From: Ralf Baechle <ralf@linux-mips.org>
To: Aleksandar Markovic <aleksandar.markovic@rt-rk.com>
Cc: linux-mips@linux-mips.org, james.hogan@imgtec.com,
paul.burton@imgtec.com, leonid.yegoshin@imgtec.com,
douglas.leung@imgtec.com, aleksandar.markovic@imgtec.com,
petar.jovanovic@imgtec.com, miodrag.dinic@imgtec.com,
goran.ferenc@imgtec.com
Subject: Re: [PATCH 1/3] MIPS: r2-on-r6-emu: Fix BLEZL and BGTZL identification
Date: Wed, 22 Mar 2017 16:03:19 +0100 [thread overview]
Message-ID: <20170322150319.GA14889@linux-mips.org> (raw)
In-Reply-To: <1489419397-25291-2-git-send-email-aleksandar.markovic@rt-rk.com>
On Mon, Mar 13, 2017 at 04:36:35PM +0100, Aleksandar Markovic wrote:
> From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>
> Fix the problem of inaccurate identification of instructions BLEZL and
> BGTZL in R2 emulation code by making sure all necessary encoding
> specifications are met.
>
> Previously, certain R6 instructions could be identified as BLEZL or
> BGTZL. R2 emulation routine didn't take into account that both BLEZL
> and BGTZL instructions require their rt field (bits 20 to 16 of
> instruction encoding) to be 0, and that, at same time, if the value in
> that field is not 0, the encoding may represent a legitimate MIPS R6
> instruction.
>
> This means that a problem could occur after emulation optimization,
> when emulation routine tried to pipeline emulation, picked up a next
> candidate, and subsequently misrecognized an R6 instruction as BLEZL
> or BGTZL.
>
> It should be said that for single pass strategy, the problem does not
> happen because CPU doesn't trap on branch-compacts which share opcode
> space with BLEZL/BGTZL (but have rt field != 0, of course).
>
> Signed-off-by: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
> Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtech.com>
> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtech.com>
> Reported-by: Douglas Leung <douglas.leung@imgtec.com>
> Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Thanks for sorting out the review comments on v1.
Applied,
Ralf
next prev parent reply other threads:[~2017-03-22 15:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-13 15:36 [PATCH 0/3] MIPS: Fix some R2/FP emulation issues Aleksandar Markovic
2017-03-13 15:36 ` [PATCH 1/3] MIPS: r2-on-r6-emu: Fix BLEZL and BGTZL identification Aleksandar Markovic
2017-03-22 15:03 ` Ralf Baechle [this message]
2017-03-13 15:36 ` [PATCH 2/3] MIPS: r2-on-r6-emu: Clear BLTZALL and BGEZALL debugfs counters Aleksandar Markovic
2017-03-22 15:05 ` Ralf Baechle
2017-03-13 15:36 ` [PATCH 3/3] MIPS: math-emu: Fix BC1EQZ and BC1NEZ condition handling Aleksandar Markovic
2017-03-22 15:05 ` Ralf Baechle
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