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 <j...@perches.com>
---
 Documentation/printk-formats.txt |    2 ++
 lib/vsprintf.c                   |   18 +++++++++++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 8ffb274..69a5ca1 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -17,6 +17,8 @@ Symbols/Function Pointers:
        %pF     versatile_init+0x0/0x110
        %pf     versatile_init
        %pS     versatile_init+0x0/0x110
+       %pSR    versatile_init+0x9/0x110
+               (with __builtin_extract_return_addr() translation)
        %ps     versatile_init
        %pB     prev_fn_of_versatile_init+0x88/0x88
 
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index fab33a9..832ff0b 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]
@@ -1059,7 +1067,7 @@ 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);
-- 
1.7.8.112.g3fd21

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