[RFC 2/3] ARM: uaccess: let UACCESS_GUP_KMAP_MEMCPY enabling

afzal mohammed
2020-06-12T10:18:15Z

Turn off existing raw_copy_{from,to}_user() using
arm_copy_{from,to}_user() when CONFIG_UACCESS_GUP_KMAP_MEMCPY is
enabled.

Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
---
arch/arm/include/asm/uaccess.h | 20 ++++++++++++++++++++
arch/arm/kernel/armksyms.c | 2 ++
arch/arm/lib/Makefile | 7 +++++--
3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 98c6b91be4a8a..4a16ae52d4978 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -512,6 +512,15 @@ do { \
extern unsigned long __must_check
arm_copy_from_user(void *to, const void __user *from, unsigned long n);

+#ifdef CONFIG_UACCESS_GUP_KMAP_MEMCPY
+extern unsigned long __must_check
+gup_kmap_copy_from_user(void *to, const void __user *from, unsigned long n);
+static inline __must_check unsigned long
+raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ return gup_kmap_copy_from_user(to, from, n);
+}
+#else
static inline unsigned long __must_check
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
@@ -522,12 +531,22 @@ raw_copy_from_user(void *to, const void __user *from, unsigned long n)
uaccess_restore(__ua_flags);
return n;
}
+#endif

extern unsigned long __must_check
arm_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __must_check
__copy_to_user_std(void __user *to, const void *from, unsigned long n);

+#ifdef CONFIG_UACCESS_GUP_KMAP_MEMCPY
+extern unsigned long __must_check
+gup_kmap_copy_to_user(void __user *to, const void *from, unsigned long n);
+static inline __must_check unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ return gup_kmap_copy_to_user(to, from, n);
+}
+#else
static inline unsigned long __must_check
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
@@ -541,6 +560,7 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
return arm_copy_to_user(to, from, n);
#endif
}
+#endif

extern unsigned long __must_check
arm_clear_user(void __user *addr, unsigned long n);
diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index 98bdea51089d5..8c92fe30d1559 100644
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -96,8 +96,10 @@ EXPORT_SYMBOL(mmiocpy);
#ifdef CONFIG_MMU
EXPORT_SYMBOL(copy_page);

+#ifndef CONFIG_UACCESS_GUP_KMAP_MEMCPY
EXPORT_SYMBOL(arm_copy_from_user);
EXPORT_SYMBOL(arm_copy_to_user);
+#endif
EXPORT_SYMBOL(arm_clear_user);

EXPORT_SYMBOL(__get_user_1);
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 6d2ba454f25b6..1aeff2cd7b4b3 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -16,8 +16,11 @@ lib-y := changebit.o csumipv6.o csumpartial.o \
io-readsb.o io-writesb.o io-readsl.o io-writesl.o \
call_with_stack.o bswapsdi2.o

-mmu-y := clear_user.o copy_page.o getuser.o putuser.o \
- copy_from_user.o copy_to_user.o
+mmu-y := clear_user.o copy_page.o getuser.o putuser.o
+
+ifndef CONFIG_UACCESS_GUP_KMAP_MEMCPY
+ mmu-y += copy_from_user.o copy_to_user.o
+endif

ifdef CONFIG_CC_IS_CLANG
lib-y += backtrace-clang.o
--
2.26.2