On Sat, 5 Jul 2008, Benjamin Herrenschmidt wrote:
>
> I'll give it a try using probe_kernel_address() instead on monday.
Here's the updated patch which uses probe_kernel_address() instead (and
moves the whole #ifdef mess out of the code that wants it and into a
helper function - and maybe we should then put that helper into
kallsyms.h, but that's a different issue).
Still all happily untested, of course. And still with no actual users
converted.
Linus
---
lib/vsprintf.c | 108 +++++++++++++++++++++++++++++++++++++++++--------------
1 files changed, 80 insertions(+), 28 deletions(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 6021757..1fbb1c0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -22,6 +22,8 @@
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
#include <asm/page.h> /* for PAGE_SIZE */
#include <asm/div64.h>
@@ -482,6 +484,77 @@ static char *number(char *buf, char *end, unsigned long
long num, int base, int
return buf;
}
+static char *string(char *buf, char *end, char *s, int field_width, int
precision, int flags)
+{
+ int len, i;
+
+ if ((unsigned long)s < PAGE_SIZE)
+ s = "<NULL>";
+
+ len = strnlen(s, precision);
+
+ if (!(flags & LEFT)) {
+ while (len < field_width--) {
+ if (buf < end)
+ *buf = ' ';
+ ++buf;
+ }
+ }
+ for (i = 0; i < len; ++i) {
+ if (buf < end)
+ *buf = *s;
+ ++buf; ++s;
+ }
+ while (len < field_width--) {
+ if (buf < end)
+ *buf = ' ';
+ ++buf;
+ }
+ return buf;
+}
+
+static inline void *dereference_function_descriptor(void *ptr)
+{
+#if defined(CONFIG_IA64) || defined(CONFIG_PPC64)
+ void *p;
+ if (!probe_kernel_address(ptr, p))
+ ptr = p;
+#endif
+ return ptr;
+}
+
+
+/*
+ * Show a '%p' thing. A kernel extension is that the '%p' is followed
+ * by an extra set of alphanumeric characters that are extended format
+ * specifiers. Right now we just handle 'F' (for symbolic Function
+ * pointers) and 'S' (for Symbolic data pointers), but this can easily
+ * be extended in the future (network address types etc).
+ *
+ * The difference between 'S' and 'F' is that on ia64 and ppc64 function
+ * pointers are really function descriptors, which contain a pointer the
+ * real address.
+ */
+static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int
base, int size, int precision, int type)
+{
+ switch (*fmt) {
+ case 'F':
+ ptr = dereference_function_descriptor(ptr);
+ /* Fallthrough */
+ case 'S': { /* Other (direct) pointer */
+#if CONFIG_KALLSYMS
+ char sym[KSYM_SYMBOL_LEN];
+ sprint_symbol(sym, (unsigned long) ptr);
+ return string(buf, end, sym, size, precision, type);
+#else
+ type |= SPECIAL;
+ break;
+#endif
+ }
+ }
+ return number(buf, end, (unsigned long long) ptr, base, size,
precision, type);
+}
+
/**
* vsnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
@@ -502,11 +575,9 @@ static char *number(char *buf, char *end, unsigned long
long num, int base, int
*/
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
- int len;
unsigned long long num;
- int i, base;
+ int base;
char *str, *end, c;
- const char *s;
int flags; /* flags to number() */
@@ -622,29 +693,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt,
va_list args)
continue;
case 's':
- s = va_arg(args, char *);
- if ((unsigned long)s < PAGE_SIZE)
- s = "<NULL>";
-
- len = strnlen(s, precision);
-
- if (!(flags & LEFT)) {
- while (len < field_width--) {
- if (str < end)
- *str = ' ';
- ++str;
- }
- }
- for (i = 0; i < len; ++i) {
- if (str < end)
- *str = *s;
- ++str; ++s;
- }
- while (len < field_width--) {
- if (str < end)
- *str = ' ';
- ++str;
- }
+ str = string(str, end, va_arg(args, char *),
field_width, precision, flags);
continue;
case 'p':
@@ -653,9 +702,12 @@ int vsnprintf(char *buf, size_t size, const char *fmt,
va_list args)
field_width = 2*sizeof(void *);
flags |= ZEROPAD;
}
- str = number(str, end,
- (unsigned long) va_arg(args,
void *),
+ str = pointer(fmt+1, str, end,
+ va_arg(args, void *),
16, field_width, precision,
flags);
+ /* Skip all alphanumeric pointer suffixes */
+ while (isalnum(fmt[1]))
+ fmt++;
continue;
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