mirror of https://github.com/torvalds/linux.git
546 lines
24 KiB
C++
546 lines
24 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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/*
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* This single-header library defines a collection of variadic macros for
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* defining and triggering USDTs (User Statically-Defined Tracepoints):
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*
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* - For USDTs without associated semaphore:
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* USDT(group, name, args...)
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*
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* - For USDTs with implicit (transparent to the user) semaphore:
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* USDT_WITH_SEMA(group, name, args...)
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* USDT_IS_ACTIVE(group, name)
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*
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* - For USDTs with explicit (user-defined and provided) semaphore:
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* USDT_WITH_EXPLICIT_SEMA(sema, group, name, args...)
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* USDT_SEMA_IS_ACTIVE(sema)
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*
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* all of which emit a NOP instruction into the instruction stream, and so
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* have *zero* overhead for the surrounding code. USDTs are identified by
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* a combination of `group` and `name` identifiers, which is used by external
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* tracing tooling (tracers) for identifying exact USDTs of interest.
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*
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* USDTs can have an associated (2-byte) activity counter (USDT semaphore),
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* automatically maintained by Linux kernel whenever any correctly written
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* BPF-based tracer is attached to the USDT. This USDT semaphore can be used
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* to check whether there is a need to do any extra data collection and
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* processing for a given USDT (if necessary), and otherwise avoid extra work
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* for a common case of USDT not being traced ("active").
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*
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* See documentation for USDT_WITH_SEMA()/USDT_IS_ACTIVE() or
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* USDT_WITH_EXPLICIT_SEMA()/USDT_SEMA_IS_ACTIVE() APIs below for details on
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* working with USDTs with implicitly or explicitly associated
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* USDT semaphores, respectively.
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*
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* There is also some additional data recorded into an auxiliary note
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* section. The data in the note section describes the operands, in terms of
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* size and location, used by tracing tooling to know where to find USDT
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* arguments. Each location is encoded as an assembler operand string.
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* Tracing tools (bpftrace and BPF-based tracers, systemtap, etc) insert
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* breakpoints on top of the nop, and decode the location operand-strings,
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* like an assembler, to find the values being passed.
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*
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* The operand strings are selected by the compiler for each operand.
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* They are constrained by inline-assembler codes.The default is:
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*
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* #define USDT_ARG_CONSTRAINT nor
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*
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* This is a good default if the operands tend to be integral and
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* moderate in number (smaller than number of registers). In other
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* cases, the compiler may report "'asm' requires impossible reload" or
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* similar. In this case, consider simplifying the macro call (fewer
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* and simpler operands), reduce optimization, or override the default
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* constraints string via:
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*
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* #define USDT_ARG_CONSTRAINT g
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* #include <usdt.h>
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*
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* For some historical description of USDT v3 format (the one used by this
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* library and generally recognized and assumed by BPF-based tracing tools)
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* see [0]. The more formal specification can be found at [1]. Additional
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* argument constraints information can be found at [2].
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*
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* Original SystemTap's sys/sdt.h implementation ([3]) was used as a base for
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* this USDT library implementation. Current implementation differs *a lot* in
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* terms of exposed user API and general usability, which was the main goal
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* and focus of the reimplementation work. Nevertheless, underlying recorded
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* USDT definitions are fully binary compatible and any USDT-based tooling
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* should work equally well with USDTs defined by either SystemTap's or this
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* library's USDT implementation.
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*
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* [0] https://ecos.sourceware.org/ml/systemtap/2010-q3/msg00145.html
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* [1] https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
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* [2] https://gcc.gnu.org/onlinedocs/gcc/Constraints.html
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* [3] https://sourceware.org/git/?p=systemtap.git;a=blob;f=includes/sys/sdt.h
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*/
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#ifndef __USDT_H
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#define __USDT_H
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/*
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* Changelog:
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*
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* 0.1.0
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* -----
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* - Initial release
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*/
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#define USDT_MAJOR_VERSION 0
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#define USDT_MINOR_VERSION 1
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#define USDT_PATCH_VERSION 0
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/* C++20 and C23 added __VA_OPT__ as a standard replacement for non-standard `##__VA_ARGS__` extension */
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#if (defined(__STDC_VERSION__) && __STDC_VERSION__ > 201710L) || (defined(__cplusplus) && __cplusplus > 201703L)
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#define __usdt_va_opt 1
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#define __usdt_va_args(...) __VA_OPT__(,) __VA_ARGS__
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#else
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#define __usdt_va_args(...) , ##__VA_ARGS__
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#endif
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/*
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* Trigger USDT with `group`:`name` identifier and pass through `args` as its
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* arguments. Zero arguments are acceptable as well. No USDT semaphore is
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* associated with this USDT.
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*
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* Such "semaphoreless" USDTs are commonly used when there is no extra data
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* collection or processing needed to collect and prepare USDT arguments and
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* they are just available in the surrounding code. USDT() macro will just
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* record their locations in CPU registers or in memory for tracing tooling to
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* be able to access them, if necessary.
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*/
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#ifdef __usdt_va_opt
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#define USDT(group, name, ...) \
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__usdt_probe(group, name, __usdt_sema_none, 0 __VA_OPT__(,) __VA_ARGS__)
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#else
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#define USDT(group, name, ...) \
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__usdt_probe(group, name, __usdt_sema_none, 0, ##__VA_ARGS__)
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#endif
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/*
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* Trigger USDT with `group`:`name` identifier and pass through `args` as its
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* arguments. Zero arguments are acceptable as well. USDT also get an
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* implicitly-defined associated USDT semaphore, which will be "activated" by
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* tracing tooling and can be used to check whether USDT is being actively
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* observed.
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*
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* USDTs with semaphore are commonly used when there is a need to perform
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* additional data collection and processing to prepare USDT arguments, which
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* otherwise might not be necessary for the rest of application logic. In such
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* case, USDT semaphore can be used to avoid unnecessary extra work. If USDT
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* is not traced (which is presumed to be a common situation), the associated
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* USDT semaphore is "inactive", and so there is no need to waste resources to
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* prepare USDT arguments. Use USDT_IS_ACTIVE(group, name) to check whether
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* USDT is "active".
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*
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* N.B. There is an inherent (albeit short) gap between checking whether USDT
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* is active and triggering corresponding USDT, in which external tracer can
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* be attached to an USDT and activate USDT semaphore after the activity check.
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* If such a race occurs, tracers might miss one USDT execution. Tracers are
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* expected to accommodate such possibility and this is expected to not be
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* a problem for applications and tracers.
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*
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* N.B. Implicit USDT semaphore defined by USDT_WITH_SEMA() is contained
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* within a single executable or shared library and is not shared outside
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* them. I.e., if you use USDT_WITH_SEMA() with the same USDT group and name
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* identifier across executable and shared library, it will work and won't
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* conflict, per se, but will define independent USDT semaphores, one for each
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* shared library/executable in which USDT_WITH_SEMA(group, name) is used.
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* That is, if you attach to this USDT in one shared library (or executable),
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* then only USDT semaphore within that shared library (or executable) will be
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* updated by the kernel, while other libraries (or executable) will not see
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* activated USDT semaphore. In short, it's best to use unique USDT group:name
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* identifiers across different shared libraries (and, equivalently, between
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* executable and shared library). This is advanced consideration and is
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* rarely (if ever) seen in practice, but just to avoid surprises this is
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* called out here. (Static libraries become a part of final executable, once
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* linked by linker, so the above considerations don't apply to them.)
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*/
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#ifdef __usdt_va_opt
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#define USDT_WITH_SEMA(group, name, ...) \
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__usdt_probe(group, name, \
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__usdt_sema_implicit, __usdt_sema_name(group, name) \
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__VA_OPT__(,) __VA_ARGS__)
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#else
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#define USDT_WITH_SEMA(group, name, ...) \
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__usdt_probe(group, name, \
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__usdt_sema_implicit, __usdt_sema_name(group, name), \
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##__VA_ARGS__)
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#endif
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struct usdt_sema { volatile unsigned short active; };
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/*
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* Check if USDT with `group`:`name` identifier is "active" (i.e., whether it
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* is attached to by external tracing tooling and is actively observed).
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*
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* This macro can be used to decide whether any additional and potentially
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* expensive data collection or processing should be done to pass extra
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* information into the given USDT. It is assumed that USDT is triggered with
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* USDT_WITH_SEMA() macro which will implicitly define associated USDT
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* semaphore. (If one needs more control over USDT semaphore, see
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* USDT_DEFINE_SEMA() and USDT_WITH_EXPLICIT_SEMA() macros below.)
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*
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* N.B. Such checks are necessarily racy and speculative. Between checking
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* whether USDT is active and triggering the USDT itself, tracer can be
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* detached with no notification. This race should be extremely rare and worst
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* case should result in one-time wasted extra data collection and processing.
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*/
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#define USDT_IS_ACTIVE(group, name) ({ \
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extern struct usdt_sema __usdt_sema_name(group, name) \
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__usdt_asm_name(__usdt_sema_name(group, name)); \
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__usdt_sema_implicit(__usdt_sema_name(group, name)); \
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__usdt_sema_name(group, name).active > 0; \
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})
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/*
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* APIs for working with user-defined explicit USDT semaphores.
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*
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* This is a less commonly used advanced API for use cases in which user needs
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* an explicit control over (potentially shared across multiple USDTs) USDT
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* semaphore instance. This can be used when there is a group of logically
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* related USDTs that all need extra data collection and processing whenever
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* any of a family of related USDTs are "activated" (i.e., traced). In such
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* a case, all such related USDTs will be associated with the same shared USDT
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* semaphore defined with USDT_DEFINE_SEMA() and the USDTs themselves will be
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* triggered with USDT_WITH_EXPLICIT_SEMA() macros, taking an explicit extra
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* USDT semaphore identifier as an extra parameter.
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*/
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/**
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* Underlying C global variable name for user-defined USDT semaphore with
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* `sema` identifier. Could be useful for debugging, but normally shouldn't be
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* used explicitly.
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*/
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#define USDT_SEMA(sema) __usdt_sema_##sema
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/*
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* Define storage for user-defined USDT semaphore `sema`.
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*
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* Should be used only once in non-header source file to let compiler allocate
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* space for the semaphore variable. Just like with any other global variable.
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*
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* This macro can be used anywhere where global variable declaration is
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* allowed. Just like with global variable definitions, there should be only
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* one definition of user-defined USDT semaphore with given `sema` identifier,
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* otherwise compiler or linker will complain about duplicate variable
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* definition.
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*
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* For C++, it is allowed to use USDT_DEFINE_SEMA() both in global namespace
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* and inside namespaces (including nested namespaces). Just make sure that
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* USDT_DECLARE_SEMA() is placed within the namespace where this semaphore is
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* referenced, or any of its parent namespaces, so the C++ language-level
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* identifier is visible to the code that needs to reference the semaphore.
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* At the lowest layer, USDT semaphores have global naming and visibility
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* (they have a corresponding `__usdt_sema_<name>` symbol, which can be linked
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* against from C or C++ code, if necessary). To keep it simple, putting
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* USDT_DECLARE_SEMA() declarations into global namespaces is the simplest
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* no-brainer solution. All these aspects are irrelevant for plain C, because
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* C doesn't have namespaces and everything is always in the global namespace.
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*
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* N.B. Due to USDT metadata being recorded in non-allocatable ELF note
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* section, it has limitations when it comes to relocations, which, in
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* practice, means that it's not possible to correctly share USDT semaphores
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* between main executable and shared libraries, or even between multiple
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* shared libraries. USDT semaphore has to be contained to individual shared
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* library or executable to avoid unpleasant surprises with half-working USDT
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* semaphores. We enforce this by marking semaphore ELF symbols as having
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* a hidden visibility. This is quite an advanced use case and consideration
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* and for most users this should have no consequences whatsoever.
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*/
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#define USDT_DEFINE_SEMA(sema) \
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struct usdt_sema __usdt_sema_sec USDT_SEMA(sema) \
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__usdt_asm_name(USDT_SEMA(sema)) \
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__attribute__((visibility("hidden"))) = { 0 }
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/*
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* Declare extern reference to user-defined USDT semaphore `sema`.
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*
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* Refers to a variable defined in another compilation unit by
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* USDT_DEFINE_SEMA() and allows to use the same USDT semaphore across
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* multiple compilation units (i.e., .c and .cpp files).
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*
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* See USDT_DEFINE_SEMA() notes above for C++ language usage peculiarities.
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*/
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#define USDT_DECLARE_SEMA(sema) \
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extern struct usdt_sema USDT_SEMA(sema) __usdt_asm_name(USDT_SEMA(sema))
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/*
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* Check if user-defined USDT semaphore `sema` is "active" (i.e., whether it
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* is attached to by external tracing tooling and is actively observed).
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*
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* This macro can be used to decide whether any additional and potentially
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* expensive data collection or processing should be done to pass extra
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* information into USDT(s) associated with USDT semaphore `sema`.
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*
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* N.B. Such checks are necessarily racy. Between checking the state of USDT
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* semaphore and triggering associated USDT(s), the active tracer might attach
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* or detach. This race should be extremely rare and worst case should result
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* in one-time missed USDT event or wasted extra data collection and
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* processing. USDT-using tracers should be written with this in mind and is
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* not a concern of the application defining USDTs with associated semaphore.
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*/
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#define USDT_SEMA_IS_ACTIVE(sema) (USDT_SEMA(sema).active > 0)
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/*
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* Invoke USDT specified by `group` and `name` identifiers and associate
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* explicitly user-defined semaphore `sema` with it. Pass through `args` as
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* USDT arguments. `args` are optional and zero arguments are acceptable.
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*
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* Semaphore is defined with the help of USDT_DEFINE_SEMA() macro and can be
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* checked whether active with USDT_SEMA_IS_ACTIVE().
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*/
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#ifdef __usdt_va_opt
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#define USDT_WITH_EXPLICIT_SEMA(sema, group, name, ...) \
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__usdt_probe(group, name, __usdt_sema_explicit, USDT_SEMA(sema), ##__VA_ARGS__)
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#else
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#define USDT_WITH_EXPLICIT_SEMA(sema, group, name, ...) \
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__usdt_probe(group, name, __usdt_sema_explicit, USDT_SEMA(sema) __VA_OPT__(,) __VA_ARGS__)
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#endif
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/*
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* Adjustable implementation aspects
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*/
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#ifndef USDT_ARG_CONSTRAINT
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#if defined __powerpc__
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#define USDT_ARG_CONSTRAINT nZr
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#elif defined __arm__
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#define USDT_ARG_CONSTRAINT g
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#elif defined __loongarch__
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#define USDT_ARG_CONSTRAINT nmr
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#else
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#define USDT_ARG_CONSTRAINT nor
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#endif
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#endif /* USDT_ARG_CONSTRAINT */
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#ifndef USDT_NOP
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#if defined(__ia64__) || defined(__s390__) || defined(__s390x__)
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#define USDT_NOP nop 0
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#else
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#define USDT_NOP nop
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#endif
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#endif /* USDT_NOP */
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/*
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* Implementation details
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*/
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/* USDT name for implicitly-defined USDT semaphore, derived from group:name */
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#define __usdt_sema_name(group, name) __usdt_sema_##group##__##name
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/* ELF section into which USDT semaphores are put */
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#define __usdt_sema_sec __attribute__((section(".probes")))
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#define __usdt_concat(a, b) a ## b
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#define __usdt_apply(fn, n) __usdt_concat(fn, n)
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#ifndef __usdt_nth
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#define __usdt_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, N, ...) N
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#endif
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#ifndef __usdt_narg
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#ifdef __usdt_va_opt
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#define __usdt_narg(...) __usdt_nth(_ __VA_OPT__(,) __VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
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#else
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#define __usdt_narg(...) __usdt_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
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#endif
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#endif /* __usdt_narg */
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#define __usdt_hash #
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#define __usdt_str_(x) #x
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#define __usdt_str(x) __usdt_str_(x)
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#ifndef __usdt_asm_name
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#define __usdt_asm_name(name) __asm__(__usdt_str(name))
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#endif
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#define __usdt_asm0() "\n"
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#define __usdt_asm1(x) __usdt_str(x) "\n"
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#define __usdt_asm2(x, ...) __usdt_str(x) "," __usdt_asm1(__VA_ARGS__)
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#define __usdt_asm3(x, ...) __usdt_str(x) "," __usdt_asm2(__VA_ARGS__)
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#define __usdt_asm4(x, ...) __usdt_str(x) "," __usdt_asm3(__VA_ARGS__)
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#define __usdt_asm5(x, ...) __usdt_str(x) "," __usdt_asm4(__VA_ARGS__)
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#define __usdt_asm6(x, ...) __usdt_str(x) "," __usdt_asm5(__VA_ARGS__)
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#define __usdt_asm7(x, ...) __usdt_str(x) "," __usdt_asm6(__VA_ARGS__)
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#define __usdt_asm8(x, ...) __usdt_str(x) "," __usdt_asm7(__VA_ARGS__)
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#define __usdt_asm9(x, ...) __usdt_str(x) "," __usdt_asm8(__VA_ARGS__)
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#define __usdt_asm10(x, ...) __usdt_str(x) "," __usdt_asm9(__VA_ARGS__)
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#define __usdt_asm11(x, ...) __usdt_str(x) "," __usdt_asm10(__VA_ARGS__)
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#define __usdt_asm12(x, ...) __usdt_str(x) "," __usdt_asm11(__VA_ARGS__)
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#define __usdt_asm(...) __usdt_apply(__usdt_asm, __usdt_narg(__VA_ARGS__))(__VA_ARGS__)
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#ifdef __LP64__
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#define __usdt_asm_addr .8byte
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#else
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#define __usdt_asm_addr .4byte
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#endif
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#define __usdt_asm_strz_(x) __usdt_asm1(.asciz #x)
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#define __usdt_asm_strz(x) __usdt_asm_strz_(x)
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#define __usdt_asm_str_(x) __usdt_asm1(.ascii #x)
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#define __usdt_asm_str(x) __usdt_asm_str_(x)
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/* "semaphoreless" USDT case */
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#ifndef __usdt_sema_none
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#define __usdt_sema_none(sema)
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#endif
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/* implicitly defined __usdt_sema__group__name semaphore (using weak symbols) */
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#ifndef __usdt_sema_implicit
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#define __usdt_sema_implicit(sema) \
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__asm__ __volatile__ ( \
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__usdt_asm1(.ifndef sema) \
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__usdt_asm3( .pushsection .probes, "aw", "progbits") \
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__usdt_asm1( .weak sema) \
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__usdt_asm1( .hidden sema) \
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__usdt_asm1( .align 2) \
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__usdt_asm1(sema:) \
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__usdt_asm1( .zero 2) \
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__usdt_asm2( .type sema, @object) \
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__usdt_asm2( .size sema, 2) \
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__usdt_asm1( .popsection) \
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__usdt_asm1(.endif) \
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);
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#endif
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/* externally defined semaphore using USDT_DEFINE_SEMA() and passed explicitly by user */
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#ifndef __usdt_sema_explicit
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#define __usdt_sema_explicit(sema) \
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__asm__ __volatile__ ("" :: "m" (sema));
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#endif
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/* main USDT definition (nop and .note.stapsdt metadata) */
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#define __usdt_probe(group, name, sema_def, sema, ...) do { \
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sema_def(sema) \
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__asm__ __volatile__ ( \
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__usdt_asm( 990: USDT_NOP) \
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__usdt_asm3( .pushsection .note.stapsdt, "", "note") \
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__usdt_asm1( .balign 4) \
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__usdt_asm3( .4byte 992f-991f,994f-993f,3) \
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__usdt_asm1(991: .asciz "stapsdt") \
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__usdt_asm1(992: .balign 4) \
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__usdt_asm1(993: __usdt_asm_addr 990b) \
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__usdt_asm1( __usdt_asm_addr _.stapsdt.base) \
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__usdt_asm1( __usdt_asm_addr sema) \
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|
__usdt_asm_strz(group) \
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|
__usdt_asm_strz(name) \
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|
__usdt_asm_args(__VA_ARGS__) \
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__usdt_asm1( .ascii "\0") \
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|
__usdt_asm1(994: .balign 4) \
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|
__usdt_asm1( .popsection) \
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__usdt_asm1(.ifndef _.stapsdt.base) \
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__usdt_asm5( .pushsection .stapsdt.base,"aG","progbits",.stapsdt.base,comdat)\
|
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__usdt_asm1( .weak _.stapsdt.base) \
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__usdt_asm1( .hidden _.stapsdt.base) \
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|
__usdt_asm1(_.stapsdt.base:) \
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|
__usdt_asm1( .space 1) \
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|
__usdt_asm2( .size _.stapsdt.base, 1) \
|
|
__usdt_asm1( .popsection) \
|
|
__usdt_asm1(.endif) \
|
|
:: __usdt_asm_ops(__VA_ARGS__) \
|
|
); \
|
|
} while (0)
|
|
|
|
/*
|
|
* NB: gdb PR24541 highlighted an unspecified corner of the sdt.h
|
|
* operand note format.
|
|
*
|
|
* The named register may be a longer or shorter (!) alias for the
|
|
* storage where the value in question is found. For example, on
|
|
* i386, 64-bit value may be put in register pairs, and a register
|
|
* name stored would identify just one of them. Previously, gcc was
|
|
* asked to emit the %w[id] (16-bit alias of some registers holding
|
|
* operands), even when a wider 32-bit value was used.
|
|
*
|
|
* Bottom line: the byte-width given before the @ sign governs. If
|
|
* there is a mismatch between that width and that of the named
|
|
* register, then a sys/sdt.h note consumer may need to employ
|
|
* architecture-specific heuristics to figure out where the compiler
|
|
* has actually put the complete value.
|
|
*/
|
|
#if defined(__powerpc__) || defined(__powerpc64__)
|
|
#define __usdt_argref(id) %I[id]%[id]
|
|
#elif defined(__i386__)
|
|
#define __usdt_argref(id) %k[id] /* gcc.gnu.org/PR80115 sourceware.org/PR24541 */
|
|
#else
|
|
#define __usdt_argref(id) %[id]
|
|
#endif
|
|
|
|
#define __usdt_asm_arg(n) __usdt_asm_str(%c[__usdt_asz##n]) \
|
|
__usdt_asm1(.ascii "@") \
|
|
__usdt_asm_str(__usdt_argref(__usdt_aval##n))
|
|
|
|
#define __usdt_asm_args0 /* no arguments */
|
|
#define __usdt_asm_args1 __usdt_asm_arg(1)
|
|
#define __usdt_asm_args2 __usdt_asm_args1 __usdt_asm1(.ascii " ") __usdt_asm_arg(2)
|
|
#define __usdt_asm_args3 __usdt_asm_args2 __usdt_asm1(.ascii " ") __usdt_asm_arg(3)
|
|
#define __usdt_asm_args4 __usdt_asm_args3 __usdt_asm1(.ascii " ") __usdt_asm_arg(4)
|
|
#define __usdt_asm_args5 __usdt_asm_args4 __usdt_asm1(.ascii " ") __usdt_asm_arg(5)
|
|
#define __usdt_asm_args6 __usdt_asm_args5 __usdt_asm1(.ascii " ") __usdt_asm_arg(6)
|
|
#define __usdt_asm_args7 __usdt_asm_args6 __usdt_asm1(.ascii " ") __usdt_asm_arg(7)
|
|
#define __usdt_asm_args8 __usdt_asm_args7 __usdt_asm1(.ascii " ") __usdt_asm_arg(8)
|
|
#define __usdt_asm_args9 __usdt_asm_args8 __usdt_asm1(.ascii " ") __usdt_asm_arg(9)
|
|
#define __usdt_asm_args10 __usdt_asm_args9 __usdt_asm1(.ascii " ") __usdt_asm_arg(10)
|
|
#define __usdt_asm_args11 __usdt_asm_args10 __usdt_asm1(.ascii " ") __usdt_asm_arg(11)
|
|
#define __usdt_asm_args12 __usdt_asm_args11 __usdt_asm1(.ascii " ") __usdt_asm_arg(12)
|
|
#define __usdt_asm_args(...) __usdt_apply(__usdt_asm_args, __usdt_narg(__VA_ARGS__))
|
|
|
|
#define __usdt_is_arr(x) (__builtin_classify_type(x) == 14 || __builtin_classify_type(x) == 5)
|
|
#define __usdt_arg_size(x) (__usdt_is_arr(x) ? sizeof(void *) : sizeof(x))
|
|
|
|
/*
|
|
* We can't use __builtin_choose_expr() in C++, so fall back to table-based
|
|
* signedness determination for known types, utilizing templates magic.
|
|
*/
|
|
#ifdef __cplusplus
|
|
|
|
#define __usdt_is_signed(x) (!__usdt_is_arr(x) && __usdt_t<__typeof(x)>::is_signed)
|
|
|
|
#include <cstddef>
|
|
|
|
template<typename T> struct __usdt_t { static const bool is_signed = false; };
|
|
template<typename A> struct __usdt_t<A[]> : public __usdt_t<A *> {};
|
|
template<typename A, size_t N> struct __usdt_t<A[N]> : public __usdt_t<A *> {};
|
|
|
|
#define __usdt_def_signed(T) \
|
|
template<> struct __usdt_t<T> { static const bool is_signed = true; }; \
|
|
template<> struct __usdt_t<const T> { static const bool is_signed = true; }; \
|
|
template<> struct __usdt_t<volatile T> { static const bool is_signed = true; }; \
|
|
template<> struct __usdt_t<const volatile T> { static const bool is_signed = true; }
|
|
#define __usdt_maybe_signed(T) \
|
|
template<> struct __usdt_t<T> { static const bool is_signed = (T)-1 < (T)1; }; \
|
|
template<> struct __usdt_t<const T> { static const bool is_signed = (T)-1 < (T)1; }; \
|
|
template<> struct __usdt_t<volatile T> { static const bool is_signed = (T)-1 < (T)1; }; \
|
|
template<> struct __usdt_t<const volatile T> { static const bool is_signed = (T)-1 < (T)1; }
|
|
|
|
__usdt_def_signed(signed char);
|
|
__usdt_def_signed(short);
|
|
__usdt_def_signed(int);
|
|
__usdt_def_signed(long);
|
|
__usdt_def_signed(long long);
|
|
__usdt_maybe_signed(char);
|
|
__usdt_maybe_signed(wchar_t);
|
|
|
|
#else /* !__cplusplus */
|
|
|
|
#define __usdt_is_inttype(x) (__builtin_classify_type(x) >= 1 && __builtin_classify_type(x) <= 4)
|
|
#define __usdt_inttype(x) __typeof(__builtin_choose_expr(__usdt_is_inttype(x), (x), 0U))
|
|
#define __usdt_is_signed(x) ((__usdt_inttype(x))-1 < (__usdt_inttype(x))1)
|
|
|
|
#endif /* __cplusplus */
|
|
|
|
#define __usdt_asm_op(n, x) \
|
|
[__usdt_asz##n] "n" ((__usdt_is_signed(x) ? (int)-1 : 1) * (int)__usdt_arg_size(x)), \
|
|
[__usdt_aval##n] __usdt_str(USDT_ARG_CONSTRAINT)(x)
|
|
|
|
#define __usdt_asm_ops0() [__usdt_dummy] "g" (0)
|
|
#define __usdt_asm_ops1(x) __usdt_asm_op(1, x)
|
|
#define __usdt_asm_ops2(a,x) __usdt_asm_ops1(a), __usdt_asm_op(2, x)
|
|
#define __usdt_asm_ops3(a,b,x) __usdt_asm_ops2(a,b), __usdt_asm_op(3, x)
|
|
#define __usdt_asm_ops4(a,b,c,x) __usdt_asm_ops3(a,b,c), __usdt_asm_op(4, x)
|
|
#define __usdt_asm_ops5(a,b,c,d,x) __usdt_asm_ops4(a,b,c,d), __usdt_asm_op(5, x)
|
|
#define __usdt_asm_ops6(a,b,c,d,e,x) __usdt_asm_ops5(a,b,c,d,e), __usdt_asm_op(6, x)
|
|
#define __usdt_asm_ops7(a,b,c,d,e,f,x) __usdt_asm_ops6(a,b,c,d,e,f), __usdt_asm_op(7, x)
|
|
#define __usdt_asm_ops8(a,b,c,d,e,f,g,x) __usdt_asm_ops7(a,b,c,d,e,f,g), __usdt_asm_op(8, x)
|
|
#define __usdt_asm_ops9(a,b,c,d,e,f,g,h,x) __usdt_asm_ops8(a,b,c,d,e,f,g,h), __usdt_asm_op(9, x)
|
|
#define __usdt_asm_ops10(a,b,c,d,e,f,g,h,i,x) __usdt_asm_ops9(a,b,c,d,e,f,g,h,i), __usdt_asm_op(10, x)
|
|
#define __usdt_asm_ops11(a,b,c,d,e,f,g,h,i,j,x) __usdt_asm_ops10(a,b,c,d,e,f,g,h,i,j), __usdt_asm_op(11, x)
|
|
#define __usdt_asm_ops12(a,b,c,d,e,f,g,h,i,j,k,x) __usdt_asm_ops11(a,b,c,d,e,f,g,h,i,j,k), __usdt_asm_op(12, x)
|
|
#define __usdt_asm_ops(...) __usdt_apply(__usdt_asm_ops, __usdt_narg(__VA_ARGS__))(__VA_ARGS__)
|
|
|
|
#endif /* __USDT_H */
|