From 4796dd200db943e36f876e7029552212e5bbdf33 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Tue, 29 May 2012 15:07:33 -0700 Subject: vsprintf: fix %ps on non symbols when using kallsyms Using %ps in a printk format will sometimes fail silently and print the empty string if the address passed in does not match a symbol that kallsyms knows about. But using %pS will fall back to printing the full address if kallsyms can't find the symbol. Make %ps act the same as %pS by falling back to printing the address. While we're here also make %ps print the module that a symbol comes from so that it matches what %pS already does. Take this simple function for example (in a module): static void test_printk(void) { int test; pr_info("with pS: %pS\n", &test); pr_info("with ps: %ps\n", &test); } Before this patch: with pS: 0xdff7df44 with ps: After this patch: with pS: 0xdff7df44 with ps: 0xdff7df44 Signed-off-by: Stephen Boyd Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kallsyms.h | 7 +++++++ kernel/kallsyms.c | 32 ++++++++++++++++++++++++-------- lib/vsprintf.c | 2 +- 3 files changed, 32 insertions(+), 9 deletions(-) diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index 387571959dd..6883e197acb 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -36,6 +36,7 @@ const char *kallsyms_lookup(unsigned long addr, /* Look up a kernel symbol and return it in a text buffer. */ extern int sprint_symbol(char *buffer, unsigned long address); +extern int sprint_symbol_no_offset(char *buffer, unsigned long address); extern int sprint_backtrace(char *buffer, unsigned long address); /* Look up a kernel symbol and print it to the kernel messages. */ @@ -80,6 +81,12 @@ static inline int sprint_symbol(char *buffer, unsigned long addr) return 0; } +static inline int sprint_symbol_no_offset(char *buffer, unsigned long addr) +{ + *buffer = '\0'; + return 0; +} + static inline int sprint_backtrace(char *buffer, unsigned long addr) { *buffer = '\0'; diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 079f1d39a8b..2169feeba52 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -343,7 +343,7 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size, /* Look up a kernel symbol and return it in a text buffer. */ static int __sprint_symbol(char *buffer, unsigned long address, - int symbol_offset) + int symbol_offset, int add_offset) { char *modname; const char *name; @@ -358,13 +358,13 @@ static int __sprint_symbol(char *buffer, unsigned long address, if (name != buffer) strcpy(buffer, name); len = strlen(buffer); - buffer += len; offset -= symbol_offset; + if (add_offset) + len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); + if (modname) - len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname); - else - len += sprintf(buffer, "+%#lx/%#lx", offset, size); + len += sprintf(buffer + len, " [%s]", modname); return len; } @@ -382,11 +382,27 @@ static int __sprint_symbol(char *buffer, unsigned long address, */ int sprint_symbol(char *buffer, unsigned long address) { - return __sprint_symbol(buffer, address, 0); + return __sprint_symbol(buffer, address, 0, 1); } - EXPORT_SYMBOL_GPL(sprint_symbol); +/** + * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function looks up a kernel symbol with @address and stores its name + * and module name to @buffer if possible. If no symbol was found, just saves + * its @address as is. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_symbol_no_offset(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, 0, 0); +} +EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); + /** * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer * @buffer: buffer to be stored @@ -403,7 +419,7 @@ EXPORT_SYMBOL_GPL(sprint_symbol); */ int sprint_backtrace(char *buffer, unsigned long address) { - return __sprint_symbol(buffer, address, -1); + return __sprint_symbol(buffer, address, -1, 1); } /* Look up a kernel symbol and print it to the kernel messages. */ diff --git a/lib/vsprintf.c b/lib/vsprintf.c index abbabec9720..f5dfe0ca34f 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -436,7 +436,7 @@ char *symbol_string(char *buf, char *end, void *ptr, else if (ext != 'f' && ext != 's') sprint_symbol(sym, value); else - kallsyms_lookup(value, NULL, NULL, NULL, sym); + sprint_symbol_no_offset(sym, value); return string(buf, end, sym, spec); #else -- cgit v1.2.3