b4f12ca391
Add a comment pointing to the SystemTap wiki page that documents the format of the arguments. Also add a pointer to the SystemTap and gdb sources which seem to be the best place to get the architecture specific details. ChangeLog: 2014-02-11 Will Newton <will.newton@linaro.org> * include/stap-probe.h: Add comment about probe argument format.
90 lines
3.0 KiB
C
90 lines
3.0 KiB
C
/* Macros for defining Systemtap <sys/sdt.h> static probe points.
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Copyright (C) 2012-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _STAP_PROBE_H
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#define _STAP_PROBE_H 1
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#ifdef USE_STAP_PROBE
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# include <sys/sdt.h>
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/* Our code uses one macro LIBC_PROBE (name, n, arg1, ..., argn).
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Without USE_STAP_PROBE, that does nothing but evaluates all
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its arguments (to prevent bit rot, unlike e.g. assert).
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Systemtap's header defines the macros STAP_PROBE (provider, name) and
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STAP_PROBEn (provider, name, arg1, ..., argn). For "provider" we paste
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in the IN_LIB name (libc, libpthread, etc.) automagically.
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The format of the arg parameters is discussed here:
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https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
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The precise details of how register names are specified is
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architecture specific and can be found in the gdb and SystemTap
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source code. */
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# ifndef NOT_IN_libc
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# define IN_LIB libc
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# elif !defined IN_LIB
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/* This is intentionally defined with extra unquoted commas in it so
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that macro substitution will bomb out when it is used. We don't
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just use #error here, so that this header can be included by
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other headers that use LIBC_PROBE inside their own macros. We
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only want such headers to fail to compile if those macros are
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actually used in a context where IN_LIB has not been defined. */
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# define IN_LIB ,,,missing -DIN_LIB=... -- not extra-lib.mk?,,,
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# endif
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# define LIBC_PROBE(name, n, ...) \
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LIBC_PROBE_1 (IN_LIB, name, n, ## __VA_ARGS__)
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# define LIBC_PROBE_1(lib, name, n, ...) \
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STAP_PROBE##n (lib, name, ## __VA_ARGS__)
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# define STAP_PROBE0 STAP_PROBE
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# define LIBC_PROBE_ASM(name, template) \
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STAP_PROBE_ASM (IN_LIB, name, template)
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# define LIBC_PROBE_ASM_OPERANDS STAP_PROBE_ASM_OPERANDS
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#else /* Not USE_STAP_PROBE. */
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# ifndef __ASSEMBLER__
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/* Evaluate all the arguments and verify that N matches their number. */
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#define LIBC_PROBE(name, n, ...) STAP_PROBE##n (__VA_ARGS__)
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#define STAP_PROBE0()
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#define STAP_PROBE1(a1)
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#define STAP_PROBE2(a1, a2)
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#define STAP_PROBE3(a1, a2, a3)
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#define STAP_PROBE4(a1, a2, a3, a4)
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# else
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# define LIBC_PROBE(name, n, ...) /* Nothing. */
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# endif
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# define LIBC_PROBE_ASM(name, template) /* Nothing. */
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# define LIBC_PROBE_ASM_OPERANDS(n, ...) /* Nothing. */
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#endif /* USE_STAP_PROBE. */
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#endif /* stap-probe.h */
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