From: Mark Rutland <mark.rutland@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Jia He <justin.he@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Anshuman Khandual <anshuman.khandual@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Richard Henderson <richard.henderson@linaro.org>,
Dave Martin <Dave.Martin@arm.com>,
Steven Price <steven.price@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Gavin Shan <gshan@redhat.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Mark Brown <broonie@kernel.org>, Marc Zyngier <maz@kernel.org>,
Cristian Marussi <cristian.marussi@arm.com>
Subject: Re: [RFC PATCH 1/2] arm64/cpuinfo: Move init_cpu_features() ahead of setup.c::early_fixmap_init()
Date: Tue, 26 Jan 2021 14:11:48 +0000 [thread overview]
Message-ID: <20210126141148.GC80448@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20210126135712.GA29956@willie-the-truck>
On Tue, Jan 26, 2021 at 01:57:13PM +0000, Will Deacon wrote:
> > @@ -297,16 +297,20 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
> > */
> > arm64_use_ng_mappings = kaslr_requires_kpti();
> >
> > - early_fixmap_init();
> > - early_ioremap_init();
> > -
> > - setup_machine_fdt(__fdt_pointer);
> > -
> > /*
> > * Initialise the static keys early as they may be enabled by the
> > * cpufeature code and early parameters.
> > */
> > jump_label_init();
>
> I don't think your patch changes this, but afaict jump_label_init() uses
> per-cpu variables via cpus_read_lock(), yet we don't initialise our offset
> until later on. Any idea how that works?
We initialize the boot CPU's offset twice during boot, once before this
in smp_setup_processor_id(), and once afterwards in
smp_prepare_boot_cpu() since setup_per_cpu_areas() will allocate a new
region for CPU0.
IIUC per-cpu writes before smp_prepare_boot_cpu() are potentially dodgy
since they might be copied to other CPUs, but reads are all fine.
Mark.
next prev parent reply other threads:[~2021-01-26 14:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 1:40 [RFC PATCH 0/2] Avoid booting stall caused by Jia He
2021-01-13 1:40 ` [RFC PATCH 1/2] arm64/cpuinfo: Move init_cpu_features() ahead of setup.c::early_fixmap_init() Jia He
2021-01-26 13:57 ` Will Deacon
2021-01-26 14:11 ` Mark Rutland [this message]
2021-01-13 1:40 ` [RFC PATCH 2/2] arm64: kpti: Update arm64_use_ng_mappings before pagetable mapping Jia He
2021-01-26 14:14 ` Will Deacon
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=20210126141148.GC80448@C02TD0UTHF1T.local \
--to=mark.rutland@arm.com \
--cc=Dave.Martin@arm.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=ardb@kernel.org \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=cristian.marussi@arm.com \
--cc=gshan@redhat.com \
--cc=gustavoars@kernel.org \
--cc=justin.he@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=richard.henderson@linaro.org \
--cc=rppt@kernel.org \
--cc=steven.price@arm.com \
--cc=suzuki.poulose@arm.com \
--cc=wangkefeng.wang@huawei.com \
--cc=will@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).