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 <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Paolo Bonzini <[email protected]> --- 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 | 64 +++++++++++++++++++++++++++++ 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, 216 insertions(+), 6 deletions(-) create mode 100644 tests/tracetool/dtrace.rs diff --git a/rust/Cargo.lock b/rust/Cargo.lock index f520597f25d..42ae857fe53 100644 --- a/rust/Cargo.lock +++ b/rust/Cargo.lock @@ -230,6 +230,10 @@ dependencies = [ "util", ] +[[package]] +name = "probe" +version = "0.5.2" + [[package]] name = "proc-macro-error" version = "1.0.4" @@ -388,6 +392,7 @@ dependencies = [ "migration", "qom", "system", + "trace", "util", ] @@ -430,6 +435,7 @@ name = "trace" version = "0.1.0" dependencies = [ "libc", + "probe", ] [[package]] diff --git a/rust/trace/Cargo.toml b/rust/trace/Cargo.toml index fc81bce5803..11e27f8d286 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 1b3498f7fc1..0071a49cf72 100644 --- a/rust/trace/meson.build +++ b/rust/trace/meson.build @@ -11,7 +11,7 @@ _trace_rs = static_library( 'trace', # Library name, lib_rs, trace_rs_targets, # List of generated `.rs` custom targets - dependencies: [libc_rs], + dependencies: [libc_rs, probe_rs], ) trace_rs = declare_dependency(link_with: _trace_rs) diff --git a/rust/trace/src/lib.rs b/rust/trace/src/lib.rs index e03bce43c47..c2abe430a52 100644 --- a/rust/trace/src/lib.rs +++ b/rust/trace/src/lib.rs @@ -6,6 +6,9 @@ #[doc(hidden)] /// 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 @@ -21,6 +24,7 @@ macro_rules! include_trace { #[allow( clippy::ptr_as_ptr, clippy::cast_lossless, + clippy::nonminimal_bool, clippy::used_underscore_binding )] mod trace { diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py index 74062d21a7c..61ba6f1ba8c 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 b4af403025c..f0b58cc1585 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<u16>;') + 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 <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 32ac4e59770..7d9af7edfee 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 00000000000..3490fcb271a --- /dev/null +++ b/tests/tracetool/dtrace.rs @@ -0,0 +1,64 @@ +// 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 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) +{ + ::trace::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) +{ + ::trace::probe!(qemu, test_wibble, _context, _value); +} + diff --git a/tests/tracetool/ftrace.rs b/tests/tracetool/ftrace.rs index 07b9259cf29..34f66004902 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 c191895c8f8..770758611d1 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 9ee39495e38..92f896ef178 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 9d3675a0b57..378d03d34b2 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 786083ad7fb..30006a99190 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 += [ -- 2.52.0
