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authorArnd Bergmann <arnd@arndb.de>2022-02-15 17:55:04 +0100
committerArnd Bergmann <arnd@arndb.de>2022-02-25 09:36:05 +0100
commit12700c17fc286149324f92d6d380bc48e43f253d (patch)
tree63157067b99d0adec5db4058ab9235b4802d1e49 /arch/alpha
parent23fc539e81295b14b50c6ccc5baeb4f3d59d822d (diff)
uaccess: generalize access_ok()
There are many different ways that access_ok() is defined across architectures, but in the end, they all just compare against the user_addr_max() value or they accept anything. Provide one definition that works for most architectures, checking against TASK_SIZE_MAX for user processes or skipping the check inside of uaccess_kernel() sections. For architectures without CONFIG_SET_FS(), this should be the fastest check, as it comes down to a single comparison of a pointer against a compile-time constant, while the architecture specific versions tend to do something more complex for historic reasons or get something wrong. Type checking for __user annotations is handled inconsistently across architectures, but this is easily simplified as well by using an inline function that takes a 'const void __user *' argument. A handful of callers need an extra __user annotation for this. Some architectures had trick to use 33-bit or 65-bit arithmetic on the addresses to calculate the overflow, however this simpler version uses fewer registers, which means it can produce better object code in the end despite needing a second (statically predicted) branch. Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64, asm-generic] Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Stafford Horne <shorne@gmail.com> Acked-by: Dinh Nguyen <dinguyen@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/alpha')
-rw-r--r--arch/alpha/include/asm/uaccess.h34
1 files changed, 5 insertions, 29 deletions
diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 1b6f25efa247..82c5743fc9cd 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -20,28 +20,7 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-/*
- * Is a address valid? This does a straightforward calculation rather
- * than tests.
- *
- * Address valid if:
- * - "addr" doesn't have any high-bits set
- * - AND "size" doesn't have any high-bits set
- * - AND "addr+size-(size != 0)" doesn't have any high-bits set
- * - OR we are in kernel mode.
- */
-#define __access_ok(addr, size) ({ \
- unsigned long __ao_a = (addr), __ao_b = (size); \
- unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \
- (get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })
-
-#define access_ok(addr, size) \
-({ \
- __chk_user_ptr(addr); \
- __access_ok(((unsigned long)(addr)), (size)); \
-})
+#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically
@@ -105,7 +84,7 @@ extern void __get_user_unknown(void);
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
- if (__access_ok((unsigned long)__gu_addr, size)) { \
+ if (__access_ok(__gu_addr, size)) { \
__gu_err = 0; \
switch (size) { \
case 1: __get_user_8(__gu_addr); break; \
@@ -200,7 +179,7 @@ extern void __put_user_unknown(void);
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
- if (__access_ok((unsigned long)__pu_addr, size)) { \
+ if (__access_ok(__pu_addr, size)) { \
__pu_err = 0; \
switch (size) { \
case 1: __put_user_8(x, __pu_addr); break; \
@@ -316,17 +295,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long len)
extern long __clear_user(void __user *to, long len);
-extern inline long
+static inline long
clear_user(void __user *to, long len)
{
- if (__access_ok((unsigned long)to, len))
+ if (__access_ok(to, len))
len = __clear_user(to, len);
return len;
}
-#define user_addr_max() \
- (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
extern long strncpy_from_user(char *dest, const char __user *src, long count);
extern __must_check long strnlen_user(const char __user *str, long n);