[Lldb-commits] [PATCH] D109738: [lldb] Fix bug 38317 - Address breakpoints don't work if set before the process launches

[Vadim Chugunov via Phabricator via lldb-commits]

vadimcn added a comment.

Hi Jim,
I think there's a bit of confusion going on here:
The original bug was opened by Ted Woodward, and I think his scenario was
motivated by embedded debugging.   He also provided that example with a
breakpoint being set in main.

I've rediscovered this bug independently, while working on an IDE
integration project.  In my case, the IDE saves just the address of the
instruction where a breakpoint was set in the previous debugging session.
In the next session, the debug adapter is expected to restore instruction
breakpoints using just the absolute addresses; the protocol does not
provide for any user interaction.  Also, this happens via the SB API, not
via LLDB commands.   Fortunately, when ASLR is disabled, modules are
usually loaded at the same address, so things tend to work out 99% of the
time.  The other 1%... well, if you are debugging on the assembly
instruction level, you are kinda expected to know what you are doing and be
prepared to deal with problems like those you've described above.

When the target is created, the modules for the target are loaded and

> mapped at whatever address is their default load address.

Clearly, this isn't happening.  From what I can see, section addresses are
not known until the process starts running.   Maybe this is another bug
that needs fixing?
Even so, I think that address breakpoints should still function when
section addresses aren't known at breakpoint creation time (for whatever
reason), if only on a best-effort basis.

3. If the address doesn't fall into any sections, then it would be fine to

> assign it to the first section that shows up at that address, but I would
> convert it to section relative at that point.

This is what I am attempting to do with my patch.  Is there something else
I should do to make sure I am not regressing other scenarios?


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