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authorJosh Poimboeuf <jpoimboe@redhat.com>2018-02-20 18:37:52 +0100
committerIngo Molnar <mingo@kernel.org>2018-02-21 16:54:06 +0100
commitdc1dd184c2f0016bec35c0d7a48c057e0ad763d3 (patch)
tree43323dde05f7db864de96e8dfbaafc1397142268 /kernel
parentjump_label: Explicitly disable jump labels in __init code (diff)
downloadlinux-dc1dd184c2f0016bec35c0d7a48c057e0ad763d3.tar.xz
linux-dc1dd184c2f0016bec35c0d7a48c057e0ad763d3.zip
jump_label: Warn on failed jump_label patching attempt
Currently when the jump label code encounters an address which isn't recognized by kernel_text_address(), it just silently fails. This can be dangerous because jump labels are used in a variety of places, and are generally expected to work. Convert the silent failure to a warning. This won't warn about attempted writes to tracepoints in __init code after initmem has been freed, as those are already guarded by the entry->code check. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/de3a271c93807adb7ed48f4e946b4f9156617680.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/jump_label.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index b71776576a66..b2f0b479191b 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -367,12 +367,15 @@ static void __jump_label_update(struct static_key *key,
{
for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
/*
- * entry->code set to 0 invalidates module init text sections
- * kernel_text_address() verifies we are not in core kernel
- * init code, see jump_label_invalidate_module_init().
+ * An entry->code of 0 indicates an entry which has been
+ * disabled because it was in an init text area.
*/
- if (entry->code && kernel_text_address(entry->code))
- arch_jump_label_transform(entry, jump_label_type(entry));
+ if (entry->code) {
+ if (kernel_text_address(entry->code))
+ arch_jump_label_transform(entry, jump_label_type(entry));
+ else
+ WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code);
+ }
}
}