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@@ -49,6 +49,35 @@ struct exception_table_entry
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extern int fixup_exception(struct pt_regs *regs);
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+/*
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+ * These two functions allow hooking accesses to userspace to increase
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+ * system integrity by ensuring that the kernel can not inadvertantly
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+ * perform such accesses (eg, via list poison values) which could then
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+ * be exploited for priviledge escalation.
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+ */
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+static inline unsigned int uaccess_save_and_enable(void)
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+{
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+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
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+ unsigned int old_domain = get_domain();
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+
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+ /* Set the current domain access to permit user accesses */
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+ set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
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+ domain_val(DOMAIN_USER, DOMAIN_CLIENT));
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+
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+ return old_domain;
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+#else
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+ return 0;
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+#endif
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+}
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+
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+static inline void uaccess_restore(unsigned int flags)
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+{
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+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
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+ /* Restore the user access mask */
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+ set_domain(flags);
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+#endif
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+}
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+
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/*
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* These two are intentionally not defined anywhere - if the kernel
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* code generates any references to them, that's a bug.
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@@ -165,6 +194,7 @@ extern int __get_user_64t_4(void *);
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register typeof(x) __r2 asm("r2"); \
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register unsigned long __l asm("r1") = __limit; \
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register int __e asm("r0"); \
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+ unsigned int __ua_flags = uaccess_save_and_enable(); \
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switch (sizeof(*(__p))) { \
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case 1: \
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if (sizeof((x)) >= 8) \
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@@ -192,6 +222,7 @@ extern int __get_user_64t_4(void *);
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break; \
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default: __e = __get_user_bad(); break; \
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} \
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+ uaccess_restore(__ua_flags); \
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x = (typeof(*(p))) __r2; \
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__e; \
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})
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@@ -224,6 +255,7 @@ extern int __put_user_8(void *, unsigned long long);
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register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
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register unsigned long __l asm("r1") = __limit; \
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register int __e asm("r0"); \
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+ unsigned int __ua_flags = uaccess_save_and_enable(); \
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switch (sizeof(*(__p))) { \
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case 1: \
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__put_user_x(__r2, __p, __e, __l, 1); \
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@@ -239,6 +271,7 @@ extern int __put_user_8(void *, unsigned long long);
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break; \
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default: __e = __put_user_bad(); break; \
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} \
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+ uaccess_restore(__ua_flags); \
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__e; \
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})
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@@ -300,20 +333,23 @@ static inline void set_fs(mm_segment_t fs)
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do { \
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unsigned long __gu_addr = (unsigned long)(ptr); \
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unsigned long __gu_val; \
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+ unsigned int __ua_flags; \
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__chk_user_ptr(ptr); \
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might_fault(); \
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+ __ua_flags = uaccess_save_and_enable(); \
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switch (sizeof(*(ptr))) { \
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case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \
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case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \
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case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \
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default: (__gu_val) = __get_user_bad(); \
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} \
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+ uaccess_restore(__ua_flags); \
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(x) = (__typeof__(*(ptr)))__gu_val; \
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} while (0)
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-#define __get_user_asm_byte(x, addr, err) \
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+#define __get_user_asm(x, addr, err, instr) \
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__asm__ __volatile__( \
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- "1: " TUSER(ldrb) " %1,[%2],#0\n" \
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+ "1: " TUSER(instr) " %1, [%2], #0\n" \
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"2:\n" \
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" .pushsection .text.fixup,\"ax\"\n" \
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" .align 2\n" \
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@@ -329,6 +365,9 @@ do { \
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: "r" (addr), "i" (-EFAULT) \
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: "cc")
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+#define __get_user_asm_byte(x, addr, err) \
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+ __get_user_asm(x, addr, err, ldrb)
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+
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#ifndef __ARMEB__
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#define __get_user_asm_half(x, __gu_addr, err) \
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({ \
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@@ -348,22 +387,7 @@ do { \
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#endif
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#define __get_user_asm_word(x, addr, err) \
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- __asm__ __volatile__( \
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- "1: " TUSER(ldr) " %1,[%2],#0\n" \
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- "2:\n" \
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- " .pushsection .text.fixup,\"ax\"\n" \
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- " .align 2\n" \
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- "3: mov %0, %3\n" \
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- " mov %1, #0\n" \
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- " b 2b\n" \
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- " .popsection\n" \
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- " .pushsection __ex_table,\"a\"\n" \
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- " .align 3\n" \
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- " .long 1b, 3b\n" \
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- " .popsection" \
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- : "+r" (err), "=&r" (x) \
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- : "r" (addr), "i" (-EFAULT) \
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- : "cc")
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+ __get_user_asm(x, addr, err, ldr)
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#define __put_user(x, ptr) \
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({ \
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@@ -381,9 +405,11 @@ do { \
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#define __put_user_err(x, ptr, err) \
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do { \
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unsigned long __pu_addr = (unsigned long)(ptr); \
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+ unsigned int __ua_flags; \
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__typeof__(*(ptr)) __pu_val = (x); \
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__chk_user_ptr(ptr); \
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might_fault(); \
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+ __ua_flags = uaccess_save_and_enable(); \
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switch (sizeof(*(ptr))) { \
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case 1: __put_user_asm_byte(__pu_val, __pu_addr, err); break; \
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case 2: __put_user_asm_half(__pu_val, __pu_addr, err); break; \
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@@ -391,11 +417,12 @@ do { \
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case 8: __put_user_asm_dword(__pu_val, __pu_addr, err); break; \
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default: __put_user_bad(); \
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} \
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+ uaccess_restore(__ua_flags); \
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} while (0)
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-#define __put_user_asm_byte(x, __pu_addr, err) \
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+#define __put_user_asm(x, __pu_addr, err, instr) \
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__asm__ __volatile__( \
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- "1: " TUSER(strb) " %1,[%2],#0\n" \
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+ "1: " TUSER(instr) " %1, [%2], #0\n" \
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"2:\n" \
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" .pushsection .text.fixup,\"ax\"\n" \
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" .align 2\n" \
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@@ -410,6 +437,9 @@ do { \
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: "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
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: "cc")
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+#define __put_user_asm_byte(x, __pu_addr, err) \
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+ __put_user_asm(x, __pu_addr, err, strb)
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+
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#ifndef __ARMEB__
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#define __put_user_asm_half(x, __pu_addr, err) \
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({ \
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@@ -427,21 +457,7 @@ do { \
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#endif
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#define __put_user_asm_word(x, __pu_addr, err) \
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- __asm__ __volatile__( \
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- "1: " TUSER(str) " %1,[%2],#0\n" \
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- "2:\n" \
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- " .pushsection .text.fixup,\"ax\"\n" \
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- " .align 2\n" \
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- "3: mov %0, %3\n" \
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- " b 2b\n" \
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- " .popsection\n" \
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- " .pushsection __ex_table,\"a\"\n" \
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- " .align 3\n" \
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- " .long 1b, 3b\n" \
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- " .popsection" \
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- : "+r" (err) \
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- : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
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- : "cc")
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+ __put_user_asm(x, __pu_addr, err, str)
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#ifndef __ARMEB__
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#define __reg_oper0 "%R2"
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@@ -474,11 +490,46 @@ do { \
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#ifdef CONFIG_MMU
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-extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
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-extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
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-extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
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-extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
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-extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
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+extern unsigned long __must_check
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+arm_copy_from_user(void *to, const void __user *from, unsigned long n);
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+
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+static inline unsigned long __must_check
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+__copy_from_user(void *to, const void __user *from, unsigned long n)
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+{
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+ unsigned int __ua_flags = uaccess_save_and_enable();
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+ n = arm_copy_from_user(to, from, n);
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+ uaccess_restore(__ua_flags);
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+ return n;
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+}
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+
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+extern unsigned long __must_check
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+arm_copy_to_user(void __user *to, const void *from, unsigned long n);
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+extern unsigned long __must_check
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+__copy_to_user_std(void __user *to, const void *from, unsigned long n);
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+
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+static inline unsigned long __must_check
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+__copy_to_user(void __user *to, const void *from, unsigned long n)
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+{
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+ unsigned int __ua_flags = uaccess_save_and_enable();
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+ n = arm_copy_to_user(to, from, n);
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+ uaccess_restore(__ua_flags);
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+ return n;
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+}
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+
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+extern unsigned long __must_check
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+arm_clear_user(void __user *addr, unsigned long n);
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+extern unsigned long __must_check
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+__clear_user_std(void __user *addr, unsigned long n);
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+
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+static inline unsigned long __must_check
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+__clear_user(void __user *addr, unsigned long n)
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+{
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+ unsigned int __ua_flags = uaccess_save_and_enable();
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+ n = arm_clear_user(addr, n);
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+ uaccess_restore(__ua_flags);
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+ return n;
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+}
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+
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#else
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#define __copy_from_user(to, from, n) (memcpy(to, (void __force *)from, n), 0)
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#define __copy_to_user(to, from, n) (memcpy((void __force *)to, from, n), 0)
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@@ -511,6 +562,7 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
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return n;
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}
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+/* These are from lib/ code, and use __get_user() and friends */
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extern long strncpy_from_user(char *dest, const char __user *src, long count);
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extern __must_check long strlen_user(const char __user *str);
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