Re: [PATCH 2/3] arm: introduce IRQ stacks
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Date: 2020-10-21 12:45:53
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On Wed, Oct 21, 2020 at 02:42:48PM +0200, Arnd Bergmann wrote:
(also resending this reply from @kernel.org) On Fri, Oct 16, 2020 at 12:19 PM Arnd Bergmann [off-list ref] wrote:quoted
On Thu, Oct 8, 2020 at 9:20 AM Maninder Singh [off-list ref] wrote:quoted
This patch adds code for switching to IRQ stack. IRQ stack and Kernel SVC stack have below design. IRQ STACK:- ------------ IRQ stack top | | ------------ . . . . . . ------------ | sp | <- irq_stack_base + 0x8 ------------ | fp | <- irq_stack_base + 0x4 ------------ |tinfo_ptr | /* pointer to thread info */ irq_stack_ptr --> ------------ IRQ stack base Kernel SVC stack:- ------------ Kernel stack top | | ------------ . . . . . . ------------ | | | | ------------ |tinfo_ptr | /* pointer to thread info */ ------------ Kernel stack baseThe extra indirection doesn't look great, and I don't see any of the other architectures need that. Since we can access percpu data without going through thread_info, maybe doing the same as x86 would work here: - define 'current' as 'this_cpu_read_stable(current_task);' - convert to CONFIG_THREAD_INFO_IN_TASK
That means we need to also code that up in assembly - remember, we need to access thread_info from assembly code. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel