From: Richard Henderson <rth@twiddle.net>
To: Thomas Hanson <thomas.hanson@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] best way to implement emulation of AArch64 tagged addresses
Date: Sat, 9 Apr 2016 08:57:55 -0700 [thread overview]
Message-ID: <57092683.5040405@twiddle.net> (raw)
In-Reply-To: <CAA8zJ3A8GgoZNa__d-=H9dh-_sCudy9knCE4nUFoi1+AZ=TXBA@mail.gmail.com>
On 04/08/2016 05:29 PM, Thomas Hanson wrote:
> Looking at tcg_out_tlb_load():
> If I'm reading the pseudo-assembler of the function names correctly, it looks
> like in the i386 code we're already masking the address being checked:
> tgen_arithi(s, ARITH_AND + trexw, r1, TARGET_PAGE_MASK | (aligned ? s_mask
> : 0), 0);
> where TARGET_PAGE_MASK is a simple all-1's mask in the appropriate upper bits.
>
> Can we just poke some 0's into that mask in the tag locations?
No, because we'd no longer have a sign-extended 32-bit value, as fits in that
immediate operand field. To load the constant you're asking for, we'd need a
64-bit move insn and another register.
r~
next prev parent reply other threads:[~2016-04-09 15:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 15:51 [Qemu-devel] best way to implement emulation of AArch64 tagged addresses Peter Maydell
2016-04-04 16:28 ` Richard Henderson
2016-04-04 16:31 ` Peter Maydell
2016-04-04 17:56 ` Richard Henderson
2016-04-08 17:20 ` Tom Hanson
2016-04-08 18:06 ` Peter Maydell
2016-04-08 18:10 ` Richard Henderson
2016-04-09 0:29 ` Thomas Hanson
2016-04-09 15:57 ` Richard Henderson [this message]
2016-04-11 12:58 ` Thomas Hanson
2016-04-13 13:36 ` Tom Hanson
2016-04-04 16:35 ` Peter Maydell
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