diff options
Diffstat (limited to '')
| -rw-r--r-- | Documentation/dev-tools/kcov.rst | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst index 1c4e1825d769..d83c9ab49427 100644 --- a/Documentation/dev-tools/kcov.rst +++ b/Documentation/dev-tools/kcov.rst @@ -50,6 +50,7 @@ program using kcov: #include <sys/mman.h> #include <unistd.h> #include <fcntl.h> + #include <linux/types.h> #define KCOV_INIT_TRACE _IOR('c', 1, unsigned long) #define KCOV_ENABLE _IO('c', 100) @@ -177,6 +178,8 @@ Comparison operands collection is similar to coverage collection: /* Read number of comparisons collected. */ n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED); for (i = 0; i < n; i++) { + uint64_t ip; + type = cover[i * KCOV_WORDS_PER_CMP + 1]; /* arg1 and arg2 - operands of the comparison. */ arg1 = cover[i * KCOV_WORDS_PER_CMP + 2]; @@ -217,14 +220,15 @@ This allows to collect coverage from two types of kernel background threads: the global ones, that are spawned during kernel boot in a limited number of instances (e.g. one USB hub_event() worker thread is spawned per USB HCD); and the local ones, that are spawned when a user interacts with -some kernel interface (e.g. vhost workers). +some kernel interface (e.g. vhost workers); as well as from soft +interrupts. -To enable collecting coverage from a global background thread, a unique -global handle must be assigned and passed to the corresponding -kcov_remote_start() call. Then a userspace process can pass a list of such -handles to the KCOV_REMOTE_ENABLE ioctl in the handles array field of the -kcov_remote_arg struct. This will attach the used kcov device to the code -sections, that are referenced by those handles. +To enable collecting coverage from a global background thread or from a +softirq, a unique global handle must be assigned and passed to the +corresponding kcov_remote_start() call. Then a userspace process can pass +a list of such handles to the KCOV_REMOTE_ENABLE ioctl in the handles +array field of the kcov_remote_arg struct. This will attach the used kcov +device to the code sections, that are referenced by those handles. Since there might be many local background threads spawned from different userspace processes, we can't use a single global handle per annotation. @@ -242,7 +246,7 @@ handles as they don't belong to a particular subsystem. The bytes 4-7 are currently reserved and must be zero. In the future the number of bytes used for the subsystem or handle ids might be increased. -When a particular userspace proccess collects coverage by via a common +When a particular userspace process collects coverage via a common handle, kcov will collect coverage for each code section that is annotated to use the common handle obtained as kcov_handle from the current task_struct. However non common handles allow to collect coverage @@ -250,6 +254,8 @@ selectively from different subsystems. .. code-block:: c + /* Same includes and defines as above. */ + struct kcov_remote_arg { __u32 trace_mode; __u32 area_size; |