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[Bug testsuite/4794] backtrace of yyy_func3 and print_stack of yyy_func3 fails on ppc64.


------- Additional Comments From srinivasa at in dot ibm dot com  2008-01-16 14:17 -------
Jim
Since we are missing 2 frame information in backtrace output of ppc64(as shown 
below),I looked in to backtrace code(runtime/stack-ppc64.c) for ppc64 and got 
some doubts.
could you please clarify.
==============
backtrace from module("systemtap_test_module2").function("yyy_func3@/home/
systemtap/tmp/stap_testing_200801141002/src/testsuite/systemtap.cont:^M
 0xd000000000bf000c : .yyy_func3+0x0/0x28 [systemtap_test_module2]^M
[0xc00000005d8938e8] [0x00000000000004d2] 0x00000000000004d2 (unreliable)^M
[0xc00000005d893b60] [0xc00000005d893c60] 0xc00000005d893c60^M
[0xc00000005d893be0] [0xd000000000bf006c] 0xd000000000bf006c : .yyy_func1+0x10/
0x28 [systemtap_test_module2]^M
[0xc00000005d893c60] [0xd000000000a2014c] 0xd000000000a2014c
 : .stm_write_cmd+0xa4/0x0 [systemtap_test_module1]^M
[0xc00000005d893cf0] [0xc0000000000ed31c] 0xc0000000000ed31c : .vfs_write+0x118/
0x200 []^M
[0xc00000005d893d90] [0xc0000000000eda8c] 0xc0000000000eda8c : .sys_write+0x4c/
0x8c []^M
[0xc00000005d893e30] [0xc0000000000086a4] 0xc0000000000086a4 : syscall_exit+0x0/
0x40 []^M
==============================
 

1) while unwinding the stack, we are not starting from REGS_SP but one frame 
below from that, 
 In above case REGS_SP = 0xc00000005d893b60 but we unwind from 
0xc00000005d8938e8.

2) Even I tried unwinding from REGS_SP, but to my surprise, I found that IP 
value from the stack( ip = _sp[2]) is not same as REGS_IP and hence we are not 
seeing symbol for first 2 frames.

 


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ananth at in dot ibm dot
                   |                            |com, jkenisto at us dot ibm
                   |                            |dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=4794

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