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Diffstat (limited to 'results/classifier/gemma3:12b/debug/2385')
| -rw-r--r-- | results/classifier/gemma3:12b/debug/2385 | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/results/classifier/gemma3:12b/debug/2385 b/results/classifier/gemma3:12b/debug/2385 new file mode 100644 index 00000000..b6b185ed --- /dev/null +++ b/results/classifier/gemma3:12b/debug/2385 @@ -0,0 +1,108 @@ + +sparc: SIGILL stepping over `std` in gdb +Description of problem: +Certain cases of single-stepping thru the `std` store double-word instruction causes SIGILL fatal trap, while normal execution of the program is fine. Unfortunately I do not have access to real SPARC hardware so I cannot attest whether this is an emulation issue or not. + +My previous bugfix #2281 fixed any single-stepping in a debugger from panicking the kernel, associated with the `lda` on ASI_USERTXT in the `default_fuword32` function. I suspect further bugs like this could be related somehow. Perhaps a different instruction is used for the 64-bit access that needs a similar fix. + +This problem was experienced while testing some shell-spawning assembly: +``` +-bash-4.3$ cat test.s +.section ".text" +.global main +main: + sethi %hi(0x2f626800), %l6 + or %l6, 0x16e, %l6 ! 0x2f62696e + sethi %hi(0x2f6b7000), %l7 + or %l7, 0x368, %l7 ! 0x2f6b7368 + and %sp, %sp, %o0 + add %sp, 0xc, %o1 + xor %o2, %o2, %o2 + add %sp, 0x14, %sp + std %l6, [ %sp + -20 ] + clr [ %sp + -12 ] + st %sp, [ %sp + -8 ] + clr [ %sp + -4 ] + mov 0x3b, %g1 + ta 8 + xor %o7, %o7, %o0 + mov 1, %g1 + ta 8 +``` + +``` +-bash-4.3$ gcc test.s -o test +-bash-4.3$ ./test +$ echo HELLO +HELLO +$ exit +``` + +As you can see the program works when ran directly from the shell, but when single-stepping in gdb, a SIGILL (illegal instruction) trap occurs +``` +-bash-4.3$ gdb test +GNU gdb (GDB) 7.4.1 +[...] +(gdb) disas main +Dump of assembler code for function main: + 0x0001061c <+0>: sethi %hi(0x2f626800), %l6 + 0x00010620 <+4>: or %l6, 0x16e, %l6 ! 0x2f62696e + 0x00010624 <+8>: sethi %hi(0x2f6b7000), %l7 + 0x00010628 <+12>: or %l7, 0x368, %l7 ! 0x2f6b7368 + 0x0001062c <+16>: and %sp, %sp, %o0 + 0x00010630 <+20>: add %sp, 0xc, %o1 + 0x00010634 <+24>: xor %o2, %o2, %o2 + 0x00010638 <+28>: add %sp, 0x14, %sp + 0x0001063c <+32>: std %l6, [ %sp + -20 ] + 0x00010640 <+36>: clr [ %sp + -12 ] + 0x00010644 <+40>: st %sp, [ %sp + -8 ] + 0x00010648 <+44>: clr [ %sp + -4 ] + 0x0001064c <+48>: mov 0x3b, %g1 + 0x00010650 <+52>: ta 8 + 0x00010654 <+56>: xor %o7, %o7, %o0 + 0x00010658 <+60>: mov 1, %g1 + 0x0001065c <+64>: ta 8 +End of assembler dump. +(gdb) b main +Breakpoint 1 at 0x1061c +(gdb) r +Starting program: /export/home/bazz/iob/test + +Breakpoint 1, 0x0001061c in main () +(gdb) si +0x00010620 in main () +(gdb) +0x00010624 in main () +[...] +Program received signal SIGILL, Illegal instruction. +0x0001063c in main () +``` + +However, if I continue execution _over_ the `std` instruction, the SIGILL does not occur. it will get to the usual SIGTRAP after execve, +but then complains about memory accesses that I've never seen before. +``` +(gdb) r +Starting program: /export/home/bazz/iob/test + +Breakpoint 1, 0x0001061c in main () +(gdb) c +Continuing. + +Program received signal SIGTRAP, Trace/breakpoint trap. +0xef783af4 in _rt_boot () from /usr/lib/ld.so.1 +(gdb) c +Continuing. +Cannot access memory at address 0x2800007 +Cannot access memory at address 0x2800003 +(gdb) c +Continuing. +Cannot access memory at address 0x2800007 +Cannot access memory at address 0x2800003 +(gdb) c +Continuing. +$ +``` + +It does eventually get a shell though. + +On mdb, instead of single-stepping into a SIGILL, everything goes unresponsive after stepping the `std` instruction. Then I have to kill mdb. |