Determining the status of run-time-instrumentation controls

Patent metadata

Field	Value
Publication number	US-9250903-B2
Application number	US-201313792276-A
Country	US
Kind code	B2
Filing date	Mar 11, 2013
Priority date	Mar 16, 2012
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

The invention relates to determining the status of run-time-instrumentation controls. The status is determined by executing a test run-time-instrumentation controls (TRIC) instruction. The TRIC instruction is executed in either a supervisor state or a lesser-privileged state. The TRIC instruction determines whether the run-time-instrumentation controls have changed. The run-time-instrumentation controls are set to an initial value using a privileged load run-time-instrumentation controls (LRIC) instruction. The TRIC instruction is fetched and executed. If the TRIC instruction is enabled, then it is determined if the initial value set by the run-time-instrumentation controls has been changed. If the initial value set by the run-time-instrumentation controls has been changed, then a condition code is set to a first value.

First claim

What is claimed is:

1. A computer implemented method for modifying run-time-instrumentation controls from a lesser-privileged state, the method comprising:
setting a set of run-time-instrumentation controls to an initial value using a privileged load run-time-instrumentation controls (LRIC) instruction;
fetching a test run-time-instrumentation controls (TRIC) instruction;
executing the TRIC instruction, the executing comprising:
determining whether the TRIC instruction is enabled;
based on determining that the TRIC instruction is enabled, determining whether the initial value set by the run-time-instrumentation controls has been changed;
based on determining that the initial value set by the run-time-instrumentation controls has been changed, setting a condition code to a first value; and
based on determining that the TRIC instruction is not-enabled, setting the condition code to a second value, the second value indicating execution of the TRIC instruction in a problem state is not permitted.

2. The method according to claim 1 , wherein determining that the TRIC instruction is enabled comprises any one of:
based on the TRIC instruction being executed in supervisor mode, determining that the TRIC instruction is enabled; and
based on the TRIC instruction being executed in the lesser-privileged state and a field of the run-time-instrumentation controls is set.

3. The method according to claim 1 , wherein the determining the initial value set by the run-time-instrumentation controls has changed comprises determining that a valid field of the run-time-instrumentation controls indicates that the run-time-instrumentation controls are valid and an initial value indicator implicitly enabled by the LRIC instruction is not-enabled.

4. The method according to claim 3 , further comprising:
executing a modify run-time-instrumentation controls (MRIC) instruction, the MRIC instruction causing the initial value indicator to be not-enabled, the MRIC instruction, executable in problem state, and only having access to a sub-set of run-time-instrumentation controls accessible to the LRIC instruction.

5. The method according to claim 1 , further comprising based on determining the initial value set by the run-time-instrumentation controls has not been changed, setting the condition code to a third value.

6. The method according to claim 5 , wherein the determining the initial value set by the run-time-instrumentation controls has not changed comprises determining that a valid field of the run-time-instrumentation controls indicates that the run-time-instrumentation controls are valid and an initial value indicator implicitly enabled by the LRIC instruction is enabled.

7. The method according to claim 1 , further comprising:
based on determining that the run-time-instrumentation controls are not valid setting the condition code to a fourth value.

Assignees

• IBM
• Internat Business Machinecs Corp

Inventors

• Farrell Mark S
• Gainey Jr Charles W
• Shum Chung-Lung K
• Smith Brian L

Classifications

• G06F11/3648

  using additional hardware · CPC title

• G06F11/3636

  by tracing the execution of the program · CPC title

• G06F9/455

  Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines · CPC title

• G06F9/3005 Primary

  to perform operations for flow control · CPC title

• G06F9/30145 Primary

  Instruction analysis, e.g. decoding, instruction word fields · CPC title