This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |
Other format: | [Raw text] |
Hello, While working on the alpha-tru64 port, I noticed that some backtraces would break: (gdb) bt #0 0x000003000003d3dc in __hstTransferRegistersPC () from /usr/shlib/libpthread.so #1 0x000003000002e694 in __osTransferContext () from /usr/shlib/libpthread.so #2 0x0000030000020e80 in __dspDispatch () from /usr/shlib/libpthread.so Backtrace stopped: previous frame inner to this frame (corrupt stack?) I traced the issue down to computing the wrong value for the SP register for frame #2. As the RA register was saved on the stack at of offset of the SP, we end up computing the wrong return address, leading to the breakage. The 'heuristic' frame unwinder relies on trad frames to compute register values. But we have to handle the case of the SP a little differently because it is not necessarily saved on the stack. In fact, in our case, the code in frame #1 looks like this: 0x000003000002e4b0 <__osTransferContext+0>: ldah gp,16322(t12) 0x000003000002e4b4 <__osTransferContext+4>: unop 0x000003000002e4b8 <__osTransferContext+8>: lda gp,-1168(gp) 0x000003000002e4bc <__osTransferContext+12>: unop 0x000003000002e4c0 <__osTransferContext+16>: lda sp,-64(sp) 0x000003000002e4c4 <__osTransferContext+20>: stq ra,0(sp) 0x000003000002e4c8 <__osTransferContext+24>: stq s0,8(sp) 0x000003000002e4cc <__osTransferContext+28>: stq s1,16(sp) 0x000003000002e4d0 <__osTransferContext+32>: stq s2,24(sp) 0x000003000002e4d4 <__osTransferContext+36>: stq s3,32(sp) 0x000003000002e4d8 <__osTransferContext+40>: stq s4,40(sp) 0x000003000002e4dc <__osTransferContext+44>: stq fp,48(sp) 0x000003000002e4e0 <__osTransferContext+48>: mov sp,fp So the SP has been saved inside the FP register. Fortunately, the prologue parser already determines the frame base (aka the "vfp"), and this frame base is in practice the sp in the caller's frame... 2008-05-29 Joel Brobecker <brobecker@adacore.com> * alpha-tdep.c (alpha_heuristic_frame_prev_register): Fix handling of the SP register. This testcase fixes the problem and was successfully tested with the AdaCore testsuite. I'll commit in a week unless we get some comments... -- Joel
Attachment:
alpha-tdep.c.diff
Description: Text document
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |