The patch titled
Subject: lib/vsprintf.c: expand field_width to 24 bits
has been added to the -mm tree. Its filename is
lib-vsprintfc-expand-field_width-to-24-bits.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-vsprintfc-expand-field_width-to-24-bits.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-vsprintfc-expand-field_width-to-24-bits.patch
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From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Subject: lib/vsprintf.c: expand field_width to 24 bits
Maurizio Lombardi reported a problem [1] with the %pb extension: It
doesn't work for sufficiently large bitmaps, since the size is stashed
in the field_width field of the struct printf_spec, which is currently
an s16. Concretely, this manifested itself in
/sys/bus/pseudo/drivers/scsi_debug/map being empty, since the bitmap
printer got a size of 0, which is the 16 bit truncation of the actual
bitmap size.
We do want to keep struct printf_spec at 8 bytes so that it can
cheaply be passed by value. The qualifier field is only used for
internal bookkeeping in format_decode, so we might as well use a local
variable for that. This gives us an additional 8 bits, which we can
then use for the field width.
To stay in 8 bytes, we need to do a little rearranging and make the
type member a bitfield as well. For consistency, change all the
members to bit fields. gcc doesn't generate much worse code with these
changes (in fact, bloat-o-meter says we save 300 bytes - which I think
is a little surprising).
I didn't find a BUILD_BUG/compiletime_assertion/... which would work
outside function context, so for now I just open-coded it.
[1] http://thread.gmane.org/gmane.linux.kernel/2034835
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Reported-by: Maurizio Lombardi <mlombard@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/vsprintf.c | 41 +++++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 20 deletions(-)
diff -puN lib/vsprintf.c~lib-vsprintfc-expand-field_width-to-24-bits lib/vsprintf.c
--- a/lib/vsprintf.c~lib-vsprintfc-expand-field_width-to-24-bits
+++ a/lib/vsprintf.c
@@ -380,13 +380,13 @@ enum format_type {
};
struct printf_spec {
- u8 type; /* format_type enum */
- u8 flags; /* flags to number() */
- u8 base; /* number base, 8, 10 or 16 only */
- u8 qualifier; /* number qualifier, one of 'hHlLtzZ' */
- s16 field_width; /* width of output field */
- s16 precision; /* # of digits/chars */
-};
+ unsigned int type:8; /* format_type enum */
+ signed int field_width:24; /* width of output field */
+ unsigned int flags:8; /* flags to number() */
+ unsigned int base:8; /* number base, 8, 10 or 16 only */
+ signed int precision:16; /* # of digits/chars */
+} __packed;
+extern char __check_printf_spec[1-2*(sizeof(struct printf_spec) != 8)];
static noinline_for_stack
char *number(char *buf, char *end, unsigned long long num,
@@ -1641,6 +1641,7 @@ static noinline_for_stack
int format_decode(const char *fmt, struct printf_spec *spec)
{
const char *start = fmt;
+ char qualifier;
/* we finished early by reading the field width */
if (spec->type == FORMAT_TYPE_WIDTH) {
@@ -1723,16 +1724,16 @@ precision:
qualifier:
/* get the conversion qualifier */
- spec->qualifier = -1;
+ qualifier = 0;
if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
_tolower(*fmt) == 'z' || *fmt == 't') {
- spec->qualifier = *fmt++;
- if (unlikely(spec->qualifier == *fmt)) {
- if (spec->qualifier == 'l') {
- spec->qualifier = 'L';
+ qualifier = *fmt++;
+ if (unlikely(qualifier == *fmt)) {
+ if (qualifier == 'l') {
+ qualifier = 'L';
++fmt;
- } else if (spec->qualifier == 'h') {
- spec->qualifier = 'H';
+ } else if (qualifier == 'h') {
+ qualifier = 'H';
++fmt;
}
}
@@ -1789,19 +1790,19 @@ qualifier:
return fmt - start;
}
- if (spec->qualifier == 'L')
+ if (qualifier == 'L')
spec->type = FORMAT_TYPE_LONG_LONG;
- else if (spec->qualifier == 'l') {
+ else if (qualifier == 'l') {
BUILD_BUG_ON(FORMAT_TYPE_ULONG + SIGN != FORMAT_TYPE_LONG);
spec->type = FORMAT_TYPE_ULONG + (spec->flags & SIGN);
- } else if (_tolower(spec->qualifier) == 'z') {
+ } else if (_tolower(qualifier) == 'z') {
spec->type = FORMAT_TYPE_SIZE_T;
- } else if (spec->qualifier == 't') {
+ } else if (qualifier == 't') {
spec->type = FORMAT_TYPE_PTRDIFF;
- } else if (spec->qualifier == 'H') {
+ } else if (qualifier == 'H') {
BUILD_BUG_ON(FORMAT_TYPE_UBYTE + SIGN != FORMAT_TYPE_BYTE);
spec->type = FORMAT_TYPE_UBYTE + (spec->flags & SIGN);
- } else if (spec->qualifier == 'h') {
+ } else if (qualifier == 'h') {
BUILD_BUG_ON(FORMAT_TYPE_USHORT + SIGN != FORMAT_TYPE_SHORT);
spec->type = FORMAT_TYPE_USHORT + (spec->flags & SIGN);
} else {
_
Patches currently in -mm which might be from linux@xxxxxxxxxxxxxxxxxx are
lib-vsprintfc-pull-out-padding-code-from-dentry_name.patch
lib-vsprintfc-move-string-below-widen_string.patch
lib-vsprintfc-eliminate-potential-race-in-string.patch
lib-vsprintfc-expand-field_width-to-24-bits.patch
lib-vsprintfc-help-gcc-make-number-smaller.patch
lib-vsprintfc-warn-about-too-large-precisions-and-field-widths.patch
lib-kasprintfc-add-sanity-check-to-kvasprintf.patch
lib-test_printfc-dont-bug.patch
lib-test_printfc-check-for-out-of-bound-writes.patch
lib-test_printfc-test-precision-quirks.patch
lib-test_printfc-add-a-few-number-tests.patch
lib-test_printfc-account-for-kvasprintf-tests.patch
lib-test_printfc-add-test-for-large-bitmaps.patch
lib-test_printfc-test-dentry-printing.patch
powerpc-fadump-rename-cpu_online_mask-member-of-struct-fadump_crash_info_header.patch
kernel-cpuc-change-type-of-cpu_possible_bits-and-friends.patch
kernel-cpuc-export-__cpu__mask.patch
drivers-base-cpuc-use-__cpu__mask-directly.patch
kernel-cpuc-eliminate-cpu__mask.patch
kernel-cpuc-make-set_cpu_-static-inlines.patch
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