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Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
-rw-r--r--arch/x86/include/asm/uaccess.h124
1 files changed, 112 insertions, 12 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 8ec57c07b125..0d592e0a5b84 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -40,22 +40,30 @@
/*
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
- *
- * This is equivalent to the following test:
- * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64)
- *
- * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
*/
+static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
+{
+ /*
+ * If we have used "sizeof()" for the size,
+ * we know it won't overflow the limit (but
+ * it might overflow the 'addr', so it's
+ * important to subtract the size from the
+ * limit, not add it to the address).
+ */
+ if (__builtin_constant_p(size))
+ return addr > limit - size;
+
+ /* Arbitrary sizes? Be careful about overflow */
+ addr += size;
+ if (addr < size)
+ return true;
+ return addr > limit;
+}
#define __range_not_ok(addr, size, limit) \
({ \
- unsigned long flag, roksum; \
__chk_user_ptr(addr); \
- asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0" \
- : "=&r" (flag), "=r" (roksum) \
- : "1" (addr), "g" ((long)(size)), \
- "rm" (limit)); \
- flag; \
+ __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
})
/**
@@ -78,7 +86,7 @@
* this function, memory access functions may still return -EFAULT.
*/
#define access_ok(type, addr, size) \
- (likely(__range_not_ok(addr, size, user_addr_max()) == 0))
+ likely(!__range_not_ok(addr, size, user_addr_max()))
/*
* The exception table consists of pairs of addresses relative to the
@@ -525,6 +533,98 @@ extern __must_check long strnlen_user(const char __user *str, long n);
unsigned long __must_check clear_user(void __user *mem, unsigned long len);
unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
+extern void __cmpxchg_wrong_size(void)
+ __compiletime_error("Bad argument size for cmpxchg");
+
+#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
+({ \
+ int __ret = 0; \
+ __typeof__(ptr) __uval = (uval); \
+ __typeof__(*(ptr)) __old = (old); \
+ __typeof__(*(ptr)) __new = (new); \
+ switch (size) { \
+ case 1: \
+ { \
+ asm volatile("\t" ASM_STAC "\n" \
+ "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
+ "2:\t" ASM_CLAC "\n" \
+ "\t.section .fixup, \"ax\"\n" \
+ "3:\tmov %3, %0\n" \
+ "\tjmp 2b\n" \
+ "\t.previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
+ : "i" (-EFAULT), "q" (__new), "1" (__old) \
+ : "memory" \
+ ); \
+ break; \
+ } \
+ case 2: \
+ { \
+ asm volatile("\t" ASM_STAC "\n" \
+ "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
+ "2:\t" ASM_CLAC "\n" \
+ "\t.section .fixup, \"ax\"\n" \
+ "3:\tmov %3, %0\n" \
+ "\tjmp 2b\n" \
+ "\t.previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
+ : "i" (-EFAULT), "r" (__new), "1" (__old) \
+ : "memory" \
+ ); \
+ break; \
+ } \
+ case 4: \
+ { \
+ asm volatile("\t" ASM_STAC "\n" \
+ "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
+ "2:\t" ASM_CLAC "\n" \
+ "\t.section .fixup, \"ax\"\n" \
+ "3:\tmov %3, %0\n" \
+ "\tjmp 2b\n" \
+ "\t.previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
+ : "i" (-EFAULT), "r" (__new), "1" (__old) \
+ : "memory" \
+ ); \
+ break; \
+ } \
+ case 8: \
+ { \
+ if (!IS_ENABLED(CONFIG_X86_64)) \
+ __cmpxchg_wrong_size(); \
+ \
+ asm volatile("\t" ASM_STAC "\n" \
+ "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
+ "2:\t" ASM_CLAC "\n" \
+ "\t.section .fixup, \"ax\"\n" \
+ "3:\tmov %3, %0\n" \
+ "\tjmp 2b\n" \
+ "\t.previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
+ : "i" (-EFAULT), "r" (__new), "1" (__old) \
+ : "memory" \
+ ); \
+ break; \
+ } \
+ default: \
+ __cmpxchg_wrong_size(); \
+ } \
+ *__uval = __old; \
+ __ret; \
+})
+
+#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
+({ \
+ access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
+ __user_atomic_cmpxchg_inatomic((uval), (ptr), \
+ (old), (new), sizeof(*(ptr))) : \
+ -EFAULT; \
+})
+
/*
* movsl can be slow when source and dest are not both 8-byte aligned
*/