From dc1dd184c2f0016bec35c0d7a48c057e0ad763d3 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 20 Feb 2018 11:37:52 -0600 Subject: 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 Acked-by: Peter Zijlstra Cc: Borislav Petkov Cc: Jason Baron Cc: Linus Torvalds Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/de3a271c93807adb7ed48f4e946b4f9156617680.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- kernel/jump_label.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'kernel/jump_label.c') 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); + } } } -- cgit