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>

8 files changed, 67 insertions, 20 deletions

diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt
index c10c022b911c..069fab3ea4d6 100644
--- a/Documentation/oops-tracing.txt
+++ b/Documentation/oops-tracing.txt
@@ -256,6 +256,7 @@ characters, each representing a particular tainted value.
   9: 'A' if the ACPI table has been overridden.
 
  10: 'W' if a warning has previously been issued by the kernel.
+     (Though some warnings may set more specific taint flags.)
 
  11: 'C' if a staging driver has been loaded.
 
diff --git a/arch/parisc/include/asm/bug.h b/arch/parisc/include/asm/bug.h
index 75e46c557a16..72cfdb0cfdd1 100644
--- a/arch/parisc/include/asm/bug.h
+++ b/arch/parisc/include/asm/bug.h
@@ -44,7 +44,7 @@
 #endif
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
-#define __WARN()                                                        \
+#define __WARN_TAINT(taint)                                             \
         do {                                                            \
                 asm volatile("\n"                                       \
                              "1:\t" PARISC_BUG_BREAK_ASM "\n"           \
@@ -54,11 +54,11 @@
                              "\t.org 2b+%c3\n"                          \
                              "\t.popsection"                            \
                              : : "i" (__FILE__), "i" (__LINE__),        \
-                             "i" (BUGFLAG_WARNING),                     \
+                             "i" (BUGFLAG_TAINT(taint)),                \
                              "i" (sizeof(struct bug_entry)) );          \
         } while(0)
 #else
-#define __WARN()                                                        \
+#define __WARN_TAINT(taint)                                             \
         do {                                                            \
                 asm volatile("\n"                                       \
                              "1:\t" PARISC_BUG_BREAK_ASM "\n"           \
@@ -67,7 +67,7 @@
                              "\t.short %c0\n"                           \
                              "\t.org 2b+%c1\n"                          \
                              "\t.popsection"                            \
-                             : : "i" (BUGFLAG_WARNING),                 \
+                             : : "i" (BUGFLAG_TAINT(taint)),            \
                              "i" (sizeof(struct bug_entry)) );          \
         } while(0)
 #endif
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 2c15212e1700..065c590c991d 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -85,12 +85,12 @@
         }                                                       \
 } while (0)
 
-#define __WARN() do {                                           \
+#define __WARN_TAINT(taint) do {                                \
         __asm__ __volatile__(                                   \
                 "1:     twi 31,0,0\n"                           \
                 _EMIT_BUG_ENTRY                                 \
                 : : "i" (__FILE__), "i" (__LINE__),             \
-                  "i" (BUGFLAG_WARNING),                        \
+                  "i" (BUGFLAG_TAINT(taint)),                   \
                   "i" (sizeof(struct bug_entry)));              \
 } while (0)
 
@@ -104,7 +104,7 @@
                 "1:     "PPC_TLNEI"     %4,0\n"                 \
                 _EMIT_BUG_ENTRY                                 \
                 : : "i" (__FILE__), "i" (__LINE__),             \
-                  "i" (BUGFLAG_WARNING),                        \
+                  "i" (BUGFLAG_TAINT(TAINT_WARN)),              \
                   "i" (sizeof(struct bug_entry)),               \
                   "r" (__ret_warn_on));                         \
         }                                                       \
diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h
index 9beeb9db9b23..bf90d1fd97a5 100644
--- a/arch/s390/include/asm/bug.h
+++ b/arch/s390/include/asm/bug.h
@@ -46,18 +46,18 @@
         unreachable();                                  \
 } while (0)
 
-#define __WARN() do {                                   \
-        __EMIT_BUG(BUGFLAG_WARNING);                    \
+#define __WARN_TAINT(taint) do {                        \
+        __EMIT_BUG(BUGFLAG_TAINT(taint));               \
 } while (0)
 
 #define WARN_ON(x) ({                                   \
         int __ret_warn_on = !!(x);                      \
         if (__builtin_constant_p(__ret_warn_on)) {      \
                 if (__ret_warn_on)                      \
-                        __EMIT_BUG(BUGFLAG_WARNING);    \
+                        __WARN();                       \
         } else {                                        \
                 if (unlikely(__ret_warn_on))            \
-                        __EMIT_BUG(BUGFLAG_WARNING);    \
+                        __WARN();                       \
         }                                               \
         unlikely(__ret_warn_on);                        \
 })
diff --git a/arch/sh/include/asm/bug.h b/arch/sh/include/asm/bug.h
index d02c01b3e6b9..6323f864d111 100644
--- a/arch/sh/include/asm/bug.h
+++ b/arch/sh/include/asm/bug.h
@@ -48,7 +48,7 @@ do {							\
                    "i" (sizeof(struct bug_entry)));     \
 } while (0)
 
-#define __WARN()                                        \
+#define __WARN_TAINT(taint)                             \
 do {                                                    \
         __asm__ __volatile__ (                          \
                 "1:\t.short %O0\n"                      \
@@ -57,7 +57,7 @@ do {							\
                  : "n" (TRAPA_BUG_OPCODE),              \
                    "i" (__FILE__),                      \
                    "i" (__LINE__),                      \
-                   "i" (BUGFLAG_WARNING),               \
+                   "i" (BUGFLAG_TAINT(taint)),          \
                    "i" (sizeof(struct bug_entry)));     \
 } while (0)
 
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))
 
diff --git a/kernel/panic.c b/kernel/panic.c
index 13d966b4c14a..8b821bce66e6 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -365,7 +365,8 @@ struct slowpath_args {
         va_list args;
 };
 
-static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
+static void warn_slowpath_common(const char *file, int line, void *caller,
+                                 unsigned taint, struct slowpath_args *args)
 {
         const char *board;
 
@@ -381,7 +382,7 @@ static void warn_slowpath_common(const char *file, int line, void *caller, struc
         print_modules();
         dump_stack();
         print_oops_end_marker();
-        add_taint(TAINT_WARN);
+        add_taint(taint);
 }
 
 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
@@ -390,14 +391,29 @@ void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 
         args.fmt = fmt;
         va_start(args.args, fmt);
-        warn_slowpath_common(file, line, __builtin_return_address(0), &args);
+        warn_slowpath_common(file, line, __builtin_return_address(0),
+                             TAINT_WARN, &args);
         va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);
 
+void warn_slowpath_fmt_taint(const char *file, int line,
+                             unsigned taint, const char *fmt, ...)
+{
+        struct slowpath_args args;
+
+        args.fmt = fmt;
+        va_start(args.args, fmt);
+        warn_slowpath_common(file, line, __builtin_return_address(0),
+                             taint, &args);
+        va_end(args.args);
+}
+EXPORT_SYMBOL(warn_slowpath_fmt_taint);
+
 void warn_slowpath_null(const char *file, int line)
 {
-        warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
+        warn_slowpath_common(file, line, __builtin_return_address(0),
+                             TAINT_WARN, NULL);
 }
 EXPORT_SYMBOL(warn_slowpath_null);
 #endif
diff --git a/lib/bug.c b/lib/bug.c
index 300e41afbf97..f13daf435211 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -165,7 +165,7 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
                                (void *)bugaddr);
 
                 show_regs(regs);
-                add_taint(TAINT_WARN);
+                add_taint(BUG_GET_TAINT(bug));
                 return BUG_TRAP_TYPE_WARN;
         }