On Tue, 11 Jun 2024 13:21:49 +0200 Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > hi, > as part of the effort on speeding up the uprobes [0] coming with > return uprobe optimization by using syscall instead of the trap > on the uretprobe trampoline. > > The speed up depends on instruction type that uprobe is installed > and depends on specific HW type, please check patch 1 for details. > > Patches 1-8 are based on bpf-next/master, but patch 2 and 3 are > apply-able on linux-trace.git tree probes/for-next branch. > Patch 9 is based on man-pages master. > > v8 changes: > - rebased (another new syscall got merged) > - added acks > > Also available at: > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > uretprobe_syscall Applied patch [1/9] - [8/9] on probes/for-next in git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git Thank you! > > thanks, > jirka > > > Notes to check list items in Documentation/process/adding-syscalls.rst: > > - System Call Alternatives > New syscall seems like the best way in here, because we need > just to quickly enter kernel with no extra arguments processing, > which we'd need to do if we decided to use another syscall. > > - Designing the API: Planning for Extension > The uretprobe syscall is very specific and most likely won't be > extended in the future. > > At the moment it does not take any arguments and even if it does > in future, it's allowed to be called only from trampoline prepared > by kernel, so there'll be no broken user. > > - Designing the API: Other Considerations > N/A because uretprobe syscall does not return reference to kernel > object. > > - Proposing the API > Wiring up of the uretprobe system call is in separate change, > selftests and man page changes are part of the patchset. > > - Generic System Call Implementation > There's no CONFIG option for the new functionality because it > keeps the same behaviour from the user POV. > > - x86 System Call Implementation > It's 64-bit syscall only. > > - Compatibility System Calls (Generic) > N/A uretprobe syscall has no arguments and is not supported > for compat processes. > > - Compatibility System Calls (x86) > N/A uretprobe syscall is not supported for compat processes. > > - System Calls Returning Elsewhere > N/A. > > - Other Details > N/A. > > - Testing > Adding new bpf selftests and ran ltp on top of this change. > > - Man Page > Attached. > > - Do not call System Calls in the Kernel > N/A. > > > [0] https://lore.kernel.org/bpf/ZeCXHKJ--iYYbmLj@krava/ > --- > Jiri Olsa (8): > x86/shstk: Make return uprobe work with shadow stack > uprobe: Wire up uretprobe system call > uprobe: Add uretprobe syscall to speed up return probe > selftests/x86: Add return uprobe shadow stack test > selftests/bpf: Add uretprobe syscall test for regs integrity > selftests/bpf: Add uretprobe syscall test for regs changes > selftests/bpf: Add uretprobe syscall call from user space test > selftests/bpf: Add uretprobe shadow stack test > > arch/x86/entry/syscalls/syscall_64.tbl | 1 + > arch/x86/include/asm/shstk.h | 4 + > arch/x86/kernel/shstk.c | 16 ++++ > arch/x86/kernel/uprobes.c | 124 ++++++++++++++++++++++++++++- > include/linux/syscalls.h | 2 + > include/linux/uprobes.h | 3 + > include/uapi/asm-generic/unistd.h | 5 +- > kernel/events/uprobes.c | 24 ++++-- > kernel/sys_ni.c | 2 + > tools/include/linux/compiler.h | 4 + > tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 123 ++++++++++++++++++++++++++++- > tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c | 385 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > tools/testing/selftests/bpf/progs/uprobe_syscall.c | 15 ++++ > tools/testing/selftests/bpf/progs/uprobe_syscall_executed.c | 17 ++++ > tools/testing/selftests/x86/test_shadow_stack.c | 145 ++++++++++++++++++++++++++++++++++ > 15 files changed, 860 insertions(+), 10 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c > create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall.c > create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall_executed.c > > Jiri Olsa (1): > man2: Add uretprobe syscall page > > man/man2/uretprobe.2 | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 56 insertions(+) > create mode 100644 man/man2/uretprobe.2 -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
