Re: [PATCH 1/4] panic: Allow warnings to set different taint flags

From: Helge Deller
Date: Mon Apr 05 2010 - 17:38:47 EST

On 04/03/2010 08:34 PM, Ben Hutchings wrote:
> 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@xxxxxxxxxxxxxxx>

Builds and works on the parisc architecture.
Acked-by: Helge Deller <deller@xxxxxx>


> ---
> Changes since the previous version:
> - Added note to Documentation/oops-tracing.txt
> - Changed the commit message to distinguish taint numbers from taint
> flags
> - Removed 'must' from last sentence of commit message; this patch
> converts all mainline architectures
>
> Ben.
>
> Documentation/oops-tracing.txt | 1 +
> arch/parisc/include/asm/bug.h | 8 ++++----
> arch/powerpc/include/asm/bug.h | 6 +++---
> arch/s390/include/asm/bug.h | 8 ++++----
> arch/sh/include/asm/bug.h | 4 ++--
> include/asm-generic/bug.h | 34 ++++++++++++++++++++++++++++++++--
> kernel/panic.c | 24 ++++++++++++++++++++----
> lib/bug.c | 2 +-
> 8 files changed, 67 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt
> index c10c022..069fab3 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 75e46c5..72cfdb0 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 2c15212..065c590 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 9beeb9d..bf90d1f 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 d02c01b..6323f86 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 18c435d..c2c9ba0 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 13d966b..8b821bc 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 300e41a..f13daf4 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;
> }
>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/