1 files changed, 47 insertions, 11 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 6f6d091b575..079f1d39a8b 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -64,14 +64,14 @@ static inline int is_kernel_text(unsigned long addr)
 	if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
 	    arch_is_kernel_text(addr))
 		return 1;
-	return in_gate_area_no_task(addr);
+	return in_gate_area_no_mm(addr);
 }
 
 static inline int is_kernel(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
 		return 1;
-	return in_gate_area_no_task(addr);
+	return in_gate_area_no_mm(addr);
 }
 
 static int is_ksym_addr(unsigned long addr)
@@ -342,13 +342,15 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
 }
 
 /* Look up a kernel symbol and return it in a text buffer. */
-int sprint_symbol(char *buffer, unsigned long address)
+static int __sprint_symbol(char *buffer, unsigned long address,
+			   int symbol_offset)
 {
 	char *modname;
 	const char *name;
 	unsigned long offset, size;
 	int len;
 
+	address += symbol_offset;
 	name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
 	if (!name)
 		return sprintf(buffer, "0x%lx", address);
@@ -357,17 +359,53 @@ int sprint_symbol(char *buffer, unsigned long address)
 		strcpy(buffer, name);
 	len = strlen(buffer);
 	buffer += len;
+	offset -= symbol_offset;
 
 	if (modname)
-		len += sprintf(buffer, "+%#lx/%#lx [%s]",
-						offset, size, modname);
+		len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname);
 	else
 		len += sprintf(buffer, "+%#lx/%#lx", offset, size);
 
 	return len;
 }
+
+/**
+ * sprint_symbol - 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,
+ * offset, size 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(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, 0);
+}
+
 EXPORT_SYMBOL_GPL(sprint_symbol);
 
+/**
+ * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
+ * @buffer: buffer to be stored
+ * @address: address to lookup
+ *
+ * This function is for stack backtrace and does the same thing as
+ * sprint_symbol() but with modified/decreased @address. If there is a
+ * tail-call to the function marked "noreturn", gcc optimized out code after
+ * the call so that the stack-saved return address could point outside of the
+ * caller. This function ensures that kallsyms will find the original caller
+ * by decreasing @address.
+ *
+ * This function returns the number of bytes stored in @buffer.
+ */
+int sprint_backtrace(char *buffer, unsigned long address)
+{
+	return __sprint_symbol(buffer, address, -1);
+}
+
 /* Look up a kernel symbol and print it to the kernel messages. */
 void __print_symbol(const char *fmt, unsigned long address)
 {
@@ -477,13 +515,11 @@ static int s_show(struct seq_file *m, void *p)
 		 */
 		type = iter->exported ? toupper(iter->type) :
 					tolower(iter->type);
-		seq_printf(m, "%0*lx %c %s\t[%s]\n",
-			   (int)(2 * sizeof(void *)),
-			   iter->value, type, iter->name, iter->module_name);
+		seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
+			   type, iter->name, iter->module_name);
 	} else
-		seq_printf(m, "%0*lx %c %s\n",
-			   (int)(2 * sizeof(void *)),
-			   iter->value, iter->type, iter->name);
+		seq_printf(m, "%pK %c %s\n", (void *)iter->value,
+			   iter->type, iter->name);
 	return 0;
 }