From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org, qemu-arm@nongnu.org
Subject: Re: [PATCH v4 02/16] accel/tcg: Fix check for page writeability in load_atomic16_or_exit
Date: Tue, 30 May 2023 08:09:22 -0700 [thread overview]
Message-ID: <528627e2-f4d5-fd44-a57b-23b37ca79935@linaro.org> (raw)
In-Reply-To: <CAFEAcA_BS4b1MR=7zwVXB+eTXcVc2QhvzcvsoQn9mZ-xeps41w@mail.gmail.com>
On 5/30/23 07:48, Peter Maydell wrote:
> On Tue, 30 May 2023 at 15:29, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> On 5/30/23 07:06, Peter Maydell wrote:
>>>> This is about falling through to the cmpxchg below: if !PAGE_WRITE_ORG, then the page is
>>>> really not writable, we will SIGSEGV, and handle_sigsegv_accerr_write will kill the process.
>>>
>>> Right, but if !PAGE_WRITE_ORG then that implies also !PAGE_WRITE,
>>> so we do that even without this change ?
>>
>> But !PAGE_WRITE does not imply !PAGE_WRITE_ORG.
>
> Hmm. In what situation do we mark a page writeable when the
> guest didn't ask for it to be writeable ?
I don't know -- it seems backward, I know.
I *think* it's a race condition, where PAGE_WRITE changes.
That's what the test case is trying to provoke, anyway.
r~
next prev parent reply other threads:[~2023-05-30 15:10 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-26 0:23 [PATCH v4 00/16] tcg: Improvements to atomic128 Richard Henderson
2023-05-26 0:23 ` [PATCH v4 01/16] tcg: Fix register move type in tcg_out_ld_helper_ret Richard Henderson
2023-05-30 13:36 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 02/16] accel/tcg: Fix check for page writeability in load_atomic16_or_exit Richard Henderson
2023-05-30 13:44 ` Peter Maydell
2023-05-30 13:58 ` Richard Henderson
2023-05-30 14:06 ` Peter Maydell
2023-05-30 14:29 ` Richard Henderson
2023-05-30 14:48 ` Peter Maydell
2023-05-30 15:09 ` Richard Henderson [this message]
2023-05-30 15:18 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 03/16] meson: Split test for __int128_t type from __int128_t arithmetic Richard Henderson
2023-05-30 13:47 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 04/16] qemu/atomic128: Add x86_64 atomic128-ldst.h Richard Henderson
2023-05-26 0:23 ` [PATCH v4 05/16] tcg/i386: Support 128-bit load/store Richard Henderson
2023-05-30 15:02 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 06/16] tcg/aarch64: Rename temporaries Richard Henderson
2023-05-26 0:23 ` [PATCH v4 07/16] tcg/aarch64: Reserve TCG_REG_TMP1, TCG_REG_TMP2 Richard Henderson
2023-05-30 13:52 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 08/16] tcg/aarch64: Simplify constraints on qemu_ld/st Richard Henderson
2023-05-30 13:55 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 09/16] tcg/aarch64: Support 128-bit load/store Richard Henderson
2023-05-26 0:23 ` [PATCH v4 10/16] tcg/ppc: " Richard Henderson
2023-05-26 0:23 ` [PATCH v4 11/16] tcg/s390x: " Richard Henderson
2023-05-26 0:23 ` [PATCH v4 12/16] accel/tcg: Extract load_atom_extract_al16_or_al8 to host header Richard Henderson
2023-05-30 13:58 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 13/16] accel/tcg: Extract store_atom_insert_al16 " Richard Henderson
2023-05-30 13:59 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 14/16] accel/tcg: Add x86_64 load_atom_extract_al16_or_al8 Richard Henderson
2023-05-30 14:01 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 15/16] accel/tcg: Add aarch64 lse2 load_atom_extract_al16_or_al8 Richard Henderson
2023-05-30 14:02 ` Peter Maydell
2023-05-26 0:23 ` [PATCH v4 16/16] accel/tcg: Add aarch64 store_atom_insert_al16 Richard Henderson
2023-05-30 14:04 ` Peter Maydell
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