On Wed, 5 Jun 2024 09:42:45 -0700 Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > On Fri, May 31, 2024 at 10:52 AM Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx> wrote: > > > > On Thu, May 23, 2024 at 5:11 AM 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. > > > > > > v7 changes: > > > - fixes in man page [Alejandro Colomar] > > > - fixed patch #1 fixes tag [Oleg] > > > > > > Also available at: > > > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > > > uretprobe_syscall > > > > > > 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 > > > > > > > Masami, Steven, > > > > It seems like the series is ready to go in. Are you planning to take > > the first 4 patches through your linux-trace tree? > > Another ping. It's been two weeks since Jiri posted the last revision > that got no more feedback to be addressed and everyone seems to be > happy with it. Sorry about late reply. I agree that this is OK to go, since no other comments. Let me pick this up to probes/for-next branch. > > This is an important speed up improvement for uprobe infrastructure in > general and for BPF ecosystem in particular. "Uprobes are slow" is one > of the top complaints from production BPF users, and sys_uretprobe > approach is significantly improving the situation for return uprobes > (aka uretprobes), potentially enabling new use cases that previously > could have been too expensive to trace in practice and reducing the > overhead of the existing ones. > > I'd appreciate the engagement from linux-trace maintainers on this > patch set. Given it's important for BPF and that a big part of the > patch set is BPF-based selftests, we'd also be happy to route all this > through the bpf-next tree (which would actually make logistics for us > much easier, but that's not the main concern). But regardless of the > tree, it would be nice to make a decision and go forward with it. I think it would be better to include those patches together in linux-tree. Can you review and ack to the last patch ? ([9/9]) Thank you, > > Thank you! > > > > > > 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>
