diff options
| -rw-r--r-- | include/linux/string.h | 3 | ||||
| -rw-r--r-- | mm/util.c | 38 |
2 files changed, 41 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index b9bc9a5d9e21..e40099e585c9 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -112,7 +112,10 @@ extern void * memchr(const void *,int,__kernel_size_t); #endif void *memchr_inv(const void *s, int c, size_t n); +extern void kfree_const(const void *x); + extern char *kstrdup(const char *s, gfp_t gfp); +extern const char *kstrdup_const(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); extern void *kmemdup(const void *src, size_t len, gfp_t gfp); diff --git a/mm/util.c b/mm/util.c index f3ef639c4857..3981ae9d1b15 100644 --- a/mm/util.c +++ b/mm/util.c @@ -12,10 +12,30 @@ #include <linux/hugetlb.h> #include <linux/vmalloc.h> +#include <asm/sections.h> #include <asm/uaccess.h> #include "internal.h" +static inline int is_kernel_rodata(unsigned long addr) +{ + return addr >= (unsigned long)__start_rodata && + addr < (unsigned long)__end_rodata; +} + +/** + * kfree_const - conditionally free memory + * @x: pointer to the memory + * + * Function calls kfree only if @x is not in .rodata section. + */ +void kfree_const(const void *x) +{ + if (!is_kernel_rodata((unsigned long)x)) + kfree(x); +} +EXPORT_SYMBOL(kfree_const); + /** * kstrdup - allocate space for and copy an existing string * @s: the string to duplicate @@ -38,6 +58,24 @@ char *kstrdup(const char *s, gfp_t gfp) EXPORT_SYMBOL(kstrdup); /** + * kstrdup_const - conditionally duplicate an existing const string + * @s: the string to duplicate + * @gfp: the GFP mask used in the kmalloc() call when allocating memory + * + * Function returns source string if it is in .rodata section otherwise it + * fallbacks to kstrdup. + * Strings allocated by kstrdup_const should be freed by kfree_const. + */ +const char *kstrdup_const(const char *s, gfp_t gfp) +{ + if (is_kernel_rodata((unsigned long)s)) + return s; + + return kstrdup(s, gfp); +} +EXPORT_SYMBOL(kstrdup_const); + +/** * kstrndup - allocate space for and copy an existing string * @s: the string to duplicate * @max: read at most @max chars from @s |