All of lore.kernel.org
 help / color / mirror / Atom feed
From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
	"QEMU Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH v5 04/19] accel/tcg: Adjust probe_access call to page_check_range
Date: Fri, 8 May 2020 09:57:02 -0700	[thread overview]
Message-ID: <62eca244-78dd-0359-d82b-30089d893d39@linaro.org> (raw)
In-Reply-To: <CAFEAcA-9bd11QTUGYdta+pDRFvd-9qtiBiBCGUCCX7Mi+swQbA@mail.gmail.com>

On 5/8/20 9:13 AM, Peter Maydell wrote:
> On Fri, 8 May 2020 at 16:44, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> We have validated that addr+size does not cross a page boundary.
>> Therefore we need to validate exactly one page.  We can achieve
>> that passing any value 1 <= x <= size to page_check_range.
>>
>> Passing 1 will simplify the next patch.
> 
> It's not clear to me how it simplifies the next patch, though --
> we have the size right there in the new function which
> calls page_check_range(), don't we? So I still don't
> understand why we're using '1' -- it isn't allowing
> us to avoid passing the size into probe_access_internal(),
> because we need to pass it anyway.
> 
> We've gone round this multiple times now so I feel like
> I must be missing something here.

While probe_access() has a size parameter, probe_access_flags() does not.

For probe_access_internal(), I currently have a "fault_size" parameter that
gets passed to tlb_fill, which is "size" for probe_access() and 0 for
probe_access_flags().

I *could* add another "check_size" parameter to probe_access_internal, to be
passed on to page_check_range(). It would be "size" for probe_access() and 1
for probe_access_flags().  But what's the point?  Always passing 1 to
page_check_range() has the same effect.

I feel like I'm missing something with your objection.


r~


  reply	other threads:[~2020-05-08 16:57 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08 15:43 [PATCH v5 00/19] target/arm: sve load/store improvements Richard Henderson
2020-05-08 15:43 ` [PATCH v5 01/19] exec: Add block comments for watchpoint routines Richard Henderson
2020-05-08 15:43 ` [PATCH v5 02/19] exec: Fix cpu_watchpoint_address_matches address length Richard Henderson
2020-05-09 11:59   ` Philippe Mathieu-Daudé
2020-05-08 15:43 ` [PATCH v5 03/19] accel/tcg: Add block comment for probe_access Richard Henderson
2020-05-08 15:43 ` [PATCH v5 04/19] accel/tcg: Adjust probe_access call to page_check_range Richard Henderson
2020-05-08 16:13   ` Peter Maydell
2020-05-08 16:57     ` Richard Henderson [this message]
2020-05-11 10:19       ` Peter Maydell
2020-05-08 15:43 ` [PATCH v5 05/19] accel/tcg: Add probe_access_flags Richard Henderson
2020-05-08 15:43 ` [PATCH v5 06/19] accel/tcg: Add endian-specific cpu_{ld, st}* operations Richard Henderson
2020-05-08 15:43 ` [PATCH v5 07/19] target/arm: Use cpu_*_data_ra for sve_ldst_tlb_fn Richard Henderson
2020-05-08 15:43 ` [PATCH v5 08/19] target/arm: Drop manual handling of set/clear_helper_retaddr Richard Henderson
2020-05-08 15:43 ` [PATCH v5 09/19] target/arm: Add sve infrastructure for page lookup Richard Henderson
2020-05-08 15:43 ` [PATCH v5 10/19] target/arm: Adjust interface of sve_ld1_host_fn Richard Henderson
2020-05-08 15:43 ` [PATCH v5 11/19] target/arm: Use SVEContLdSt in sve_ld1_r Richard Henderson
2020-05-08 15:43 ` [PATCH v5 12/19] target/arm: Handle watchpoints " Richard Henderson
2020-05-08 15:43 ` [PATCH v5 13/19] target/arm: Use SVEContLdSt for multi-register contiguous loads Richard Henderson
2020-05-08 15:43 ` [PATCH v5 14/19] target/arm: Update contiguous first-fault and no-fault loads Richard Henderson
2020-05-08 15:43 ` [PATCH v5 15/19] target/arm: Use SVEContLdSt for contiguous stores Richard Henderson
2020-05-08 15:43 ` [PATCH v5 16/19] target/arm: Reuse sve_probe_page for gather first-fault loads Richard Henderson
2020-05-08 15:43 ` [PATCH v5 17/19] target/arm: Reuse sve_probe_page for scatter stores Richard Henderson
2020-05-08 15:43 ` [PATCH v5 18/19] target/arm: Reuse sve_probe_page for gather loads Richard Henderson
2020-05-08 15:43 ` [PATCH v5 19/19] target/arm: Remove sve_memopidx Richard Henderson
2020-05-09  1:45 ` [PATCH v5 00/19] target/arm: sve load/store improvements no-reply
2020-05-09  9:02 ` no-reply
2020-05-11 10:35 ` Peter Maydell

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=62eca244-78dd-0359-d82b-30089d893d39@linaro.org \
    --to=richard.henderson@linaro.org \
    --cc=alex.bennee@linaro.org \
    --cc=peter.maydell@linaro.org \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.