* [PATCH 0/2] trace: add Rust DTrace/SystemTap SDT support @ 2025-11-19 18:18 Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 1/2] subprojects: add probe crate Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi 0 siblings, 2 replies; 4+ messages in thread From: Stefan Hajnoczi @ 2025-11-19 18:18 UTC (permalink / raw) To: qemu-devel Cc: Paolo Bonzini, Mads Ynddal, qemu-rust, Josh Stone, Philippe Mathieu-Daudé, Manos Pitsidianakis, Stefan Hajnoczi, Thomas Huth, Alex Bennée This series adds SDT probe support so that SystemTap, GDB, etc can trace QEMU's Rust code when compiled with `./configure --enable-trace-backends=dtrace`. The dtrace(1) tool that generates the .o and C header file does not support Rust. Use the probe crate (https://crates.io/crates/probe), which takes care of emitting SDT probes, and extend tracetool to emit code for the trace events. While SDT is cross-platform, the probe crate currently only supports Linux (SystemTap). On other platforms the crate is a nop - it compiles but does nothing. Future changes to the probe crate may add support for other operating systems like FreeBSD, macOS, etc without much needed in the way of QEMU code changes. Josh: I CCed you just to let you know that QEMU will use the probes crate. There is no need to review the code unless you want to. Based-on: <20251106215606.36598-1-stefanha@redhat.com> Stefan Hajnoczi (2): subprojects: add probe crate tracetool: add Rust DTrace/SystemTap SDT support rust/Cargo.lock | 6 ++ rust/hw/char/pl011/meson.build | 1 + rust/hw/timer/hpet/meson.build | 1 + rust/meson.build | 2 + rust/trace/Cargo.toml | 1 + rust/trace/meson.build | 2 +- scripts/archive-source.sh | 1 + scripts/make-release | 2 +- scripts/tracetool/__init__.py | 1 + scripts/tracetool/backend/dtrace.py | 32 +++++++++ scripts/tracetool/format/rs.py | 27 ++++++-- subprojects/.gitignore | 1 + .../packagefiles/probe-0.5-rs/meson.build | 22 +++++++ subprojects/probe-0.5-rs.wrap | 7 ++ 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 +- 20 files changed, 250 insertions(+), 7 deletions(-) create mode 100644 subprojects/packagefiles/probe-0.5-rs/meson.build create mode 100644 subprojects/probe-0.5-rs.wrap create mode 100644 tests/tracetool/dtrace.rs -- 2.51.1 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/2] subprojects: add probe crate 2025-11-19 18:18 [PATCH 0/2] trace: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi @ 2025-11-19 18:18 ` Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi 1 sibling, 0 replies; 4+ messages in thread From: Stefan Hajnoczi @ 2025-11-19 18:18 UTC (permalink / raw) To: qemu-devel Cc: Paolo Bonzini, Mads Ynddal, qemu-rust, Josh Stone, Philippe Mathieu-Daudé, Manos Pitsidianakis, Stefan Hajnoczi, Thomas Huth, Alex Bennée The probe crate (https://crates.io/crates/probe) provides a probe!() macro that defines SystemTap SDT probes on Linux hosts or does nothing on other host OSes. This crate will be used to implement DTrace support for Rust. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- rust/meson.build | 2 ++ scripts/archive-source.sh | 1 + scripts/make-release | 2 +- subprojects/.gitignore | 1 + .../packagefiles/probe-0.5-rs/meson.build | 22 +++++++++++++++++++ subprojects/probe-0.5-rs.wrap | 7 ++++++ 6 files changed, 34 insertions(+), 1 deletion(-) create mode 100644 subprojects/packagefiles/probe-0.5-rs/meson.build create mode 100644 subprojects/probe-0.5-rs.wrap diff --git a/rust/meson.build b/rust/meson.build index 76e10699b3..afbeeeb47a 100644 --- a/rust/meson.build +++ b/rust/meson.build @@ -4,6 +4,7 @@ subproject('bilge-impl-0.2-rs', required: true) subproject('foreign-0.3-rs', required: true) subproject('glib-sys-0.21-rs', required: true) subproject('libc-0.2-rs', required: true) +subproject('probe-0.5-rs', required: true) anyhow_rs = dependency('anyhow-1-rs') bilge_rs = dependency('bilge-0.2-rs') @@ -11,6 +12,7 @@ bilge_impl_rs = dependency('bilge-impl-0.2-rs') foreign_rs = dependency('foreign-0.3-rs') glib_sys_rs = dependency('glib-sys-0.21-rs') libc_rs = dependency('libc-0.2-rs') +probe_rs = dependency('probe-0.5-rs') subproject('proc-macro2-1-rs', required: true) subproject('quote-1-rs', required: true) diff --git a/scripts/archive-source.sh b/scripts/archive-source.sh index 8f97b19a08..a37acab524 100755 --- a/scripts/archive-source.sh +++ b/scripts/archive-source.sh @@ -41,6 +41,7 @@ subprojects=( keycodemapdb libc-0.2-rs libvfio-user + probe-0.5-rs proc-macro-error-1-rs proc-macro-error-attr-1-rs proc-macro2-1-rs diff --git a/scripts/make-release b/scripts/make-release index bc1b43caa2..5f54b0e793 100755 --- a/scripts/make-release +++ b/scripts/make-release @@ -42,7 +42,7 @@ fi SUBPROJECTS="libvfio-user keycodemapdb berkeley-softfloat-3 berkeley-testfloat-3 anyhow-1-rs arbitrary-int-1-rs attrs-0.2-rs bilge-0.2-rs bilge-impl-0.2-rs either-1-rs foreign-0.3-rs itertools-0.11-rs - libc-0.2-rs proc-macro2-1-rs + libc-0.2-rs probe-0.5-rs proc-macro2-1-rs proc-macro-error-1-rs proc-macro-error-attr-1-rs quote-1-rs syn-2-rs unicode-ident-1-rs" diff --git a/subprojects/.gitignore b/subprojects/.gitignore index c00c847837..011ce4dc3b 100644 --- a/subprojects/.gitignore +++ b/subprojects/.gitignore @@ -16,6 +16,7 @@ /glib-sys-* /itertools-* /libc-* +/probe-* /proc-macro-error-* /proc-macro-error-attr-* /proc-macro* diff --git a/subprojects/packagefiles/probe-0.5-rs/meson.build b/subprojects/packagefiles/probe-0.5-rs/meson.build new file mode 100644 index 0000000000..e6ea69533b --- /dev/null +++ b/subprojects/packagefiles/probe-0.5-rs/meson.build @@ -0,0 +1,22 @@ +project('probe-0.5-rs', 'rust', + meson_version: '>=1.5.0', + version: '0.5.2', + license: 'Apache-2.0 OR MIT', + default_options: []) + +_probe_rs = static_library( + 'probe', + files('src/lib.rs'), + gnu_symbol_visibility: 'hidden', + override_options: ['rust_std=2021', 'build.rust_std=2021'], + rust_abi: 'rust', + rust_args: [ + '--cap-lints', 'allow', + ], +) + +probe_deps = declare_dependency( + link_with: _probe_rs, +) + +meson.override_dependency('probe-0.5-rs', probe_deps) diff --git a/subprojects/probe-0.5-rs.wrap b/subprojects/probe-0.5-rs.wrap new file mode 100644 index 0000000000..73229ee1c2 --- /dev/null +++ b/subprojects/probe-0.5-rs.wrap @@ -0,0 +1,7 @@ +[wrap-file] +directory = probe-0.5.2 +source_url = https://crates.io/api/v1/crates/probe/0.5.2/download +source_filename = probe-0.5.2.tar.gz +source_hash = 136558b6e1ebaecc92755d0ffaf9421f519531bed30cc2ad23b22cb00965cc5e +#method = cargo +patch_directory = probe-0.5-rs -- 2.51.1 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support 2025-11-19 18:18 [PATCH 0/2] trace: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 1/2] subprojects: add probe crate Stefan Hajnoczi @ 2025-11-19 18:18 ` Stefan Hajnoczi 2025-11-19 19:36 ` Paolo Bonzini 1 sibling, 1 reply; 4+ messages in thread From: Stefan Hajnoczi @ 2025-11-19 18:18 UTC (permalink / raw) To: qemu-devel Cc: Paolo Bonzini, Mads Ynddal, qemu-rust, Josh Stone, Philippe Mathieu-Daudé, Manos Pitsidianakis, Stefan Hajnoczi, Thomas Huth, Alex Bennée 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_<name>_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-<dir>.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 <stefanha@redhat.com> --- I'm not sure if Cargo.toml, Cargo.lock, and meson.build are in sync/consistent, but it builds successfully. I find the Rust build system integration confusing because I'm not an expert in cargo or meson. Please review the build system changes carefully. --- rust/Cargo.lock | 6 +++ rust/hw/char/pl011/meson.build | 1 + rust/hw/timer/hpet/meson.build | 1 + rust/trace/Cargo.toml | 1 + rust/trace/meson.build | 2 +- scripts/tracetool/__init__.py | 1 + scripts/tracetool/backend/dtrace.py | 32 ++++++++++++++ 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 +- 14 files changed, 216 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/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build index 33b91f2191..5b6ea274a2 100644 --- a/rust/hw/char/pl011/meson.build +++ b/rust/hw/char/pl011/meson.build @@ -37,6 +37,7 @@ _libpl011_rs = static_library( util_rs, migration_rs, bql_rs, + probe_rs, qom_rs, chardev_rs, system_rs, diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build index 465995bb5a..4e95754b20 100644 --- a/rust/hw/timer/hpet/meson.build +++ b/rust/hw/timer/hpet/meson.build @@ -8,6 +8,7 @@ _libhpet_rs = static_library( util_rs, migration_rs, bql_rs, + probe_rs, qom_rs, system_rs, hwcore_rs, 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/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..548e228c81 100644 --- a/scripts/tracetool/backend/dtrace.py +++ b/scripts/tracetool/backend/dtrace.py @@ -70,3 +70,35 @@ 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 probe::probe;', + '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<u16>;') + out('}', + '') + + +def generate_rs(event, group): + args = event.args.rust_call_extern() + if args: + args = ', ' + args + + out(f' probe!(qemu, {event.name}{args});') + + +def generate_rs_backend_dstate(event, group): + # Rust does not have access to the <provider>_<name>_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<u16>; + #[allow(dead_code)] + static qemu_test_wibble_semaphore: UnsafeCell<u16>; +} + +#[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 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support 2025-11-19 18:18 ` [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi @ 2025-11-19 19:36 ` Paolo Bonzini 0 siblings, 0 replies; 4+ messages in thread From: Paolo Bonzini @ 2025-11-19 19:36 UTC (permalink / raw) To: Stefan Hajnoczi Cc: qemu-devel, Mads Ynddal, open list:Rust-related patc..., Josh Stone, Philippe Mathieu-Daudé, Manos Pitsidianakis, Thomas Huth, Alex Bennée [-- Attachment #1: Type: text/plain, Size: 17665 bytes --] Il mer 19 nov 2025, 19:18 Stefan Hajnoczi <stefanha@redhat.com> ha scritto: > 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_<name>_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-<dir>.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 <stefanha@redhat.com> > --- > I'm not sure if Cargo.toml, Cargo.lock, and meson.build are in > sync/consistent, but it builds successfully. I find the Rust build > system integration confusing because I'm not an expert in cargo or > meson. Please review the build system changes carefully. > The only change I'd make, is to re-export probe::probe from the trace crate, like it already does for libc. This way you don't need the change to rust/hw/char/pl011/meson.build. Otherwise it works great, and it's nice that we can reuse the C semaphore to avoid changes to the probe crate. Hopefully within a few months all the subprojects will not need anymore the current boilerplate. Paolo --- > rust/Cargo.lock | 6 +++ > rust/hw/char/pl011/meson.build | 1 + > rust/hw/timer/hpet/meson.build | 1 + > rust/trace/Cargo.toml | 1 + > rust/trace/meson.build | 2 +- > scripts/tracetool/__init__.py | 1 + > scripts/tracetool/backend/dtrace.py | 32 ++++++++++++++ > 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 +- > 14 files changed, 216 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/hw/char/pl011/meson.build > b/rust/hw/char/pl011/meson.build > index 33b91f2191..5b6ea274a2 100644 > --- a/rust/hw/char/pl011/meson.build > +++ b/rust/hw/char/pl011/meson.build > @@ -37,6 +37,7 @@ _libpl011_rs = static_library( > util_rs, > migration_rs, > bql_rs, > + probe_rs, > qom_rs, > chardev_rs, > system_rs, > diff --git a/rust/hw/timer/hpet/meson.build > b/rust/hw/timer/hpet/meson.build > index 465995bb5a..4e95754b20 100644 > --- a/rust/hw/timer/hpet/meson.build > +++ b/rust/hw/timer/hpet/meson.build > @@ -8,6 +8,7 @@ _libhpet_rs = static_library( > util_rs, > migration_rs, > bql_rs, > + probe_rs, > qom_rs, > system_rs, > hwcore_rs, > 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/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..548e228c81 100644 > --- a/scripts/tracetool/backend/dtrace.py > +++ b/scripts/tracetool/backend/dtrace.py > @@ -70,3 +70,35 @@ 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 probe::probe;', > + '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<u16>;') > + out('}', > + '') > + > + > +def generate_rs(event, group): > + args = event.args.rust_call_extern() > + if args: > + args = ', ' + args > + > + out(f' probe!(qemu, {event.name}{args});') > + > + > +def generate_rs_backend_dstate(event, group): > + # Rust does not have access to the <provider>_<name>_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<u16>; > + #[allow(dead_code)] > + static qemu_test_wibble_semaphore: UnsafeCell<u16>; > +} > + > +#[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 > > [-- Attachment #2: Type: text/html, Size: 24247 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-11-19 19:38 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-11-19 18:18 [PATCH 0/2] trace: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 1/2] subprojects: add probe crate Stefan Hajnoczi 2025-11-19 18:18 ` [PATCH 2/2] tracetool: add Rust DTrace/SystemTap SDT support Stefan Hajnoczi 2025-11-19 19:36 ` Paolo Bonzini
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).