powerpc/lib: Implement UACCESS_FLUSHCACHE API

Implement the architecture specific portitions of the UACCESS_FLUSHCACHE
API. This provides functions for the copy_user_flushcache iterator that
ensure that when the copy is finished the destination buffer contains
a copy of the original and that the destination buffer is clean in the
processor caches.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig

@@ -142,6 +142,7 @@ config PPC
 	select ARCH_HAS_SCALED_CPUTIME		if VIRT_CPU_ACCOUNTING_NATIVE
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_TICK_BROADCAST		if GENERIC_CLOCKEVENTS_BROADCAST
+	select ARCH_HAS_UACCESS_FLUSHCACHE	if PPC64
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAS_ZONE_DEVICE		if PPC_BOOK3S_64
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG

arch/powerpc/include/asm/string.h

@@ -11,6 +11,7 @@
 #define __HAVE_ARCH_MEMCMP
 #define __HAVE_ARCH_MEMCHR
 #define __HAVE_ARCH_MEMSET16
+#define __HAVE_ARCH_MEMCPY_FLUSHCACHE
 
 extern char * strcpy(char *,const char *);
 extern char * strncpy(char *,const char *, __kernel_size_t);
@@ -23,6 +24,7 @@ extern void * memcpy(void *,const void *,__kernel_size_t);
 extern void * memmove(void *,const void *,__kernel_size_t);
 extern int memcmp(const void *,const void *,__kernel_size_t);
 extern void * memchr(const void *,int,__kernel_size_t);
+extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
 
 #ifdef CONFIG_PPC64
 #define __HAVE_ARCH_MEMSET32

arch/powerpc/include/asm/uaccess.h

@@ -356,4 +356,9 @@ static inline unsigned long clear_user(void __user *addr, unsigned long size)
 extern long strncpy_from_user(char *dst, const char __user *src, long count);
 extern __must_check long strnlen_user(const char __user *str, long n);
 
+extern long __copy_from_user_flushcache(void *dst, const void __user *src,
+		unsigned size);
+extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
+			   size_t len);
+
 #endif	/* _ARCH_POWERPC_UACCESS_H */

arch/powerpc/lib/pmem.c

@@ -13,6 +13,7 @@
 
 #include <linux/string.h>
 #include <linux/export.h>
+#include <linux/uaccess.h>
 
 #include <asm/cacheflush.h>
 
@@ -32,3 +33,35 @@ void arch_invalidate_pmem(void *addr, size_t size)
 	flush_inval_dcache_range(start, start + size);
 }
 EXPORT_SYMBOL(arch_invalidate_pmem);
+
+/*
+ * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols
+ */
+long __copy_from_user_flushcache(void *dest, const void __user *src,
+		unsigned size)
+{
+	unsigned long copied, start = (unsigned long) dest;
+
+	copied = __copy_from_user(dest, src, size);
+	flush_inval_dcache_range(start, start + size);
+
+	return copied;
+}
+
+void *memcpy_flushcache(void *dest, const void *src, size_t size)
+{
+	unsigned long start = (unsigned long) dest;
+
+	memcpy(dest, src, size);
+	flush_inval_dcache_range(start, start + size);
+
+	return dest;
+}
+EXPORT_SYMBOL(memcpy_flushcache);
+
+void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
+	size_t len)
+{
+	memcpy_flushcache(to, page_to_virt(page) + offset, len);
+}
+EXPORT_SYMBOL(memcpy_page_flushcache);