From: Lukas Funke lukas.funke@weidmueller.com
The commit enables vsprintf() to handle the '%pbl' format specifier in order to print bitmaps and its derivatives such as cpumask and nodemask [1]. This can be used to derive kernel boot parameters from bitmaks such as 'isolcpu' or 'nohz_full' [2].
[1] https://www.kernel.org/doc/Documentation/printk-formats.txt [2] https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
Signed-off-by: Lukas Funke lukas.funke@weidmueller.com ---
Changes in v3: - Remove bitmap_string() conversion function since the same function can be achieved using other format specifier
lib/vsprintf.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 27ea9c907a..e1779d75f8 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -24,6 +24,7 @@ #include <linux/err.h> #include <linux/types.h> #include <linux/string.h> +#include <linux/bitmap.h>
/* we use this so that we can do without the ctype library */ #define is_digit(c) ((c) >= '0' && (c) <= '9') @@ -389,6 +390,33 @@ static char *ip4_addr_string(char *buf, char *end, u8 *addr, int field_width, flags & ~SPECIAL); }
+static char *bitmap_list_string(char *buf, char *end, unsigned long *addr, + int field_width, int precision, int flags) +{ + int nr_bits = max_t(int, field_width, 0); + int first = 1; + int rbot, rtop; + + for_each_set_bitrange(rbot, rtop, addr, nr_bits) { + if (!first) { + if (buf < end) + *buf = ','; + buf++; + } + first = 0; + + buf = number(buf, end, rbot, 10, 0, -1, 0); + if (rtop == rbot + 1) + continue; + + if (buf < end) + *buf = '-'; + buf = number(++buf, end, rtop - 1, 10, 0, -1, 0); + } + + return buf; +} + #ifdef CONFIG_LIB_UUID /* * This works (roughly) the same way as Linux's. @@ -502,6 +530,20 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr, precision, flags); flags &= ~SPECIAL; break; + case 'b': + switch (fmt[1]) { + case 'l': + /* if the field width is not a multiple of the underlying + * datatype (ulong), we get incorrect results from the bit twiddle + * macros. Thus, round up to a multiple of field width of ulong + */ + field_width = field_width % BITS_PER_LONG ? + ALIGN(field_width, BITS_PER_LONG) : field_width; + return bitmap_list_string(buf, end, ptr, field_width, + precision, flags); + default: + return ERR_PTR(-EINVAL); + } #ifdef CONFIG_LIB_UUID case 'U': return uuid_string(buf, end, ptr, field_width, precision,