panic: Allow warnings to set different taint flags

WARN() is used in some places to report firmware or hardware bugs that
are then worked-around.  These bugs do not affect the stability of the
kernel and should not set the flag for TAINT_WARN.  To allow for this,
add WARN_TAINT() and WARN_TAINT_ONCE() macros that take a taint number
as argument.

Architectures that implement warnings using trap instructions instead
of calls to warn_slowpath_*() now implement __WARN_TAINT(taint)
instead of __WARN().

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Helge Deller <deller@gmx.de>
Tested-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 32 insertions, 2 deletions

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 18c435d7c082..c2c9ba032d46 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -25,7 +25,10 @@ struct bug_entry {
 };
 #endif          /* __ASSEMBLY__ */
 
-#define BUGFLAG_WARNING (1<<0)
+#define BUGFLAG_WARNING         (1 << 0)
+#define BUGFLAG_TAINT(taint)    (BUGFLAG_WARNING | ((taint) << 8))
+#define BUG_GET_TAINT(bug)      ((bug)->flags >> 8)
+
 #endif  /* CONFIG_GENERIC_BUG */
 
 /*
@@ -56,17 +59,25 @@ struct bug_entry {
  * appear at runtime.  Use the versions with printk format strings
  * to provide better diagnostics.
  */
-#ifndef __WARN
+#ifndef __WARN_TAINT
 #ifndef __ASSEMBLY__
 extern void warn_slowpath_fmt(const char *file, const int line,
                 const char *fmt, ...) __attribute__((format(printf, 3, 4)));
+extern void warn_slowpath_fmt_taint(const char *file, const int line,
+                                    unsigned taint, const char *fmt, ...)
+        __attribute__((format(printf, 4, 5)));
 extern void warn_slowpath_null(const char *file, const int line);
 #define WANT_WARN_ON_SLOWPATH
 #endif
 #define __WARN()                warn_slowpath_null(__FILE__, __LINE__)
 #define __WARN_printf(arg...)   warn_slowpath_fmt(__FILE__, __LINE__, arg)
+#define __WARN_printf_taint(taint, arg...)                              \
+        warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
 #else
+#define __WARN()                __WARN_TAINT(TAINT_WARN)
 #define __WARN_printf(arg...)   do { printk(arg); __WARN(); } while (0)
+#define __WARN_printf_taint(taint, arg...)                              \
+        do { printk(arg); __WARN_TAINT(taint); } while (0)
 #endif
 
 #ifndef WARN_ON
@@ -87,6 +98,13 @@ extern void warn_slowpath_null(const char *file, const int line);
 })
 #endif
 
+#define WARN_TAINT(condition, taint, format...) ({                      \
+        int __ret_warn_on = !!(condition);                              \
+        if (unlikely(__ret_warn_on))                                    \
+                __WARN_printf_taint(taint, format);                     \
+        unlikely(__ret_warn_on);                                        \
+})
+
 #else /* !CONFIG_BUG */
 #ifndef HAVE_ARCH_BUG
 #define BUG() do {} while(0)
@@ -110,6 +128,8 @@ extern void warn_slowpath_null(const char *file, const int line);
 })
 #endif
 
+#define WARN_TAINT(condition, taint, format...) WARN_ON(condition)
+
 #endif
 
 #define WARN_ON_ONCE(condition) ({                              \
@@ -132,6 +152,16 @@ extern void warn_slowpath_null(const char *file, const int line);
         unlikely(__ret_warn_once);                              \
 })
 
+#define WARN_TAINT_ONCE(condition, taint, format...)    ({      \
+        static bool __warned;                                   \
+        int __ret_warn_once = !!(condition);                    \
+                                                                \
+        if (unlikely(__ret_warn_once))                          \
+                if (WARN_TAINT(!__warned, taint, format))       \
+                        __warned = true;                        \
+        unlikely(__ret_warn_once);                              \
+})
+
 #define WARN_ON_RATELIMIT(condition, state)                     \
                 WARN_ON((condition) && __ratelimit(state))