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> /* Definition of S390_* constants */
10       #include <sys/syscall.h>       /* Definition of SYS_* constants */
11       #include <unistd.h>
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13       int syscall(SYS_s390_runtime_instr, int command, int signum);
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15       Note: glibc provides no wrapper for s390_runtime_instr(), necessitating
16       the use of syscall(2).
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DESCRIPTION

19       The s390_runtime_instr() system call starts or stops CPU  run-time  in‐
20       strumentation for the calling thread.
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22       The  command  argument  controls  whether  run-time  instrumentation is
23       started  (S390_RUNTIME_INSTR_START,  1)  or  stopped  (S390_RUNTIME_IN‐
24       STR_STOP, 2) for the calling thread.
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26       The  signum  argument specifies the number of a real-time signal.  This
27       argument was used to specify a signal number that should  be  delivered
28       to the thread if the run-time instrumentation buffer was full or if the
29       run-time-instrumentation-halted interrupt had occurred.   This  feature
30       was  never used, and in Linux 4.4 support for this feature was removed;
31       thus, in current kernels, this argument is ignored.
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RETURN VALUE

34       On success, s390_runtime_instr() returns 0 and enables the  thread  for
35       run-time instrumentation by assigning the thread a default run-time in‐
36       strumentation control block.  The caller can then read and  modify  the
37       control  block and start the run-time instrumentation.  On error, -1 is
38       returned and errno is set to indicate the error.
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ERRORS

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

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

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

62       The asm/runtime_instr.h header file is available since Linux 4.16.
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64       Starting with Linux 4.4, support for signalling was removed, as was the
65       check whether signum is a valid real-time signal.  For  backwards  com‐
66       patibility  with older kernels, it is recommended to pass a valid real-
67       time signal number in signum and install a handler for that signal.
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COLOPHON

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74       description  of  the project, information about reporting bugs, and the
75       latest    version    of    this    page,    can     be     found     at
76       https://www.kernel.org/doc/man-pages/.
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80Linux Programmer's Manual         2021-03-22             S390_RUNTIME_INSTR(2)