[Bug uprobes/10836] uprobes-provided pt_regs* are unreliable

[jkenisto at us dot ibm dot com]

------- 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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