taint/module: Clean up global and module taint flags handling

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/r/cfba2c823bb984690b73572aaae1db596b54a082.1472137475.git.jpoimboe@redhat.com

Also struct module uses an incompatible type for mod-taints flags.
It survived from the commit 2bc2d61a9638dab670d ("[PATCH] list module
taint flags in Oops/panic"). There was used "int" for the global taint
flags at these times. But only the global tain flags was later changed
to "unsigned long" by the commit 25ddbb18aae33ad2 ("Make the taint
flags reliable").

This patch defines TAINT_FLAGS_COUNT that can be used to create
arrays and buffers of the right size. Note that we could not use
enum because the taint flag indexes are used also in assembly code.

Then it reworks the table that describes the taint flags. The TAINT_*
numbers can be used as the index. Instead, we add information
if the taint flag is also shown per-module.

Finally, it uses "unsigned long", bit operations, and the updated
taint_flags table also for mod->taints.

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 <pmladek@suse.com>
Link: http://lkml.kernel.org/r/1474458442-21581-1-git-send-email-pmladek@suse.com
[jeyu@redhat.com: fix broken lkml link in changelog]
Signed-off-by: Jessica Yu <jeyu@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index bc6ed52a39b9..441def77246d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -506,6 +506,15 @@ extern enum system_states {
 #define TAINT_UNSIGNED_MODULE		13
 #define TAINT_SOFTLOCKUP		14
 #define TAINT_LIVEPATCH			15
+#define TAINT_FLAGS_COUNT		16
+
+struct taint_flag {
+	char true;	/* character printed when tainted */
+	char false;	/* character printed when not tainted */
+	bool module;	/* also show as a per-module taint flag */
+};
+
+extern const struct taint_flag taint_flags[TAINT_FLAGS_COUNT];
 
 extern const char hex_asc[];
 #define hex_asc_lo(x)	hex_asc[((x) & 0x0f)]