Re: [PATCH 12/27] asm-generic: add a NOMMU uaccess.h

[Michal Simek <monstr@monstr.eu>]

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@arndb.de>
> Signed-off-by: Remis Lima Baima <remis.developer@googlemail.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