vsprintf: Add extension %pSR - print_symbol replacement

print_symbol takes a long and converts it to a function
name and offset.  %pS does something similar, but doesn't
translate the address via __builtin_extract_return_addr.
%pSR does the translation.

This will enable replacing multiple calls like
	printk(...);
	printk_symbol(addr);
	printk("\n");
with a single non-interleavable in dmesg
	printk("... %pSR\n", (void *)addr);

Update documentation too.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 13 insertions, 5 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 0d62fd700f68..e149c6416384 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -534,14 +534,21 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec)
 
 static noinline_for_stack
 char *symbol_string(char *buf, char *end, void *ptr,
-                    struct printf_spec spec, char ext)
+                    struct printf_spec spec, const char *fmt)
 {
-        unsigned long value = (unsigned long) ptr;
+        unsigned long value;
 #ifdef CONFIG_KALLSYMS
         char sym[KSYM_SYMBOL_LEN];
-        if (ext == 'B')
+#endif
+
+        if (fmt[1] == 'R')
+                ptr = __builtin_extract_return_addr(ptr);
+        value = (unsigned long)ptr;
+
+#ifdef CONFIG_KALLSYMS
+        if (*fmt == 'B')
                 sprint_backtrace(sym, value);
-        else if (ext != 'f' && ext != 's')
+        else if (*fmt != 'f' && *fmt != 's')
                 sprint_symbol(sym, value);
         else
                 sprint_symbol_no_offset(sym, value);
@@ -987,6 +994,7 @@ int kptr_restrict __read_mostly;
  * - 'f' For simple symbolic function names without offset
  * - 'S' For symbolic direct pointers with offset
  * - 's' For symbolic direct pointers without offset
+ * - '[FfSs]R' as above with __builtin_extract_return_addr() translation
  * - 'B' For backtraced symbolic direct pointers with offset
  * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
  * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
@@ -1060,7 +1068,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
         case 'S':
         case 's':
         case 'B':
-                return symbol_string(buf, end, ptr, spec, *fmt);
+                return symbol_string(buf, end, ptr, spec, fmt);
         case 'R':
         case 'r':
                 return resource_string(buf, end, ptr, spec, fmt);