Merge tag 'riscv-for-linus-5.10-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull more RISC-V updates from Palmer Dabbelt:
 "Just a single patch set: the remainder of Christoph's work to remove
  set_fs, including the RISC-V portion"

* tag 'riscv-for-linus-5.10-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: remove address space overrides using set_fs()
  riscv: implement __get_kernel_nofault and __put_user_nofault
  riscv: refactor __get_user and __put_user
  riscv: use memcpy based uaccess for nommu again
  asm-generic: make the set_fs implementation optional
  asm-generic: add nommu implementations of __{get,put}_kernel_nofault
  asm-generic: improve the nommu {get,put}_user handling
  uaccess: provide a generic TASK_SIZE_MAX definition

arch/riscv/Kconfig

@@ -88,7 +88,7 @@ config RISCV
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
-	select SET_FS
+	select UACCESS_MEMCPY if !MMU
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT

arch/riscv/include/asm/thread_info.h

@@ -24,10 +24,6 @@
 #include <asm/processor.h>
 #include <asm/csr.h>
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 /*
  * low level task data that entry.S needs immediate access to
  * - this struct should fit entirely inside of one cache line
@@ -39,7 +35,6 @@ typedef struct {
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	int                     preempt_count;  /* 0=>preemptible, <0=>BUG */
-	mm_segment_t		addr_limit;
 	/*
 	 * These stack pointers are overwritten on every system call or
 	 * exception.  SP is also saved to the stack it can be recovered when
@@ -59,7 +54,6 @@ struct thread_info {
 {						\
 	.flags		= 0,			\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\
-	.addr_limit	= KERNEL_DS,		\
 }
 
 #endif /* !__ASSEMBLY__ */

arch/riscv/include/asm/uaccess.h

@@ -13,24 +13,6 @@
 /*
  * User space memory access functions
  */
-
-extern unsigned long __must_check __asm_copy_to_user(void __user *to,
-	const void *from, unsigned long n);
-extern unsigned long __must_check __asm_copy_from_user(void *to,
-	const void __user *from, unsigned long n);
-
-static inline unsigned long
-raw_copy_from_user(void *to, const void __user *from, unsigned long n)
-{
-	return __asm_copy_from_user(to, from, n);
-}
-
-static inline unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long n)
-{
-	return __asm_copy_to_user(to, from, n);
-}
-
 #ifdef CONFIG_MMU
 #include <linux/errno.h>
 #include <linux/compiler.h>
@@ -44,29 +26,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 #define __disable_user_access()							\
 	__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
 
-/*
- * The fs value determines whether argument validity checking should be
- * performed or not.  If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
-
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-
-#define KERNEL_DS	MAKE_MM_SEG(~0UL)
-#define USER_DS		MAKE_MM_SEG(TASK_SIZE)
-
-#define get_fs()	(current_thread_info()->addr_limit)
-
-static inline void set_fs(mm_segment_t fs)
-{
-	current_thread_info()->addr_limit = fs;
-}
-
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-#define user_addr_max()	(get_fs().seg)
-
 /**
  * access_ok: - Checks if a user space pointer is valid
  * @addr: User space pointer to start of block to check
@@ -94,9 +53,7 @@ static inline void set_fs(mm_segment_t fs)
  */
 static inline int __access_ok(unsigned long addr, unsigned long size)
 {
-	const mm_segment_t fs = get_fs();
-
-	return size <= fs.seg && addr <= fs.seg - size;
+	return size <= TASK_SIZE && addr <= TASK_SIZE - size;
 }
 
 /*
@@ -125,7 +82,6 @@ static inline int __access_ok(unsigned long addr, unsigned long size)
 do {								\
 	uintptr_t __tmp;					\
 	__typeof__(x) __x;					\
-	__enable_user_access();					\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
 		"	" insn " %1, %3\n"			\
@@ -143,7 +99,6 @@ do {								\
 		"	.previous"				\
 		: "+r" (err), "=&r" (__x), "=r" (__tmp)		\
 		: "m" (*(ptr)), "i" (-EFAULT));			\
-	__disable_user_access();				\
 	(x) = __x;						\
 } while (0)
 
@@ -156,7 +111,6 @@ do {								\
 	u32 __user *__ptr = (u32 __user *)(ptr);		\
 	u32 __lo, __hi;						\
 	uintptr_t __tmp;					\
-	__enable_user_access();					\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
 		"	lw %1, %4\n"				\
@@ -180,12 +134,30 @@ do {								\
 			"=r" (__tmp)				\
 		: "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),	\
 			"i" (-EFAULT));				\
-	__disable_user_access();				\
 	(x) = (__typeof__(x))((__typeof__((x)-(x)))(		\
 		(((u64)__hi << 32) | __lo)));			\
 } while (0)
 #endif /* CONFIG_64BIT */
 
+#define __get_user_nocheck(x, __gu_ptr, __gu_err)		\
+do {								\
+	switch (sizeof(*__gu_ptr)) {				\
+	case 1:							\
+		__get_user_asm("lb", (x), __gu_ptr, __gu_err);	\
+		break;						\
+	case 2:							\
+		__get_user_asm("lh", (x), __gu_ptr, __gu_err);	\
+		break;						\
+	case 4:							\
+		__get_user_asm("lw", (x), __gu_ptr, __gu_err);	\
+		break;						\
+	case 8:							\
+		__get_user_8((x), __gu_ptr, __gu_err);	\
+		break;						\
+	default:						\
+		BUILD_BUG();					\
+	}							\
+} while (0)
 
 /**
  * __get_user: - Get a simple variable from user space, with less checking.
@@ -209,25 +181,15 @@ do {								\
  */
 #define __get_user(x, ptr)					\
 ({								\
-	register long __gu_err = 0;				\
 	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);	\
+	long __gu_err = 0;					\
+								\
 	__chk_user_ptr(__gu_ptr);				\
-	switch (sizeof(*__gu_ptr)) {				\
-	case 1:							\
-		__get_user_asm("lb", (x), __gu_ptr, __gu_err);	\
-		break;						\
-	case 2:							\
-		__get_user_asm("lh", (x), __gu_ptr, __gu_err);	\
-		break;						\
-	case 4:							\
-		__get_user_asm("lw", (x), __gu_ptr, __gu_err);	\
-		break;						\
-	case 8:							\
-		__get_user_8((x), __gu_ptr, __gu_err);	\
-		break;						\
-	default:						\
-		BUILD_BUG();					\
-	}							\
+								\
+	__enable_user_access();					\
+	__get_user_nocheck(x, __gu_ptr, __gu_err);		\
+	__disable_user_access();				\
+								\
 	__gu_err;						\
 })
 
@@ -261,7 +223,6 @@ do {								\
 do {								\
 	uintptr_t __tmp;					\
 	__typeof__(*(ptr)) __x = x;				\
-	__enable_user_access();					\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
 		"	" insn " %z3, %2\n"			\
@@ -278,7 +239,6 @@ do {								\
 		"	.previous"				\
 		: "+r" (err), "=r" (__tmp), "=m" (*(ptr))	\
 		: "rJ" (__x), "i" (-EFAULT));			\
-	__disable_user_access();				\
 } while (0)
 
 #ifdef CONFIG_64BIT
@@ -290,7 +250,6 @@ do {								\
 	u32 __user *__ptr = (u32 __user *)(ptr);		\
 	u64 __x = (__typeof__((x)-(x)))(x);			\
 	uintptr_t __tmp;					\
-	__enable_user_access();					\
 	__asm__ __volatile__ (					\
 		"1:\n"						\
 		"	sw %z4, %2\n"				\
@@ -312,10 +271,28 @@ do {								\
 			"=m" (__ptr[__LSW]),			\
 			"=m" (__ptr[__MSW])			\
 		: "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT));	\
-	__disable_user_access();				\
 } while (0)
 #endif /* CONFIG_64BIT */
 
+#define __put_user_nocheck(x, __gu_ptr, __pu_err)					\
+do {								\
+	switch (sizeof(*__gu_ptr)) {				\
+	case 1:							\
+		__put_user_asm("sb", (x), __gu_ptr, __pu_err);	\
+		break;						\
+	case 2:							\
+		__put_user_asm("sh", (x), __gu_ptr, __pu_err);	\
+		break;						\
+	case 4:							\
+		__put_user_asm("sw", (x), __gu_ptr, __pu_err);	\
+		break;						\
+	case 8:							\
+		__put_user_8((x), __gu_ptr, __pu_err);	\
+		break;						\
+	default:						\
+		BUILD_BUG();					\
+	}							\
+} while (0)
 
 /**
  * __put_user: - Write a simple value into user space, with less checking.
@@ -338,25 +315,15 @@ do {								\
  */
 #define __put_user(x, ptr)					\
 ({								\
-	register long __pu_err = 0;				\
 	__typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
+	long __pu_err = 0;					\
+								\
 	__chk_user_ptr(__gu_ptr);				\
-	switch (sizeof(*__gu_ptr)) {				\
-	case 1:							\
-		__put_user_asm("sb", (x), __gu_ptr, __pu_err);	\
-		break;						\
-	case 2:							\
-		__put_user_asm("sh", (x), __gu_ptr, __pu_err);	\
-		break;						\
-	case 4:							\
-		__put_user_asm("sw", (x), __gu_ptr, __pu_err);	\
-		break;						\
-	case 8:							\
-		__put_user_8((x), __gu_ptr, __pu_err);	\
-		break;						\
-	default:						\
-		BUILD_BUG();					\
-	}							\
+								\
+	__enable_user_access();					\
+	__put_user_nocheck(x, __gu_ptr, __pu_err);		\
+	__disable_user_access();				\
+								\
 	__pu_err;						\
 })
 
@@ -385,6 +352,24 @@ do {								\
 		-EFAULT;					\
 })
 
+
+unsigned long __must_check __asm_copy_to_user(void __user *to,
+	const void *from, unsigned long n);
+unsigned long __must_check __asm_copy_from_user(void *to,
+	const void __user *from, unsigned long n);
+
+static inline unsigned long
+raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	return __asm_copy_from_user(to, from, n);
+}
+
+static inline unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	return __asm_copy_to_user(to, from, n);
+}
+
 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 
 extern long __must_check strlen_user(const char __user *str);
@@ -476,6 +461,26 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
 	__ret;							\
 })
 
+#define HAVE_GET_KERNEL_NOFAULT
+
+#define __get_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+	long __kr_err;							\
+									\
+	__get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);	\
+	if (unlikely(__kr_err))						\
+		goto err_label;						\
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+	long __kr_err;							\
+									\
+	__put_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);	\
+	if (unlikely(__kr_err))						\
+		goto err_label;						\
+} while (0)
+
 #else /* CONFIG_MMU */
 #include <asm-generic/uaccess.h>
 #endif /* CONFIG_MMU */

arch/riscv/kernel/process.c

@@ -84,7 +84,6 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
 	}
 	regs->epc = pc;
 	regs->sp = sp;
-	set_fs(USER_DS);
 }
 
 void flush_thread(void)

arch/riscv/lib/Makefile

@@ -2,5 +2,5 @@
 lib-y			+= delay.o
 lib-y			+= memcpy.o
 lib-y			+= memset.o
-lib-y			+= uaccess.o
+lib-$(CONFIG_MMU)	+= uaccess.o
 lib-$(CONFIG_64BIT)	+= tishift.o

include/asm-generic/uaccess.h

@@ -10,56 +10,83 @@
 #include <linux/string.h>
 
 #ifdef CONFIG_UACCESS_MEMCPY
-static inline __must_check unsigned long
-raw_copy_from_user(void *to, const void __user * from, unsigned long n)
+#include <asm/unaligned.h>
+
+static inline int __get_user_fn(size_t size, const void __user *from, void *to)
 {
-	if (__builtin_constant_p(n)) {
-		switch(n) {
+	BUILD_BUG_ON(!__builtin_constant_p(size));
+
+	switch (size) {
 	case 1:
-			*(u8 *)to = *(u8 __force *)from;
+		*(u8 *)to = get_unaligned((u8 __force *)from);
 		return 0;
 	case 2:
-			*(u16 *)to = *(u16 __force *)from;
+		*(u16 *)to = get_unaligned((u16 __force *)from);
 		return 0;
 	case 4:
-			*(u32 *)to = *(u32 __force *)from;
+		*(u32 *)to = get_unaligned((u32 __force *)from);
 		return 0;
-#ifdef CONFIG_64BIT
 	case 8:
-			*(u64 *)to = *(u64 __force *)from;
+		*(u64 *)to = get_unaligned((u64 __force *)from);
+		return 0;
+	default:
+		BUILD_BUG();
 		return 0;
-#endif
-		}
 	}
 
-	memcpy(to, (const void __force *)from, n);
-	return 0;
 }
+#define __get_user_fn(sz, u, k)	__get_user_fn(sz, u, k)
 
-static inline __must_check unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+static inline int __put_user_fn(size_t size, void __user *to, void *from)
 {
-	if (__builtin_constant_p(n)) {
-		switch(n) {
+	BUILD_BUG_ON(!__builtin_constant_p(size));
+
+	switch (size) {
 	case 1:
-			*(u8 __force *)to = *(u8 *)from;
+		put_unaligned(*(u8 *)from, (u8 __force *)to);
 		return 0;
 	case 2:
-			*(u16 __force *)to = *(u16 *)from;
+		put_unaligned(*(u16 *)from, (u16 __force *)to);
 		return 0;
 	case 4:
-			*(u32 __force *)to = *(u32 *)from;
+		put_unaligned(*(u32 *)from, (u32 __force *)to);
 		return 0;
-#ifdef CONFIG_64BIT
 	case 8:
-			*(u64 __force *)to = *(u64 *)from;
+		put_unaligned(*(u64 *)from, (u64 __force *)to);
 		return 0;
-#endif
 	default:
-			break;
-		}
+		BUILD_BUG();
+		return 0;
 	}
+}
+#define __put_user_fn(sz, u, k)	__put_user_fn(sz, u, k)
+
+#define __get_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+	*((type *)dst) = get_unaligned((type *)(src));			\
+	if (0) /* make sure the label looks used to the compiler */	\
+		goto err_label;						\
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+	put_unaligned(*((type *)src), (type *)(dst));			\
+	if (0) /* make sure the label looks used to the compiler */	\
+		goto err_label;						\
+} while (0)
+
+#define HAVE_GET_KERNEL_NOFAULT 1
+
+static inline __must_check unsigned long
+raw_copy_from_user(void *to, const void __user * from, unsigned long n)
+{
+	memcpy(to, (const void __force *)from, n);
+	return 0;
+}
 
+static inline __must_check unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
 	memcpy((void __force *)to, from, n);
 	return 0;
 }
@@ -67,6 +94,7 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 #define INLINE_COPY_TO_USER
 #endif /* CONFIG_UACCESS_MEMCPY */
 
+#ifdef CONFIG_SET_FS
 #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
 
 #ifndef KERNEL_DS
@@ -89,6 +117,7 @@ static inline void set_fs(mm_segment_t fs)
 #ifndef uaccess_kernel
 #define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
 #endif
+#endif /* CONFIG_SET_FS */
 
 #define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
 

include/linux/uaccess.h

@@ -33,6 +33,10 @@ 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)