linux-kernel - Re: [PATCH V4 19/23] RISC-V: Add ACPI initialization in setup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZC2PuiY5Xscz305H@sunil-laptop>
Date:   Wed, 5 Apr 2023 20:41:54 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     Conor Dooley <conor@...nel.org>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-crypto@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        llvm@...ts.linux.dev,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Tom Rix <trix@...hat.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Weili Qian <qianweili@...wei.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Jonathan Corbet <corbet@....net>,
        Marc Zyngier <maz@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Andrew Jones <ajones@...tanamicro.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Mark Gross <markgross@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Len Brown <lenb@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH V4 19/23] RISC-V: Add ACPI initialization in setup_arch()

On Tue, Apr 04, 2023 at 10:38:56PM +0100, Conor Dooley wrote:
> On Tue, Apr 04, 2023 at 11:50:33PM +0530, Sunil V L wrote:
> > Initialize the ACPI core for RISC-V during boot.
> > 
> > ACPI tables and interpreter are initialized based on
> > the information passed from the firmware and the value of
> > the kernel parameter 'acpi'.
> > 
> > With ACPI support added for RISC-V, the kernel parameter 'acpi'
> > is also supported on RISC-V. Hence, update the documentation.
> > 
> > Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
> > Acked-by: Conor Dooley <conor.dooley@...rochip.com>
> 
> > +	/* Parse the ACPI tables for possible boot-time configuration */
> > +	acpi_boot_table_init();
> > +	if (acpi_disabled) {
> > +		if (IS_ENABLED(CONFIG_BUILTIN_DTB)) {
> > +			unflatten_and_copy_device_tree();
> > +		} else {
> > +			if (early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa))))
> > +				unflatten_device_tree();
> > +			else
> > +				pr_err("No DTB found in kernel mappings\n");
> > +		}
> > +	} else {
> > +		early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa)));
> 
> I'm probably forgetting something, but this seems very non-obvious to
> me:
> Why are you running early_init_dt_verify() when ACPI is enabled?
> I think that one deserves a comment so that next time someone looks at
> this (that doesn't live in ACPI land) they've know exactly why this is
> like it is.
> 
> Doubly so since this is likely to change with some of Alex's bits moving
> the dtb back into the fixmap.
> 
Good question. The kernel creates a tiny DTB even when the FW didn't
pass the FDT (ACPI systems). Please see update_fdt(). So, parse_dtb()
would have set initial_boot_params to early VA and if we don't call
early_init_dt_verify() again with __va, it panics since
initial_boot_params can not be translated.

Thanks,
Sunil