Inter-revision diff: patch 7

Comparing v2 (message) to v1 (message)

--- v2
+++ v1
@@ -1,88 +1,1109 @@
 From: Arnd Bergmann <arnd@arndb.de>
 
-Unlike other architectures, the nios2 version of __put_user() has an
-extra check for access_ok(), preventing it from being used to implement
-__put_kernel_nofault().
+There are many different ways that access_ok() is defined across
+architectures, but in the end, they all just compare against the
+user_addr_max() value or they accept anything.
 
-Split up put_user() along the same lines as __get_user()/get_user()
+Provide one definition that works for most architectures, checking
+against TASK_SIZE_MAX for user processes or skipping the check inside
+of uaccess_kernel() sections.
+
+For architectures without CONFIG_SET_FS(), this should be the fastest
+check, as it comes down to a single comparison of a pointer against a
+compile-time constant, while the architecture specific versions tend to
+do something more complex for historic reasons or get something wrong.
+
+Type checking for __user annotations is handled inconsistently across
+architectures, but this is easily simplified as well by using an inline
+function that takes a 'const void __user *' argument. A handful of
+callers need an extra __user annotation for this.
+
+Some architectures had trick to use 33-bit or 65-bit arithmetic on the
+addresses to calculate the overflow, however this simpler version uses
+fewer registers, which means it can produce better object code in the
+end despite needing a second (statically predicted) branch.
 
 Signed-off-by: Arnd Bergmann <arnd@arndb.de>
 ---
- arch/nios2/include/asm/uaccess.h | 56 +++++++++++++++++++-------------
- 1 file changed, 33 insertions(+), 23 deletions(-)
+ arch/alpha/include/asm/uaccess.h      | 34 +++------------
+ arch/arc/include/asm/uaccess.h        | 29 -------------
+ arch/arm/include/asm/uaccess.h        | 20 +--------
+ arch/arm/kernel/swp_emulate.c         |  2 +-
+ arch/arm/kernel/traps.c               |  2 +-
+ arch/arm64/include/asm/uaccess.h      |  5 ++-
+ arch/csky/include/asm/uaccess.h       |  8 ----
+ arch/csky/kernel/signal.c             |  2 +-
+ arch/hexagon/include/asm/uaccess.h    | 25 ------------
+ arch/ia64/include/asm/uaccess.h       |  5 +--
+ arch/m68k/include/asm/uaccess.h       |  5 ++-
+ arch/microblaze/include/asm/uaccess.h |  8 +---
+ arch/mips/include/asm/uaccess.h       | 29 +------------
+ arch/nds32/include/asm/uaccess.h      |  7 +---
+ arch/nios2/include/asm/uaccess.h      | 11 +----
+ arch/nios2/kernel/signal.c            | 20 +++++----
+ arch/openrisc/include/asm/uaccess.h   | 19 +--------
+ arch/parisc/include/asm/uaccess.h     | 10 +++--
+ arch/powerpc/include/asm/uaccess.h    | 11 +----
+ arch/powerpc/lib/sstep.c              |  4 +-
+ arch/riscv/include/asm/uaccess.h      | 31 +-------------
+ arch/riscv/kernel/perf_callchain.c    |  2 +-
+ arch/s390/include/asm/uaccess.h       | 11 ++---
+ arch/sh/include/asm/uaccess.h         | 22 +---------
+ arch/sparc/include/asm/uaccess.h      |  3 --
+ arch/sparc/include/asm/uaccess_32.h   | 18 ++------
+ arch/sparc/include/asm/uaccess_64.h   | 35 ++++------------
+ arch/sparc/kernel/signal_32.c         |  2 +-
+ arch/um/include/asm/uaccess.h         |  5 ++-
+ arch/x86/include/asm/uaccess.h        | 14 +------
+ arch/xtensa/include/asm/uaccess.h     | 10 +----
+ include/asm-generic/access_ok.h       | 59 +++++++++++++++++++++++++++
+ include/asm-generic/uaccess.h         | 21 +---------
+ include/linux/uaccess.h               |  7 ----
+ 34 files changed, 130 insertions(+), 366 deletions(-)
+ create mode 100644 include/asm-generic/access_ok.h
 
+diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
+index 1b6f25efa247..82c5743fc9cd 100644
+--- a/arch/alpha/include/asm/uaccess.h
++++ b/arch/alpha/include/asm/uaccess.h
+@@ -20,28 +20,7 @@
+ #define get_fs()  (current_thread_info()->addr_limit)
+ #define set_fs(x) (current_thread_info()->addr_limit = (x))
+ 
+-#define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
+-
+-/*
+- * Is a address valid? This does a straightforward calculation rather
+- * than tests.
+- *
+- * Address valid if:
+- *  - "addr" doesn't have any high-bits set
+- *  - AND "size" doesn't have any high-bits set
+- *  - AND "addr+size-(size != 0)" doesn't have any high-bits set
+- *  - OR we are in kernel mode.
+- */
+-#define __access_ok(addr, size) ({				\
+-	unsigned long __ao_a = (addr), __ao_b = (size);		\
+-	unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;	\
+-	(get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })
+-
+-#define access_ok(addr, size)				\
+-({							\
+-	__chk_user_ptr(addr);				\
+-	__access_ok(((unsigned long)(addr)), (size));	\
+-})
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They automatically
+@@ -105,7 +84,7 @@ extern void __get_user_unknown(void);
+ 	long __gu_err = -EFAULT;				\
+ 	unsigned long __gu_val = 0;				\
+ 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
+-	if (__access_ok((unsigned long)__gu_addr, size)) {	\
++	if (__access_ok(__gu_addr, size)) {			\
+ 		__gu_err = 0;					\
+ 		switch (size) {					\
+ 		  case 1: __get_user_8(__gu_addr); break;	\
+@@ -200,7 +179,7 @@ extern void __put_user_unknown(void);
+ ({								\
+ 	long __pu_err = -EFAULT;				\
+ 	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
+-	if (__access_ok((unsigned long)__pu_addr, size)) {	\
++	if (__access_ok(__pu_addr, size)) {			\
+ 		__pu_err = 0;					\
+ 		switch (size) {					\
+ 		  case 1: __put_user_8(x, __pu_addr); break;	\
+@@ -316,17 +295,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long len)
+ 
+ extern long __clear_user(void __user *to, long len);
+ 
+-extern inline long
++static inline long
+ clear_user(void __user *to, long len)
+ {
+-	if (__access_ok((unsigned long)to, len))
++	if (__access_ok(to, len))
+ 		len = __clear_user(to, len);
+ 	return len;
+ }
+ 
+-#define user_addr_max() \
+-        (uaccess_kernel() ? ~0UL : TASK_SIZE)
+-
+ extern long strncpy_from_user(char *dest, const char __user *src, long count);
+ extern __must_check long strnlen_user(const char __user *str, long n);
+ 
+diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
+index 783bfdb3bfa3..30f80b4be2ab 100644
+--- a/arch/arc/include/asm/uaccess.h
++++ b/arch/arc/include/asm/uaccess.h
+@@ -23,35 +23,6 @@
+ 
+ #include <linux/string.h>	/* for generic string functions */
+ 
+-
+-#define __kernel_ok		(uaccess_kernel())
+-
+-/*
+- * Algorithmically, for __user_ok() we want do:
+- * 	(start < TASK_SIZE) && (start+len < TASK_SIZE)
+- * where TASK_SIZE could either be retrieved from thread_info->addr_limit or
+- * emitted directly in code.
+- *
+- * This can however be rewritten as follows:
+- *	(len <= TASK_SIZE) && (start+len < TASK_SIZE)
+- *
+- * Because it essentially checks if buffer end is within limit and @len is
+- * non-ngeative, which implies that buffer start will be within limit too.
+- *
+- * The reason for rewriting being, for majority of cases, @len is generally
+- * compile time constant, causing first sub-expression to be compile time
+- * subsumed.
+- *
+- * The second part would generate weird large LIMMs e.g. (0x6000_0000 - 0x10),
+- * so we check for TASK_SIZE using get_fs() since the addr_limit load from mem
+- * would already have been done at this call site for __kernel_ok()
+- *
+- */
+-#define __user_ok(addr, sz)	(((sz) <= TASK_SIZE) && \
+-				 ((addr) <= (get_fs() - (sz))))
+-#define __access_ok(addr, sz)	(unlikely(__kernel_ok) || \
+-				 likely(__user_ok((addr), (sz))))
+-
+ /*********** Single byte/hword/word copies ******************/
+ 
+ #define __get_user_fn(sz, u, k)					\
+diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
+index d20d78c34b94..2fcbec9c306c 100644
+--- a/arch/arm/include/asm/uaccess.h
++++ b/arch/arm/include/asm/uaccess.h
+@@ -55,21 +55,6 @@ extern int __put_user_bad(void);
+ 
+ #ifdef CONFIG_MMU
+ 
+-/*
+- * We use 33-bit arithmetic here.  Success returns zero, failure returns
+- * addr_limit.  We take advantage that addr_limit will be zero for KERNEL_DS,
+- * so this will always return success in that case.
+- */
+-#define __range_ok(addr, size) ({ \
+-	unsigned long flag, roksum; \
+-	__chk_user_ptr(addr);	\
+-	__asm__(".syntax unified\n" \
+-		"adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
+-		: "=&r" (flag), "=&r" (roksum) \
+-		: "r" (addr), "Ir" (size), "0" (TASK_SIZE) \
+-		: "cc"); \
+-	flag; })
+-
+ /*
+  * This is a type: either unsigned long, if the argument fits into
+  * that type, or otherwise unsigned long long.
+@@ -241,15 +226,12 @@ extern int __put_user_8(void *, unsigned long long);
+ 
+ #else /* CONFIG_MMU */
+ 
+-#define __addr_ok(addr)		((void)(addr), 1)
+-#define __range_ok(addr, size)	((void)(addr), 0)
+-
+ #define get_user(x, p)	__get_user(x, p)
+ #define __put_user_check __put_user_nocheck
+ 
+ #endif /* CONFIG_MMU */
+ 
+-#define access_ok(addr, size)	(__range_ok(addr, size) == 0)
++#include <asm-generic/access_ok.h>
+ 
+ #ifdef CONFIG_CPU_SPECTRE
+ /*
+diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
+index 6166ba38bf99..b74bfcf94fb1 100644
+--- a/arch/arm/kernel/swp_emulate.c
++++ b/arch/arm/kernel/swp_emulate.c
+@@ -195,7 +195,7 @@ static int swp_handler(struct pt_regs *regs, unsigned int instr)
+ 		 destreg, EXTRACT_REG_NUM(instr, RT2_OFFSET), data);
+ 
+ 	/* Check access in reasonable access range for both SWP and SWPB */
+-	if (!access_ok((address & ~3), 4)) {
++	if (!access_ok((void __user *)(address & ~3), 4)) {
+ 		pr_debug("SWP{B} emulation: access to %p not allowed!\n",
+ 			 (void *)address);
+ 		res = -EFAULT;
+diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
+index da04ed85855a..26c8c8276297 100644
+--- a/arch/arm/kernel/traps.c
++++ b/arch/arm/kernel/traps.c
+@@ -576,7 +576,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
+ 	if (end < start || flags)
+ 		return -EINVAL;
+ 
+-	if (!access_ok(start, end - start))
++	if (!access_ok((void __user *)start, end - start))
+ 		return -EFAULT;
+ 
+ 	return __do_cache_op(start, end);
+diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
+index 2e20879fe3cf..357f7bd9c981 100644
+--- a/arch/arm64/include/asm/uaccess.h
++++ b/arch/arm64/include/asm/uaccess.h
+@@ -33,7 +33,7 @@
+  * This is equivalent to the following test:
+  * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX
+  */
+-static inline unsigned long __range_ok(const void __user *addr, unsigned long size)
++static inline unsigned long __access_ok(const void __user *addr, unsigned long size)
+ {
+ 	unsigned long ret, limit = TASK_SIZE_MAX - 1;
+ 
+@@ -66,8 +66,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
+ 
+ 	return ret;
+ }
++#define __access_ok __access_ok
+ 
+-#define access_ok(addr, size)	__range_ok(addr, size)
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * User access enabling/disabling.
+diff --git a/arch/csky/include/asm/uaccess.h b/arch/csky/include/asm/uaccess.h
+index ac5a54f57d40..fec8f77ffc99 100644
+--- a/arch/csky/include/asm/uaccess.h
++++ b/arch/csky/include/asm/uaccess.h
+@@ -5,14 +5,6 @@
+ 
+ #define user_addr_max() (current_thread_info()->addr_limit.seg)
+ 
+-static inline int __access_ok(unsigned long addr, unsigned long size)
+-{
+-	unsigned long limit = user_addr_max();
+-
+-	return (size <= limit) && (addr <= (limit - size));
+-}
+-#define __access_ok __access_ok
+-
+ /*
+  * __put_user_fn
+  */
+diff --git a/arch/csky/kernel/signal.c b/arch/csky/kernel/signal.c
+index c7b763d2f526..8867ddf3e6c7 100644
+--- a/arch/csky/kernel/signal.c
++++ b/arch/csky/kernel/signal.c
+@@ -136,7 +136,7 @@ static inline void __user *get_sigframe(struct ksignal *ksig,
+ static int
+ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
+ {
+-	struct rt_sigframe *frame;
++	struct rt_sigframe __user *frame;
+ 	int err = 0;
+ 
+ 	frame = get_sigframe(ksig, regs, sizeof(*frame));
+diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
+index 719ba3f3c45c..bff77efc0d9a 100644
+--- a/arch/hexagon/include/asm/uaccess.h
++++ b/arch/hexagon/include/asm/uaccess.h
+@@ -12,31 +12,6 @@
+  */
+ #include <asm/sections.h>
+ 
+-/*
+- * access_ok: - Checks if a user space pointer is valid
+- * @addr: User space pointer to start of block to check
+- * @size: Size of block to check
+- *
+- * Context: User context only. This function may sleep if pagefaults are
+- *          enabled.
+- *
+- * Checks if a pointer to a block of memory in user space is valid.
+- *
+- * Returns true (nonzero) if the memory block *may* be valid, false (zero)
+- * if it is definitely invalid.
+- *
+- */
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
+-
+-static inline int __access_ok(unsigned long addr, unsigned long size)
+-{
+-	unsigned long limit = TASK_SIZE;
+-
+-	return (size <= limit) && (addr <= (limit - size));
+-}
+-#define __access_ok __access_ok
+-
+ /*
+  * When a kernel-mode page fault is taken, the faulting instruction
+  * address is checked against a table of exception_table_entries.
+diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
+index e19d2dcc0ced..e242a3cc1330 100644
+--- a/arch/ia64/include/asm/uaccess.h
++++ b/arch/ia64/include/asm/uaccess.h
+@@ -50,8 +50,6 @@
+ #define get_fs()  (current_thread_info()->addr_limit)
+ #define set_fs(x) (current_thread_info()->addr_limit = (x))
+ 
+-#define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
+-
+ /*
+  * When accessing user memory, we need to make sure the entire area really is in
+  * user-level space.  In order to do this efficiently, we make sure that the page at
+@@ -65,7 +63,8 @@ static inline int __access_ok(const void __user *p, unsigned long size)
+ 	return likely(addr <= seg) &&
+ 	 (seg == KERNEL_DS.seg || likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
+ }
+-#define access_ok(addr, size)	__access_ok((addr), (size))
++#define __access_ok __access_ok
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They automatically
+diff --git a/arch/m68k/include/asm/uaccess.h b/arch/m68k/include/asm/uaccess.h
+index 79617c0b2f91..d6bb5720365a 100644
+--- a/arch/m68k/include/asm/uaccess.h
++++ b/arch/m68k/include/asm/uaccess.h
+@@ -12,15 +12,18 @@
+ #include <asm/extable.h>
+ 
+ /* We let the MMU do all checking */
+-static inline int access_ok(const void __user *addr,
++static inline int __access_ok(const void __user *addr,
+ 			    unsigned long size)
+ {
+ 	/*
+ 	 * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check
+ 	 * for TASK_SIZE!
++	 * Removing this helper is probably sufficient.
+ 	 */
+ 	return 1;
+ }
++#define __access_ok __access_ok
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * Not all varients of the 68k family support the notion of address spaces.
+diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
+index 5b6e0e7788f4..dd82e90adb52 100644
+--- a/arch/microblaze/include/asm/uaccess.h
++++ b/arch/microblaze/include/asm/uaccess.h
+@@ -39,13 +39,7 @@
+ 
+ # define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
+ 
+-static inline int __access_ok(unsigned long addr, unsigned long size)
+-{
+-	unsigned long limit = user_addr_max();
+-
+-	return (size <= limit) && (addr <= (limit - size));
+-}
+-#define access_ok(addr, size) __access_ok((unsigned long)addr, size)
++#include <asm-generic/access_ok.h>
+ 
+ # define __FIXUP_SECTION	".section .fixup,\"ax\"\n"
+ # define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"
+diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
+index d7c89dc3426c..436248652b28 100644
+--- a/arch/mips/include/asm/uaccess.h
++++ b/arch/mips/include/asm/uaccess.h
+@@ -44,34 +44,7 @@ extern u64 __ua_limit;
+ 
+ #endif /* CONFIG_64BIT */
+ 
+-/*
+- * access_ok: - Checks if a user space pointer is valid
+- * @addr: User space pointer to start of block to check
+- * @size: Size of block to check
+- *
+- * Context: User context only. This function may sleep if pagefaults are
+- *          enabled.
+- *
+- * Checks if a pointer to a block of memory in user space is valid.
+- *
+- * Returns true (nonzero) if the memory block may be valid, false (zero)
+- * if it is definitely invalid.
+- *
+- * Note that, depending on architecture, this function probably just
+- * checks that the pointer is in the user space range - after calling
+- * this function, memory access functions may still return -EFAULT.
+- */
+-
+-static inline int __access_ok(const void __user *p, unsigned long size)
+-{
+-	unsigned long addr = (unsigned long)p;
+-	unsigned long limit = TASK_SIZE_MAX;
+-
+-	return (size <= limit) && (addr <= (limit - size));
+-}
+-
+-#define access_ok(addr, size)					\
+-	likely(__access_ok((addr), (size)))
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * put_user: - Write a simple value into user space.
+diff --git a/arch/nds32/include/asm/uaccess.h b/arch/nds32/include/asm/uaccess.h
+index 37a40981deb3..832d642a4068 100644
+--- a/arch/nds32/include/asm/uaccess.h
++++ b/arch/nds32/include/asm/uaccess.h
+@@ -38,18 +38,15 @@ extern int fixup_exception(struct pt_regs *regs);
+ 
+ #define get_fs()	(current_thread_info()->addr_limit)
+ #define user_addr_max	get_fs
++#define uaccess_kernel() (get_fs() == KERNEL_DS)
+ 
+ static inline void set_fs(mm_segment_t fs)
+ {
+ 	current_thread_info()->addr_limit = fs;
+ }
+ 
+-#define uaccess_kernel()	(get_fs() == KERNEL_DS)
++#include <asm-generic/access_ok.h>
+ 
+-#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs() -size))
+-
+-#define access_ok(addr, size)	\
+-	__range_ok((unsigned long)addr, (unsigned long)size)
+ /*
+  * Single-value transfer routines.  They automatically use the right
+  * size if we just have the right pointer type.  Note that the functions
 diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
-index ca9285a915ef..a5cbe07cf0da 100644
+index ba9340e96fd4..9a7658df7f8d 100644
 --- a/arch/nios2/include/asm/uaccess.h
 +++ b/arch/nios2/include/asm/uaccess.h
-@@ -167,34 +167,44 @@ do {									\
- 	: "r" (val), "r" (ptr), "i" (-EFAULT));				\
+@@ -30,19 +30,10 @@
+ #define get_fs()		(current_thread_info()->addr_limit)
+ #define set_fs(seg)		(current_thread_info()->addr_limit = (seg))
+ 
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+-
+-#define __access_ok(addr, len)			\
+-	(((signed long)(((long)get_fs().seg) &	\
+-		((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)
+-
+-#define access_ok(addr, len)		\
+-	likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))
++#include <asm-generic/access_ok.h>
+ 
+ # define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"
+ 
+-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
+-
+ /*
+  * Zero Userspace
+  */
+diff --git a/arch/nios2/kernel/signal.c b/arch/nios2/kernel/signal.c
+index 2009ae2d3c3b..386e46443b60 100644
+--- a/arch/nios2/kernel/signal.c
++++ b/arch/nios2/kernel/signal.c
+@@ -36,10 +36,10 @@ struct rt_sigframe {
+ 
+ static inline int rt_restore_ucontext(struct pt_regs *regs,
+ 					struct switch_stack *sw,
+-					struct ucontext *uc, int *pr2)
++					struct ucontext __user *uc, int *pr2)
+ {
+ 	int temp;
+-	unsigned long *gregs = uc->uc_mcontext.gregs;
++	unsigned long __user *gregs = uc->uc_mcontext.gregs;
+ 	int err;
+ 
+ 	/* Always make any pending restarted system calls return -EINTR */
+@@ -102,10 +102,11 @@ asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
+ {
+ 	struct pt_regs *regs = (struct pt_regs *)(sw + 1);
+ 	/* Verify, can we follow the stack back */
+-	struct rt_sigframe *frame = (struct rt_sigframe *) regs->sp;
++	struct rt_sigframe __user *frame;
+ 	sigset_t set;
+ 	int rval;
+ 
++	frame = (struct rt_sigframe __user *) regs->sp;
+ 	if (!access_ok(frame, sizeof(*frame)))
+ 		goto badframe;
+ 
+@@ -124,10 +125,10 @@ asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
+ 	return 0;
  }
  
--#define put_user(x, ptr)						\
-+#define __put_user_common(__pu_val, __pu_ptr)				\
- ({									\
- 	long __pu_err = -EFAULT;					\
--	__typeof__(*(ptr)) __user *__pu_ptr = (ptr);			\
--	__typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x);		\
--	if (access_ok(__pu_ptr, sizeof(*__pu_ptr))) {	\
--		switch (sizeof(*__pu_ptr)) {				\
--		case 1:							\
--			__put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \
--			break;						\
--		case 2:							\
--			__put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \
--			break;						\
--		case 4:							\
--			__put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \
--			break;						\
--		default:						\
--			/* XXX: This looks wrong... */			\
--			__pu_err = 0;					\
--			if (copy_to_user(__pu_ptr, &(__pu_val),		\
--				sizeof(*__pu_ptr)))			\
--				__pu_err = -EFAULT;			\
--			break;						\
--		}							\
-+	switch (sizeof(*__pu_ptr)) {					\
-+	case 1:								\
-+		__put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err);	\
-+		break;							\
-+	case 2:								\
-+		__put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err);	\
-+		break;							\
-+	case 4:								\
-+		__put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err);	\
-+		break;							\
-+	default:							\
-+		/* XXX: This looks wrong... */				\
-+		__pu_err = 0;						\
-+		if (__copy_to_user(__pu_ptr, &(__pu_val),		\
-+			sizeof(*__pu_ptr)))				\
-+			__pu_err = -EFAULT;				\
-+		break;							\
- 	}								\
- 	__pu_err;							\
+-static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
++static inline int rt_setup_ucontext(struct ucontext __user *uc, struct pt_regs *regs)
+ {
+ 	struct switch_stack *sw = (struct switch_stack *)regs - 1;
+-	unsigned long *gregs = uc->uc_mcontext.gregs;
++	unsigned long __user *gregs = uc->uc_mcontext.gregs;
+ 	int err = 0;
+ 
+ 	err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
+@@ -162,8 +163,9 @@ static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
+ 	return err;
+ }
+ 
+-static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
+-				 size_t frame_size)
++static inline void __user *get_sigframe(struct ksignal *ksig,
++					struct pt_regs *regs,
++					size_t frame_size)
+ {
+ 	unsigned long usp;
+ 
+@@ -174,13 +176,13 @@ static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
+ 	usp = sigsp(usp, ksig);
+ 
+ 	/* Verify, is it 32 or 64 bit aligned */
+-	return (void *)((usp - frame_size) & -8UL);
++	return (void __user *)((usp - frame_size) & -8UL);
+ }
+ 
+ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+ 			  struct pt_regs *regs)
+ {
+-	struct rt_sigframe *frame;
++	struct rt_sigframe __user *frame;
+ 	int err = 0;
+ 
+ 	frame = get_sigframe(ksig, regs, sizeof(*frame));
+diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
+index 120f5005461b..8f049ec99b3e 100644
+--- a/arch/openrisc/include/asm/uaccess.h
++++ b/arch/openrisc/include/asm/uaccess.h
+@@ -45,21 +45,7 @@
+ 
+ #define uaccess_kernel()	(get_fs() == KERNEL_DS)
+ 
+-/* Ensure that the range from addr to addr+size is all within the process'
+- * address space
+- */
+-static inline int __range_ok(unsigned long addr, unsigned long size)
+-{
+-	const mm_segment_t fs = get_fs();
+-
+-	return size <= fs && addr <= (fs - size);
+-}
+-
+-#define access_ok(addr, size)						\
+-({ 									\
+-	__chk_user_ptr(addr);						\
+-	__range_ok((unsigned long)(addr), (size));			\
+-})
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They automatically
+@@ -268,9 +254,6 @@ clear_user(void __user *addr, unsigned long size)
+ 	return size;
+ }
+ 
+-#define user_addr_max() \
+-	(uaccess_kernel() ? ~0UL : TASK_SIZE)
+-
+ extern long strncpy_from_user(char *dest, const char __user *src, long count);
+ 
+ extern __must_check long strnlen_user(const char __user *str, long n);
+diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
+index 0925bbd6db67..b68f19e11361 100644
+--- a/arch/parisc/include/asm/uaccess.h
++++ b/arch/parisc/include/asm/uaccess.h
+@@ -17,9 +17,13 @@
+  * We just let the page fault handler do the right thing. This also means
+  * that put_user is the same as __put_user, etc.
+  */
+-
+-#define access_ok(uaddr, size)	\
+-	( (uaddr) == (uaddr) )
++static inline int __access_ok(const void __user *addr, unsigned long size)
++{
++	return 1;
++}
++#define __access_ok __access_ok
++#define TASK_SIZE_MAX DEFAULT_TASK_SIZE
++#include <asm-generic/access_ok.h>
+ 
+ #define put_user __put_user
+ #define get_user __get_user
+diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
+index a0032c2e7550..2e83217f52de 100644
+--- a/arch/powerpc/include/asm/uaccess.h
++++ b/arch/powerpc/include/asm/uaccess.h
+@@ -11,18 +11,9 @@
+ #ifdef __powerpc64__
+ /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
+ #define TASK_SIZE_MAX		TASK_SIZE_USER64
+-#else
+-#define TASK_SIZE_MAX		TASK_SIZE
+ #endif
+ 
+-static inline bool __access_ok(unsigned long addr, unsigned long size)
+-{
+-	return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr;
+-}
+-
+-#define access_ok(addr, size)		\
+-	(__chk_user_ptr(addr),		\
+-	 __access_ok((unsigned long)(addr), (size)))
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They automatically
+diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
+index a94b0cd0bdc5..022d23ae300b 100644
+--- a/arch/powerpc/lib/sstep.c
++++ b/arch/powerpc/lib/sstep.c
+@@ -112,9 +112,9 @@ static nokprobe_inline long address_ok(struct pt_regs *regs,
+ {
+ 	if (!user_mode(regs))
+ 		return 1;
+-	if (__access_ok(ea, nb))
++	if (access_ok((void __user *)ea, nb))
+ 		return 1;
+-	if (__access_ok(ea, 1))
++	if (access_ok((void __user *)ea, 1))
+ 		/* Access overlaps the end of the user region */
+ 		regs->dar = TASK_SIZE_MAX - 1;
+ 	else
+diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
+index 4407b9e48d2c..855450bed9f5 100644
+--- a/arch/riscv/include/asm/uaccess.h
++++ b/arch/riscv/include/asm/uaccess.h
+@@ -21,42 +21,13 @@
+ #include <asm/byteorder.h>
+ #include <asm/extable.h>
+ #include <asm/asm.h>
++#include <asm-generic/access_ok.h>
+ 
+ #define __enable_user_access()							\
+ 	__asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
+ #define __disable_user_access()							\
+ 	__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
+ 
+-/**
+- * access_ok: - Checks if a user space pointer is valid
+- * @addr: User space pointer to start of block to check
+- * @size: Size of block to check
+- *
+- * Context: User context only.  This function may sleep.
+- *
+- * Checks if a pointer to a block of memory in user space is valid.
+- *
+- * Returns true (nonzero) if the memory block may be valid, false (zero)
+- * if it is definitely invalid.
+- *
+- * Note that, depending on architecture, this function probably just
+- * checks that the pointer is in the user space range - after calling
+- * this function, memory access functions may still return -EFAULT.
+- */
+-#define access_ok(addr, size) ({					\
+-	__chk_user_ptr(addr);						\
+-	likely(__access_ok((unsigned long __force)(addr), (size)));	\
+-})
+-
+-/*
+- * Ensure that the range [addr, addr+size) is within the process's
+- * address space
+- */
+-static inline int __access_ok(unsigned long addr, unsigned long size)
+-{
+-	return size <= TASK_SIZE && addr <= TASK_SIZE - size;
+-}
+-
+ /*
+  * 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
+diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
+index 1fc075b8f764..f0c7bb98119a 100644
+--- a/arch/riscv/kernel/perf_callchain.c
++++ b/arch/riscv/kernel/perf_callchain.c
+@@ -15,7 +15,7 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
+ {
+ 	struct stackframe buftail;
+ 	unsigned long ra = 0;
+-	unsigned long *user_frame_tail =
++	unsigned long __user *user_frame_tail =
+ 			(unsigned long *)(fp - sizeof(struct stackframe));
+ 
+ 	/* Check accessibility of one struct frame_tail beyond */
+diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
+index 29332edf46f0..f84d70c8e188 100644
+--- a/arch/s390/include/asm/uaccess.h
++++ b/arch/s390/include/asm/uaccess.h
+@@ -20,18 +20,13 @@
+ 
+ void debug_user_asce(int exit);
+ 
+-static inline int __range_ok(unsigned long addr, unsigned long size)
++static inline int __access_ok(const void __user *addr, unsigned long size)
+ {
+ 	return 1;
+ }
++#define __access_ok __access_ok
+ 
+-#define __access_ok(addr, size)				\
+-({							\
+-	__chk_user_ptr(addr);				\
+-	__range_ok((unsigned long)(addr), (size));	\
+-})
+-
+-#define access_ok(addr, size) __access_ok(addr, size)
++#include <asm-generic/access_ok.h>
+ 
+ unsigned long __must_check
+ raw_copy_from_user(void *to, const void __user *from, unsigned long n);
+diff --git a/arch/sh/include/asm/uaccess.h b/arch/sh/include/asm/uaccess.h
+index 8867bb04b00e..ccd219d74851 100644
+--- a/arch/sh/include/asm/uaccess.h
++++ b/arch/sh/include/asm/uaccess.h
+@@ -5,28 +5,10 @@
+ #include <asm/segment.h>
+ #include <asm/extable.h>
+ 
+-#define __addr_ok(addr) \
+-	((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg)
+-
+-/*
+- * __access_ok: Check if address with size is OK or not.
+- *
+- * Uhhuh, this needs 33-bit arithmetic. We have a carry..
+- *
+- * sum := addr + size;  carry? --> flag = true;
+- * if (sum >= addr_limit) flag = true;
+- */
+-#define __access_ok(addr, size)	({				\
+-	unsigned long __ao_a = (addr), __ao_b = (size);		\
+-	unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;	\
+-	__ao_end >= __ao_a && __addr_ok(__ao_end); })
+-
+-#define access_ok(addr, size)	\
+-	(__chk_user_ptr(addr),		\
+-	 __access_ok((unsigned long __force)(addr), (size)))
+-
+ #define user_addr_max()	(current_thread_info()->addr_limit.seg)
+ 
++#include <asm-generic/access_ok.h>
++
+ /*
+  * Uh, these should become the main single-value transfer routines ...
+  * They automatically use the right size if we just have the right
+diff --git a/arch/sparc/include/asm/uaccess.h b/arch/sparc/include/asm/uaccess.h
+index 390094200fc4..ee75f69e3fcd 100644
+--- a/arch/sparc/include/asm/uaccess.h
++++ b/arch/sparc/include/asm/uaccess.h
+@@ -10,9 +10,6 @@
+ #include <asm/uaccess_32.h>
+ #endif
+ 
+-#define user_addr_max() \
+-	(uaccess_kernel() ? ~0UL : TASK_SIZE)
+-
+ long strncpy_from_user(char *dest, const char __user *src, long count);
+ 
+ #endif
+diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
+index 4a12346bb69c..367747116260 100644
+--- a/arch/sparc/include/asm/uaccess_32.h
++++ b/arch/sparc/include/asm/uaccess_32.h
+@@ -25,17 +25,7 @@
+ #define get_fs()	(current->thread.current_ds)
+ #define set_fs(val)	((current->thread.current_ds) = (val))
+ 
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+-
+-/* We have there a nice not-mapped page at PAGE_OFFSET - PAGE_SIZE, so that this test
+- * can be fairly lightweight.
+- * No one can read/write anything from userland in the kernel space by setting
+- * large size and address near to PAGE_OFFSET - a fault will break his intentions.
+- */
+-#define __user_ok(addr, size) ({ (void)(size); (addr) < STACK_TOP; })
+-#define __kernel_ok (uaccess_kernel())
+-#define __access_ok(addr, size) (__user_ok((addr) & get_fs().seg, (size)))
+-#define access_ok(addr, size) __access_ok((unsigned long)(addr), size)
++#include <asm-generic/access_ok.h>
+ 
+ /* Uh, these should become the main single-value transfer routines..
+  * They automatically use the right size if we just have the right
+@@ -47,13 +37,13 @@
+  * and hide all the ugliness from the user.
+  */
+ #define put_user(x, ptr) ({ \
+-	unsigned long __pu_addr = (unsigned long)(ptr); \
++	void __user *__pu_addr = (ptr); \
+ 	__chk_user_ptr(ptr); \
+ 	__put_user_check((__typeof__(*(ptr)))(x), __pu_addr, sizeof(*(ptr))); \
  })
  
--#define __put_user(x, ptr) put_user(x, ptr)
-+#define __put_user(x, ptr)						\
-+({									\
-+	__auto_type __pu_ptr = (ptr);					\
-+	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
-+	__put_user_common(__pu_val, __pu_ptr);				\
-+})
+ #define get_user(x, ptr) ({ \
+-	unsigned long __gu_addr = (unsigned long)(ptr); \
++	const void __user *__gu_addr = (ptr); \
+ 	__chk_user_ptr(ptr); \
+ 	__get_user_check((x), __gu_addr, sizeof(*(ptr)), __typeof__(*(ptr))); \
+ })
+@@ -232,7 +222,7 @@ static inline unsigned long __clear_user(void __user *addr, unsigned long size)
+ 
+ static inline unsigned long clear_user(void __user *addr, unsigned long n)
+ {
+-	if (n && __access_ok((unsigned long) addr, n))
++	if (n && __access_ok(addr, n))
+ 		return __clear_user(addr, n);
+ 	else
+ 		return n;
+diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
+index 5c12fb46bc61..000bac67cf31 100644
+--- a/arch/sparc/include/asm/uaccess_64.h
++++ b/arch/sparc/include/asm/uaccess_64.h
+@@ -31,7 +31,12 @@
+ 
+ #define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})
+ 
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
++static inline int __access_ok(const void __user *addr, unsigned long size)
++{
++	return 1;
++}
++#define __access_ok __access_ok
++#include <asm-generic/access_ok.h>
+ 
+ #define set_fs(val)								\
+ do {										\
+@@ -43,33 +48,7 @@ do {										\
+  * Test whether a block of memory is a valid user space address.
+  * Returns 0 if the range is valid, nonzero otherwise.
+  */
+-static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
+-{
+-	if (__builtin_constant_p(size))
+-		return addr > limit - size;
+-
+-	addr += size;
+-	if (addr < size)
+-		return true;
+-
+-	return addr > limit;
+-}
+-
+-#define __range_not_ok(addr, size, limit)                               \
+-({                                                                      \
+-	__chk_user_ptr(addr);                                           \
+-	__chk_range_not_ok((unsigned long __force)(addr), size, limit); \
+-})
+-
+-static inline int __access_ok(const void __user * addr, unsigned long size)
+-{
+-	return 1;
+-}
+-
+-static inline int access_ok(const void __user * addr, unsigned long size)
+-{
+-	return 1;
+-}
++#define __range_not_ok(addr, size, limit) (!__access_ok(addr, size))
+ 
+ void __retl_efault(void);
+ 
+diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c
+index ffab16369bea..74f80443b195 100644
+--- a/arch/sparc/kernel/signal_32.c
++++ b/arch/sparc/kernel/signal_32.c
+@@ -65,7 +65,7 @@ struct rt_signal_frame {
+  */
+ static inline bool invalid_frame_pointer(void __user *fp, int fplen)
+ {
+-	if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen))
++	if ((((unsigned long) fp) & 15) || !access_ok(fp, fplen))
+ 		return true;
+ 
+ 	return false;
+diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
+index 1ecfc96bcc50..7d9d60e41e4e 100644
+--- a/arch/um/include/asm/uaccess.h
++++ b/arch/um/include/asm/uaccess.h
+@@ -25,7 +25,7 @@
+ extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
+ extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
+ extern unsigned long __clear_user(void __user *mem, unsigned long len);
+-static inline int __access_ok(unsigned long addr, unsigned long size);
++static inline int __access_ok(const void __user *ptr, unsigned long size);
+ 
+ /* Teach asm-generic/uaccess.h that we have C functions for these. */
+ #define __access_ok __access_ok
+@@ -36,8 +36,9 @@ static inline int __access_ok(unsigned long addr, unsigned long size);
+ 
+ #include <asm-generic/uaccess.h>
+ 
+-static inline int __access_ok(unsigned long addr, unsigned long size)
++static inline int __access_ok(const void __user *ptr, unsigned long size)
+ {
++	unsigned long addr = (unsigned long)ptr;
+ 	return __addr_range_nowrap(addr, size) &&
+ 		(__under_task_size(addr, size) ||
+ 		 __access_ok_vsyscall(addr, size));
+diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
+index c6d9dc42724d..c5e4bb7161bc 100644
+--- a/arch/x86/include/asm/uaccess.h
++++ b/arch/x86/include/asm/uaccess.h
+@@ -12,18 +12,6 @@
+ #include <asm/smap.h>
+ #include <asm/extable.h>
+ 
+-/*
+- * Test whether a block of memory is a valid user space address.
+- * Returns 0 if the range is valid, nonzero otherwise.
+- */
+-static inline bool __access_ok(void __user *ptr, unsigned long size)
+-{
+-	unsigned long limit = TASK_SIZE_MAX;
+-	unsigned long addr = ptr;
+-
+-	return (size <= limit) && (addr <= (limit - size));
+-}
+-
+ #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
+ static inline bool pagefault_disabled(void);
+ # define WARN_ON_IN_IRQ()	\
+@@ -55,6 +43,8 @@ static inline bool pagefault_disabled(void);
+ 	likely(__access_ok(addr, size));\
+ })
+ 
++#include <asm-generic/access_ok.h>
 +
-+#define put_user(x, ptr)						\
-+({									\
-+	__auto_type __pu_ptr = (ptr);					\
-+	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
-+	access_ok(__pu_ptr, sizeof(*__pu_ptr)) ?			\
-+		__put_user_common(__pu_val, __pu_ptr) :			\
-+		-EFAULT;						\
-+})
- 
- #endif /* _ASM_NIOS2_UACCESS_H */
+ #define __range_not_ok(addr, size, limit)	(!__access_ok(addr, size))
+ #define __chk_range_not_ok(addr, size, limit)	(!__access_ok((void __user *)addr, size))
+ 
+diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
+index 75bd8fbf52ba..0edd9e4b23d0 100644
+--- a/arch/xtensa/include/asm/uaccess.h
++++ b/arch/xtensa/include/asm/uaccess.h
+@@ -35,15 +35,7 @@
+ #define get_fs()	(current->thread.current_ds)
+ #define set_fs(val)	(current->thread.current_ds = (val))
+ 
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+-
+-#define __kernel_ok (uaccess_kernel())
+-#define __user_ok(addr, size) \
+-		(((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
+-#define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size)))
+-#define access_ok(addr, size) __access_ok((unsigned long)(addr), (size))
+-
+-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They
+diff --git a/include/asm-generic/access_ok.h b/include/asm-generic/access_ok.h
+new file mode 100644
+index 000000000000..883b573af5fe
+--- /dev/null
++++ b/include/asm-generic/access_ok.h
+@@ -0,0 +1,59 @@
++/* SPDX-License-Identifier: GPL-2.0 */
++#ifndef __ASM_GENERIC_ACCESS_OK_H__
++#define __ASM_GENERIC_ACCESS_OK_H__
++
++/*
++ * Checking whether a pointer is valid for user space access.
++ * These definitions work on most architectures, but overrides can
++ * be used where necessary.
++ */
++
++/*
++ * architectures with compat tasks have a variable TASK_SIZE and should
++ * override this to a constant.
++ */
++#ifndef TASK_SIZE_MAX
++#define TASK_SIZE_MAX			TASK_SIZE
++#endif
++
++#ifndef uaccess_kernel
++#ifdef CONFIG_SET_FS
++#define uaccess_kernel()		(get_fs().seg == KERNEL_DS.seg)
++#else
++#define uaccess_kernel()		(0)
++#endif
++#endif
++
++#ifndef user_addr_max
++#define user_addr_max()			(uaccess_kernel() ? ~0UL : TASK_SIZE_MAX)
++#endif
++
++#ifndef __access_ok
++/*
++ * 'size' is a compile-time constant for most callers, so optimize for
++ * this case to turn the check into a single comparison against a constant
++ * limit and catch all possible overflows.
++ * On architectures with separate user address space (m68k, s390, parisc,
++ * sparc64) or those without an MMU, this should always return true.
++ *
++ * This version was originally contributed by Jonas Bonn for the
++ * OpenRISC architecture, and was found to be the most efficient
++ * for constant 'size' and 'limit' values.
++ */
++static inline int __access_ok(const void __user *ptr, unsigned long size)
++{
++	unsigned long limit = user_addr_max();
++	unsigned long addr = (unsigned long)ptr;
++
++	if (limit == ULONG_MAX)
++		return true;
++
++	return (size <= limit) && (addr <= (limit - size));
++}
++#endif
++
++#ifndef access_ok
++#define access_ok(addr, size) likely(__access_ok(addr, size))
++#endif
++
++#endif
+diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
+index 0870fa11a7c5..ebc685dc8d74 100644
+--- a/include/asm-generic/uaccess.h
++++ b/include/asm-generic/uaccess.h
+@@ -114,28 +114,9 @@ static inline void set_fs(mm_segment_t fs)
+ }
+ #endif
+ 
+-#ifndef uaccess_kernel
+-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
+-#endif
+-
+-#ifndef user_addr_max
+-#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
+-#endif
+-
+ #endif /* CONFIG_SET_FS */
+ 
+-#define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
+-
+-/*
+- * The architecture should really override this if possible, at least
+- * doing a check on the get_fs()
+- */
+-#ifndef __access_ok
+-static inline int __access_ok(unsigned long addr, unsigned long size)
+-{
+-	return 1;
+-}
+-#endif
++#include <asm-generic/access_ok.h>
+ 
+ /*
+  * These are the main single-value transfer routines.  They automatically
+diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
+index 67e9bc94dc40..2c31667e62e0 100644
+--- a/include/linux/uaccess.h
++++ b/include/linux/uaccess.h
+@@ -33,13 +33,6 @@ typedef struct {
+ 	/* empty dummy */
+ } mm_segment_t;
+ 
+-#ifndef TASK_SIZE_MAX
+-#define TASK_SIZE_MAX			TASK_SIZE
+-#endif
+-
+-#define uaccess_kernel()		(false)
+-#define user_addr_max()			(TASK_SIZE_MAX)
+-
+ static inline mm_segment_t force_uaccess_begin(void)
+ {
+ 	return (mm_segment_t) { };
 -- 
 2.29.2
 
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