On Sun, Sep 29, 2024 at 1:57 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > This change allows the uprobe consumer to behave as session which > means that 'handler' and 'ret_handler' callbacks are connected in > a way that allows to: > > - control execution of 'ret_handler' from 'handler' callback > - share data between 'handler' and 'ret_handler' callbacks > > The session concept fits to our common use case where we do filtering > on entry uprobe and based on the result we decide to run the return > uprobe (or not). > > It's also convenient to share the data between session callbacks. > > To achive this we are adding new return value the uprobe consumer > can return from 'handler' callback: > > UPROBE_HANDLER_IGNORE > - Ignore 'ret_handler' callback for this consumer. > > And store cookie and pass it to 'ret_handler' when consumer has both > 'handler' and 'ret_handler' callbacks defined. > > We store shared data in the return_consumer object array as part of > the return_instance object. This way the handle_uretprobe_chain can > find related return_consumer and its shared data. > > We also store entry handler return value, for cases when there are > multiple consumers on single uprobe and some of them are ignored and > some of them not, in which case the return probe gets installed and > we need to have a way to find out which consumer needs to be ignored. > > The tricky part is when consumer is registered 'after' the uprobe > entry handler is hit. In such case this consumer's 'ret_handler' gets > executed as well, but it won't have the proper data pointer set, > so we can filter it out. > > Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > --- > include/linux/uprobes.h | 21 +++++- > kernel/events/uprobes.c | 148 +++++++++++++++++++++++++++++++--------- > 2 files changed, 137 insertions(+), 32 deletions(-) > LGTM, Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Note also that I just resent the last patch from my patch set ([0]), hopefully it will get applied, in which case you'd need to do a tiny rebase. [0] https://lore.kernel.org/linux-trace-kernel/20240930212246.1829395-1-andrii@xxxxxxxxxx/ [...]
