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Diffstat (limited to 'results/classifier/deepseek-r1:32b/output/runtime/1143')
| -rw-r--r-- | results/classifier/deepseek-r1:32b/output/runtime/1143 | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/results/classifier/deepseek-r1:32b/output/runtime/1143 b/results/classifier/deepseek-r1:32b/output/runtime/1143 new file mode 100644 index 00000000..12f8fe91 --- /dev/null +++ b/results/classifier/deepseek-r1:32b/output/runtime/1143 @@ -0,0 +1,81 @@ + + + +Breakpoints missed when a function is split into two memory pages. +Description of problem: +Qemu seems to ignore some breakpoints when the start of a function is +in another page than where the breakpoint is set. + +In my case, I've a function `__gnat_debug_raise_exception` which starts at `0x10bff2` and I've set with gdb a breakpoint at `0x10c00e` (in another page). +While running with `qemu -d in_asm,exec`, I can see that the whole function is executed at once and that no breakpoint is fired. + +``` +(gdb) b *0x00108fbc +(gdb) b *0x0010c00e +(gdb) target remote :1234 +(gdb) c + +Trace 0: 0x7f277c0174c0 [0000000000000000/0000000000108fb9/0040c0b0/ff000201] ada__exceptions__complete_occurrence +---------------- + +// gdb hits first breakpoint here. +Breakpoint 3, 0x0000000000108fbc .... +(gdb) ni + +IN: ada__exceptions__complete_occurrence +0x00108fbc: e8 31 30 00 00 callq 0x10bff2 + +Trace 0: 0x7f277c000100 [0000000000000000/0000000000108fbc/0040c0b0/ff000e01] ada__exceptions__complete_occurrence +---------------- +IN: __gnat_debug_raise_exception +0x0010bff2: 55 pushq %rbp +0x0010bff3: 48 89 e5 movq %rsp, %rbp +0x0010bff6: 48 89 7d f8 movq %rdi, -8(%rbp) +0x0010bffa: 48 89 d1 movq %rdx, %rcx +0x0010bffd: 48 89 f0 movq %rsi, %rax +0x0010c000: 48 89 fa movq %rdi, %rdx +0x0010c003: 48 89 ca movq %rcx, %rdx +0x0010c006: 48 89 45 e0 movq %rax, -0x20(%rbp) +0x0010c00a: 48 89 55 e8 movq %rdx, -0x18(%rbp) +0x0010c00e: 48 8b 45 e0 movq -0x20(%rbp), %rax +0x0010c012: 90 nop +0x0010c013: 5d popq %rbp +0x0010c014: c3 retq + +Trace 0: 0x7f277c000100 [0000000000000000/000000000010bff2/0040c0b0/ff000000] __gnat_debug_raise_exception +Digging a bit more, it seems that it seems related to + +// gdb ni stop here. Breakpoints at 0x10c00e have been ignored. +``` + +Note that if I'm setting another breakpoint at `0x0010bffd` (thus not at the start of the function but still in the same page), the execution +will be executed step by step and the breakpoint at 0x10c00e will be triggered normally. + + +``` +IN: ada__exceptions__complete_occurrence +0x00108fbc: e8 31 30 00 00 callq 0x10bff2 + +Trace 0: 0x7f6af4000100 [0000000000000000/0000000000108fbc/0040c0b0/ff000e01] ada__exceptions__complete_occurrence +---------------- +IN: __gnat_debug_raise_exception +0x0010bff2: 55 pushq %rbp + +Trace 0: 0x7f6af4000100 [0000000000000000/000000000010bff2/0040c0b0/ff000201] __gnat_debug_raise_exception +---------------- +IN: __gnat_debug_raise_exception +0x0010bff3: 48 89 e5 movq %rsp, %rbp + +Trace 0: 0x7f6af4000280 [0000000000000000/000000000010bff3/0040c0b0/ff000201] __gnat_debug_raise_exception +---------------- +IN: __gnat_debug_raise_exception +0x0010bff6: 48 89 7d f8 movq %rdi, -8(%rbp) +... +``` + +I've dug a bit into qemu translator code and I guess `check_for_breakpoint` should check that the whole function is in the same page before skipping step by step. But I'm not sure if it's possible because the TB is created after `check_for_breakpoint` IIUC. + +Sadly as of now, I don't have a C reproducer. I can try to provide you my "foo" program which is an Ada program. But maybe if you've a better idea how to reproduce that or an idea of to fix that, I'll be glad to help you. + +Thanks, +Clément |