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SubjectRe: [PATCHv3 bpf-next 0/7] uprobe: uretprobe speed up
Hi Jiri,

On Sun, 21 Apr 2024 21:41:59 +0200
Jiri Olsa <jolsa@kernel.org> 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 1-6 are based on bpf-next/master, but path 1 and 2 are
> apply-able on linux-trace.git tree probes/for-next branch.
> Patch 7 is based on man-pages master.

Thanks for updated! I reviewed the series and just except for the
manpage, it looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

for the series.
If Linux API maintainers are OK, I can pick this in probes/for-next.
(BTW, who will pick the manpage patch?)

Thank you,

>
> v3 changes:
> - added source ip check if the uretprobe syscall is called from
> trampoline and sending SIGILL to process if it's not
> - keep x86 compat process to use standard breakpoint
> - split syscall wiring into separate change
> - ran ltp and syzkaller locally, no issues found [Masami]
> - building uprobe_compat binary in selftests which breaks
> CI atm because of missing 32-bit delve packages, I will
> need to fix that in separate changes once this is acked
> - added man page change
> - there were several changes so I removed acks [Oleg Andrii]
>
> 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, becase 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 si 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 (6):
> uprobe: Wire up uretprobe system call
> uprobe: Add uretprobe syscall to speed up return probe
> 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 compat test
>
> arch/x86/entry/syscalls/syscall_64.tbl | 1 +
> arch/x86/kernel/uprobes.c | 115 ++++++++++++++++++++++++++++++
> 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/.gitignore | 1 +
> tools/testing/selftests/bpf/Makefile | 6 +-
> tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 123 +++++++++++++++++++++++++++++++-
> tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c | 362 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> tools/testing/selftests/bpf/progs/uprobe_syscall.c | 15 ++++
> tools/testing/selftests/bpf/progs/uprobe_syscall_call.c | 15 ++++
> tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c | 13 ++++
> 15 files changed, 681 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_call.c
> create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c
>
>
> Jiri Olsa (1):
> man2: Add uretprobe syscall page
>
> man2/uretprobe.2 | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
> create mode 100644 man2/uretprobe.2


--
Masami Hiramatsu (Google) <mhiramat@kernel.org>

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