RISC-V: Generic library routines and assembly

This patch contains code that is more specific to the RISC-V ISA than it
is to Linux.  It contains string and math operations, C wrappers for
various assembly instructions, stack walking code, and uaccess.

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>

1 files changed, 513 insertions, 0 deletions

diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
new file mode 100644
index 000000000000..27b90d64814b
--- /dev/null
+++ b/arch/riscv/include/asm/uaccess.h
@@ -0,0 +1,513 @@
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   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.
+ *
+ * This file was copied from include/asm-generic/uaccess.h
+ */
+
+#ifndef _ASM_RISCV_UACCESS_H
+#define _ASM_RISCV_UACCESS_H
+
+/*
+ * User space memory access functions
+ */
+#include <linux/errno.h>
+#include <linux/compiler.h>
+#include <linux/thread_info.h>
+#include <asm/byteorder.h>
+#include <asm/asm.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")
+
+/*
+ * 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 KERNEL_DS	(~0UL)
+#define USER_DS		(TASK_SIZE)
+
+#define get_ds()	(KERNEL_DS)
+#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))
+
+#define user_addr_max()	(get_fs())
+
+
+#define VERIFY_READ	0
+#define VERIFY_WRITE	1
+
+/**
+ * access_ok: - Checks if a user space pointer is valid
+ * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
+ *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
+ *        to write to a block, it is always safe to read from it.
+ * @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(type, 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)
+{
+	const mm_segment_t fs = get_fs();
+
+	return (size <= fs) && (addr <= (fs - 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
+ * 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 *state);
+
+#if defined(__LITTLE_ENDIAN)
+#define __MSW	1
+#define __LSW	0
+#elif defined(__BIG_ENDIAN)
+#define __MSW	0
+#define	__LSW	1
+#else
+#error "Unknown endianness"
+#endif
+
+/*
+ * 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.
+ */
+
+#ifdef CONFIG_MMU
+#define __get_user_asm(insn, x, ptr, err)			\
+do {								\
+	uintptr_t __tmp;					\
+	__typeof__(x) __x;					\
+	__enable_user_access();					\
+	__asm__ __volatile__ (					\
+		"1:\n"						\
+		"	" insn " %1, %3\n"			\
+		"2:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.balign 4\n"				\
+		"3:\n"						\
+		"	li %0, %4\n"				\
+		"	li %1, 0\n"				\
+		"	jump 2b, %2\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 3b\n"			\
+		"	.previous"				\
+		: "+r" (err), "=&r" (__x), "=r" (__tmp)		\
+		: "m" (*(ptr)), "i" (-EFAULT));			\
+	__disable_user_access();				\
+	(x) = __x;						\
+} while (0)
+#endif /* CONFIG_MMU */
+
+#ifdef CONFIG_64BIT
+#define __get_user_8(x, ptr, err) \
+	__get_user_asm("ld", x, ptr, err)
+#else /* !CONFIG_64BIT */
+#ifdef CONFIG_MMU
+#define __get_user_8(x, ptr, err)				\
+do {								\
+	u32 __user *__ptr = (u32 __user *)(ptr);		\
+	u32 __lo, __hi;						\
+	uintptr_t __tmp;					\
+	__enable_user_access();					\
+	__asm__ __volatile__ (					\
+		"1:\n"						\
+		"	lw %1, %4\n"				\
+		"2:\n"						\
+		"	lw %2, %5\n"				\
+		"3:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.balign 4\n"				\
+		"4:\n"						\
+		"	li %0, %6\n"				\
+		"	li %1, 0\n"				\
+		"	li %2, 0\n"				\
+		"	jump 3b, %3\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 4b\n"			\
+		"	" RISCV_PTR " 2b, 4b\n"			\
+		"	.previous"				\
+		: "+r" (err), "=&r" (__lo), "=r" (__hi),	\
+			"=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_MMU */
+#endif /* CONFIG_64BIT */
+
+
+/**
+ * __get_user: - Get a simple variable from user space, with less checking.
+ * @x:   Variable to store result.
+ * @ptr: Source address, in user space.
+ *
+ * Context: User context only.  This function may sleep.
+ *
+ * This macro copies a single simple variable from user space to kernel
+ * space.  It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and the result of
+ * dereferencing @ptr must be assignable to @x without a cast.
+ *
+ * Caller must check the pointer with access_ok() before calling this
+ * function.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ * On error, the variable @x is set to zero.
+ */
+#define __get_user(x, ptr)					\
+({								\
+	register long __gu_err = 0;				\
+	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);	\
+	__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();					\
+	}							\
+	__gu_err;						\
+})
+
+/**
+ * get_user: - Get a simple variable from user space.
+ * @x:   Variable to store result.
+ * @ptr: Source address, in user space.
+ *
+ * Context: User context only.  This function may sleep.
+ *
+ * This macro copies a single simple variable from user space to kernel
+ * space.  It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and the result of
+ * dereferencing @ptr must be assignable to @x without a cast.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ * On error, the variable @x is set to zero.
+ */
+#define get_user(x, ptr)					\
+({								\
+	const __typeof__(*(ptr)) __user *__p = (ptr);		\
+	might_fault();						\
+	access_ok(VERIFY_READ, __p, sizeof(*__p)) ?		\
+		__get_user((x), __p) :				\
+		((x) = 0, -EFAULT);				\
+})
+
+
+#ifdef CONFIG_MMU
+#define __put_user_asm(insn, x, ptr, err)			\
+do {								\
+	uintptr_t __tmp;					\
+	__typeof__(*(ptr)) __x = x;				\
+	__enable_user_access();					\
+	__asm__ __volatile__ (					\
+		"1:\n"						\
+		"	" insn " %z3, %2\n"			\
+		"2:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.balign 4\n"				\
+		"3:\n"						\
+		"	li %0, %4\n"				\
+		"	jump 2b, %1\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 3b\n"			\
+		"	.previous"				\
+		: "+r" (err), "=r" (__tmp), "=m" (*(ptr))	\
+		: "rJ" (__x), "i" (-EFAULT));			\
+	__disable_user_access();				\
+} while (0)
+#endif /* CONFIG_MMU */
+
+
+#ifdef CONFIG_64BIT
+#define __put_user_8(x, ptr, err) \
+	__put_user_asm("sd", x, ptr, err)
+#else /* !CONFIG_64BIT */
+#ifdef CONFIG_MMU
+#define __put_user_8(x, ptr, err)				\
+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"				\
+		"2:\n"						\
+		"	sw %z5, %3\n"				\
+		"3:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.balign 4\n"				\
+		"4:\n"						\
+		"	li %0, %6\n"				\
+		"	jump 2b, %1\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 4b\n"			\
+		"	" RISCV_PTR " 2b, 4b\n"			\
+		"	.previous"				\
+		: "+r" (err), "=r" (__tmp),			\
+			"=m" (__ptr[__LSW]),			\
+			"=m" (__ptr[__MSW])			\
+		: "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT));	\
+	__disable_user_access();				\
+} while (0)
+#endif /* CONFIG_MMU */
+#endif /* CONFIG_64BIT */
+
+
+/**
+ * __put_user: - Write a simple value into user space, with less checking.
+ * @x:   Value to copy to user space.
+ * @ptr: Destination address, in user space.
+ *
+ * Context: User context only.  This function may sleep.
+ *
+ * This macro copies a single simple value from kernel space to user
+ * space.  It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and @x must be assignable
+ * to the result of dereferencing @ptr.
+ *
+ * Caller must check the pointer with access_ok() before calling this
+ * function.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ */
+#define __put_user(x, ptr)					\
+({								\
+	register long __pu_err = 0;				\
+	__typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
+	__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();					\
+	}							\
+	__pu_err;						\
+})
+
+/**
+ * put_user: - Write a simple value into user space.
+ * @x:   Value to copy to user space.
+ * @ptr: Destination address, in user space.
+ *
+ * Context: User context only.  This function may sleep.
+ *
+ * This macro copies a single simple value from kernel space to user
+ * space.  It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and @x must be assignable
+ * to the result of dereferencing @ptr.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ */
+#define put_user(x, ptr)					\
+({								\
+	__typeof__(*(ptr)) __user *__p = (ptr);			\
+	might_fault();						\
+	access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?		\
+		__put_user((x), __p) :				\
+		-EFAULT;					\
+})
+
+
+extern unsigned long __must_check __copy_user(void __user *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 __copy_user(to, from, n);
+}
+
+static inline unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	return __copy_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);
+extern long __must_check strnlen_user(const char __user *str, long n);
+
+extern
+unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
+
+static inline
+unsigned long __must_check clear_user(void __user *to, unsigned long n)
+{
+	might_fault();
+	return access_ok(VERIFY_WRITE, to, n) ?
+		__clear_user(to, n) : n;
+}
+
+/*
+ * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
+ * will set "err" to -EFAULT, while successful accesses return the previous
+ * value.
+ */
+#ifdef CONFIG_MMU
+#define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)	\
+({								\
+	__typeof__(ptr) __ptr = (ptr);				\
+	__typeof__(*(ptr)) __old = (old);			\
+	__typeof__(*(ptr)) __new = (new);			\
+	__typeof__(*(ptr)) __ret;				\
+	__typeof__(err) __err = 0;				\
+	register unsigned int __rc;				\
+	__enable_user_access();					\
+	switch (size) {						\
+	case 4:							\
+		__asm__ __volatile__ (				\
+		"0:\n"						\
+		"	lr.w" #scb " %[ret], %[ptr]\n"		\
+		"	bne          %[ret], %z[old], 1f\n"	\
+		"	sc.w" #lrb " %[rc], %z[new], %[ptr]\n"	\
+		"	bnez         %[rc], 0b\n"		\
+		"1:\n"						\
+		".section .fixup,\"ax\"\n"			\
+		".balign 4\n"					\
+		"2:\n"						\
+		"	li %[err], %[efault]\n"			\
+		"	jump 1b, %[rc]\n"			\
+		".previous\n"					\
+		".section __ex_table,\"a\"\n"			\
+		".balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 2b\n"			\
+		".previous\n"					\
+			: [ret] "=&r" (__ret),			\
+			  [rc]  "=&r" (__rc),			\
+			  [ptr] "+A" (*__ptr),			\
+			  [err] "=&r" (__err)			\
+			: [old] "rJ" (__old),			\
+			  [new] "rJ" (__new),			\
+			  [efault] "i" (-EFAULT));		\
+		break;						\
+	case 8:							\
+		__asm__ __volatile__ (				\
+		"0:\n"						\
+		"	lr.d" #scb " %[ret], %[ptr]\n"		\
+		"	bne          %[ret], %z[old], 1f\n"	\
+		"	sc.d" #lrb " %[rc], %z[new], %[ptr]\n"	\
+		"	bnez         %[rc], 0b\n"		\
+		"1:\n"						\
+		".section .fixup,\"ax\"\n"			\
+		".balign 4\n"					\
+		"2:\n"						\
+		"	li %[err], %[efault]\n"			\
+		"	jump 1b, %[rc]\n"			\
+		".previous\n"					\
+		".section __ex_table,\"a\"\n"			\
+		".balign " RISCV_SZPTR "\n"			\
+		"	" RISCV_PTR " 1b, 2b\n"			\
+		".previous\n"					\
+			: [ret] "=&r" (__ret),			\
+			  [rc]  "=&r" (__rc),			\
+			  [ptr] "+A" (*__ptr),			\
+			  [err] "=&r" (__err)			\
+			: [old] "rJ" (__old),			\
+			  [new] "rJ" (__new),			\
+			  [efault] "i" (-EFAULT));		\
+		break;						\
+	default:						\
+		BUILD_BUG();					\
+	}							\
+	__disable_user_access();				\
+	(err) = __err;						\
+	__ret;							\
+})
+#endif /* CONFIG_MMU */
+
+#endif /* _ASM_RISCV_UACCESS_H */