Commit 4796dd20 authored by Stephen Boyd's avatar Stephen Boyd Committed by Linus Torvalds
Browse files

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: default avatarStephen Boyd <sboyd@codeaurora.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05a6c8a9

include/linux/kallsyms.h

+7 −0
Original line number Diff line number Diff line
@@ -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';

kernel/kallsyms.c

+24 −8
Original line number Diff line number Diff line
@@ -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. */

lib/vsprintf.c

+1 −1
Original line number Diff line number Diff line
@@ -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

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