Re: [PATCH v3 00/15] uprobes: Add uprobes support for ARM

[David Long]

On 12/04/13 12:51, Taras Kondratiuk wrote:
> On 11/27/2013 04:53 AM, David Long wrote:
> > From: "David A. Long" <dave.long@xxxxxxxxxx>
> >
> > This patch series adds basic uprobes support to ARM. It is based on patches
> > developed earlier by Rabin Vincent. That approach of adding hooks into
> > the kprobes instruction parsing code was not well received. This approach
> > separates the ARM instruction parsing code in kprobes out into a separate set
> > of functions which can be used by both kprobes and uprobes. Both kprobes and
> > uprobes then provide their own semantic action tables to process the results of
> > the parsing.
> >
> > The following are noteworthy changes made for v3:
> >
> > 1) The ARM uprobes functionality no longer depends on kprobes. As
> > a side effect of this there are no longer any changes to the common
> > kprobes include file (or any other common kprobes files).
> > 2) A couple large patches have been broken down into more smaller
> > patches.
> > 3) A problem with uretprobes has been fixed.
> > 4) The kprobes-test module has been made more useable for thumb tests.
> > 5) The argument list to the "action" functions has been shrunk.
> > 6) Alignment with a few recent patches that were made to common
> > uprobes code specifically to support this patchset.
> >
> > This patchset is based on v3.13-rc1
>
> Hi Dave
>
> I've tested this series in big-endian mode.
> There is an issue within __create_xol_area() function.
> It writes UPROBE_SWBP_INSN directly to memory, but UPROBE_SWBP_INSN
> stores canonical opcode, which leads to a wrong instruction endianness
> if CPU runs in BE.
>
> I think the easies way to fix it without touching generic uprobes code
> is to store opcode in native endianness in UPROBE_SWBP_INSN, and use
> another macro for canonical form in ARM specific code.
> Please check a diff below. With this diff plus addressed comment for
> patch 14/15 plus fixed Ben's BE kprobes series I have uprobes working
> on LE and BE.

Thanks Taras.  I am preparing a v4 addressing these issues and also 
addressing the issue that, after duplicating your earlier observations, 
 my claim in "1)" above has proven to be incorrect.

-dl


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