v4.19.13 snapshot.
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
new file mode 100644
index 0000000..efe79c1
--- /dev/null
+++ b/include/linux/uaccess.h
@@ -0,0 +1,284 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_UACCESS_H__
+#define __LINUX_UACCESS_H__
+
+#include <linux/sched.h>
+#include <linux/thread_info.h>
+#include <linux/kasan-checks.h>
+
+#define VERIFY_READ 0
+#define VERIFY_WRITE 1
+
+#define uaccess_kernel() segment_eq(get_fs(), KERNEL_DS)
+
+#include <asm/uaccess.h>
+
+/*
+ * Architectures should provide two primitives (raw_copy_{to,from}_user())
+ * and get rid of their private instances of copy_{to,from}_user() and
+ * __copy_{to,from}_user{,_inatomic}().
+ *
+ * raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
+ * return the amount left to copy. They should assume that access_ok() has
+ * already been checked (and succeeded); they should *not* zero-pad anything.
+ * No KASAN or object size checks either - those belong here.
+ *
+ * Both of these functions should attempt to copy size bytes starting at from
+ * into the area starting at to. They must not fetch or store anything
+ * outside of those areas. Return value must be between 0 (everything
+ * copied successfully) and size (nothing copied).
+ *
+ * If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
+ * at to must become equal to the bytes fetched from the corresponding area
+ * starting at from. All data past to + size - N must be left unmodified.
+ *
+ * If copying succeeds, the return value must be 0. If some data cannot be
+ * fetched, it is permitted to copy less than had been fetched; the only
+ * hard requirement is that not storing anything at all (i.e. returning size)
+ * should happen only when nothing could be copied. In other words, you don't
+ * have to squeeze as much as possible - it is allowed, but not necessary.
+ *
+ * For raw_copy_from_user() to always points to kernel memory and no faults
+ * on store should happen. Interpretation of from is affected by set_fs().
+ * For raw_copy_to_user() it's the other way round.
+ *
+ * Both can be inlined - it's up to architectures whether it wants to bother
+ * with that. They should not be used directly; they are used to implement
+ * the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
+ * that are used instead. Out of those, __... ones are inlined. Plain
+ * copy_{to,from}_user() might or might not be inlined. If you want them
+ * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
+ *
+ * NOTE: only copy_from_user() zero-pads the destination in case of short copy.
+ * Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
+ * at all; their callers absolutely must check the return value.
+ *
+ * Biarch ones should also provide raw_copy_in_user() - similar to the above,
+ * but both source and destination are __user pointers (affected by set_fs()
+ * as usual) and both source and destination can trigger faults.
+ */
+
+static __always_inline unsigned long
+__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
+{
+ kasan_check_write(to, n);
+ check_object_size(to, n, false);
+ return raw_copy_from_user(to, from, n);
+}
+
+static __always_inline unsigned long
+__copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ might_fault();
+ kasan_check_write(to, n);
+ check_object_size(to, n, false);
+ return raw_copy_from_user(to, from, n);
+}
+
+/**
+ * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
+ * @to: Destination address, in user space.
+ * @from: Source address, in kernel space.
+ * @n: Number of bytes to copy.
+ *
+ * Context: User context only.
+ *
+ * Copy data from kernel space to user space. Caller must check
+ * the specified block with access_ok() before calling this function.
+ * The caller should also make sure he pins the user space address
+ * so that we don't result in page fault and sleep.
+ */
+static __always_inline unsigned long
+__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
+{
+ kasan_check_read(from, n);
+ check_object_size(from, n, true);
+ return raw_copy_to_user(to, from, n);
+}
+
+static __always_inline unsigned long
+__copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ might_fault();
+ kasan_check_read(from, n);
+ check_object_size(from, n, true);
+ return raw_copy_to_user(to, from, n);
+}
+
+#ifdef INLINE_COPY_FROM_USER
+static inline unsigned long
+_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ unsigned long res = n;
+ might_fault();
+ if (likely(access_ok(VERIFY_READ, from, n))) {
+ kasan_check_write(to, n);
+ res = raw_copy_from_user(to, from, n);
+ }
+ if (unlikely(res))
+ memset(to + (n - res), 0, res);
+ return res;
+}
+#else
+extern unsigned long
+_copy_from_user(void *, const void __user *, unsigned long);
+#endif
+
+#ifdef INLINE_COPY_TO_USER
+static inline unsigned long
+_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ might_fault();
+ if (access_ok(VERIFY_WRITE, to, n)) {
+ kasan_check_read(from, n);
+ n = raw_copy_to_user(to, from, n);
+ }
+ return n;
+}
+#else
+extern unsigned long
+_copy_to_user(void __user *, const void *, unsigned long);
+#endif
+
+static __always_inline unsigned long __must_check
+copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ if (likely(check_copy_size(to, n, false)))
+ n = _copy_from_user(to, from, n);
+ return n;
+}
+
+static __always_inline unsigned long __must_check
+copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ if (likely(check_copy_size(from, n, true)))
+ n = _copy_to_user(to, from, n);
+ return n;
+}
+#ifdef CONFIG_COMPAT
+static __always_inline unsigned long __must_check
+copy_in_user(void __user *to, const void __user *from, unsigned long n)
+{
+ might_fault();
+ if (access_ok(VERIFY_WRITE, to, n) && access_ok(VERIFY_READ, from, n))
+ n = raw_copy_in_user(to, from, n);
+ return n;
+}
+#endif
+
+static __always_inline void pagefault_disabled_inc(void)
+{
+ current->pagefault_disabled++;
+}
+
+static __always_inline void pagefault_disabled_dec(void)
+{
+ current->pagefault_disabled--;
+}
+
+/*
+ * These routines enable/disable the pagefault handler. If disabled, it will
+ * not take any locks and go straight to the fixup table.
+ *
+ * User access methods will not sleep when called from a pagefault_disabled()
+ * environment.
+ */
+static inline void pagefault_disable(void)
+{
+ pagefault_disabled_inc();
+ /*
+ * make sure to have issued the store before a pagefault
+ * can hit.
+ */
+ barrier();
+}
+
+static inline void pagefault_enable(void)
+{
+ /*
+ * make sure to issue those last loads/stores before enabling
+ * the pagefault handler again.
+ */
+ barrier();
+ pagefault_disabled_dec();
+}
+
+/*
+ * Is the pagefault handler disabled? If so, user access methods will not sleep.
+ */
+#define pagefault_disabled() (current->pagefault_disabled != 0)
+
+/*
+ * The pagefault handler is in general disabled by pagefault_disable() or
+ * when in irq context (via in_atomic()).
+ *
+ * This function should only be used by the fault handlers. Other users should
+ * stick to pagefault_disabled().
+ * Please NEVER use preempt_disable() to disable the fault handler. With
+ * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
+ * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
+ */
+#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
+
+#ifndef ARCH_HAS_NOCACHE_UACCESS
+
+static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
+ const void __user *from, unsigned long n)
+{
+ return __copy_from_user_inatomic(to, from, n);
+}
+
+#endif /* ARCH_HAS_NOCACHE_UACCESS */
+
+/*
+ * probe_kernel_read(): safely attempt to read from a location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_kernel_read(void *dst, const void *src, size_t size);
+extern long __probe_kernel_read(void *dst, const void *src, size_t size);
+
+/*
+ * probe_kernel_write(): safely attempt to write to a location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
+extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
+
+extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
+
+/**
+ * probe_kernel_address(): safely attempt to read from a location
+ * @addr: address to read from
+ * @retval: read into this variable
+ *
+ * Returns 0 on success, or -EFAULT.
+ */
+#define probe_kernel_address(addr, retval) \
+ probe_kernel_read(&retval, addr, sizeof(retval))
+
+#ifndef user_access_begin
+#define user_access_begin() do { } while (0)
+#define user_access_end() do { } while (0)
+#define unsafe_get_user(x, ptr, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0)
+#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
+#endif
+
+#ifdef CONFIG_HARDENED_USERCOPY
+void usercopy_warn(const char *name, const char *detail, bool to_user,
+ unsigned long offset, unsigned long len);
+void __noreturn usercopy_abort(const char *name, const char *detail,
+ bool to_user, unsigned long offset,
+ unsigned long len);
+#endif
+
+#endif /* __LINUX_UACCESS_H__ */