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[Bug gdb/13431] New: jit code registration cleanup
- From: "sphink at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: Tue, 22 Nov 2011 21:31:35 +0000
- Subject: [Bug gdb/13431] New: jit code registration cleanup
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=13431
Bug #: 13431
Summary: jit code registration cleanup
Product: gdb
Version: unknown
Status: NEW
Severity: normal
Priority: P2
Component: gdb
AssignedTo: unassigned@sourceware.org
ReportedBy: sphink@gmail.com
Classification: Unclassified
When using the JIT CFI registration API, I very commonly run into
Unsupported JIT protocol version in descriptor!
Or, when I'm unlucky, extremely bizarre behavior: the inferior starts jumping
to invalid locations. I generally notice it when it lands between two
instructions and I get a SIGILL, though I have noticed at least one case where
it just silently executed the wrong code.
I haven't seen the latter failure mode for a while.
I believe the problem is triggered when I am debugging a binary, and then I
recompile it in a way that changes the location of __jit_debug_descriptor. It
seems to reload the object file, then use the old location to unregister the
old JIT code. Or something.
The exact series of events goes something like:
1. (gdb) run
2. ...stop at a breakpoint...
3. recompile
4. (gdb) run
Unsupported JIT protocol version in descriptor!
5. (gdb) run
`/home/sfink/src/MI-jitprofiler/obj/dist/bin/js' has changed; re-reading
symbols.
Unsupported JIT protocol version in descriptor!
6. (gdb) run
Warning:
Cannot insert breakpoint -14865.
Error accessing memory address 0x378d805b60: Input/output error.
Cannot insert breakpoint -14866.
Error accessing memory address 0x378d805b70: Input/output error.
7. (gdb) run
Now it runs, but all CFI information is completely mangled. Stack traces have
bogus return addresses.
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