Here I am casually using GDB with Infinity
Name: Gary Benson
Member since: 2001-05-31 00:39:54
Last Login: 2012-10-24 12:18:42
I work for Red Hat.
Here I am casually using GDB with Infinity
Full-system Infinity preview coming up
I’ve released bits and pieces of Infinity over the past year, but nothing that really brings everything together. Right now I’m working on an initial full-system release of everything to do with Infinity so far. It’s codenamed “First Flight”, and you’ll be able to actually use it, see how everything hangs together, and generally get a better idea of what the point of it all is.
First Flight will be just enough for GDB to attach to a live process or start with a core file. “
info threads” should work, “
print errno” will not. First Flight will comprise:
git cloneand build to get a libpthread.so with Infinity notes for
The libthread_db.so shim won’t be used in future releases—they’ll have support for Infinity built into GDB—but it’ll likely remain as a nice example of how to use libi8x.
Infinity client library
This past few weeks I’ve been working on an Infinity client library. This is what GDB will use to execute notes it finds. It’s early days, but it executed its first note this morning so I thought I’d put something together so people can see what I’m doing. Here’s how to try it out:
tlsdumpexample program needs it:
sudo yum install elfutils-libelf-devel # Fedora, RHEL, etc... sudo apt-get install libelf-dev # Debian, Ubuntu, etc...
git clone -b libi8x-0.0.1 https://github.com/gbenson/libi8x.git libi8x-0.0.1 cd libi8x-0.0.1 ./autogen.sh ./configure --enable-logging --enable-debug make
tlsdumpexample program built:
bash$ ls -l examples/tlsdump -rwxr-xr-x. 1 gary gary 5540 Apr 20 12:52 examples/tlsdump
Yeah, there it is! (if it’s not there go back to step 0)
gcc -o tests/ifact tests/ifact.S tests/main.c
bash$ tests/ifact &  8301 Hello world I'm 8301
tlsdumpexample program with the test program’s PID as it’s argument:
$ examples/tlsdump 8301 0! = 1 1! = 1 2! = 2 3! = 6 4! = 24 5! = 120 6! = 720 7! = 5040 8! = 40320 9! = 362880 10! = 3628800 11! = 39916800 12! = 479001600
What just happened? The executable
test/ifact you built contains a single Infinity note,
test::factorial(i)i, the source for which is in
tlsdump example located the
ifact executable, loaded
test::factorial(i)i from it, and ran it a few times printing the result:
err = i8x_ctx_get_funcref (ctx, "test", "factorial", "i", "i", &fr); if (err != I8X_OK) error_i8x (ctx, err); err = i8x_xctx_new (ctx, 512, &xctx); if (err != I8X_OK) error_i8x (ctx, err); for (int i = 0; i
To see some debug output try this:I8X_LOG=debug examples/tlsdump PID
I8X_DEBUG=truein addition to
I8X_LOG=debugto trace the bytecode as it executes.
I’m winding down for a month away from Infinity. The current status is that the language and note format changes for 0.0.2 are all done. You can get them with:
git clone https://github.com/gbenson/i8c.git
There’s also the beginnings of an Emacs major mode for i8 in there too. My glibc tree now has notes for
td_ta_thr_iter as well as
td_ta_map_lwp2thr. That’s two of the three hard ones done. Get them with:
git clone https://github.com/gbenson/glibc.git -b infinity2
td_thr_get_info is just legwork and
td_thr_tls_get_addr is just a wrapper for
td_thr_tlsbase is the other hard note.
All notes have testcases with 100% bytecode coverage. I may add a flag for I8X to make not having 100% coverage a failure, and make glibc use it so nobody can commit notes with untested code.
The total note size so far is 720 bytes so I may still manage to get all five libpthread notes implemented in less than 1k:
Displaying notes found at file offset 0x00018f54 with length 0x000002d0: Owner Data size Description GNU 0x00000063 NT_GNU_INFINITY (inspection function) Signature: libpthread::__lookup_th_unique(i)ip GNU 0x00000088 NT_GNU_INFINITY (inspection function) Signature: libpthread::map_lwp2thr(i)ip GNU 0x000000cd NT_GNU_INFINITY (inspection function) Signature: libpthread::__iterate_thread_list(Fi(po)oipii)ii GNU 0x000000d2 NT_GNU_INFINITY (inspection function) Signature: libpthread::thr_iter(Fi(po)oiipi)i
In case you hadn’t noticed, I8C 0.0.1 was released last week. As well as the note compiler, this package contains I8X, an interpreter for unit testing compiled notes.
In case you had noticed and you’ve been working with it, please note there’s some compatibility-breaking source language and note format changes in the pipeline.
Infinity has a mailing list, and I want you to subscribe to it. Infinity isn’t just my project–anybody who might either produce or consume Infinity notes has a stake in this:
I don’t know every issue that Infinity will have to solve, and you know things I need to know. So don’t sit on the sidelines! Send an empty message to email@example.com and get involved.
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