From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Subject: kcov: use t->kcov_mode as enabled indicator Currently kcov_remote_start() and kcov_remote_stop() check t->kcov to find out whether the coverage is already being collected by the current task. Use t->kcov_mode for that instead. This doesn't change the overall behavior in any way, but serves as a preparation for the following softirq coverage collection support patch. Link: http://lkml.kernel.org/r/f70377945d1d8e6e4916cbce871a12303d6186b4.1585233617.git.andreyknvl@xxxxxxxxxx Link: http://lkml.kernel.org/r/ee1a1dec43059da5d7664c85c1addc89c4cd58de.1584655448.git.andreyknvl@xxxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/kcov.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) --- a/kernel/kcov.c~kcov-use-t-kcov_mode-as-enabled-indicator +++ a/kernel/kcov.c @@ -746,26 +746,33 @@ static const struct file_operations kcov * In turns kcov_remote_stop() clears those pointers from task_struct to stop * collecting coverage and copies all collected coverage into the kcov area. */ + +static inline bool kcov_mode_enabled(unsigned int mode) +{ + return (mode & ~KCOV_IN_CTXSW) != KCOV_MODE_DISABLED; +} + void kcov_remote_start(u64 handle) { + struct task_struct *t = current; struct kcov_remote *remote; struct kcov *kcov; + unsigned int mode; void *area; - struct task_struct *t; unsigned int size; - enum kcov_mode mode; int sequence; if (WARN_ON(!kcov_check_handle(handle, true, true, true))) return; if (WARN_ON(!in_task())) return; - t = current; + /* * Check that kcov_remote_start is not called twice * nor called by user tasks (with enabled kcov). */ - if (WARN_ON(t->kcov)) + mode = READ_ONCE(t->kcov_mode); + if (WARN_ON(kcov_mode_enabled(mode))) return; kcov_debug("handle = %llx\n", handle); @@ -863,13 +870,20 @@ static void kcov_move_area(enum kcov_mod void kcov_remote_stop(void) { struct task_struct *t = current; - struct kcov *kcov = t->kcov; - void *area = t->kcov_area; - unsigned int size = t->kcov_size; - int sequence = t->kcov_sequence; + struct kcov *kcov; + unsigned int mode; + void *area; + unsigned int size; + int sequence; - if (!kcov) - return; + mode = READ_ONCE(t->kcov_mode); + barrier(); + if (!kcov_mode_enabled(mode)) + return; + kcov = t->kcov; + area = t->kcov_area; + size = t->kcov_size; + sequence = t->kcov_sequence; kcov_stop(t); _
