| Issue |
160219
|
| Summary |
[LLDB] `si` (step instruction) stops multiple times at the same PC starting from LLDB 21
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
patryk4815
|
Starting with LLDB 21, the `si` (step instruction) command may stop multiple times at the same program counter (PC).
This behavior was not present in earlier releases (e.g. LLDB 16-20), where only a single stop event would occur.
### Compile bug binary
```console
cat << EOF > bug.S
.section .text
.global _start
_start:
mov x1, 1
foo:
mov x1, 2
bar:
mov x1, 3
EOF
zig cc -target aarch64-freestanding bug.S -o bug.elf
```
### Repro
```console
$ lldb ./bug.elf
(lldb) target create "./bug.elf"
Current executable set to '/Users/psondej/projekty/pwndbg/bug.elf' (aarch64).
(lldb) version
lldb version 21.1.1
(lldb) b foo
Breakpoint 1: where = bug.elf`foo, address = 0x0000000001010124
(lldb) b bar
Breakpoint 2: where = bug.elf`bar, address = 0x0000000001010128
(lldb) process launch -s
Process 353436 stopped
* thread #1, name = 'bug.elf', stop reason = signal SIGSTOP
frame #0: 0x0000000001010120 bug.elf`_start at bug.S:4
1 .section .text
2 .global _start
3 _start:
-> 4 mov x1, 1
5 foo:
6 mov x1, 2
7 bar:
Process 353436 launched: '/Users/psondej/projekty/pwndbg/bug.elf' (aarch64)
(lldb) si
Process 353436 stopped
* thread #1, name = 'bug.elf', stop reason = instruction step into
frame #0: 0x0000000001010124 bug.elf`foo at bug.S:6
3 _start:
4 mov x1, 1
5 foo:
-> 6 mov x1, 2
7 bar:
8 mov x1, 3
(lldb) si
Process 353436 stopped
* thread #1, name = 'bug.elf', stop reason = breakpoint 1.1
frame #0: 0x0000000001010124 bug.elf`foo at bug.S:6
3 _start:
4 mov x1, 1
5 foo:
-> 6 mov x1, 2
7 bar:
8 mov x1, 3
>>>
```
### Actual behavior:
The debugger stops multiple times at the same instruction:
- once due to the step
- once again due to the breakpoint at the same address
### Expected
`si` should trigger a stop only once per instruction, not multiple times at the same PC.
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