IBM Mainframe Forum

bobguo wrote:This is some dump under RMODE ANY:

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COMPLETION CODE      SYSTEM = 0C4      REASON CODE = 00000010           
                                                                       
  PSW AT ENTRY TO ABEND   078C0000  00DD2EAC  ILC  04  INTC  0010       
PSW ADDRESS 00DD2EAC AT TIME OF ERROR DOES NOT POINT TO AN ACTIVE MODULE
...
IEA995I SYMPTOM DUMP OUTPUT  333                           
SYSTEM COMPLETION CODE=0C4  REASON CODE=00000010           
 TIME=10.03.02  SEQ=06443  CPU=0000  ASID=0017             
 PSW AT TIME OF ERROR  078C0000   00DD2EAC  ILC 4  INTC 10
   NO ACTIVE MODULE FOUND                                 
   NAME=UNKNOWN                                           
   DATA AT PSW  00DD2EA6 - 1B224111  0000BF27  10014770   
   GR 0: FD000008   1: 00600E9C                           
      2: 00000000   3: 00DD24CA                           
      4: 008EA188   5: 008FCD08                           
      6: 92600E9C   7: 00F75000                           
      8: 00000000   9: 80FFC89C                           
      A: 008FCDC8   B: 008EA188                           
      C: 92600E8E   D: 12600FB4                           
      E: 90DD2510   F: 008EA188                           
 END OF SYMPTOM DUMP

first of all, i'm sorry for more questions about it.
1. when the abend happened, this program should run with rmode=31, but why AMODE bit in the PSW is 0?
2. my source code uses R12 as base register, why 'C: 92600E8E' right now? i thought it should be 'C: 12600E8E'
3. in general, when 'PSW ADDRESS 00DD2EAC AT TIME OF ERROR DOES NOT POINT TO AN ACTIVE MODULE' appeared, i can NOT find anything useful from dump, can you share some experiences about it?
thanks.

Bob

1. If "should run" and "is running" are different, it is the job of the analyst to deduce the reason.
2. It is the job of the analyst to deduce what is going on.
3. The DATA AT PSW is sometimes useful. In this case we see
   
   SR 2,2
   LA 1,0(,1)
   ICM 2,B'0111',0(1)
   BNE ???
   
   Now you are probably wondering how I deduced this. After a while an analyst will memorize some of the more common op-codes. It took me a little before I recalled BF, and 1B bothered me a little, but 41 and 47 are so common I didn't have to think about them. The 7 condition mask in 4770 is also very common.
   
   The LA is dangerous since it is AMODE dependent. This used to be common in AMODE 24 code, but it is dangerous. Only the first two bytes of the BNE are in the Symptom dump, but even if they were there the last 2 bytes of the BNE would not be very useful.
   
   Since INTC is not 04, the error was detected by the paging hardware rather than a storage key issue, so the ICM is the failing instruction. Had INTC been 04, the LA would have (in theory, since LA does not access storage) been the failing instruction.
   
   ICM is a single address instruction; its base register is 1, which was compromised by the LA instruction.

These users thanked the author steve-myers for the post:

bobguo (Fri Nov 01, 2013 11:21 am)

1. You have been told repeatedly that any DCB you are going to use must be below the 16 meg line.
2. When you linked the module you received a message like this: IEW2635I 4B34 THREE BYTE ADCON IN SECTION xxxxxx AT OFFSET xxxxxxxx IN CLASS B_TEXT WITH RMODE=ANY CANNOT BE RELOCATED. It seems to me the load module should be marked not executable, but it isn't. This message should also say DO NOT ATTEMPT TO EXECUTE THIS LOAD MODULE!
3. Your save area setup does not match any example you have been given. Why?

These users thanked the author steve-myers for the post:

bobguo (Fri Nov 01, 2013 11:17 am)

You have been told repeatedly that any DCB you are going to use must be below the 16 meg line.

When you linked the module you received a message like this: IEW2635I 4B34 THREE BYTE ADCON IN SECTION xxxxxx AT OFFSET xxxxxxxx IN CLASS B_TEXT WITH RMODE=ANY CANNOT BE RELOCATED. It seems to me the load module should be marked not executable, but it isn't. This message should also say DO NOT ATTEMPT TO EXECUTE THIS LOAD MODULE!

Since INTC is not 04, the error was detected by the paging hardware rather than a storage key issue, so the ICM is the failing instruction. Had INTC been 04, the LA would have (in theory, since LA does not access storage) been the failing instruction.

ICM is a single address instruction; its base register is 1, which was compromised by the LA instruction.

• Just the fact the system is in AMODE 24.
• An analysis of the PSW clearly shows supervisor state rather than problem state. The first two bytes are X'078C'. The 07 is the interrupt mask, which is usually 7. 8 is the protect key; it's 8 because OPEN presumably is getting data from user storage. Almost all user programs run in key 8. C is miscellaneous flags. One of the flags - which is not on - is for problem state. I use this so infrequently I had to look it up! If you were in problem state the C would be D.

AMODE is a hint to the Assembler and Linkage Editor to tell the OS to EXECUTE the program in 24/31/64 bit.
RMODE is a hint to the Assembler and Linkage Editor to tell the OS to LOAD the program below 16M or 2G, if needed.