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Subject[PATCH v2 20/31] arm64: User access library functions
Date
This patch add support for various user access functions. These
functions use the standard LDR/STR instructions and not the LDRT/STRT
variants in order to allow kernel addresses (after set_fs(KERNEL_DS)).

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/uaccess.h | 377 ++++++++++++++++++++++++++++++++++++
arch/arm64/lib/clear_user.S | 58 ++++++
arch/arm64/lib/copy_from_user.S | 66 +++++++
arch/arm64/lib/copy_in_user.S | 63 ++++++
arch/arm64/lib/copy_to_user.S | 61 ++++++
arch/arm64/lib/getuser.S | 75 +++++++
arch/arm64/lib/putuser.S | 73 +++++++
arch/arm64/lib/strncpy_from_user.S | 50 +++++
arch/arm64/lib/strnlen_user.S | 47 +++++
9 files changed, 870 insertions(+), 0 deletions(-)
create mode 100644 arch/arm64/include/asm/uaccess.h
create mode 100644 arch/arm64/lib/clear_user.S
create mode 100644 arch/arm64/lib/copy_from_user.S
create mode 100644 arch/arm64/lib/copy_in_user.S
create mode 100644 arch/arm64/lib/copy_to_user.S
create mode 100644 arch/arm64/lib/getuser.S
create mode 100644 arch/arm64/lib/putuser.S
create mode 100644 arch/arm64/lib/strncpy_from_user.S
create mode 100644 arch/arm64/lib/strnlen_user.S
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
new file mode 100644
index 0000000..09d7b53
--- /dev/null
+++ b/arch/arm64/include/asm/uaccess.h
@@ -0,0 +1,377 @@
+/*
+ * Based on arch/arm/include/asm/uaccess.h
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_UACCESS_H
+#define __ASM_UACCESS_H
+
+/*
+ * User space memory access functions
+ */
+#include <linux/string.h>
+#include <linux/thread_info.h>
+
+#include <asm/ptrace.h>
+#include <asm/errno.h>
+#include <asm/memory.h>
+#include <asm/compiler.h>
+
+#define VERIFY_READ 0
+#define VERIFY_WRITE 1
+
+/*
+ * The exception table consists of pairs of addresses: the first is the
+ * address of an instruction that is allowed to fault, and the second is
+ * the address at which the program should continue. No registers are
+ * modified, so it is entirely up to the continuation code to figure out
+ * what to do.
+ *
+ * All the routines below use bits of fixup code that are out of line
+ * with the main instruction path. This means when everything is well,
+ * we don't even have to jump over them. Further, they do not intrude
+ * on our cache or tlb entries.
+ */
+
+struct exception_table_entry
+{
+ unsigned long insn, fixup;
+};
+
+extern int fixup_exception(struct pt_regs *regs);
+
+/*
+ * These two are intentionally not defined anywhere - if the kernel
+ * code generates any references to them, that's a bug.
+ */
+extern long __get_user_bad(void);
+extern long __put_user_bad(void);
+
+#define KERNEL_DS (-1UL)
+#define get_ds() (KERNEL_DS)
+
+#define USER_DS TASK_SIZE_64
+#define get_fs() (current_thread_info()->addr_limit)
+
+static inline void set_fs(mm_segment_t fs)
+{
+ current_thread_info()->addr_limit = fs;
+}
+
+#define segment_eq(a,b) ((a) == (b))
+
+/*
+ * Return 1 if addr < current->addr_limit, 0 otherwise.
+ */
+#define __addr_ok(addr) \
+({ \
+ unsigned long flag; \
+ asm("cmp %1, %0; cset %0, lo" \
+ : "=&r" (flag) \
+ : "r" (addr), "0" (current_thread_info()->addr_limit) \
+ : "cc"); \
+ flag; \
+})
+
+/*
+ * Test whether a block of memory is a valid user space address.
+ * Returns 1 if the range is valid, 0 otherwise.
+ *
+ * This is equivalent to the following test:
+ * (u65)addr + (u65)size < (u65)current->addr_limit
+ *
+ * This needs 65-bit arithmetic.
+ */
+#define __range_ok(addr,size) \
+({ \
+ unsigned long flag, roksum; \
+ __chk_user_ptr(addr); \
+ asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, cc" \
+ : "=&r" (flag), "=&r" (roksum) \
+ : "1" (addr), "Ir" (size), \
+ "r" (current_thread_info()->addr_limit) \
+ : "cc"); \
+ flag; \
+})
+
+/*
+ * Single-value transfer routines. They automatically use the right
+ * size if we just have the right pointer type. Note that the functions
+ * which read from user space (*get_*) need to take care not to leak
+ * kernel data even if the calling code is buggy and fails to check
+ * the return value. This means zeroing out the destination variable
+ * or buffer on error. Normally this is done out of line by the
+ * fixup code, but there are a few places where it intrudes on the
+ * main code path. When we only write to user space, there is no
+ * problem.
+ */
+extern long __get_user_1(void *);
+extern long __get_user_2(void *);
+extern long __get_user_4(void *);
+extern long __get_user_8(void *);
+
+#define __get_user_x(__r2,__p,__e,__s,__i...) \
+ asm volatile( \
+ __asmeq("%0", "x0") __asmeq("%1", "x2") \
+ "bl __get_user_" #__s \
+ : "=&r" (__e), "=r" (__r2) \
+ : "0" (__p) \
+ : __i, "cc")
+
+#define get_user(x,p) \
+ ({ \
+ register const typeof(*(p)) __user *__p asm("x0") = (p);\
+ register unsigned long __r2 asm("x2"); \
+ register long __e asm("x0"); \
+ switch (sizeof(*(__p))) { \
+ case 1: \
+ __get_user_x(__r2, __p, __e, 1, "x30"); \
+ break; \
+ case 2: \
+ __get_user_x(__r2, __p, __e, 2, "x3", "x30"); \
+ break; \
+ case 4: \
+ __get_user_x(__r2, __p, __e, 4, "x30"); \
+ break; \
+ case 8: \
+ __get_user_x(__r2, __p, __e, 8, "x30"); \
+ break; \
+ default: __e = __get_user_bad(); break; \
+ } \
+ x = (typeof(*(p))) __r2; \
+ __e; \
+ })
+
+#define __get_user_unaligned __get_user
+
+extern long __put_user_1(void *, unsigned long);
+extern long __put_user_2(void *, unsigned long);
+extern long __put_user_4(void *, unsigned long);
+extern long __put_user_8(void *, unsigned long);
+
+#define __put_user_x(__r2,__p,__e,__s) \
+ asm volatile( \
+ __asmeq("%0", "x0") __asmeq("%2", "x2") \
+ "bl __put_user_" #__s \
+ : "=&r" (__e) \
+ : "0" (__p), "r" (__r2) \
+ : "x8", "x30", "cc")
+
+#define put_user(x,p) \
+ ({ \
+ register const typeof(*(p)) __r2 asm("x2") = (x); \
+ register const typeof(*(p)) __user *__p asm("x0") = (p);\
+ register long __e asm("x0"); \
+ switch (sizeof(*(__p))) { \
+ case 1: \
+ __put_user_x(__r2, __p, __e, 1); \
+ break; \
+ case 2: \
+ __put_user_x(__r2, __p, __e, 2); \
+ break; \
+ case 4: \
+ __put_user_x(__r2, __p, __e, 4); \
+ break; \
+ case 8: \
+ __put_user_x(__r2, __p, __e, 8); \
+ break; \
+ default: __e = __put_user_bad(); break; \
+ } \
+ __e; \
+ })
+
+#define __put_user_unaligned __put_user
+
+#define access_ok(type,addr,size) __range_ok(addr,size)
+
+/*
+ * The "__xxx" versions of the user access functions do not verify the
+ * address space - it must have been done previously with a separate
+ * "access_ok()" call.
+ *
+ * The "xxx_error" versions set the third argument to EFAULT if an
+ * error occurs, and leave it unchanged on success. Note that these
+ * versions are void (ie, don't return a value as such).
+ */
+#define __get_user(x,ptr) \
+({ \
+ long __gu_err = 0; \
+ __get_user_err((x),(ptr),__gu_err); \
+ __gu_err; \
+})
+
+#define __get_user_error(x,ptr,err) \
+({ \
+ __get_user_err((x),(ptr),err); \
+ (void) 0; \
+})
+
+#define __get_user_err(x,ptr,err) \
+do { \
+ unsigned long __gu_addr = (unsigned long)(ptr); \
+ unsigned long __gu_val; \
+ __chk_user_ptr(ptr); \
+ switch (sizeof(*(ptr))) { \
+ case 1: \
+ __get_user_asm("ldrb", "%w", __gu_val, __gu_addr, err); \
+ break; \
+ case 2: \
+ __get_user_asm("ldrh", "%w", __gu_val, __gu_addr, err); \
+ break; \
+ case 4: \
+ __get_user_asm("ldr", "%w", __gu_val, __gu_addr, err); \
+ break; \
+ case 8: \
+ __get_user_asm("ldr", "%", __gu_val, __gu_addr, err); \
+ break; \
+ default: \
+ (__gu_val) = __get_user_bad(); \
+ } \
+ (x) = (__typeof__(*(ptr)))__gu_val; \
+} while (0)
+
+#define __get_user_asm(instr, reg, x, addr, err) \
+ asm volatile( \
+ "1: " instr " " reg "1, [%2]\n" \
+ "2:\n" \
+ " .section .fixup, \"ax\"\n" \
+ " .align 2\n" \
+ "3: mov %0, %3\n" \
+ " mov %1, #0\n" \
+ " b 2b\n" \
+ " .previous\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 3\n" \
+ " .quad 1b, 3b\n" \
+ " .previous" \
+ : "+r" (err), "=&r" (x) \
+ : "r" (addr), "i" (-EFAULT) \
+ : "cc")
+
+#define __put_user(x,ptr) \
+({ \
+ long __pu_err = 0; \
+ __put_user_err((x),(ptr),__pu_err); \
+ __pu_err; \
+})
+
+#define __put_user_error(x,ptr,err) \
+({ \
+ __put_user_err((x),(ptr),err); \
+ (void) 0; \
+})
+
+#define __put_user_err(x,ptr,err) \
+do { \
+ unsigned long __pu_addr = (unsigned long)(ptr); \
+ __typeof__(*(ptr)) __pu_val = (x); \
+ __chk_user_ptr(ptr); \
+ switch (sizeof(*(ptr))) { \
+ case 1: \
+ __put_user_asm("strb", "%w", __pu_val, __pu_addr, err); \
+ break; \
+ case 2: \
+ __put_user_asm("strh", "%w", __pu_val, __pu_addr, err); \
+ break; \
+ case 4: \
+ __put_user_asm("str", "%w", __pu_val, __pu_addr, err); \
+ break; \
+ case 8: \
+ __put_user_asm("str", "%", __pu_val, __pu_addr, err); \
+ break; \
+ default: \
+ __put_user_bad(); \
+ } \
+} while (0)
+
+#define __put_user_asm(instr, reg, x, __pu_addr, err) \
+ asm volatile( \
+ "1: " instr " " reg "1, [%2]\n" \
+ "2:\n" \
+ " .section .fixup,\"ax\"\n" \
+ " .align 2\n" \
+ "3: mov %0, %3\n" \
+ " b 2b\n" \
+ " .previous\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 3\n" \
+ " .quad 1b, 3b\n" \
+ " .previous" \
+ : "+r" (err) \
+ : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
+ : "cc")
+
+extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
+extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
+extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
+extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
+
+extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
+extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
+
+static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ if (access_ok(VERIFY_READ, from, n))
+ n = __copy_from_user(to, from, n);
+ else /* security hole - plug it */
+ memset(to, 0, n);
+ return n;
+}
+
+static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ if (access_ok(VERIFY_WRITE, to, n))
+ n = __copy_to_user(to, from, n);
+ return n;
+}
+
+static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n)
+{
+ if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n))
+ n = __copy_in_user(to, from, n);
+ return n;
+}
+
+#define __copy_to_user_inatomic __copy_to_user
+#define __copy_from_user_inatomic __copy_from_user
+
+static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
+{
+ if (access_ok(VERIFY_WRITE, to, n))
+ n = __clear_user(to, n);
+ return n;
+}
+
+static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
+{
+ long res = -EFAULT;
+ if (access_ok(VERIFY_READ, src, 1))
+ res = __strncpy_from_user(dst, src, count);
+ return res;
+}
+
+#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
+
+static inline long __must_check strnlen_user(const char __user *s, long n)
+{
+ unsigned long res = 0;
+
+ if (__addr_ok(s))
+ res = __strnlen_user(s, n);
+
+ return res;
+}
+
+#endif /* __ASM_UACCESS_H */
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
new file mode 100644
index 0000000..6e0ed93
--- /dev/null
+++ b/arch/arm64/lib/clear_user.S
@@ -0,0 +1,58 @@
+/*
+ * Based on arch/arm/lib/clear_user.S
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+ .text
+
+/* Prototype: int __clear_user(void *addr, size_t sz)
+ * Purpose : clear some user memory
+ * Params : addr - user memory address to clear
+ * : sz - number of bytes to clear
+ * Returns : number of bytes NOT cleared
+ *
+ * Alignment fixed up by hardware.
+ */
+ENTRY(__clear_user)
+ mov x2, x1 // save the size for fixup return
+ subs x1, x1, #8
+ b.mi 2f
+1:
+USER(9f, str xzr, [x0], #8 )
+ subs x1, x1, #8
+ b.pl 1b
+2: adds x1, x1, #4
+ b.mi 3f
+USER(9f, str wzr, [x0], #4 )
+ sub x1, x1, #4
+3: adds x1, x1, #2
+ b.mi 4f
+USER(9f, strh wzr, [x0], #2 )
+ sub x1, x1, #2
+4: adds x1, x1, #1
+ b.mi 5f
+ strb wzr, [x0]
+5: mov x0, #0
+ ret
+ENDPROC(__clear_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: mov x0, x2 // return the original size
+ ret
+ .previous
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
new file mode 100644
index 0000000..5e27add
--- /dev/null
+++ b/arch/arm64/lib/copy_from_user.S
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Copy from user space to a kernel buffer (alignment handled by the hardware)
+ *
+ * Parameters:
+ * x0 - to
+ * x1 - from
+ * x2 - n
+ * Returns:
+ * x0 - bytes not copied
+ */
+ENTRY(__copy_from_user)
+ add x4, x1, x2 // upper user buffer boundary
+ subs x2, x2, #8
+ b.mi 2f
+1:
+USER(9f, ldr x3, [x1], #8 )
+ subs x2, x2, #8
+ str x3, [x0], #8
+ b.pl 1b
+2: adds x2, x2, #4
+ b.mi 3f
+USER(9f, ldr w3, [x1], #4 )
+ sub x2, x2, #4
+ str w3, [x0], #4
+3: adds x2, x2, #2
+ b.mi 4f
+USER(9f, ldrh w3, [x1], #2 )
+ sub x2, x2, #2
+ strh w3, [x0], #2
+4: adds x2, x2, #1
+ b.mi 5f
+USER(9f, ldrb w3, [x1] )
+ strb w3, [x0]
+5: mov x0, #0
+ ret
+ENDPROC(__copy_from_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: sub x2, x4, x1
+ mov x3, x2
+10: strb wzr, [x0], #1 // zero remaining buffer space
+ subs x3, x3, #1
+ b.ne 10b
+ mov x0, x2 // bytes not copied
+ ret
+ .previous
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
new file mode 100644
index 0000000..84b6c9b
--- /dev/null
+++ b/arch/arm64/lib/copy_in_user.S
@@ -0,0 +1,63 @@
+/*
+ * Copy from user space to user space
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Copy from user space to user space (alignment handled by the hardware)
+ *
+ * Parameters:
+ * x0 - to
+ * x1 - from
+ * x2 - n
+ * Returns:
+ * x0 - bytes not copied
+ */
+ENTRY(__copy_in_user)
+ add x4, x0, x2 // upper user buffer boundary
+ subs x2, x2, #8
+ b.mi 2f
+1:
+USER(9f, ldr x3, [x1], #8 )
+ subs x2, x2, #8
+USER(9f, str x3, [x0], #8 )
+ b.pl 1b
+2: adds x2, x2, #4
+ b.mi 3f
+USER(9f, ldr w3, [x1], #4 )
+ sub x2, x2, #4
+USER(9f, str w3, [x0], #4 )
+3: adds x2, x2, #2
+ b.mi 4f
+USER(9f, ldrh w3, [x1], #2 )
+ sub x2, x2, #2
+USER(9f, strh w3, [x0], #2 )
+4: adds x2, x2, #1
+ b.mi 5f
+USER(9f, ldrb w3, [x1] )
+USER(9f, strb w3, [x0] )
+5: mov x0, #0
+ ret
+ENDPROC(__copy_in_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: sub x0, x4, x0 // bytes not copied
+ ret
+ .previous
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
new file mode 100644
index 0000000..a0aeeb9
--- /dev/null
+++ b/arch/arm64/lib/copy_to_user.S
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Copy to user space from a kernel buffer (alignment handled by the hardware)
+ *
+ * Parameters:
+ * x0 - to
+ * x1 - from
+ * x2 - n
+ * Returns:
+ * x0 - bytes not copied
+ */
+ENTRY(__copy_to_user)
+ add x4, x0, x2 // upper user buffer boundary
+ subs x2, x2, #8
+ b.mi 2f
+1:
+ ldr x3, [x1], #8
+ subs x2, x2, #8
+USER(9f, str x3, [x0], #8 )
+ b.pl 1b
+2: adds x2, x2, #4
+ b.mi 3f
+ ldr w3, [x1], #4
+ sub x2, x2, #4
+USER(9f, str w3, [x0], #4 )
+3: adds x2, x2, #2
+ b.mi 4f
+ ldrh w3, [x1], #2
+ sub x2, x2, #2
+USER(9f, strh w3, [x0], #2 )
+4: adds x2, x2, #1
+ b.mi 5f
+ ldrb w3, [x1]
+USER(9f, strb w3, [x0] )
+5: mov x0, #0
+ ret
+ENDPROC(__copy_to_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: sub x0, x4, x0 // bytes not copied
+ ret
+ .previous
diff --git a/arch/arm64/lib/getuser.S b/arch/arm64/lib/getuser.S
new file mode 100644
index 0000000..1b4da22
--- /dev/null
+++ b/arch/arm64/lib/getuser.S
@@ -0,0 +1,75 @@
+/*
+ * Based on arch/arm/lib/getuser.S
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Idea from x86 version, (C) Copyright 1998 Linus Torvalds
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * These functions have a non-standard call interface to make them more
+ * efficient, especially as they return an error value in addition to
+ * the "real" return value.
+ *
+ * __get_user_X
+ *
+ * Inputs: x0 contains the address
+ * Outputs: x0 is the error code
+ * x2, x3 contains the zero-extended value
+ * lr corrupted
+ *
+ * No other registers must be altered. (see <asm/uaccess.h>
+ * for specific ASM register usage).
+ *
+ * Note also that it is intended that __get_user_bad is not global.
+ */
+
+#include <linux/linkage.h>
+#include <asm/errno.h>
+
+ENTRY(__get_user_1)
+1: ldrb w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__get_user_1)
+
+ENTRY(__get_user_2)
+2: ldrh w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__get_user_2)
+
+ENTRY(__get_user_4)
+3: ldr w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__get_user_4)
+
+ENTRY(__get_user_8)
+4: ldr x2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__get_user_4)
+
+__get_user_bad:
+ mov x2, #0
+ mov x0, #-EFAULT
+ ret
+ENDPROC(__get_user_bad)
+
+.section __ex_table, "a"
+ .quad 1b, __get_user_bad
+ .quad 2b, __get_user_bad
+ .quad 3b, __get_user_bad
+ .quad 4b, __get_user_bad
+.previous
diff --git a/arch/arm64/lib/putuser.S b/arch/arm64/lib/putuser.S
new file mode 100644
index 0000000..62d4a42
--- /dev/null
+++ b/arch/arm64/lib/putuser.S
@@ -0,0 +1,73 @@
+/*
+ * Based on arch/arm/lib/putuser.S
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Idea from x86 version, (C) Copyright 1998 Linus Torvalds
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * These functions have a non-standard call interface to make
+ * them more efficient, especially as they return an error
+ * value in addition to the "real" return value.
+ *
+ * __put_user_X
+ *
+ * Inputs: x0 contains the address
+ * x2, x3 contains the value
+ * Outputs: x0 is the error code
+ * lr corrupted
+ *
+ * No other registers must be altered. (see <asm/uaccess.h>
+ * for specific ASM register usage).
+ *
+ * Note that it is intended that __put_user_bad is not global.
+ */
+
+#include <linux/linkage.h>
+#include <asm/errno.h>
+
+ENTRY(__put_user_1)
+1: strb w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__put_user_1)
+
+ENTRY(__put_user_2)
+2: strh w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__put_user_2)
+
+ENTRY(__put_user_4)
+3: str w2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__put_user_4)
+
+ENTRY(__put_user_8)
+4: str x2, [x0]
+ mov x0, #0
+ ret
+ENDPROC(__put_user_8)
+
+__put_user_bad:
+ mov x0, #-EFAULT
+ ret
+ENDPROC(__put_user_bad)
+
+.section __ex_table, "a"
+ .quad 1b, __put_user_bad
+ .quad 2b, __put_user_bad
+ .quad 3b, __put_user_bad
+ .quad 4b, __put_user_bad
+.previous
diff --git a/arch/arm64/lib/strncpy_from_user.S b/arch/arm64/lib/strncpy_from_user.S
new file mode 100644
index 0000000..56e448a
--- /dev/null
+++ b/arch/arm64/lib/strncpy_from_user.S
@@ -0,0 +1,50 @@
+/*
+ * Based on arch/arm/lib/strncpy_from_user.S
+ *
+ * Copyright (C) 1995-2000 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/errno.h>
+
+ .text
+ .align 5
+
+/*
+ * Copy a string from user space to kernel space.
+ * x0 = dst, x1 = src, x2 = byte length
+ * returns the number of characters copied (strlen of copied string),
+ * -EFAULT on exception, or "len" if we fill the whole buffer
+ */
+ENTRY(__strncpy_from_user)
+ mov x4, x1
+1: subs x2, x2, #1
+ bmi 2f
+USER(9f, ldrb w3, [x1], #1 )
+ strb w3, [x0], #1
+ cbnz w3, 1b
+ sub x1, x1, #1 // take NUL character out of count
+2: sub x0, x1, x4
+ ret
+ENDPROC(__strncpy_from_user)
+
+ .section .fixup,"ax"
+ .align 0
+9: strb wzr, [x0] // null terminate
+ mov x0, #-EFAULT
+ ret
+ .previous
diff --git a/arch/arm64/lib/strnlen_user.S b/arch/arm64/lib/strnlen_user.S
new file mode 100644
index 0000000..7f7b176
--- /dev/null
+++ b/arch/arm64/lib/strnlen_user.S
@@ -0,0 +1,47 @@
+/*
+ * Based on arch/arm/lib/strnlen_user.S
+ *
+ * Copyright (C) 1995-2000 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/errno.h>
+
+ .text
+ .align 5
+
+/* Prototype: unsigned long __strnlen_user(const char *str, long n)
+ * Purpose : get length of a string in user memory
+ * Params : str - address of string in user memory
+ * Returns : length of string *including terminator*
+ * or zero on exception, or n if too long
+ */
+ENTRY(__strnlen_user)
+ mov x2, x0
+1: subs x1, x1, #1
+ b.mi 2f
+USER(9f, ldrb w3, [x0], #1 )
+ cbnz w3, 1b
+2: sub x0, x0, x2
+ ret
+ENDPROC(__strnlen_user)
+
+ .section .fixup,"ax"
+ .align 0
+9: mov x0, #0
+ ret
+ .previous


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