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    Subject[PATCH] bitmap: separate bitmap parsing for user buffer and kernel buffer
    Date
    lib/bitmap.c:bitmap_parse() is a library function that received as 
    input a user buffer. This seemed to have originated from the way
    the write_proc function of the /proc filesystem operates.

    This has been reworked to not use kmalloc and eliminates a lot of
    get_user overhead by performing one access_ok before using __get_user.

    This function will be useful for other uses as well; for example,
    taking input for /sysfs instead of /proc, so it was changed to accept
    kernel buffers. We have this use for the Linux UWB project, as part
    as the upcoming bandwidth allocator code.

    Only a few routines used this function and they were changed too.


    Signed-off-by: Reinette Chatre <reinette.chatre@linux.intel.com>

    ---
    This is an updated version of patch
    bitmap-bitmap_parse-takes-a-kernel-buffer-instead-of-a-user-buffer.patch

    With the usage of access_ok() before __get_user(), is it still necessary
    to check the return code of __get_user? We currently do this.

    include/linux/bitmap.h | 13 +++++++++--
    include/linux/cpumask.h | 14 ++++++------
    include/linux/nodemask.h | 14 ++++++------
    kernel/irq/proc.c | 2 -
    kernel/profile.c | 2 -
    lib/bitmap.c | 53 +++++++++++++++++++++++++++++++++++++----------
    6 files changed, 69 insertions(+), 29 deletions(-)


    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/bitmap.h linux-2.6.hg/include/linux/bitmap.h
    --- linux-2.6.hg.vanilla/include/linux/bitmap.h 2006-10-02 14:04:35.000000000 -0700
    +++ linux-2.6.hg/include/linux/bitmap.h 2006-10-04 14:31:51.000000000 -0700
    @@ -46,7 +46,8 @@
    * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
    * bitmap_bitremap(oldbit, old, new, nbits) newbit = map(old, new)(oldbit)
    * bitmap_scnprintf(buf, len, src, nbits) Print bitmap src to buf
    - * bitmap_parse(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
    + * bitmap_parse(buf, buflen, dst, nbits) Parse bitmap dst from kernel buf
    + * bitmap_parse_user(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
    * bitmap_scnlistprintf(buf, len, src, nbits) Print bitmap src as list to buf
    * bitmap_parselist(buf, dst, nbits) Parse bitmap dst from list
    * bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region
    @@ -106,7 +107,9 @@ extern int __bitmap_weight(const unsigne

    extern int bitmap_scnprintf(char *buf, unsigned int len,
    const unsigned long *src, int nbits);
    -extern int bitmap_parse(const char __user *ubuf, unsigned int ulen,
    +extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
    + unsigned long *dst, int nbits);
    +extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
    unsigned long *dst, int nbits);
    extern int bitmap_scnlistprintf(char *buf, unsigned int len,
    const unsigned long *src, int nbits);
    @@ -270,6 +273,12 @@ static inline void bitmap_shift_left(uns
    __bitmap_shift_left(dst, src, n, nbits);
    }

    +static inline int bitmap_parse(const char *buf, unsigned int buflen,
    + unsigned long *maskp, int nmaskbits)
    +{
    + return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
    +}
    +
    #endif /* __ASSEMBLY__ */

    #endif /* __LINUX_BITMAP_H */
    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/lib/bitmap.c linux-2.6.hg/lib/bitmap.c
    --- linux-2.6.hg.vanilla/lib/bitmap.c 2006-10-02 14:04:39.000000000 -0700
    +++ linux-2.6.hg/lib/bitmap.c 2006-10-04 14:30:47.000000000 -0700
    @@ -316,10 +316,11 @@ int bitmap_scnprintf(char *buf, unsigned
    EXPORT_SYMBOL(bitmap_scnprintf);

    /**
    - * bitmap_parse - convert an ASCII hex string into a bitmap.
    - * @ubuf: pointer to buffer in user space containing string.
    - * @ubuflen: buffer size in bytes. If string is smaller than this
    + * __bitmap_parse - convert an ASCII hex string into a bitmap.
    + * @buf: pointer to buffer containing string.
    + * @buflen: buffer size in bytes. If string is smaller than this
    * then it must be terminated with a \0.
    + * @is_user: location of buffer, 0 indicates kernel space
    * @maskp: pointer to bitmap array that will contain result.
    * @nmaskbits: size of bitmap, in bits.
    *
    @@ -330,8 +331,9 @@ EXPORT_SYMBOL(bitmap_scnprintf);
    * characters and for grouping errors such as "1,,5", ",44", "," and "".
    * Leading and trailing whitespace accepted, but not embedded whitespace.
    */
    -int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
    - unsigned long *maskp, int nmaskbits)
    +int __bitmap_parse(const char *buf, unsigned int buflen,
    + int is_user, unsigned long *maskp,
    + int nmaskbits)
    {
    int c, old_c, totaldigits, ndigits, nchunks, nbits;
    u32 chunk;
    @@ -343,11 +345,15 @@ int bitmap_parse(const char __user *ubuf
    chunk = ndigits = 0;

    /* Get the next chunk of the bitmap */
    - while (ubuflen) {
    + while (buflen) {
    old_c = c;
    - if (get_user(c, ubuf++))
    - return -EFAULT;
    - ubuflen--;
    + if (is_user) {
    + if (__get_user(c, buf++))
    + return -EFAULT;
    + }
    + else
    + c = *buf++;
    + buflen--;
    if (isspace(c))
    continue;

    @@ -388,11 +394,36 @@ int bitmap_parse(const char __user *ubuf
    nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
    if (nbits > nmaskbits)
    return -EOVERFLOW;
    - } while (ubuflen && c == ',');
    + } while (buflen && c == ',');

    return 0;
    }
    -EXPORT_SYMBOL(bitmap_parse);
    +EXPORT_SYMBOL(__bitmap_parse);
    +
    +/**
    + * bitmap_parse_user()
    + *
    + * @ubuf: pointer to user buffer containing string.
    + * @ulen: buffer size in bytes. If string is smaller than this
    + * then it must be terminated with a \0.
    + * @maskp: pointer to bitmap array that will contain result.
    + * @nmaskbits: size of bitmap, in bits.
    + *
    + * Wrapper for __bitmap_parse(), providing it with user buffer.
    + *
    + * We cannot have this as an inline function in bitmap.h because it needs
    + * linux/uaccess.h to get the access_ok() declaration and this causes
    + * cyclic dependencies.
    + */
    +int bitmap_parse_user(const char __user *ubuf,
    + unsigned int ulen, unsigned long *maskp,
    + int nmaskbits)
    +{
    + if (!access_ok(VERIFY_READ, ubuf, ulen))
    + return -EFAULT;
    + return __bitmap_parse((const char *)ubuf, ulen, 1, maskp, nmaskbits);
    +}
    +EXPORT_SYMBOL(bitmap_parse_user);

    /*
    * bscnl_emit(buf, buflen, rbot, rtop, bp)
    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/cpumask.h linux-2.6.hg/include/linux/cpumask.h
    --- linux-2.6.hg.vanilla/include/linux/cpumask.h 2006-10-02 14:04:35.000000000 -0700
    +++ linux-2.6.hg/include/linux/cpumask.h 2006-10-04 09:07:47.000000000 -0700
    @@ -8,8 +8,8 @@
    * See detailed comments in the file linux/bitmap.h describing the
    * data type on which these cpumasks are based.
    *
    - * For details of cpumask_scnprintf() and cpumask_parse(),
    - * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
    + * For details of cpumask_scnprintf() and cpumask_parse_user(),
    + * see bitmap_scnprintf() and bitmap_parse_user() in lib/bitmap.c.
    * For details of cpulist_scnprintf() and cpulist_parse(), see
    * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
    * For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
    @@ -49,7 +49,7 @@
    * unsigned long *cpus_addr(mask) Array of unsigned long's in mask
    *
    * int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
    - * int cpumask_parse(ubuf, ulen, mask) Parse ascii string as cpumask
    + * int cpumask_parse_user(ubuf, ulen, mask) Parse ascii string as cpumask
    * int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
    * int cpulist_parse(buf, map) Parse ascii string as cpulist
    * int cpu_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
    @@ -273,12 +273,12 @@ static inline int __cpumask_scnprintf(ch
    return bitmap_scnprintf(buf, len, srcp->bits, nbits);
    }

    -#define cpumask_parse(ubuf, ulen, dst) \
    - __cpumask_parse((ubuf), (ulen), &(dst), NR_CPUS)
    -static inline int __cpumask_parse(const char __user *buf, int len,
    +#define cpumask_parse_user(ubuf, ulen, dst) \
    + __cpumask_parse_user((ubuf), (ulen), &(dst), NR_CPUS)
    +static inline int __cpumask_parse_user(const char __user *buf, int len,
    cpumask_t *dstp, int nbits)
    {
    - return bitmap_parse(buf, len, dstp->bits, nbits);
    + return bitmap_parse_user(buf, len, dstp->bits, nbits);
    }

    #define cpulist_scnprintf(buf, len, src) \
    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/kernel/irq/proc.c linux-2.6.hg/kernel/irq/proc.c
    --- linux-2.6.hg.vanilla/kernel/irq/proc.c 2006-10-02 14:04:38.000000000 -0700
    +++ linux-2.6.hg/kernel/irq/proc.c 2006-10-04 09:05:55.000000000 -0700
    @@ -57,7 +57,7 @@ static int irq_affinity_write_proc(struc
    if (!irq_desc[irq].chip->set_affinity || no_irq_affinity)
    return -EIO;

    - err = cpumask_parse(buffer, count, new_value);
    + err = cpumask_parse_user(buffer, count, new_value);
    if (err)
    return err;

    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/kernel/profile.c linux-2.6.hg/kernel/profile.c
    --- linux-2.6.hg.vanilla/kernel/profile.c 2006-10-02 14:04:38.000000000 -0700
    +++ linux-2.6.hg/kernel/profile.c 2006-10-04 09:45:01.000000000 -0700
    @@ -396,7 +396,7 @@ static int prof_cpu_mask_write_proc (str
    unsigned long full_count = count, err;
    cpumask_t new_value;

    - err = cpumask_parse(buffer, count, new_value);
    + err = cpumask_parse_user(buffer, count, new_value);
    if (err)
    return err;

    diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/nodemask.h linux-2.6.hg/include/linux/nodemask.h
    --- linux-2.6.hg.vanilla/include/linux/nodemask.h 2006-10-03 16:58:10.000000000 -0700
    +++ linux-2.6.hg/include/linux/nodemask.h 2006-10-04 09:19:52.000000000 -0700
    @@ -8,8 +8,8 @@
    * See detailed comments in the file linux/bitmap.h describing the
    * data type on which these nodemasks are based.
    *
    - * For details of nodemask_scnprintf() and nodemask_parse(),
    - * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
    + * For details of nodemask_scnprintf() and nodemask_parse_user(),
    + * see bitmap_scnprintf() and bitmap_parse_user() in lib/bitmap.c.
    * For details of nodelist_scnprintf() and nodelist_parse(), see
    * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
    * For details of node_remap(), see bitmap_bitremap in lib/bitmap.c.
    @@ -51,7 +51,7 @@
    * unsigned long *nodes_addr(mask) Array of unsigned long's in mask
    *
    * int nodemask_scnprintf(buf, len, mask) Format nodemask for printing
    - * int nodemask_parse(ubuf, ulen, mask) Parse ascii string as nodemask
    + * int nodemask_parse_user(ubuf, ulen, mask) Parse ascii string as nodemask
    * int nodelist_scnprintf(buf, len, mask) Format nodemask as list for printing
    * int nodelist_parse(buf, map) Parse ascii string as nodelist
    * int node_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
    @@ -288,12 +288,12 @@ static inline int __nodemask_scnprintf(c
    return bitmap_scnprintf(buf, len, srcp->bits, nbits);
    }

    -#define nodemask_parse(ubuf, ulen, dst) \
    - __nodemask_parse((ubuf), (ulen), &(dst), MAX_NUMNODES)
    -static inline int __nodemask_parse(const char __user *buf, int len,
    +#define nodemask_parse_user(ubuf, ulen, dst) \
    + __nodemask_parse_user((ubuf), (ulen), &(dst), MAX_NUMNODES)
    +static inline int __nodemask_parse_user(const char __user *buf, int len,
    nodemask_t *dstp, int nbits)
    {
    - return bitmap_parse(buf, len, dstp->bits, nbits);
    + return bitmap_parse_user(buf, len, dstp->bits, nbits);
    }

    #define nodelist_scnprintf(buf, len, src) \
    -
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