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asm-generic: improve the nommu {get,put}_user handling

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Instead of reusing raw_{copy,to}_from_user implement separate handlers
using {get,put}_unaligned.  This ensures unaligned access is handled
correctly, and avoid the need for the small constant size optimization
in raw_{copy,to}_from_user.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Christoph Hellwig 2020-09-07 07:58:19 +02:00 committed by Palmer Dabbelt
parent 24ce66c04a
commit 931de11f5a
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GPG Key ID: 2E1319F35FBB1889
1 changed files with 51 additions and 40 deletions
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91
include/asm-generic/uaccess.h
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@ -10,28 +10,60 @@
#include <linux/string.h>
#ifdef CONFIG_UACCESS_MEMCPY
#include <asm/unaligned.h>
static inline int __get_user_fn(size_t size, const void __user *from, void *to)
{
BUILD_BUG_ON(!__builtin_constant_p(size));
switch (size) {
case 1:
*(u8 *)to = get_unaligned((u8 __force *)from);
return 0;
case 2:
*(u16 *)to = get_unaligned((u16 __force *)from);
return 0;
case 4:
*(u32 *)to = get_unaligned((u32 __force *)from);
return 0;
case 8:
*(u64 *)to = get_unaligned((u64 __force *)from);
return 0;
default:
BUILD_BUG();
return 0;
}
}
#define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
static inline int __put_user_fn(size_t size, void __user *to, void *from)
{
BUILD_BUG_ON(!__builtin_constant_p(size));
switch (size) {
case 1:
put_unaligned(*(u8 *)from, (u8 __force *)to);
return 0;
case 2:
put_unaligned(*(u16 *)from, (u16 __force *)to);
return 0;
case 4:
put_unaligned(*(u32 *)from, (u32 __force *)to);
return 0;
case 8:
put_unaligned(*(u64 *)from, (u64 __force *)to);
return 0;
default:
BUILD_BUG();
return 0;
}
}
#define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
static inline __must_check unsigned long
raw_copy_from_user(void *to, const void __user * from, unsigned long n)
{
if (__builtin_constant_p(n)) {
switch(n) {
case 1:
*(u8 *)to = *(u8 __force *)from;
return 0;
case 2:
*(u16 *)to = *(u16 __force *)from;
return 0;
case 4:
*(u32 *)to = *(u32 __force *)from;
return 0;
#ifdef CONFIG_64BIT
case 8:
*(u64 *)to = *(u64 __force *)from;
return 0;
#endif
}
}
memcpy(to, (const void __force *)from, n);
return 0;
}
@ -39,27 +71,6 @@ raw_copy_from_user(void *to, const void __user * from, unsigned long n)
static inline __must_check unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
if (__builtin_constant_p(n)) {
switch(n) {
case 1:
*(u8 __force *)to = *(u8 *)from;
return 0;
case 2:
*(u16 __force *)to = *(u16 *)from;
return 0;
case 4:
*(u32 __force *)to = *(u32 *)from;
return 0;
#ifdef CONFIG_64BIT
case 8:
*(u64 __force *)to = *(u64 *)from;
return 0;
#endif
default:
break;
}
}
memcpy((void __force *)to, from, n);
return 0;
}