kcov: properly handle subsequent mmap calls
authorAleksandr Nogikh <nogikh@google.com>
Wed, 23 Mar 2022 23:07:15 +0000 (16:07 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 24 Mar 2022 02:00:35 +0000 (19:00 -0700)
commitb3d7fe86fbd06638c71dd851ba921adf50d912ce
treeac567b3981ea70b0ebfca87372d8e361392b93a7
parent17581aa13680e1c38759cbb0ed32d04aa8849bea
kcov: properly handle subsequent mmap calls

Allocate the kcov buffer during KCOV_MODE_INIT in order to untie mmapping
of a kcov instance and the actual coverage collection process. Modify
kcov_mmap, so that it can be reliably used any number of times once
KCOV_MODE_INIT has succeeded.

These changes to the user-facing interface of the tool only weaken the
preconditions, so all existing user space code should remain compatible
with the new version.

Link: https://lkml.kernel.org/r/20220117153634.150357-3-nogikh@google.com
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/kcov.c