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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>
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1 changed files with 40 additions and 1 deletions
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@ -22,6 +22,8 @@
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#include <linux/string.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <linux/ctype.h>
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#include <linux/kernel.h>
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#include <linux/kernel.h>
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#include <linux/kallsyms.h>
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#include <linux/uaccess.h>
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#include <asm/page.h> /* for PAGE_SIZE */
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#include <asm/page.h> /* for PAGE_SIZE */
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#include <asm/div64.h>
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#include <asm/div64.h>
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@ -511,15 +513,52 @@ static char *string(char *buf, char *end, char *s, int field_width, int precisio
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return buf;
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return buf;
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}
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}
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static inline void *dereference_function_descriptor(void *ptr)
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{
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#if defined(CONFIG_IA64) || defined(CONFIG_PPC64)
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void *p;
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if (!probe_kernel_address(ptr, p))
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ptr = p;
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#endif
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return ptr;
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}
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static char *symbol_string(char *buf, char *end, void *ptr, int field_width, int precision, int flags)
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{
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unsigned long value = (unsigned long) ptr;
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#ifdef CONFIG_KALLSYMS
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char sym[KSYM_SYMBOL_LEN];
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sprint_symbol(sym, value);
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return string(buf, end, sym, field_width, precision, flags);
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#else
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field_width = 2*sizeof(void *);
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flags |= SPECIAL | SMALL | ZEROPAD;
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return number(buf, end, value, 16, field_width, precision, flags);
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#endif
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}
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/*
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/*
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* Show a '%p' thing. A kernel extension is that the '%p' is followed
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* Show a '%p' thing. A kernel extension is that the '%p' is followed
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* by an extra set of alphanumeric characters that are extended format
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* by an extra set of alphanumeric characters that are extended format
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* specifiers.
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* specifiers.
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*
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*
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* Right now don't actually handle any such, but we will..
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* Right now we just handle 'F' (for symbolic Function descriptor pointers)
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* and 'S' (for Symbolic direct pointers), but this can easily be
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* extended in the future (network address types etc).
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*
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* The difference between 'S' and 'F' is that on ia64 and ppc64 function
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* pointers are really function descriptors, which contain a pointer the
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* real address.
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*/
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*/
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static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
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static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
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{
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{
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switch (*fmt) {
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case 'F':
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ptr = dereference_function_descriptor(ptr);
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/* Fallthrough */
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case 'S':
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return symbol_string(buf, end, ptr, field_width, precision, flags);
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}
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flags |= SMALL;
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flags |= SMALL;
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if (field_width == -1) {
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if (field_width == -1) {
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field_width = 2*sizeof(void *);
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field_width = 2*sizeof(void *);
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