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-rw-r--r--mm/util.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/mm/util.c b/mm/util.c
index f3ef639..3981ae9 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

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