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[Bug uprobes/5273] New: x86 arch_validate_probed_insn(): lighten up?
- From: "jkenisto at us dot ibm dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 5 Nov 2007 21:59:24 -0000
- Subject: [Bug uprobes/5273] New: x86 arch_validate_probed_insn(): lighten up?
- Reply-to: sourceware-bugzilla at sourceware dot org
In uprobes_i386.c and uprobes_x86_64.c, we spend quite a bit of code on refusing
to probe certain types of instructions, such as undefined opcodes and other
instructions that are likely to yield SIGILL when single-stepped in user mode.
There's also some paranoia about how instruction prefixes and such might affect
our decisions about which instructions need to be treated specially when
single-stepping them out of line.
We could probably lighten up here. One disadvantage of the paranoia is that
tests that try to probe (say) EVERY instruction in a .o file will choke on
things like hlt.
For illegal instructions, if the SIGILL kills the task before the SIGTRAP from
the single-step is reported to us -- we need to test this -- then we should be
OK. Testing suggests that we know how to handle tasks that die of other causes
during probepoint processing.
And I think we've successfully identified instructions that need special
attention during SSOL. It's probably just a matter of testing each currently
banned instruction type to verify that it doesn't present an unforeseen problem.
Summary: x86 arch_validate_probed_insn(): lighten up?
AssignedTo: systemtap at sources dot redhat dot com
ReportedBy: jkenisto at us dot ibm dot com
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