From: Deepak Gupta <debug@rivosinc.com>
To: Guo Ren <guoren@kernel.org>
Cc: palmer@dabbelt.com, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org, paul.walmsley@sifive.com,
Jisheng Zhang <jszhang@kernel.org>
Subject: Re: [PATCH] riscv: VMAP_STACK overflow detection thread-safe
Date: Thu, 24 Nov 2022 01:07:14 -0800 [thread overview]
Message-ID: <20221124090714.GB1896875@debug.ba.rivosinc.com> (raw)
In-Reply-To: <20221124082612.GC1149630@debug.ba.rivosinc.com>
On Thu, Nov 24, 2022 at 12:26:12AM -0800, Deepak Gupta wrote:
>On Thu, Nov 24, 2022 at 09:32:19AM +0800, Guo Ren wrote:
>>>+.macro asm_per_cpu dst sym tmp
>>>+ REG_L \tmp, TASK_TI_CPU_NUM(tp)
>>>+ slli \tmp, \tmp, 0x3
>>>+ la \dst, __per_cpu_offset
>>>+ add \dst, \dst, \tmp
>>>+ REG_L \tmp, 0(\dst)
>>>+ la \dst, \sym
>>>+ add \dst, \dst, \tmp
>>Another tricky asm code of using percpu, I don't know how the percpu
>>maintenance guy thinks.
>
>On this, if you can point me to someone, I would like to get their feedback.
>While discussing this, one issue that comes in my mind is if the shift
>of 0x3 is correct or not on 32bit systems. I don't know what's the
>size of each entry
>in `__per_cpu_offset`. On 64bit it's 8 bytes and thus 3 bit shift.
Yes this would need a fix for 32bit.
`__per_cpu_offset` is an array of `unsigned long` and thus shift should be 2 bit
on 32bit systems.
next prev parent reply other threads:[~2022-11-24 9:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-24 0:50 [PATCH] riscv: VMAP_STACK overflow detection thread-safe Deepak Gupta
2022-11-24 1:32 ` Guo Ren
2022-11-24 8:26 ` Deepak Gupta
2022-11-24 9:07 ` Deepak Gupta [this message]
[not found] ` <CAJF2gTQ=Vr6neABtz9JSCei6oPEsyWTpb-Y=Rxt5jy6n1VEtGA@mail.gmail.com>
2022-11-24 5:56 ` Deepak Gupta
2022-11-24 6:31 ` Guo Ren
2022-11-24 7:10 ` Deepak Gupta
2022-11-24 8:59 ` Conor Dooley
2022-11-24 9:10 ` Deepak Gupta
2022-11-24 9:36 ` Guo Ren
2022-11-24 6:30 ` Conor Dooley
2022-11-24 7:23 ` Deepak Gupta
2022-11-24 7:39 ` Conor Dooley
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=20221124090714.GB1896875@debug.ba.rivosinc.com \
--to=debug@rivosinc.com \
--cc=guoren@kernel.org \
--cc=jszhang@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox