From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B5C51CF58E5 for ; Wed, 19 Nov 2025 20:52:36 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vLpA4-0007xu-0U; Wed, 19 Nov 2025 15:52:20 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLpA2-0007x7-G9 for qemu-rust@nongnu.org; Wed, 19 Nov 2025 15:52:18 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLpA0-00024p-5X for qemu-rust@nongnu.org; Wed, 19 Nov 2025 15:52:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763585535; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=inJHY2mpT+t2Kxjje60f2B/u2frM4y4WcLTs+HH+0ts=; b=ivDq7EbugVJ8Fl4IhfYUqL7tG2hQvkBDBv96ZTXse4mXcJc1f15vBDK41FPcgbMjscJTcT Q4S9BJ7O6z/uxMRXrsU4zqJZrONlWK9AxrqSPCIxNx+7O4TNM5CKPfI9LEtR+cKdBE8kAz XCJnqet85s6hqH48B6f2H3mK0kR9V3E= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-151-S6oWsReUPuCHqRRSu_RpWg-1; Wed, 19 Nov 2025 15:52:12 -0500 X-MC-Unique: S6oWsReUPuCHqRRSu_RpWg-1 X-Mimecast-MFC-AGG-ID: S6oWsReUPuCHqRRSu_RpWg_1763585531 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 54F851801233; Wed, 19 Nov 2025 20:52:11 +0000 (UTC) Received: from localhost (unknown [10.2.16.175]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 57E3230001A4; Wed, 19 Nov 2025 20:52:10 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , qemu-rust@nongnu.org, Mads Ynddal , Thomas Huth , Manos Pitsidianakis , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Paolo Bonzini , Josh Stone , Stefan Hajnoczi Subject: [PATCH v2 4/4] tracetool: add Rust DTrace/SystemTap SDT support Date: Wed, 19 Nov 2025 15:52:00 -0500 Message-ID: <20251119205200.173170-5-stefanha@redhat.com> In-Reply-To: <20251119205200.173170-1-stefanha@redhat.com> References: <20251119205200.173170-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-rust@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: QEMU Rust-related patches and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-rust-bounces+qemu-rust=archiver.kernel.org@nongnu.org Sender: qemu-rust-bounces+qemu-rust=archiver.kernel.org@nongnu.org Implement DTrace/SystemTap SDT by emitting the following: - The probe crate's probe!() macro is used to emit a DTrace/SystemTap SDT probe. - Every trace event gets a corresponding trace__enabled() -> bool generated function that Rust code can use to avoid expensive computation when a trace event is disabled. This API works for other trace backends too. `#[allow(dead_code)]` additions are necessary for QEMU's dstate in generated trace-.rs files since they are unused by the dtrace backend. `./configure --enable-trace-backends=` can enable multiple backends, so keep it simple and just silence the warning instead of trying to detect the condition when generating the dstate code can be skipped. The tracetool tests are updated. Take a look at tests/tracetool/dtrace.rs to see what the new generated code looks like. Signed-off-by: Stefan Hajnoczi --- rust/Cargo.lock | 6 +++ rust/trace/Cargo.toml | 1 + rust/trace/meson.build | 2 +- rust/trace/src/lib.rs | 4 ++ scripts/tracetool/__init__.py | 1 + scripts/tracetool/backend/dtrace.py | 31 ++++++++++++++ scripts/tracetool/format/rs.py | 27 ++++++++++-- tests/tracetool/dtrace.rs | 65 +++++++++++++++++++++++++++++ tests/tracetool/ftrace.rs | 21 ++++++++++ tests/tracetool/log.rs | 21 ++++++++++ tests/tracetool/simple.rs | 21 ++++++++++ tests/tracetool/syslog.rs | 21 ++++++++++ tests/tracetool/tracetool-test.py | 2 +- 13 files changed, 217 insertions(+), 6 deletions(-) create mode 100644 tests/tracetool/dtrace.rs diff --git a/rust/Cargo.lock b/rust/Cargo.lock index 0c1df625df..5bd768cb0d 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -144,6 +144,7 @@ dependencies = [ "migration", "qom", "system", + "trace", "util", ] @@ -229,6 +230,10 @@ dependencies = [ "util", ] +[[package]] +name = "probe" +version = "0.5.2" + [[package]] name = "proc-macro-error" version = "1.0.4" @@ -429,6 +434,7 @@ name = "trace" version = "0.1.0" dependencies = [ "libc", + "probe", ] [[package]] diff --git a/rust/trace/Cargo.toml b/rust/trace/Cargo.toml index fc81bce580..11e27f8d28 100644 --- a/rust/trace/Cargo.toml +++ b/rust/trace/Cargo.toml @@ -14,6 +14,7 @@ rust-version.workspace = true [dependencies] libc = { workspace = true } +probe = "0.5" [lints] workspace = true diff --git a/rust/trace/meson.build b/rust/trace/meson.build index adca57e550..cf6b0355a8 100644 --- a/rust/trace/meson.build +++ b/rust/trace/meson.build @@ -12,7 +12,7 @@ _trace_rs = static_library( lib_rs, trace_rs_targets, # List of generated `.rs` custom targets override_options: ['rust_std=2021', 'build.rust_std=2021'], - dependencies: [libc_rs], + dependencies: [libc_rs, probe_rs], rust_abi: 'rust', ) diff --git a/rust/trace/src/lib.rs b/rust/trace/src/lib.rs index e03bce43c4..49331f07c6 100644 --- a/rust/trace/src/lib.rs +++ b/rust/trace/src/lib.rs @@ -7,6 +7,10 @@ /// Re-exported item to avoid adding libc as a dependency everywhere. pub use libc::{syslog, LOG_INFO}; +#[doc(hidden)] +/// Re-exported item to avoid adding probe as a dependency everywhere. +pub use probe::probe; + #[macro_export] /// Define the trace-points from the named directory (which should have slashes /// replaced by underscore characters) as functions in a module called `trace`. diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py index 74062d21a7..61ba6f1ba8 100644 --- a/scripts/tracetool/__init__.py +++ b/scripts/tracetool/__init__.py @@ -461,6 +461,7 @@ def formats(self): QEMU_TRACE = "trace_%(name)s" QEMU_TRACE_TCG = QEMU_TRACE + "_tcg" + QEMU_RUST_DSTATE = "trace_%(name)s_enabled" QEMU_DSTATE = "_TRACE_%(NAME)s_DSTATE" QEMU_BACKEND_DSTATE = "TRACE_%(NAME)s_BACKEND_DSTATE" QEMU_EVENT = "_TRACE_%(NAME)s_EVENT" diff --git a/scripts/tracetool/backend/dtrace.py b/scripts/tracetool/backend/dtrace.py index b4af403025..f0b58cc158 100644 --- a/scripts/tracetool/backend/dtrace.py +++ b/scripts/tracetool/backend/dtrace.py @@ -70,3 +70,34 @@ def generate_h(event, group): def generate_h_backend_dstate(event, group): out(' QEMU_%(uppername)s_ENABLED() || \\', uppername=event.name.upper()) + + +def generate_rs_begin(events, group): + out('use std::cell::UnsafeCell;', + '', + 'extern "C" {') + # These are the Rust declarations of the .probes section semaphores + # generated by dtrace(1) in its .o file output. + for e in events: + if 'disable' in e.properties: + continue + out(' #[allow(dead_code)]', + f' static qemu_{e.name}_semaphore: UnsafeCell;') + out('}', + '') + + +def generate_rs(event, group): + args = event.args.rust_call_extern() + if args: + args = ', ' + args + + out(f' ::trace::probe!(qemu, {event.name}{args});') + + +def generate_rs_backend_dstate(event, group): + # Rust does not have access to the __ENABLED() macro from + # the dtrace(1) generated .h file. Use the matching semaphore declarations + # generated by generate_rs_begin() instead. + out(' (unsafe {qemu_%(n)s_semaphore.get().read_volatile()}) != 0 ||', + n=event.name) diff --git a/scripts/tracetool/format/rs.py b/scripts/tracetool/format/rs.py index 32ac4e5977..7d9af7edfe 100644 --- a/scripts/tracetool/format/rs.py +++ b/scripts/tracetool/format/rs.py @@ -24,25 +24,43 @@ def generate(events, backend, group): '#[allow(unused_imports)]', 'use util::bindings;', '', + '#[allow(dead_code)]', '#[inline(always)]', 'fn trace_event_state_is_enabled(dstate: u16) -> bool {', ' (unsafe { trace_events_enabled_count }) != 0 && dstate != 0', '}', '', 'extern "C" {', + ' #[allow(dead_code)]', ' static mut trace_events_enabled_count: u32;', '}',) out('extern "C" {') for e in events: - out(' static mut %s: u16;' % e.api(e.QEMU_DSTATE)) - out('}') + out(' #[allow(dead_code)]', + ' static mut %s: u16;' % e.api(e.QEMU_DSTATE)) + out('}', + '') backend.generate_begin(events, group) for e in events: - out('', + out('#[inline(always)]', + '#[allow(dead_code)]', + 'pub fn %(api)s() -> bool', + '{', + api=e.api(e.QEMU_RUST_DSTATE)) + + if "disable" not in e.properties: + backend.generate_backend_dstate(e, group) + if backend.check_trace_event_get_state: + out(' trace_event_state_is_enabled(unsafe { _%(event_id)s_DSTATE}) ||', + event_id = 'TRACE_' + e.name.upper()) + + out(' false', + '}', + '', '#[inline(always)]', '#[allow(dead_code)]', 'pub fn %(api)s(%(args)s)', @@ -59,6 +77,7 @@ def generate(events, backend, group): api=e.api()) backend.generate(e, group, check_trace_event_get_state=True) out(' }') - out('}') + out('}', + '') backend.generate_end(events, group) diff --git a/tests/tracetool/dtrace.rs b/tests/tracetool/dtrace.rs new file mode 100644 index 0000000000..233c2ef159 --- /dev/null +++ b/tests/tracetool/dtrace.rs @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +// This file is @generated by tracetool, do not edit. + +#[allow(unused_imports)] +use std::ffi::c_char; +#[allow(unused_imports)] +use util::bindings; + +#[allow(dead_code)] +#[inline(always)] +fn trace_event_state_is_enabled(dstate: u16) -> bool { + (unsafe { trace_events_enabled_count }) != 0 && dstate != 0 +} + +extern "C" { + #[allow(dead_code)] + static mut trace_events_enabled_count: u32; +} +extern "C" { + #[allow(dead_code)] + static mut _TRACE_TEST_BLAH_DSTATE: u16; + #[allow(dead_code)] + static mut _TRACE_TEST_WIBBLE_DSTATE: u16; +} + +use probe::probe; +use std::cell::UnsafeCell; + +extern "C" { + #[allow(dead_code)] + static qemu_test_blah_semaphore: UnsafeCell; + #[allow(dead_code)] + static qemu_test_wibble_semaphore: UnsafeCell; +} + +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah_enabled() -> bool +{ + (unsafe {qemu_test_blah_semaphore.get().read_volatile()}) != 0 || + false +} + +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) +{ + probe!(qemu, test_blah, _context, _filename.as_ptr()); +} + +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble_enabled() -> bool +{ + (unsafe {qemu_test_wibble_semaphore.get().read_volatile()}) != 0 || + false +} + +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) +{ + probe!(qemu, test_wibble, _context, _value); +} + diff --git a/tests/tracetool/ftrace.rs b/tests/tracetool/ftrace.rs index 07b9259cf2..34f6600490 100644 --- a/tests/tracetool/ftrace.rs +++ b/tests/tracetool/ftrace.rs @@ -6,19 +6,31 @@ #[allow(unused_imports)] use util::bindings; +#[allow(dead_code)] #[inline(always)] fn trace_event_state_is_enabled(dstate: u16) -> bool { (unsafe { trace_events_enabled_count }) != 0 && dstate != 0 } extern "C" { + #[allow(dead_code)] static mut trace_events_enabled_count: u32; } extern "C" { + #[allow(dead_code)] static mut _TRACE_TEST_BLAH_DSTATE: u16; + #[allow(dead_code)] static mut _TRACE_TEST_WIBBLE_DSTATE: u16; } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_BLAH_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) @@ -29,6 +41,14 @@ pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) } } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_WIBBLE_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) @@ -38,3 +58,4 @@ pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) unsafe {bindings::ftrace_write(format_string.as_ptr() as *const c_char, _context /* as *mut () */, _value /* as std::ffi::c_int */);} } } + diff --git a/tests/tracetool/log.rs b/tests/tracetool/log.rs index c191895c8f..770758611d 100644 --- a/tests/tracetool/log.rs +++ b/tests/tracetool/log.rs @@ -6,19 +6,31 @@ #[allow(unused_imports)] use util::bindings; +#[allow(dead_code)] #[inline(always)] fn trace_event_state_is_enabled(dstate: u16) -> bool { (unsafe { trace_events_enabled_count }) != 0 && dstate != 0 } extern "C" { + #[allow(dead_code)] static mut trace_events_enabled_count: u32; } extern "C" { + #[allow(dead_code)] static mut _TRACE_TEST_BLAH_DSTATE: u16; + #[allow(dead_code)] static mut _TRACE_TEST_WIBBLE_DSTATE: u16; } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_BLAH_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) @@ -31,6 +43,14 @@ pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) } } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_WIBBLE_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) @@ -42,3 +62,4 @@ pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) } } } + diff --git a/tests/tracetool/simple.rs b/tests/tracetool/simple.rs index 9ee39495e3..92f896ef17 100644 --- a/tests/tracetool/simple.rs +++ b/tests/tracetool/simple.rs @@ -6,19 +6,31 @@ #[allow(unused_imports)] use util::bindings; +#[allow(dead_code)] #[inline(always)] fn trace_event_state_is_enabled(dstate: u16) -> bool { (unsafe { trace_events_enabled_count }) != 0 && dstate != 0 } extern "C" { + #[allow(dead_code)] static mut trace_events_enabled_count: u32; } extern "C" { + #[allow(dead_code)] static mut _TRACE_TEST_BLAH_DSTATE: u16; + #[allow(dead_code)] static mut _TRACE_TEST_WIBBLE_DSTATE: u16; } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_BLAH_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) @@ -29,6 +41,14 @@ pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) } } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_WIBBLE_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) @@ -38,3 +58,4 @@ pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) unsafe { _simple_trace_test_wibble(_context, _value); } } } + diff --git a/tests/tracetool/syslog.rs b/tests/tracetool/syslog.rs index 9d3675a0b5..378d03d34b 100644 --- a/tests/tracetool/syslog.rs +++ b/tests/tracetool/syslog.rs @@ -6,19 +6,31 @@ #[allow(unused_imports)] use util::bindings; +#[allow(dead_code)] #[inline(always)] fn trace_event_state_is_enabled(dstate: u16) -> bool { (unsafe { trace_events_enabled_count }) != 0 && dstate != 0 } extern "C" { + #[allow(dead_code)] static mut trace_events_enabled_count: u32; } extern "C" { + #[allow(dead_code)] static mut _TRACE_TEST_BLAH_DSTATE: u16; + #[allow(dead_code)] static mut _TRACE_TEST_WIBBLE_DSTATE: u16; } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_blah_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_BLAH_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) @@ -29,6 +41,14 @@ pub fn trace_test_blah(_context: *mut (), _filename: &std::ffi::CStr) } } +#[inline(always)] +#[allow(dead_code)] +pub fn trace_test_wibble_enabled() -> bool +{ + trace_event_state_is_enabled(unsafe { _TRACE_TEST_WIBBLE_DSTATE}) || + false +} + #[inline(always)] #[allow(dead_code)] pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) @@ -38,3 +58,4 @@ pub fn trace_test_wibble(_context: *mut (), _value: std::ffi::c_int) unsafe {::trace::syslog(::trace::LOG_INFO, format_string.as_ptr() as *const c_char, _context /* as *mut () */, _value /* as std::ffi::c_int */);} } } + diff --git a/tests/tracetool/tracetool-test.py b/tests/tracetool/tracetool-test.py index 786083ad7f..30006a9919 100755 --- a/tests/tracetool/tracetool-test.py +++ b/tests/tracetool/tracetool-test.py @@ -14,7 +14,7 @@ def get_formats(backend): "c", "h", ] - if backend in {"ftrace", "log", "simple", "syslog"}: + if backend in {"dtrace", "ftrace", "log", "simple", "syslog"}: formats += ["rs"] if backend == "dtrace": formats += [ -- 2.51.1