+++ Petr Mladek [07/09/16 15:13 +0200]:
The commit 66cc69e34e86a231 ("Fix: module signature vs tracepoints:
add new TAINT_UNSIGNED_MODULE") updated module_taint_flags() to
potentially print one more character. But it did not increase the
size of the corresponding buffers in m_show() and print_modules().

We have recently done the same mistake when adding a taint flag
for livepatching, see
https://lkml.kernel.org/g/cfba2c823bb984690b73572aaae1db596b54a082.1472137475.git.jpoim...@redhat.com

Let's convert the taint flags into enum and handle the buffer size
almost automatically.

It is not optimal because only few taint flags can be printed by
module_taint_flags(). But better be on the safe side. IMHO, it is
not worth the optimization and this is a good compromise.

Signed-off-by: Petr Mladek <pmla...@suse.com>
---
include/linux/kernel.h | 44 ++++++++++++++++++++++++--------------------
kernel/module.c        |  8 ++++++--
kernel/panic.c         |  4 ++--
3 files changed, 32 insertions(+), 24 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d96a6118d26a..1809bc82b7a5 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -472,14 +472,10 @@ static inline void set_arch_panic_timeout(int timeout, 
int arch_default_timeout)
        if (panic_timeout == arch_default_timeout)
                panic_timeout = timeout;
}
-extern const char *print_tainted(void);
enum lockdep_ok {
        LOCKDEP_STILL_OK,
        LOCKDEP_NOW_UNRELIABLE
};
-extern void add_taint(unsigned flag, enum lockdep_ok);
-extern int test_taint(unsigned flag);
-extern unsigned long get_taint(void);
extern int root_mountflags;

extern bool early_boot_irqs_disabled;
@@ -493,22 +489,30 @@ extern enum system_states {
        SYSTEM_RESTART,
} system_state;

-#define TAINT_PROPRIETARY_MODULE       0
-#define TAINT_FORCED_MODULE            1
-#define TAINT_CPU_OUT_OF_SPEC          2
-#define TAINT_FORCED_RMMOD             3
-#define TAINT_MACHINE_CHECK            4
-#define TAINT_BAD_PAGE                 5
-#define TAINT_USER                     6
-#define TAINT_DIE                      7
-#define TAINT_OVERRIDDEN_ACPI_TABLE    8
-#define TAINT_WARN                     9
-#define TAINT_CRAP                     10
-#define TAINT_FIRMWARE_WORKAROUND      11
-#define TAINT_OOT_MODULE               12
-#define TAINT_UNSIGNED_MODULE          13
-#define TAINT_SOFTLOCKUP               14
-#define TAINT_LIVEPATCH                        15
+enum taint_flags {
+       TAINT_PROPRIETARY_MODULE,       /*  0 */
+       TAINT_FORCED_MODULE,            /*  1 */
+       TAINT_CPU_OUT_OF_SPEC,          /*  2 */
+       TAINT_FORCED_RMMOD,             /*  3 */
+       TAINT_MACHINE_CHECK,            /*  4 */
+       TAINT_BAD_PAGE,                 /*  5 */
+       TAINT_USER,                     /*  6 */
+       TAINT_DIE,                      /*  7 */
+       TAINT_OVERRIDDEN_ACPI_TABLE,    /*  8 */
+       TAINT_WARN,                     /*  9 */
+       TAINT_CRAP,                     /* 10 */
+       TAINT_FIRMWARE_WORKAROUND,      /* 11 */
+       TAINT_OOT_MODULE,               /* 12 */
+       TAINT_UNSIGNED_MODULE,          /* 13 */
+       TAINT_SOFTLOCKUP,               /* 14 */
+       TAINT_LIVEPATCH,                /* 15 */
+       TAINT_FLAGS_COUNT               /* keep last! */
+};

I liked the enum idea because we got TAINT_FLAGS_COUNT for free :-)
however I think we need to switch back to the #defines because of the kbuild
error.

The "Error: invalid operands...for `<<'" messages are related to the
__WARN_TAINT() macro (arch/arm64/include/asm/bug.h) which emits some assembly
that relies on the taint values. We don't have access to the enum values
in the assembler so we start getting things like:

       .short ((1 << 0) | ((TAINT_WARN) << 8))

where TAINT_WARN should have already been preprocessed, and this is where that
invalid operand error is coming from.

Jessica

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