After hitting a breakpoint, we single step the program to execute the
instruction we breaked on and re-enable the breakpoint.
We also single step the program when the user of LibDebug returned a
DebugDecision::SingleStep.
Previously, if we hit a breakpoint and then were asked to to a
DebugDecision::SingleStep, we would single step twice.
This bug can actually crash programs, because it might cause us to
skip over a patched INT3 instruction in the second single-step.
Interestingely enough, this bug manifested as functrace crashing
certain programs: after hitting a breakpoint on a CALL instruction,
functrace single steps the program to see where the CALL jumps to
(yes, this can be optimized :D). functrace crashed when a CALL
instruction jumps to another CALL, because it inserts breakpoints on CALL
instructions, and so the INT3 in the 2nd CALL was skipped over, and we
executed garbage :).
This commit fixes this by making sure not to single-step twice.
When the user of the DebugSession uses this decision, the debugged
program will be continued until it is either stopped by a singal (e.g
as a reuslt of a breakpoint), or enters a syscall.
functrace traces the function calls a program makes.
It's like strace, but for userspace.
It works by using Debugging functionality to insert breakpoints
at call&ret instructions.
2020-04-16 11:17:33 +02:00
Renamed from Applications/Debugger/DebugSession.cpp (Browse further)
