linux-kernel - Re: [PATCH v3 12/13] riscv: Initialize thread pointer before calling C functions

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Message-ID: <44e6e00e-0b80-8329-bcc9-820940e02023@ghiti.fr>
Date:   Mon, 10 Jan 2022 09:03:49 +0100
From:   Alexandre ghiti <alex@...ti.fr>
To:     Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Jonathan Corbet <corbet@....net>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        Atish Patra <Atish.Patra@...osinc.com>,
        Christoph Hellwig <hch@....de>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        panqinglin2020@...as.ac.cn, linux-doc@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-efi@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH v3 12/13] riscv: Initialize thread pointer before calling
 C functions

Hi Palmer,

I fell onto this issue again today, do you think you could take this 
patch in for-next? Because I assume it is too late now to take the sv48 
patchset: if not, I can respin it today or tomorrow.

Thanks,

Alex

On 12/6/21 11:46, Alexandre Ghiti wrote:
> Because of the stack canary feature that reads from the current task
> structure the stack canary value, the thread pointer register "tp" must
> be set before calling any C function from head.S: by chance, setup_vm
> and all the functions that it calls does not seem to be part of the
> functions where the canary check is done, but in the following commits,
> some functions will.
>
> Fixes: f2c9699f65557a31 ("riscv: Add STACKPROTECTOR supported")
> Signed-off-by: Alexandre Ghiti <alexandre.ghiti@...onical.com>
> ---
>   arch/riscv/kernel/head.S | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index c3c0ed559770..86f7ee3d210d 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -302,6 +302,7 @@ clear_bss_done:
>   	REG_S a0, (a2)
>   
>   	/* Initialize page tables and relocate to virtual addresses */
> +	la tp, init_task
>   	la sp, init_thread_union + THREAD_SIZE
>   	XIP_FIXUP_OFFSET sp
>   #ifdef CONFIG_BUILTIN_DTB