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 <a...@arndb.de> wrote: > > On Thu, Oct 8, 2020 at 9:20 AM Maninder Singh <maninder...@samsung.com> > > wrote: > > > > > > 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 base > > > > The 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!
