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@@ -49,14 +49,11 @@ pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp)
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return 1;
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}
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-unsigned long
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-__copy_to_user(void __user *to, const void *from, unsigned long n)
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+static unsigned long noinline
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+__copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
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{
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int atomic;
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- if (n < 1024)
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- return __copy_to_user_std(to, from, n);
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-
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if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
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memcpy((void *)to, from, n);
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return 0;
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@@ -99,11 +96,24 @@ out:
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return n;
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}
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-unsigned long __clear_user(void __user *addr, unsigned long n)
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+unsigned long
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+__copy_to_user(void __user *to, const void *from, unsigned long n)
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+{
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+ /*
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+ * This test is stubbed out of the main function above to keep
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+ * the overhead for small copies low by avoiding a large
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+ * register dump on the stack just to reload them right away.
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+ * With frame pointer disabled, tail call optimization kicks in
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+ * as well making this test almost invisible.
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+ */
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+ if (n < 1024)
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+ return __copy_to_user_std(to, from, n);
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+ return __copy_to_user_memcpy(to, from, n);
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+}
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+
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+static unsigned long noinline
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+__clear_user_memset(void __user *addr, unsigned long n)
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{
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- if (n < 256)
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- return __clear_user_std(addr, n);
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-
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if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
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memset((void *)addr, 0, n);
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return 0;
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@@ -137,3 +147,11 @@ unsigned long __clear_user(void __user *addr, unsigned long n)
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out:
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return n;
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}
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+
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+unsigned long __clear_user(void __user *addr, unsigned long n)
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+{
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+ /* See rational for this in __copy_to_user() above. */
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+ if (n < 256)
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+ return __clear_user_std(addr, n);
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+ return __clear_user_memset(addr, n);
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+}
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