
+{
+	purge_kernel_dcache_page((unsigned long)page);
+	purge_tlb_start();
+	pdtlb_kernel(page);
+	purge_tlb_end();
+	clear_user_page_asm(page, vaddr);
+}
+
+void flush_kernel_dcache_page_addr(void *addr)
+{
+	flush_kernel_dcache_page_asm(addr);
+	purge_tlb_start();
+	pdtlb_kernel(addr);
+	purge_tlb_end();
+}
+EXPORT_SYMBOL(flush_kernel_dcache_page_addr);
+
+void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
+		    struct page *pg)
+{
+	/* no coherency needed (all in kmap/kunmap) */
+	copy_user_page_asm(vto, vfrom);
+	if (!parisc_requires_coherency())
+		flush_kernel_dcache_page_asm(vto);
+}
+EXPORT_SYMBOL(copy_user_page);
+
+#ifdef CONFIG_PA8X00
+
+void kunmap_parisc(void *addr)
+{
+	if (parisc_requires_coherency())
+		flush_kernel_dcache_page_addr(addr);
+}
+EXPORT_SYMBOL(kunmap_parisc);
+#endif

include/asm-parisc/cacheflush.h

@@ -191,16 +191,38 @@ flush_anon_page(struct page *page, unsigned long vmaddr)
 }
 #define ARCH_HAS_FLUSH_ANON_PAGE
 
-static inline void
-flush_kernel_dcache_page(struct page *page)
-{
-	flush_kernel_dcache_page_asm(page_address(page));
-}
 #define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
+void flush_kernel_dcache_page_addr(void *addr);
+static inline void flush_kernel_dcache_page(struct page *page)
+{
+	flush_kernel_dcache_page_addr(page_address(page));
+}
 
 #ifdef CONFIG_DEBUG_RODATA
 void mark_rodata_ro(void);
 #endif
 
+#ifdef CONFIG_PA8X00
+/* Only pa8800, pa8900 needs this */
+#define ARCH_HAS_KMAP
+
+void kunmap_parisc(void *addr);
+
+static inline void *kmap(struct page *page)
+{
+	might_sleep();
+	return page_address(page);
+}
+
+#define kunmap(page)			kunmap_parisc(page_address(page))
+
+#define kmap_atomic(page, idx)		page_address(page)
+
+#define kunmap_atomic(addr, idx)	kunmap_parisc(addr)
+
+#define kmap_atomic_pfn(pfn, idx)	page_address(pfn_to_page(pfn))
+#define kmap_atomic_to_page(ptr)	virt_to_page(ptr)
+#endif
+
 #endif /* _PARISC_CACHEFLUSH_H */
 

include/asm-parisc/page.h

@@ -26,24 +26,10 @@
 
 struct page;
 
-extern void purge_kernel_dcache_page(unsigned long);
+void copy_user_page_asm(void *to, void *from);
-extern void copy_user_page_asm(void *to, void *from);
+void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
-extern void clear_user_page_asm(void *page, unsigned long vaddr);
+			   struct page *pg);
-
+void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
-static inline void
-copy_user_page(void *vto, void *vfrom, unsigned long vaddr, struct page *pg)
-{
-	copy_user_page_asm(vto, vfrom);
-	flush_kernel_dcache_page_asm(vto);
-	/* XXX: ppc flushes icache too, should we? */
-}
-
-static inline void
-clear_user_page(void *page, unsigned long vaddr, struct page *pg)
-{
-	purge_kernel_dcache_page((unsigned long)page);
-	clear_user_page_asm(page, vaddr);
-}
 
 /*
  * These are used to make use of C type-checking..

include/asm-parisc/processor.h

@@ -332,6 +332,19 @@ extern unsigned long get_wchan(struct task_struct *p);
 
 #define cpu_relax()	barrier()
 
+/* Used as a macro to identify the combined VIPT/PIPT cached
+ * CPUs which require a guarantee of coherency (no inequivalent
+ * aliases with different data, whether clean or not) to operate */
+static inline int parisc_requires_coherency(void)
+{
+#ifdef CONFIG_PA8X00
+	/* FIXME: also pa8900 - when we see one */
+	return boot_cpu_data.cpu_type == mako;
+#else
+	return 0;
+#endif
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __ASM_PARISC_PROCESSOR_H */