Determining the status of run-time-instrumentation controls

• US 9,250,903 B2
• Filed: 03/11/2013
• Issued: 02/02/2016
• Est. Priority Date: 03/16/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Farrell, Mark S., Gainey, Charles W. Jr., Shum, Chung-Lung K., Smith, Brian L.
• Primary Examiner(s): GEIB, BENJAMIN P
• Application Number:
  US13/792,276
• Publication Number:
  US 20130246748A1
• Time in Patent Office: 1,058 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/3648 using additional hardware
• CPC Class Codes: G06F 9/30021 Compare instructions, e.g. Greater-Than, Equal-To, MINMAX
• CPC Class Codes: G06F 9/3005 to perform operations for flow control
• CPC Class Codes: G06F 9/30076 to perform miscellaneous control operations, e.g. NOP
• CPC Class Codes: G06F 9/30101 Special purpose registers
• CPC Class Codes: G06F 9/30145 Instruction analysis, e.g. decoding, instruction word fields
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines

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.

Claims

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.