s390_runtime_instr(2)

1S390_RUNTIME_INSTR(2)         System Calls Manual        S390_RUNTIME_INSTR(2)
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NAME

6       s390_runtime_instr - enable/disable s390 CPU run-time instrumentation
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SYNOPSIS

9       #include <asm/runtime_instr.h>
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11       int s390_runtime_instr(int command, int signum);
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DESCRIPTION

14       The  s390_runtime_instr()  system  call  starts  or  stops CPU run-time
15       instrumentation for the calling thread.
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17       The command  argument  controls  whether  run-time  instrumentation  is
18       started    (S390_RUNTIME_INSTR_START,    1)   or   stopped   (S390_RUN‐
19       TIME_INSTR_STOP, 2) for the calling thread.
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21       The signum argument specifies the number of a real-time  signal.   This
22       argument  was  used to specify a signal number that should be delivered
23       to the thread if the run-time instrumentation buffer was full or if the
24       run-time-instrumentation-halted  interrupt  had occurred.  This feature
25       was never used, and in Linux 4.4 support for this feature was  removed;
26       thus, in current kernels, this argument is ignored.
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RETURN VALUE

29       On  success,  s390_runtime_instr() returns 0 and enables the thread for
30       run-time instrumentation by assigning the  thread  a  default  run-time
31       instrumentation control block.  The caller can then read and modify the
32       control block and start the run-time instrumentation.  On error, -1  is
33       returned and errno is set to one of the error codes listed below.
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ERRORS

36       EINVAL The value specified in command is not a valid command.
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38       EINVAL The  value specified in signum is not a real-time signal number.
39              From Linux 4.4 onwards, the signum argument has  no  effect,  so
40              that an invalid signal number will not result in an error.
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42       ENOMEM Allocating memory for the run-time instrumentation control block
43              failed.
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45       EOPNOTSUPP
46              The run-time instrumentation facility is not available.
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VERSIONS

49       This system call is available since Linux 3.7.
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CONFORMING TO

52       This Linux-specific system call is available only on the s390 architec‐
53       ture.   The  run-time  instrumentation  facility is available beginning
54       with System z EC12.
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NOTES

57       Glibc does not provide a wrapper for this system call,  use  syscall(2)
58       to call it.
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60       The asm/runtime_instr.h header file is available since Linux 4.16.
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62       Starting with Linux 4.4, support for signalling was removed, as was the
63       check whether signum is a valid real-time signal.  For  backwards  com‐
64       patibility  with older kernels, it is recommended to pass a valid real-
65       time signal number in signum and install a handler for that signal.
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COLOPHON

71       This page is part of release 5.07 of the Linux  man-pages  project.   A
72       description  of  the project, information about reporting bugs, and the
73       latest    version    of    this    page,    can     be     found     at
74       https://www.kernel.org/doc/man-pages/.
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78Linux Programmer's Manual         2020-06-09             S390_RUNTIME_INSTR(2)