20802d8d47
Inspired by commit 2e77a62cb3 ("arm64: extable: add a dedicated
uaccess handler"), do similar to riscv to add a dedicated uaccess
exception handler to update registers in exception context and
subsequently return back into the function which faulted, so we remove
the need for fixups specialized to each faulting instruction.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
373 lines
10 KiB
C
373 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2012 Regents of the University of California
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*
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* This file was copied from include/asm-generic/uaccess.h
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*/
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#ifndef _ASM_RISCV_UACCESS_H
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#define _ASM_RISCV_UACCESS_H
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#include <asm/asm-extable.h>
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#include <asm/pgtable.h> /* for TASK_SIZE */
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/*
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* User space memory access functions
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*/
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#ifdef CONFIG_MMU
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#include <linux/errno.h>
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#include <linux/compiler.h>
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#include <linux/thread_info.h>
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#include <asm/byteorder.h>
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#include <asm/extable.h>
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#include <asm/asm.h>
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#define __enable_user_access() \
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__asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
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#define __disable_user_access() \
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__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
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/**
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* access_ok: - Checks if a user space pointer is valid
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* @addr: User space pointer to start of block to check
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* @size: Size of block to check
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*
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* Context: User context only. This function may sleep.
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*
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* Checks if a pointer to a block of memory in user space is valid.
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*
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* Returns true (nonzero) if the memory block may be valid, false (zero)
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* if it is definitely invalid.
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*
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* Note that, depending on architecture, this function probably just
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* checks that the pointer is in the user space range - after calling
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* this function, memory access functions may still return -EFAULT.
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*/
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#define access_ok(addr, size) ({ \
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__chk_user_ptr(addr); \
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likely(__access_ok((unsigned long __force)(addr), (size))); \
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})
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/*
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* Ensure that the range [addr, addr+size) is within the process's
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* address space
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*/
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static inline int __access_ok(unsigned long addr, unsigned long size)
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{
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return size <= TASK_SIZE && addr <= TASK_SIZE - size;
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}
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/*
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* The exception table consists of pairs of addresses: the first is the
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* address of an instruction that is allowed to fault, and the second is
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* the address at which the program should continue. No registers are
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* modified, so it is entirely up to the continuation code to figure out
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* what to do.
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*
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* All the routines below use bits of fixup code that are out of line
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* with the main instruction path. This means when everything is well,
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* we don't even have to jump over them. Further, they do not intrude
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* on our cache or tlb entries.
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*/
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#define __LSW 0
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#define __MSW 1
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/*
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* The "__xxx" versions of the user access functions do not verify the address
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* space - it must have been done previously with a separate "access_ok()"
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* call.
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*/
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#define __get_user_asm(insn, x, ptr, err) \
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do { \
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__typeof__(x) __x; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" " insn " %1, %2\n" \
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"2:\n" \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %0, %1) \
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: "+r" (err), "=&r" (__x) \
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: "m" (*(ptr))); \
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(x) = __x; \
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} while (0)
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#ifdef CONFIG_64BIT
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#define __get_user_8(x, ptr, err) \
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__get_user_asm("ld", x, ptr, err)
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#else /* !CONFIG_64BIT */
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#define __get_user_8(x, ptr, err) \
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do { \
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u32 __user *__ptr = (u32 __user *)(ptr); \
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u32 __lo, __hi; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" lw %1, %3\n" \
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"2:\n" \
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" lw %2, %4\n" \
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"3:\n" \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 3b, %0, %1) \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(2b, 3b, %0, %1) \
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: "+r" (err), "=&r" (__lo), "=r" (__hi) \
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: "m" (__ptr[__LSW]), "m" (__ptr[__MSW])); \
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if (err) \
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__hi = 0; \
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(x) = (__typeof__(x))((__typeof__((x)-(x)))( \
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(((u64)__hi << 32) | __lo))); \
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} while (0)
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#endif /* CONFIG_64BIT */
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#define __get_user_nocheck(x, __gu_ptr, __gu_err) \
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do { \
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switch (sizeof(*__gu_ptr)) { \
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case 1: \
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__get_user_asm("lb", (x), __gu_ptr, __gu_err); \
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break; \
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case 2: \
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__get_user_asm("lh", (x), __gu_ptr, __gu_err); \
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break; \
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case 4: \
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__get_user_asm("lw", (x), __gu_ptr, __gu_err); \
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break; \
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case 8: \
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__get_user_8((x), __gu_ptr, __gu_err); \
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break; \
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default: \
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BUILD_BUG(); \
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} \
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} while (0)
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/**
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* __get_user: - Get a simple variable from user space, with less checking.
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* @x: Variable to store result.
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* @ptr: Source address, in user space.
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*
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* Context: User context only. This function may sleep.
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*
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* This macro copies a single simple variable from user space to kernel
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and the result of
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* dereferencing @ptr must be assignable to @x without a cast.
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*
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* Caller must check the pointer with access_ok() before calling this
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* function.
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*
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* Returns zero on success, or -EFAULT on error.
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* On error, the variable @x is set to zero.
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*/
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#define __get_user(x, ptr) \
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({ \
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const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
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long __gu_err = 0; \
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\
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__chk_user_ptr(__gu_ptr); \
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\
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__enable_user_access(); \
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__get_user_nocheck(x, __gu_ptr, __gu_err); \
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__disable_user_access(); \
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\
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__gu_err; \
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})
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/**
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* get_user: - Get a simple variable from user space.
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* @x: Variable to store result.
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* @ptr: Source address, in user space.
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*
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* Context: User context only. This function may sleep.
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*
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* This macro copies a single simple variable from user space to kernel
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and the result of
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* dereferencing @ptr must be assignable to @x without a cast.
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*
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* Returns zero on success, or -EFAULT on error.
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* On error, the variable @x is set to zero.
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*/
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#define get_user(x, ptr) \
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({ \
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const __typeof__(*(ptr)) __user *__p = (ptr); \
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might_fault(); \
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access_ok(__p, sizeof(*__p)) ? \
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__get_user((x), __p) : \
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((x) = 0, -EFAULT); \
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})
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#define __put_user_asm(insn, x, ptr, err) \
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do { \
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__typeof__(*(ptr)) __x = x; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" " insn " %z2, %1\n" \
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"2:\n" \
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_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %0) \
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: "+r" (err), "=m" (*(ptr)) \
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: "rJ" (__x)); \
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} while (0)
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#ifdef CONFIG_64BIT
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#define __put_user_8(x, ptr, err) \
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__put_user_asm("sd", x, ptr, err)
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#else /* !CONFIG_64BIT */
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#define __put_user_8(x, ptr, err) \
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do { \
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u32 __user *__ptr = (u32 __user *)(ptr); \
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u64 __x = (__typeof__((x)-(x)))(x); \
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__asm__ __volatile__ ( \
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"1:\n" \
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" sw %z3, %1\n" \
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"2:\n" \
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" sw %z4, %2\n" \
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"3:\n" \
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_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0) \
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_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0) \
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: "+r" (err), \
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"=m" (__ptr[__LSW]), \
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"=m" (__ptr[__MSW]) \
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: "rJ" (__x), "rJ" (__x >> 32)); \
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} while (0)
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#endif /* CONFIG_64BIT */
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#define __put_user_nocheck(x, __gu_ptr, __pu_err) \
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do { \
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switch (sizeof(*__gu_ptr)) { \
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case 1: \
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__put_user_asm("sb", (x), __gu_ptr, __pu_err); \
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break; \
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case 2: \
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__put_user_asm("sh", (x), __gu_ptr, __pu_err); \
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break; \
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case 4: \
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__put_user_asm("sw", (x), __gu_ptr, __pu_err); \
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break; \
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case 8: \
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__put_user_8((x), __gu_ptr, __pu_err); \
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break; \
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default: \
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BUILD_BUG(); \
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} \
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} while (0)
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/**
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* __put_user: - Write a simple value into user space, with less checking.
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* @x: Value to copy to user space.
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* @ptr: Destination address, in user space.
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*
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* Context: User context only. This function may sleep.
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*
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* This macro copies a single simple value from kernel space to user
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and @x must be assignable
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* to the result of dereferencing @ptr. The value of @x is copied to avoid
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* re-ordering where @x is evaluated inside the block that enables user-space
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* access (thus bypassing user space protection if @x is a function).
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*
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* Caller must check the pointer with access_ok() before calling this
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* function.
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*
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* Returns zero on success, or -EFAULT on error.
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*/
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#define __put_user(x, ptr) \
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({ \
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__typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
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__typeof__(*__gu_ptr) __val = (x); \
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long __pu_err = 0; \
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\
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__chk_user_ptr(__gu_ptr); \
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\
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__enable_user_access(); \
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__put_user_nocheck(__val, __gu_ptr, __pu_err); \
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__disable_user_access(); \
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\
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__pu_err; \
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})
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/**
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* put_user: - Write a simple value into user space.
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* @x: Value to copy to user space.
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* @ptr: Destination address, in user space.
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*
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* Context: User context only. This function may sleep.
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*
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* This macro copies a single simple value from kernel space to user
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and @x must be assignable
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* to the result of dereferencing @ptr.
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*
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* Returns zero on success, or -EFAULT on error.
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*/
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#define put_user(x, ptr) \
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({ \
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__typeof__(*(ptr)) __user *__p = (ptr); \
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might_fault(); \
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access_ok(__p, sizeof(*__p)) ? \
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__put_user((x), __p) : \
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-EFAULT; \
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})
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unsigned long __must_check __asm_copy_to_user(void __user *to,
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const void *from, unsigned long n);
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unsigned long __must_check __asm_copy_from_user(void *to,
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const void __user *from, unsigned long n);
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static inline unsigned long
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raw_copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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return __asm_copy_from_user(to, from, n);
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}
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static inline unsigned long
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raw_copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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return __asm_copy_to_user(to, from, n);
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}
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extern long strncpy_from_user(char *dest, const char __user *src, long count);
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extern long __must_check strnlen_user(const char __user *str, long n);
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extern
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unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
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static inline
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unsigned long __must_check clear_user(void __user *to, unsigned long n)
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{
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might_fault();
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return access_ok(to, n) ?
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__clear_user(to, n) : n;
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}
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#define HAVE_GET_KERNEL_NOFAULT
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#define __get_kernel_nofault(dst, src, type, err_label) \
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do { \
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long __kr_err; \
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\
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__get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \
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if (unlikely(__kr_err)) \
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goto err_label; \
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} while (0)
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#define __put_kernel_nofault(dst, src, type, err_label) \
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do { \
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long __kr_err; \
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\
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__put_user_nocheck(*((type *)(src)), (type *)(dst), __kr_err); \
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if (unlikely(__kr_err)) \
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goto err_label; \
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} while (0)
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#else /* CONFIG_MMU */
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#include <asm-generic/uaccess.h>
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#endif /* CONFIG_MMU */
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#endif /* _ASM_RISCV_UACCESS_H */
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