1  /* Macros for defining Systemtap <sys/sdt.h> static probe points.
       2     Copyright (C) 2012-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _STAP_PROBE_H
      20  #define _STAP_PROBE_H 1
      21  
      22  #ifdef USE_STAP_PROBE
      23  
      24  # include <stap-probe-machine.h>
      25  # include <sys/sdt.h>
      26  
      27  /* Our code uses one macro LIBC_PROBE (name, n, arg1, ..., argn).
      28  
      29     Without USE_STAP_PROBE, that does nothing but evaluates all
      30     its arguments (to prevent bit rot, unlike e.g. assert).
      31  
      32     Systemtap's header defines the macros STAP_PROBE (provider, name) and
      33     STAP_PROBEn (provider, name, arg1, ..., argn).  For "provider" we paste
      34     in MODULE_NAME (libc, libpthread, etc.) automagically.
      35  
      36     The format of the arg parameters is discussed here:
      37  
      38     https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
      39  
      40     The precise details of how register names are specified is
      41     architecture specific and can be found in the gdb and SystemTap
      42     source code.  */
      43  
      44  # define LIBC_PROBE(name, n, ...)	\
      45    LIBC_PROBE_1 (MODULE_NAME, name, n, ## __VA_ARGS__)
      46  
      47  # define LIBC_PROBE_1(lib, name, n, ...) \
      48    STAP_PROBE##n (lib, name, ## __VA_ARGS__)
      49  
      50  # define STAP_PROBE0		STAP_PROBE
      51  
      52  # define LIBC_PROBE_ASM(name, template) \
      53    STAP_PROBE_ASM (MODULE_NAME, name, template)
      54  
      55  # define LIBC_PROBE_ASM_OPERANDS STAP_PROBE_ASM_OPERANDS
      56  
      57  #else  /* Not USE_STAP_PROBE.  */
      58  
      59  # ifndef __ASSEMBLER__
      60  /* Evaluate all the arguments and verify that N matches their number.  */
      61  #  define LIBC_PROBE(name, n, ...) STAP_PROBE##n (__VA_ARGS__)
      62  
      63  #  define STAP_PROBE0()				do {} while (0)
      64  #  define STAP_PROBE1(a1)			do {} while (0)
      65  #  define STAP_PROBE2(a1, a2)			do {} while (0)
      66  #  define STAP_PROBE3(a1, a2, a3)		do {} while (0)
      67  #  define STAP_PROBE4(a1, a2, a3, a4)		do {} while (0)
      68  
      69  # else
      70  #  define LIBC_PROBE(name, n, ...)		/* Nothing.  */
      71  # endif
      72  
      73  # define LIBC_PROBE_ASM(name, template)		/* Nothing.  */
      74  # define LIBC_PROBE_ASM_OPERANDS(n, ...)	/* Nothing.  */
      75  
      76  #endif	/* USE_STAP_PROBE.  */
      77  
      78  #endif	/* stap-probe.h */