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From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Keith Packard <keithpac@amazon.com>,
	Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v4 4/5] ARM: smp: Store current pointer in TPIDRURO register if available
Date: Mon, 13 Sep 2021 14:52:45 +0100	[thread overview]
Message-ID: <YT9XrdCY5JbdpOMl@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAMj1kXF+B-N0bTykEsfPZNwRTP+YnwhNB=-+vf+nqi27AT0Y6g@mail.gmail.com>

On Mon, Sep 13, 2021 at 02:52:46PM +0200, Ard Biesheuvel wrote:
> Hi Russell,
> 
> Thanks for taking a look.
> 
> However, the next patch drops the 'ldr ip, [r4, #TI_TASK]' I am adding
> here, so I won't be able to use this as-is.
> 
> I could just split the ldr/set_current sequence into two, and change
> the first one into a mov in the following patch, and move the
> set_current to right before where sp is updated.
> 
> I.e., in this patch
> 
> @@ -762,6 +764,8 @@ ENTRY(__switch_to)
>         add     r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK
>         .endif
>         ldr     r7, [r7, #TSK_STACK_CANARY & IMM12_MASK]
> +#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
> +       ldr     r7, [r2, #TI_TASK]
>  #endif
>  #ifdef CONFIG_CPU_USE_DOMAINS
>         mcr     p15, 0, r6, c3, c0, 0           @ Set domain register
> @@ -776,6 +780,7 @@ ENTRY(__switch_to)
>  #endif
>   THUMB(        mov     ip, r4                     )
>         mov     r0, r5
> +       set_current r7
>   ARM(  ldmia   r4, {r4 - sl, fp, sp, pc}  )
>   THUMB(        ldmia   ip!, {r4 - sl, fp}         )
>   THUMB(        ldr     sp, [ip], #4               )
> 
> and in the next one
> 
> @@ -765,7 +765,7 @@ ENTRY(__switch_to)
>         .endif
>         ldr     r7, [r7, #TSK_STACK_CANARY & IMM12_MASK]
>  #elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
> -       ldr     r7, [r2, #TI_TASK]
> +       mov     r7, r2                          @ Preserve 'next'
>  #endif
>  #ifdef CONFIG_CPU_USE_DOMAINS
>         mcr     p15, 0, r6, c3, c0, 0           @ Set domain register
> 
> Would that work for you?

Definitely does! Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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  reply	other threads:[~2021-09-13 13:54 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13 10:39 [PATCH v4 0/5] ARM: support THREAD_INFO_IN_TASK Ard Biesheuvel
2021-09-13 10:39 ` [PATCH v4 1/5] gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support Ard Biesheuvel
2021-09-13 15:40   ` Kees Cook
2021-09-14 22:04   ` Linus Walleij
2021-09-15  6:37     ` Ard Biesheuvel
2021-09-15 16:26       ` Kees Cook
2021-09-13 10:39 ` [PATCH v4 2/5] ARM: smp: Pass task to secondary_start_kernel Ard Biesheuvel
2021-09-13 23:25   ` Linus Walleij
2021-09-13 10:39 ` [PATCH v4 3/5] ARM: smp: Free up the TLS register while running in the kernel Ard Biesheuvel
2021-09-13 10:40 ` [PATCH v4 4/5] ARM: smp: Store current pointer in TPIDRURO register if available Ard Biesheuvel
2021-09-13 11:22   ` Russell King (Oracle)
2021-09-13 12:52     ` Ard Biesheuvel
2021-09-13 13:52       ` Russell King (Oracle) [this message]
2021-09-13 10:40 ` [PATCH v4 5/5] ARM: smp: Enable THREAD_INFO_IN_TASK Ard Biesheuvel
2021-09-13 11:23 ` [PATCH v4 0/5] ARM: support THREAD_INFO_IN_TASK Russell King (Oracle)
2021-09-13 15:40 ` Kees Cook
2021-09-14  9:44 ` Arnd Bergmann
2021-09-14  9:50   ` Ard Biesheuvel
2021-09-14 13:07     ` Arnd Bergmann
2021-09-14 17:10       ` Ard Biesheuvel

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