jump_label: Sort entries of the same key by the code

In the batching mode, all the entries of a given key are updated at once.
During the update of a key, a hit in the int3 handler will check if the
hitting code address belongs to one of these keys.

To optimize the search of a given code in the vector of entries being
updated, a binary search is used. The binary search relies on the order
of the entries of a key by its code. Hence the keys need to be sorted
by the code too, so sort the entries of a given key by the code.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/f57ae83e0592418ba269866bb7ade570fc8632e0.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 24f0d3b1526b115dbec8a383916ff9e3b68b130e..ca00ac10d9b9ee7bcc434e00e4df2652722d996d 100644 (file)
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -37,12 +37,26 @@ static int jump_label_cmp(const void *a, const void *b)
        const struct jump_entry *jea = a;
        const struct jump_entry *jeb = b;
 
+       /*
+        * Entrires are sorted by key.
+        */
        if (jump_entry_key(jea) < jump_entry_key(jeb))
                return -1;
 
        if (jump_entry_key(jea) > jump_entry_key(jeb))
                return 1;
 
+       /*
+        * In the batching mode, entries should also be sorted by the code
+        * inside the already sorted list of entries, enabling a bsearch in
+        * the vector.
+        */
+       if (jump_entry_code(jea) < jump_entry_code(jeb))
+               return -1;
+
+       if (jump_entry_code(jea) > jump_entry_code(jeb))
+               return 1;
+
        return 0;
 }