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author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-06 16:43:12 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-06 16:55:51 -0700 |
commit | 0fe1ef24f7bd0020f29ffe287dfdb9ead33ca0b2 (patch) | |
tree | 0069dd9dba6554f74436ea1d836ecc054a6b95d7 /lib | |
parent | 4d8a743cdd2690c0bc8d1b8cbd02cffb1ead849f (diff) | |
download | linux-stable-0fe1ef24f7bd0020f29ffe287dfdb9ead33ca0b2.tar.gz linux-stable-0fe1ef24f7bd0020f29ffe287dfdb9ead33ca0b2.tar.bz2 linux-stable-0fe1ef24f7bd0020f29ffe287dfdb9ead33ca0b2.zip |
vsprintf: add support for '%pS' and '%pF' pointer formats
They print out a pointer in symbolic format, if possible (ie using
symbolic KALLSYMS information). The '%pS' format is for regular direct
pointers (which can point to data or code and that you find on the stack
during backtraces etc), while '%pF' is for C function pointer types.
On most architectures, the two mean exactly the same thing, but some
architectures use an indirect pointer for C function pointers, where the
function pointer points to a function descriptor (which in turn contains
the actual pointer to the code). The '%pF' code automatically does the
appropriate function descriptor dereference on such architectures.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/vsprintf.c | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 5d6f0718b6d9..1dc2d1d18fa8 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> @@ -511,15 +513,52 @@ static char *string(char *buf, char *end, char *s, int field_width, int precisio 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; +} + +static char *symbol_string(char *buf, char *end, void *ptr, int field_width, int precision, int flags) +{ + unsigned long value = (unsigned long) ptr; +#ifdef CONFIG_KALLSYMS + char sym[KSYM_SYMBOL_LEN]; + sprint_symbol(sym, value); + return string(buf, end, sym, field_width, precision, flags); +#else + field_width = 2*sizeof(void *); + flags |= SPECIAL | SMALL | ZEROPAD; + return number(buf, end, value, 16, field_width, precision, flags); +#endif +} + /* * 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 don't actually handle any such, but we will.. + * Right now we just handle 'F' (for symbolic Function descriptor pointers) + * and 'S' (for Symbolic direct 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 field_width, int precision, int flags) { + switch (*fmt) { + case 'F': + ptr = dereference_function_descriptor(ptr); + /* Fallthrough */ + case 'S': + return symbol_string(buf, end, ptr, field_width, precision, flags); + } flags |= SMALL; if (field_width == -1) { field_width = 2*sizeof(void *); |