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[Bug uprobes/10836] uprobes-provided pt_regs* are unreliable
- From: "jkenisto at us dot ibm dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 28 Oct 2009 16:53:13 -0000
- Subject: [Bug uprobes/10836] uprobes-provided pt_regs* are unreliable
- References: <20091023162529.10836.fche@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From jkenisto at us dot ibm dot com 2009-10-28 16:53 -------
(In reply to comment #3)
> "synthesized pt_regs" is a loony concept considered only by systemtap.
> It has no place in the general utrace world. user_regset is there, it's what
> should be used. The only reason pt_regs is passed into some callbacks is
> because the pointer is handy and in some circumstances a few of its fields might
> be sufficiently useful for particular code that knows exactly what it is looking
> at. General-case code can use the asm/syscall.h macros on it, for example. For
> any generalized register access, user_regset is the only right thing to use.
Previous advice (as I understood it) from Roland during the uprobes 2 port
(~August '08) was to continue using the pt_regs pointer passed to
uprobe_report_signal(). So before Srikar adds a lot of user_regset code to
uprobes, it'd be nice clarify what Roland means by "any generalized register
access." For example, at least some architectures' user_regset code boils down
to references to the pt_regs pointer provided by task_pt_regs(). For the
registers that SystemTap actually references, would the pointer provided by
task_pt_regs() be sufficient?
--
http://sourceware.org/bugzilla/show_bug.cgi?id=10836
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