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Date: Fri, 01 May 2009 12:07:40 +0200
From: Michal Simek <monstr@...str.eu>
To: Arnd Bergmann <arnd@...db.de>
CC: linux-arch@...r.kernel.org,
Remis Lima Baima <remis.developer@...glemail.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/27] asm-generic: add a NOMMU uaccess.h
Arnd Bergmann wrote:
> This uaccess.h can be used by all NOMMU architectures,
> but it does not provide exception handlers that would
> be needed for an architecture with an MMU.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Remis Lima Baima <remis.developer@...glemail.com>
> ---
> arch/parisc/include/asm/uaccess.h | 2 +-
> arch/sparc/include/asm/uaccess_64.h | 2 +-
> .../asm-generic/{uaccess.h => uaccess-unaligned.h} | 6 +-
> include/asm-generic/uaccess.h | 235 +++++++++++++++++---
> 4 files changed, 214 insertions(+), 31 deletions(-)
> rename include/asm-generic/{uaccess.h => uaccess-unaligned.h} (82%)
> rewrite include/asm-generic/uaccess.h (96%)
>
> diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
> index cd4c0b2..7cf799d 100644
> --- a/arch/parisc/include/asm/uaccess.h
> +++ b/arch/parisc/include/asm/uaccess.h
> @@ -7,7 +7,7 @@
> #include <asm/page.h>
> #include <asm/system.h>
> #include <asm/cache.h>
> -#include <asm-generic/uaccess.h>
> +#include <asm-generic/uaccess-unaligned.h>
>
> #define VERIFY_READ 0
> #define VERIFY_WRITE 1
> diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
> index c64e767..a38c032 100644
> --- a/arch/sparc/include/asm/uaccess_64.h
> +++ b/arch/sparc/include/asm/uaccess_64.h
> @@ -12,7 +12,7 @@
> #include <asm/asi.h>
> #include <asm/system.h>
> #include <asm/spitfire.h>
> -#include <asm-generic/uaccess.h>
> +#include <asm-generic/uaccess-unaligned.h>
> #endif
>
> #ifndef __ASSEMBLY__
> diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess-unaligned.h
> similarity index 82%
> rename from include/asm-generic/uaccess.h
> rename to include/asm-generic/uaccess-unaligned.h
> index 549cb3a..67deb89 100644
> --- a/include/asm-generic/uaccess.h
> +++ b/include/asm-generic/uaccess-unaligned.h
> @@ -1,5 +1,5 @@
> -#ifndef _ASM_GENERIC_UACCESS_H_
> -#define _ASM_GENERIC_UACCESS_H_
> +#ifndef __ASM_GENERIC_UACCESS_UNALIGNED_H
> +#define __ASM_GENERIC_UACCESS_UNALIGNED_H
>
> /*
> * This macro should be used instead of __get_user() when accessing
> @@ -23,4 +23,4 @@
> __copy_to_user((ptr), &__x, sizeof(*(ptr))) ? -EFAULT : 0; \
> })
>
> -#endif /* _ASM_GENERIC_UACCESS_H */
> +#endif /* __ASM_GENERIC_UACCESS_UNALIGNED_H */
> diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
> dissimilarity index 96%
> index 549cb3a..ebeacd9 100644
> --- a/include/asm-generic/uaccess.h
> +++ b/include/asm-generic/uaccess.h
> @@ -1,26 +1,209 @@
> -#ifndef _ASM_GENERIC_UACCESS_H_
> -#define _ASM_GENERIC_UACCESS_H_
> -
> -/*
> - * This macro should be used instead of __get_user() when accessing
> - * values at locations that are not known to be aligned.
> - */
> -#define __get_user_unaligned(x, ptr) \
> -({ \
> - __typeof__ (*(ptr)) __x; \
> - __copy_from_user(&__x, (ptr), sizeof(*(ptr))) ? -EFAULT : 0; \
> - (x) = __x; \
> -})
> -
> -
> -/*
> - * This macro should be used instead of __put_user() when accessing
> - * values at locations that are not known to be aligned.
> - */
> -#define __put_user_unaligned(x, ptr) \
> -({ \
> - __typeof__ (*(ptr)) __x = (x); \
> - __copy_to_user((ptr), &__x, sizeof(*(ptr))) ? -EFAULT : 0; \
> -})
> -
> -#endif /* _ASM_GENERIC_UACCESS_H */
> +#ifndef __ASM_GENERIC_UACCESS_H
> +#define __ASM_GENERIC_UACCESS_H
> +
> +/*
> + * User space memory access functions, these should work
> + * on a ny machine that has kernel and user data in the same
> + * address space, e.g. all NOMMU machines.
> + */
> +#include <linux/sched.h>
> +#include <linux/mm.h>
> +#include <linux/string.h>
> +
> +#include <asm/segment.h>
> +
> +#ifndef get_fs
> +#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
> +#define KERNEL_DS MAKE_MM_SEG(~0UL)
> +#define USER_DS MAKE_MM_SEG(TASK_SIZE - 1)
> +
> +#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;
> +}
> +#endif
> +
> +#define segment_eq(a, b) ((a).seg == (b).seg)
> +
> +#define VERIFY_READ 0
> +#define VERIFY_WRITE 1
> +
> +#define access_ok(type, 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
> +
> +/*
> + * 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;
> +};
> +
> +/* Returns 0 if exception not found and fixup otherwise. */
> +extern unsigned long search_exception_table(unsigned long);
> +
> +/*
> + * These are the main single-value transfer routines. They automatically
> + * use the right size if we just have the right pointer type.
> + */
> +#ifndef __put_user
> +#define __put_user(x, ptr) \
> +({ \
> + int __pu_err = 0; \
> + typeof(*(ptr)) __pu_val = (x); \
> + switch (sizeof (*(ptr))) { \
> + case 1: \
> + case 2: \
> + case 4: \
> + *(ptr) = (__pu_val); \
> + break; \
> + case 8: \
> + memcpy(ptr, &__pu_val, sizeof (*(ptr)));\
> + break; \
> + default: \
> + __pu_err = __put_user_bad(); \
> + break; \
> + } \
> + __pu_err; \
> +})
> +extern int __put_user_bad(void);
> +#endif
> +
> +#define put_user(x, ptr) ( \
> + access_ok(VERIFY_WRITE, ptr, sizeof (*ptr)) ? \
> + __put_user(x, ptr) : \
> + -EFAULT)
> +
> +#ifndef __get_user
> +#define __get_user(x, ptr) \
> +({ \
> + int __gu_err = 0; \
> + unsigned long __gu_val = (unsigned long)*ptr; \
> + switch (sizeof(*(ptr))) { \
> + case 1: \
> + case 2: \
> + case 4: \
> + case 8: \
> + break; \
> + default: \
> + __gu_err = __get_user_bad(); \
> + __gu_val = 0; \
> + break; \
> + } \
> + (x) = (typeof(*ptr))__gu_val; \
> + __gu_err; \
> +})
> +extern int __get_user_bad(void);
> +#endif
> +
> +#define get_user(x, ptr) ( \
> + access_ok(VERIFY_READ, ptr, sizeof (*ptr)) ? \
> + __get_user(x, ptr) : \
> + -EFAULT)
> +
> +#define __copy_from_user(to, from, n) (memcpy(to, from, n), 0)
> +#define __copy_to_user(to, from, n) (memcpy(to, from, n), 0)
> +#define __copy_to_user_inatomic __copy_to_user
> +#define __copy_from_user_inatomic __copy_from_user
> +
> +#define copy_to_user_ret(to,from,n,retval) ({ if (copy_to_user(to,from,n)) return retval; })
> +
> +#define copy_from_user_ret(to,from,n,retval) ({ if (copy_from_user(to,from,n)) return retval; })
> +
> +static inline long copy_from_user(void *to,
> + const void __user * from, unsigned long n)
> +{
> + if (access_ok(VERIFY_READ, from, n))
> + __copy_from_user(to, from, n);
> + else
> + return n;
> + return 0;
> +}
> +
> +static inline long copy_to_user(void *to,
> + const void __user * from, unsigned long n)
> +{
> + if (access_ok(VERIFY_WRITE, to, n))
> + __copy_to_user(to, from, n);
> + else
> + return n;
> + return 0;
> +}
> +
> +/*
> + * Copy a null terminated string from userspace.
> + */
> +
> +static inline long
> +__do_strncpy_from_user(char *dst, const char __user *src, long count)
> +{
> + char *tmp;
> + strncpy(dst, src, count);
> + for (tmp = dst; *tmp && count > 0; tmp++, count--)
> + ;
> + return (tmp - dst);
> +}
> +
> +static inline long
> +strncpy_from_user(char *dst, const char __user *src, long count)
> +{
> + if (!access_ok(VERIFY_READ, src, 1))
> + return -EFAULT;
> + return __do_strncpy_from_user(dst, src, count);
> +}
> +
> +static inline long
> +__strncpy_from_user(char *dst, const char __user *src, long count)
> +{
> + return __do_strncpy_from_user(dst, src, count);
> +}
> +
> +/*
> + * Return the size of a string (including the ending 0)
> + *
> + * Return 0 on exception, a value greater than N if too long
> + */
> +static inline long strnlen_user(const char *src, long n)
> +{
> + return strlen(src) + 1;
> +}
Here is the cast problem too.
Michal
> +
> +#define strlen_user(str) strnlen_user(str, 32767)
> +
> +/*
> + * Zero Userspace
> + */
> +
> +static inline unsigned long
> +__clear_user(void *to, unsigned long n)
> +{
> + memset(to, 0, n);
> + return 0;
> +}
> +
> +#define clear_user(to, n) __clear_user(to, n)
> +
> +#endif /* __ASM_GENERIC_UACCESS_H */
--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
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