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From: Arnd Bergmann <arnd@arndb.de>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 Russell King - ARM Linux <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
	 Keith Packard <keithpac@amazon.com>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v2 4/9] ARM: unwind: support unwinding across multiple stacks
Date: Tue, 5 Oct 2021 14:17:50 +0200	[thread overview]
Message-ID: <CAK8P3a0jdCPa=+KhSUg=c-HXN40_FZNbTuDjQAZQe0j4EiwNFQ@mail.gmail.com> (raw)
In-Reply-To: <20211005071542.3127341-5-ardb@kernel.org>

On Tue, Oct 5, 2021 at 9:15 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> Implement support in the unwinder for dealing with multiple stacks.
> This will be needed once we add support for IRQ stacks, or for the
> overflow stack used by the vmap'ed stacks code.
>
> This involves tracking the unwind opcodes that either update the virtual
> stack pointer from another virtual register, or perform an explicit
> subtract on the virtual stack pointer, and updating the low and high
> bounds that we use to sanitize the stack pointer accordingly.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

I can't say I understand the code in detail, but I see nothing wrong here
either.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

> -       else if ((insn & 0xf0) == 0xa0) {
> +               ctrl->sp_low = ctrl->vrs[SP];
> +               ctrl->sp_high = ALIGN(ctrl->sp_low, THREAD_SIZE);
> +       } else if ((insn & 0xf0) == 0xa0) {

Would this break if the IRQ stack is not aligned to THREAD_SIZE?
If it would, it may be good to document this somewhere, probably
in patch 7, not here.

        Arnd

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  reply	other threads:[~2021-10-05 12:20 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-05  7:15 [PATCH v2 0/9] ARM: add support for IRQ stacks Ard Biesheuvel
2021-10-05  7:15 ` [PATCH v2 1/9] ARM: remove some dead code Ard Biesheuvel
2021-10-05 12:06   ` Arnd Bergmann
2021-10-05  7:15 ` [PATCH v2 2/9] ARM: assembler: introduce bl_r and bl_m macros Ard Biesheuvel
2021-10-05 12:10   ` Arnd Bergmann
2021-10-05 12:14     ` Ard Biesheuvel
2021-10-05  7:15 ` [PATCH v2 3/9] ARM: optimize indirect call to handle_arch_irq for v7 cores Ard Biesheuvel
2021-10-05 12:11   ` Arnd Bergmann
2021-10-05  7:15 ` [PATCH v2 4/9] ARM: unwind: support unwinding across multiple stacks Ard Biesheuvel
2021-10-05 12:17   ` Arnd Bergmann [this message]
2021-10-05  7:15 ` [PATCH v2 5/9] ARM: export dump_mem() to other objects Ard Biesheuvel
2021-10-05 12:15   ` Arnd Bergmann
2021-10-05  7:15 ` [PATCH v2 6/9] ARM: unwind: dump exception stack from calling frame Ard Biesheuvel
2021-10-05 12:20   ` Arnd Bergmann
2021-10-05  7:15 ` [PATCH v2 7/9] ARM: implement IRQ stacks Ard Biesheuvel
2021-10-05 12:26   ` Arnd Bergmann
2021-10-05  7:15 ` [PATCH v2 8/9] ARM: call_with_stack: add unwind support Ard Biesheuvel
2021-10-05 12:22   ` Arnd Bergmann
2021-10-05 18:46     ` Nick Desaulniers
2021-10-05 18:46       ` Nick Desaulniers
2021-10-05 18:57       ` Ard Biesheuvel
2021-10-05 18:57         ` Ard Biesheuvel
2021-10-05  7:15 ` [PATCH v2 9/9] ARM: run softirqs on the per-CPU IRQ stack Ard Biesheuvel
2021-10-05 12:23   ` Arnd Bergmann
2021-10-06 15:21     ` Ard Biesheuvel
2021-10-11 23:29 ` [PATCH v2 0/9] ARM: add support for IRQ stacks Keith Packard
2021-10-16 22:04 ` Linus Walleij

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