Re: [PATCH -next V12 1/3] riscv: stack: Support HAVE_IRQ_EXIT_ON_IRQ_STACK

[Guo Ren <guoren@kernel.org>]

On Tue, Jun 13, 2023 at 9:01 PM Clément Léger <cleger@rivosinc.com> wrote:
>
>
>
> On 29/05/2023 10:45, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Add independent irq stacks for percpu to prevent kernel stack overflows.
> > It is also compatible with VMAP_STACK by arch_alloc_vmap_stack.
> >
> > Tested-by: Jisheng Zhang <jszhang@kernel.org>
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
> > Cc: Conor Dooley <conor.dooley@microchip.com>
> > ---
> >   arch/riscv/Kconfig                   |  7 ++++++
> >   arch/riscv/include/asm/irq_stack.h   | 32 +++++++++++++++++++++++++
> >   arch/riscv/include/asm/thread_info.h |  2 ++
> >   arch/riscv/kernel/irq.c              | 33 ++++++++++++++++++++++++++
> >   arch/riscv/kernel/traps.c            | 35 ++++++++++++++++++++++++++--
> >   5 files changed, 107 insertions(+), 2 deletions(-)
> >   create mode 100644 arch/riscv/include/asm/irq_stack.h
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index fa256f2e23c1..44b4c9690f94 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -588,6 +588,13 @@ config FPU
> >
> >         If you don't know what to do here, say Y.
> >
> > +config IRQ_STACKS
> > +     bool "Independent irq stacks" if EXPERT
> > +     default y
> > +     select HAVE_IRQ_EXIT_ON_IRQ_STACK
> > +     help
> > +       Add independent irq stacks for percpu to prevent kernel stack overflows.
> > +
> >   endmenu # "Platform type"
> >
> >   menu "Kernel features"
> > diff --git a/arch/riscv/include/asm/irq_stack.h b/arch/riscv/include/asm/irq_stack.h
> > new file mode 100644
> > index 000000000000..b0dcee9a3fa2
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/irq_stack.h
> > @@ -0,0 +1,32 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +
> > +#ifndef _ASM_RISCV_IRQ_STACK_H
> > +#define _ASM_RISCV_IRQ_STACK_H
> > +
> > +#include <linux/bug.h>
> > +#include <linux/gfp.h>
> > +#include <linux/kconfig.h>
> > +#include <linux/vmalloc.h>
> > +#include <linux/pgtable.h>
> > +#include <asm/thread_info.h>
> > +
> > +DECLARE_PER_CPU(ulong *, irq_stack_ptr);
> > +
> > +#ifdef CONFIG_VMAP_STACK
> > +/*
> > + * To ensure that VMAP'd stack overflow detection works correctly, all VMAP'd
> > + * stacks need to have the same alignment.
> > + */
> > +static inline unsigned long *arch_alloc_vmap_stack(size_t stack_size, int node)
> > +{
> > +     void *p;
> > +
> > +     BUILD_BUG_ON(!IS_ENABLED(CONFIG_VMAP_STACK));
>
> Hi Guo,
>
> Since this function is already guarded with #ifdef CONFIG_VMAP_STACK, I
> guess this BUILD_BUG_ON() is unnecessary).
Yes, my carelessness. I would remove it in the next version.

>
> Clément




--
Best Regards
 Guo Ren