2010/4/16 Artyom Tarasenko <atar4q...@googlemail.com>: > 2010/4/15 Artyom Tarasenko <atar4q...@googlemail.com>: >> 2010/4/15 Blue Swirl <blauwir...@gmail.com>: >>> On 4/15/10, Artyom Tarasenko <atar4q...@googlemail.com> wrote: >>>> 2010/4/15 Artyom Tarasenko <atar4q...@googlemail.com>: >>>> >>>> > One of LX's tests crashes pretty hard, causing qemu abort. >>>> > I've tried to look how does the execution flow works with -d in_asm. >>>> > Does the address in the log show the guest's PC register? >>>> >>>> >>>> It's probably sort of a "timing" issue. >>>> >>>> Can we check exceptions not just on jumps, but also on floating poit >>>> operations which may cause a trap? >>>> These traps are supposed to be syncronous. >>> >>> Yes, the bug is that PC and NPC are not saved before executing FPU >>> instructions. Please try this patch. >> >> The patch gets it a couple of tests further: >> >> FPU SP Invalid CEXC Test >> FPU SP Overflow CEXC Test >> FPU SP Divide-by-0 CEXC Test >> FPU SP Inexact CEXC Test >> FPU SP Trap Priority > Test Unassigned mem write access of 4 bytes to >> 000000008421f000 from 700030f8 >> >> FPU SP Trap Priority < Test >> ERROR : Unexpected Synchronous Trap Taken, Trap Type = 00000008, >> PSR = 414010c4, PC = 70003190, TBR = 00000080 >> STATUS : Entering scope loop .... Press <A> key to Abort!qemu: >> fatal: Trap 0x03 while interrupts disabled, Error state >> pc: 0000217c npc: 00003170 >> General Registers: >> %g0-7: 00000000 00003170 00000055 00000001 00000002 00000000 00000000 >> 00000000 >> >> Current Register Window: >> %o0-7: 00000000 00000999 00000000 00000000 00000000 00000000 0001fba0 >> 7000971c >> %l0-7: 0002fff8 00000000 00000000 00000000 00000000 ffffffff 00000000 >> 00000000 >> %i0-7: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> 00000000 >> >> Floating Point Registers: >> %f00: 000000002.890625 000000025.000000 000000000.000000 000000000.000000 >> %f04: 000000002.890625 000000000.000000 000000002.890625 000000000.000000 >> %f08: 000000003.390625 000000000.000000 000000002.250000 000000000.000000 >> %f12: 000000002.890625 000000000.000000 000000002.312500 000000000.000000 >> %f16: 000000002.312500 000000000.000000 000000002.890625 000000000.000000 >> %f20: 000000002.718750 000000000.000000 000000002.562500 000000000.000000 >> %f24: 000000002.890625 000000000.000000 000000002.968750 000000000.000000 >> %f28: 000000002.312500 000000000.000000 000000002.890625 000000000.000000 >> psr: 41000000 (icc: ---- SPE: ---) wim: 00000002 >> fsr: 0f884002 y: 00000000 >> Aborted >> >> >> The code: >> >> 0x70003174: sethi %hi(0x41c80000), %l3 >> 0x70003178: add %l4, 2, %l5 >> 0x7000317c: st %l3, [ %l4 ] >> 0x70003180: ld [ %l4 ], %f1 >> 0x70003184: clr [ %l4 ] >> 0x70003188: ld [ %l4 ], %f2 >> 0x7000318c: mov 7, %g5 >> 0x70003190: fdivs %f1, %f2, %f3 > > And what is even more strange it looks in qemu.log like if trap is taken, > gdb doesn't stop at the 0x080 breakpoint after this operation. > Whether I do a stepi or nexti, it just continues up to the crash. > Let me know if I can provide more information. > > Breakpoint 2, 0x00000080 in ?? () > (gdb) cont > Continuing. > > Breakpoint 6, 0x70003190 in ?? () > (gdb) stepi > Remote connection closed > (gdb)
The trick was not to set the breakpoint at 0x70003190. Then the breakpoint at 0x80 works. And I think I found a hint: http://www.cmpe.boun.edu.tr/courses/cmpe511/fall2004/Ozan Aktan - Supersparc Architecture.doc "One unique feature of the floating-point unit is that dependent floating-point instructions may be issued in the same instruction group as the dependent floating-point operation. As an example, the following instructions can issue in a single clock cycle: LDD [%i0 + %i1], %f2 FMULD %f2, %f4, %f6 " We also have a dependent instructions 0x700030f4: fdivs %f1, %f2, %f3 0x700030f8: st %f3, [ %l6 ] which must produce two traps simultaneously: division by zero and unaligned access. Unaligned access is a higher priority trap, so it must be processed first. In the previous test (which passed) the store produces a data access exception which has lower priority than division by zero. The test passes because it is bad. -- Regards, Artyom Tarasenko solaris/sparc under qemu blog: http://tyom.blogspot.com/
