From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: "Oleg Nesterov" <oleg@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Andrii Nakryiko" <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-trace-kernel <linux-trace-kernel@vger.kernel.org>,
"X86 ML" <x86@kernel.org>, "Song Liu" <songliubraving@fb.com>,
"Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"Hao Luo" <haoluo@google.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Alan Maguire" <alan.maguire@oracle.com>,
"David Laight" <David.Laight@aculab.com>,
"Thomas Weißschuh" <thomas@t-8ch.de>
Subject: Re: [PATCH RFCv2 08/18] uprobes/x86: Add uprobe syscall to speed up uprobe
Date: Tue, 25 Feb 2025 10:06:19 -0800 [thread overview]
Message-ID: <CAADnVQKNeWKFkZxb_-Fuenvmfy47-t6Z7KLY_j3UUOrj5pFP-g@mail.gmail.com> (raw)
In-Reply-To: <Z73HDU5IZ5NV3BtM@krava>
On Tue, Feb 25, 2025 at 5:35 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> > In later patches I see nop5 is replaced with a call to
> > uprobe_trampoline_entry, but which part saves
> > rdi and other regs?
> > Compiler doesn't automatically spill/fill around USDT's nop/nop5.
> > Selftest is doing:
> > +__naked noinline void uprobe_test(void)
> > so just lucky ?
>
> if you mean registers that would carry usdt arguments, ebpf programs
> access those based on assembler operand string stored in usdt record:
No. I'm talking about all normal registers that trap-style uprobe
preserves, but this nop5->call will scratch.
Instead of void uprobe_test(void)
add some arguments to it, and read them before and after nop5 uprobe.
They must remain the same.
next prev parent reply other threads:[~2025-02-25 18:06 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-24 14:01 [PATCH RFCv2 00/18] uprobes: Add support to optimize usdt probes on x86_64 Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 01/18] uprobes: Rename arch_uretprobe_trampoline function Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 02/18] uprobes: Make copy_from_page global Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 03/18] uprobes: Move ref_ctr_offset update out of uprobe_write_opcode Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 04/18] uprobes: Add uprobe_write function Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 05/18] uprobes: Add nbytes argument to uprobe_write_opcode Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 06/18] uprobes: Add orig argument to uprobe_write and uprobe_write_opcode Jiri Olsa
2025-02-28 19:07 ` Andrii Nakryiko
2025-02-28 23:12 ` Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 07/18] uprobes: Add swbp argument to arch_uretprobe_hijack_return_addr Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 08/18] uprobes/x86: Add uprobe syscall to speed up uprobe Jiri Olsa
2025-02-24 19:22 ` Alexei Starovoitov
2025-02-25 13:35 ` Jiri Olsa
2025-02-25 17:10 ` Andrii Nakryiko
2025-02-25 18:06 ` Alexei Starovoitov [this message]
2025-02-26 2:36 ` Alexei Starovoitov
2025-02-24 14:01 ` [PATCH RFCv2 09/18] uprobes/x86: Add mapping for optimized uprobe trampolines Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 10/18] uprobes/x86: Add mm_uprobe objects to track uprobes within mm Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 11/18] uprobes/x86: Add support to emulate nop5 instruction Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 12/18] uprobes/x86: Add support to optimize uprobes Jiri Olsa
2025-02-28 18:55 ` Andrii Nakryiko
2025-02-28 22:55 ` Jiri Olsa
2025-02-28 23:00 ` Andrii Nakryiko
2025-02-28 23:18 ` Jiri Olsa
2025-02-28 23:27 ` Andrii Nakryiko
2025-02-28 23:00 ` Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 13/18] selftests/bpf: Reorg the uprobe_syscall test function Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 14/18] selftests/bpf: Use 5-byte nop for x86 usdt probes Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 15/18] selftests/bpf: Add uprobe/usdt syscall tests Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 16/18] selftests/bpf: Add hit/attach/detach race optimized uprobe test Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 17/18] selftests/bpf: Add uprobe syscall sigill signal test Jiri Olsa
2025-02-24 14:01 ` [PATCH RFCv2 18/18] selftests/bpf: Add 5-byte nop uprobe trigger bench Jiri Olsa
2025-02-24 18:46 ` [PATCH RFCv2 00/18] uprobes: Add support to optimize usdt probes on x86_64 Ingo Molnar
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