diff mbox series

[-next,V10,09/10] riscv: stack: Support HAVE_SOFTIRQ_ON_OWN_STACK

Message ID 20221208025816.138712-10-guoren@kernel.org (mailing list archive)
State Superseded
Headers show
Series riscv: Add GENERIC_ENTRY support and related features | expand

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Commit Message

Guo Ren Dec. 8, 2022, 2:58 a.m. UTC 
From: Guo Ren <guoren@linux.alibaba.com>

Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
irq and softirq use the same independent irq_stack of percpu by time
division multiplexing.

Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 arch/riscv/Kconfig      |  7 ++++---
 arch/riscv/kernel/irq.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

Comments

Björn Töpel Dec. 8, 2022, 10:12 a.m. UTC | #1 
guoren@kernel.org writes:

> From: Guo Ren <guoren@linux.alibaba.com>
>
> Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
> irq and softirq use the same independent irq_stack of percpu by time
> division multiplexing.
>
> Tested-by: Jisheng Zhang <jszhang@kernel.org>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> ---
>  arch/riscv/Kconfig      |  7 ++++---
>  arch/riscv/kernel/irq.c | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 0a9d4bdc0338..bd4c4ae4cdc9 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -447,12 +447,13 @@ config FPU
>  	  If you don't know what to do here, say Y.
>  
>  config IRQ_STACKS
> -	bool "Independent irq stacks" if EXPERT
> +	bool "Independent irq & softirq stacks" if EXPERT
>  	default y
>  	select HAVE_IRQ_EXIT_ON_IRQ_STACK
> +	select HAVE_SOFTIRQ_ON_OWN_STACK

HAVE_IRQ_EXIT_ON_IRQ_STACK is used by softirq.c Shouldn't that be
selected introduced in this patch, instead of the previous one?

>  	help
> -	  Add independent irq stacks for percpu to prevent kernel stack overflows.
> -	  We may save some memory footprint by disabling IRQ_STACKS.
> +	  Add independent irq & softirq stacks for percpu to prevent kernel stack
> +	  overflows. We may save some memory footprint by disabling IRQ_STACKS.

Same comment from previous patch. Please use the same wording/config as
other archs.

>  endmenu # "Platform type"
>  
> diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
> index 5d77f692b198..a6406da34937 100644
> --- a/arch/riscv/kernel/irq.c
> +++ b/arch/riscv/kernel/irq.c
> @@ -11,6 +11,7 @@
>  #include <linux/seq_file.h>
>  #include <asm/smp.h>
>  #include <asm/vmap_stack.h>
> +#include <asm/softirq_stack.h>
>  
>  #ifdef CONFIG_IRQ_STACKS
>  static DEFINE_PER_CPU(ulong *, irq_stack_ptr);
> @@ -38,6 +39,38 @@ static void init_irq_stacks(void)
>  		per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);
>  }
>  #endif /* CONFIG_VMAP_STACK */
> +
> +#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
> +void do_softirq_own_stack(void)
> +{
> +#ifdef CONFIG_IRQ_STACKS
> +	if (on_thread_stack()) {
> +		ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
> +					+ IRQ_STACK_SIZE/sizeof(ulong);
> +		__asm__ __volatile(
> +		"addi	sp, sp, -"RISCV_SZPTR  "\n"
> +		REG_S"  ra, (sp)		\n"
> +		"addi	sp, sp, -"RISCV_SZPTR  "\n"
> +		REG_S"  s0, (sp)		\n"
> +		"addi	s0, sp, 2*"RISCV_SZPTR "\n"
> +		"move	sp, %[sp]		\n"
> +		"call	__do_softirq		\n"
> +		"addi	sp, s0, -2*"RISCV_SZPTR"\n"
> +		REG_L"  s0, (sp)		\n"
> +		"addi	sp, sp, "RISCV_SZPTR   "\n"
> +		REG_L"  ra, (sp)		\n"
> +		"addi	sp, sp, "RISCV_SZPTR   "\n"
> +		:
> +		: [sp] "r" (sp)
> +		: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
> +		  "t0", "t1", "t2", "t3", "t4", "t5", "t6",
> +		  "memory");

Same as previous patch. Please avoid C&P and have a look at how
call_on_stack is done on x86.


Björn
Guo Ren Dec. 9, 2022, 2:09 a.m. UTC | #2 
On Thu, Dec 8, 2022 at 6:12 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> guoren@kernel.org writes:
>
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
> > irq and softirq use the same independent irq_stack of percpu by time
> > division multiplexing.
> >
> > Tested-by: Jisheng Zhang <jszhang@kernel.org>
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
> > ---
> >  arch/riscv/Kconfig      |  7 ++++---
> >  arch/riscv/kernel/irq.c | 33 +++++++++++++++++++++++++++++++++
> >  2 files changed, 37 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 0a9d4bdc0338..bd4c4ae4cdc9 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -447,12 +447,13 @@ config FPU
> >         If you don't know what to do here, say Y.
> >
> >  config IRQ_STACKS
> > -     bool "Independent irq stacks" if EXPERT
> > +     bool "Independent irq & softirq stacks" if EXPERT
> >       default y
> >       select HAVE_IRQ_EXIT_ON_IRQ_STACK
> > +     select HAVE_SOFTIRQ_ON_OWN_STACK
>
> HAVE_IRQ_EXIT_ON_IRQ_STACK is used by softirq.c Shouldn't that be
> selected introduced in this patch, instead of the previous one?
This patch depends on the previous one. And the previous one could
work separately.

>
> >       help
> > -       Add independent irq stacks for percpu to prevent kernel stack overflows.
> > -       We may save some memory footprint by disabling IRQ_STACKS.
> > +       Add independent irq & softirq stacks for percpu to prevent kernel stack
> > +       overflows. We may save some memory footprint by disabling IRQ_STACKS.
>
> Same comment from previous patch. Please use the same wording/config as
> other archs.
>
> >  endmenu # "Platform type"
> >
> > diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
> > index 5d77f692b198..a6406da34937 100644
> > --- a/arch/riscv/kernel/irq.c
> > +++ b/arch/riscv/kernel/irq.c
> > @@ -11,6 +11,7 @@
> >  #include <linux/seq_file.h>
> >  #include <asm/smp.h>
> >  #include <asm/vmap_stack.h>
> > +#include <asm/softirq_stack.h>
> >
> >  #ifdef CONFIG_IRQ_STACKS
> >  static DEFINE_PER_CPU(ulong *, irq_stack_ptr);
> > @@ -38,6 +39,38 @@ static void init_irq_stacks(void)
> >               per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);
> >  }
> >  #endif /* CONFIG_VMAP_STACK */
> > +
> > +#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
> > +void do_softirq_own_stack(void)
> > +{
> > +#ifdef CONFIG_IRQ_STACKS
> > +     if (on_thread_stack()) {
> > +             ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
> > +                                     + IRQ_STACK_SIZE/sizeof(ulong);
> > +             __asm__ __volatile(
> > +             "addi   sp, sp, -"RISCV_SZPTR  "\n"
> > +             REG_S"  ra, (sp)                \n"
> > +             "addi   sp, sp, -"RISCV_SZPTR  "\n"
> > +             REG_S"  s0, (sp)                \n"
> > +             "addi   s0, sp, 2*"RISCV_SZPTR "\n"
> > +             "move   sp, %[sp]               \n"
> > +             "call   __do_softirq            \n"
> > +             "addi   sp, s0, -2*"RISCV_SZPTR"\n"
> > +             REG_L"  s0, (sp)                \n"
> > +             "addi   sp, sp, "RISCV_SZPTR   "\n"
> > +             REG_L"  ra, (sp)                \n"
> > +             "addi   sp, sp, "RISCV_SZPTR   "\n"
> > +             :
> > +             : [sp] "r" (sp)
> > +             : "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
> > +               "t0", "t1", "t2", "t3", "t4", "t5", "t6",
> > +               "memory");
>
> Same as previous patch. Please avoid C&P and have a look at how
> call_on_stack is done on x86.
Okay.

>
>
> Björn
Björn Töpel Dec. 9, 2022, 7:49 a.m. UTC | #3 
Guo Ren <guoren@kernel.org> writes:

> On Thu, Dec 8, 2022 at 6:12 PM Björn Töpel <bjorn@kernel.org> wrote:
>>
>> guoren@kernel.org writes:
>>
>> > From: Guo Ren <guoren@linux.alibaba.com>
>> >
>> > Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
>> > irq and softirq use the same independent irq_stack of percpu by time
>> > division multiplexing.
>> >
>> > Tested-by: Jisheng Zhang <jszhang@kernel.org>
>> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
>> > Signed-off-by: Guo Ren <guoren@kernel.org>
>> > ---
>> >  arch/riscv/Kconfig      |  7 ++++---
>> >  arch/riscv/kernel/irq.c | 33 +++++++++++++++++++++++++++++++++
>> >  2 files changed, 37 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> > index 0a9d4bdc0338..bd4c4ae4cdc9 100644
>> > --- a/arch/riscv/Kconfig
>> > +++ b/arch/riscv/Kconfig
>> > @@ -447,12 +447,13 @@ config FPU
>> >         If you don't know what to do here, say Y.
>> >
>> >  config IRQ_STACKS
>> > -     bool "Independent irq stacks" if EXPERT
>> > +     bool "Independent irq & softirq stacks" if EXPERT
>> >       default y
>> >       select HAVE_IRQ_EXIT_ON_IRQ_STACK
>> > +     select HAVE_SOFTIRQ_ON_OWN_STACK
>>
>> HAVE_IRQ_EXIT_ON_IRQ_STACK is used by softirq.c Shouldn't that be
>> selected introduced in this patch, instead of the previous one?
> This patch depends on the previous one. And the previous one could
> work separately.

Let me try to be more clear: IRQ_STACKS should be introduced in the
previous patch, which adds per-cpu stacks to hardirq. This patch adds
per-cpu stacks for softirq, and the softirq related selects:

 select HAVE_IRQ_EXIT_ON_IRQ_STACK
 select HAVE_SOFTIRQ_ON_OWN_STACK

Hence, the "HAVE_IRQ_EXIT_ON_IRQ_STACK" select should be part of *this*
patch, not the previous.

Or am I missing something?


Björn
Guo Ren Dec. 10, 2022, 10:21 a.m. UTC | #4 
On Fri, Dec 9, 2022 at 3:50 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> Guo Ren <guoren@kernel.org> writes:
>
> > On Thu, Dec 8, 2022 at 6:12 PM Björn Töpel <bjorn@kernel.org> wrote:
> >>
> >> guoren@kernel.org writes:
> >>
> >> > From: Guo Ren <guoren@linux.alibaba.com>
> >> >
> >> > Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config. The
> >> > irq and softirq use the same independent irq_stack of percpu by time
> >> > division multiplexing.
> >> >
> >> > Tested-by: Jisheng Zhang <jszhang@kernel.org>
> >> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> >> > Signed-off-by: Guo Ren <guoren@kernel.org>
> >> > ---
> >> >  arch/riscv/Kconfig      |  7 ++++---
> >> >  arch/riscv/kernel/irq.c | 33 +++++++++++++++++++++++++++++++++
> >> >  2 files changed, 37 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> > index 0a9d4bdc0338..bd4c4ae4cdc9 100644
> >> > --- a/arch/riscv/Kconfig
> >> > +++ b/arch/riscv/Kconfig
> >> > @@ -447,12 +447,13 @@ config FPU
> >> >         If you don't know what to do here, say Y.
> >> >
> >> >  config IRQ_STACKS
> >> > -     bool "Independent irq stacks" if EXPERT
> >> > +     bool "Independent irq & softirq stacks" if EXPERT
> >> >       default y
> >> >       select HAVE_IRQ_EXIT_ON_IRQ_STACK
> >> > +     select HAVE_SOFTIRQ_ON_OWN_STACK
> >>
> >> HAVE_IRQ_EXIT_ON_IRQ_STACK is used by softirq.c Shouldn't that be
> >> selected introduced in this patch, instead of the previous one?
> > This patch depends on the previous one. And the previous one could
> > work separately.
>
> Let me try to be more clear: IRQ_STACKS should be introduced in the
> previous patch, which adds per-cpu stacks to hardirq. This patch adds
> per-cpu stacks for softirq, and the softirq related selects:
>
>  select HAVE_IRQ_EXIT_ON_IRQ_STACK
>  select HAVE_SOFTIRQ_ON_OWN_STACK
>
> Hence, the "HAVE_IRQ_EXIT_ON_IRQ_STACK" select should be part of *this*
> patch, not the previous.
>
> Or am I missing something?
You are right, HAVE_IRQ_EXIT_ON_IRQ_STACK is belong to SOFTIRQ:
static inline void invoke_softirq(void)
{
...
        if (!force_irqthreads() || !__this_cpu_read(ksoftirqd)) {
#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
...
                __do_softirq();
#else
...
                do_softirq_own_stack();
#endif
...
}

I would fix that in the next version.

>
>
> Björn
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0a9d4bdc0338..bd4c4ae4cdc9 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -447,12 +447,13 @@  config FPU
 	  If you don't know what to do here, say Y.
 
 config IRQ_STACKS
-	bool "Independent irq stacks" if EXPERT
+	bool "Independent irq & softirq stacks" if EXPERT
 	default y
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
+	select HAVE_SOFTIRQ_ON_OWN_STACK
 	help
-	  Add independent irq stacks for percpu to prevent kernel stack overflows.
-	  We may save some memory footprint by disabling IRQ_STACKS.
+	  Add independent irq & softirq stacks for percpu to prevent kernel stack
+	  overflows. We may save some memory footprint by disabling IRQ_STACKS.
 
 endmenu # "Platform type"
 
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 5d77f692b198..a6406da34937 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -11,6 +11,7 @@ 
 #include <linux/seq_file.h>
 #include <asm/smp.h>
 #include <asm/vmap_stack.h>
+#include <asm/softirq_stack.h>
 
 #ifdef CONFIG_IRQ_STACKS
 static DEFINE_PER_CPU(ulong *, irq_stack_ptr);
@@ -38,6 +39,38 @@  static void init_irq_stacks(void)
 		per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);
 }
 #endif /* CONFIG_VMAP_STACK */
+
+#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
+void do_softirq_own_stack(void)
+{
+#ifdef CONFIG_IRQ_STACKS
+	if (on_thread_stack()) {
+		ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
+					+ IRQ_STACK_SIZE/sizeof(ulong);
+		__asm__ __volatile(
+		"addi	sp, sp, -"RISCV_SZPTR  "\n"
+		REG_S"  ra, (sp)		\n"
+		"addi	sp, sp, -"RISCV_SZPTR  "\n"
+		REG_S"  s0, (sp)		\n"
+		"addi	s0, sp, 2*"RISCV_SZPTR "\n"
+		"move	sp, %[sp]		\n"
+		"call	__do_softirq		\n"
+		"addi	sp, s0, -2*"RISCV_SZPTR"\n"
+		REG_L"  s0, (sp)		\n"
+		"addi	sp, sp, "RISCV_SZPTR   "\n"
+		REG_L"  ra, (sp)		\n"
+		"addi	sp, sp, "RISCV_SZPTR   "\n"
+		:
+		: [sp] "r" (sp)
+		: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6",
+		  "memory");
+	} else
+#endif
+		__do_softirq();
+}
+#endif /* CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK */
+
 #else
 static void init_irq_stacks(void) {}
 #endif /* CONFIG_IRQ_STACKS */