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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2018-02-20 11:37:52 -0600 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-02-21 16:54:06 +0100 |
| commit | dc1dd184c2f0016bec35c0d7a48c057e0ad763d3 (patch) | |
| tree | 43323dde05f7db864de96e8dfbaafc1397142268 /kernel | |
| parent | 33352244706369ea6736781ae41fe41692eb69bb (diff) | |
| download | lwn-dc1dd184c2f0016bec35c0d7a48c057e0ad763d3.tar.gz lwn-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.c | 13 |
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); + } } } |