On Fri, Oct 22, 2021 at 4:52 PM Mark Rutland [off-list ref] wrote:

On Fri, Oct 22, 2021 at 10:33:53AM +0800, Guo Ren wrote:

quoted

On Fri, Oct 22, 2021 at 2:03 AM Mark Rutland [off-list ref] wrote:

quoted

Several architectures select GENERIC_IRQ_MULTI_HANDLER and branch to
handle_arch_irq() without performing any entry accounting.

Add a generic wrapper to handle the commoon irqentry work when invoking

Ah, I'd typo'd 'common' there; I'll go fix that...

quoted

quoted

handle_arch_irq(). Where an architecture needs to perform some entry
accounting itself, it will need to invoke handle_arch_irq() itself.

In subsequent patches it will become the responsibilty of the entry code
to set the irq regs when entering an IRQ (rather than deferring this to
an irqchip handler), so generic_handle_arch_irq() is made to set the irq
regs now. This can be redundant in some cases, but is never harmful as
saving/restoring the old regs nests safely.

Shall we remove old_regs save/restore in handle_domain_irq? It's duplicated.

We do, in patch 15 when handle_domain_irq() is removed entirely. :)

I miss that patch. Yes, in generic_handle_domain_nmi.

Removing it immediately in this patch would require more ifdeffery and/or
another copy of handle_domain_irq(), and since the duplication doesn't cause a
functional problem, I think it's better to live with the temporary duplication
for the next few patches than to try to optimize the intermediate steps at the
cost of legibility.

Thx for explaining.

Reviewed-by: Guo Ren <guoren@kernel.org>

Thanks,
Mark.

quoted

quoted

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <redacted>
---
 kernel/irq/handle.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 221d80c31e94..27182003b879 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c

@@ -14,6 +14,8 @@
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>

+#include <asm/irq_regs.h>
+
 #include <trace/events/irq.h>

 #include "internals.h"

@@ -226,4 +228,20 @@ int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
        handle_arch_irq = handle_irq;
        return 0;
 }
+
+/**
+ * generic_handle_arch_irq - root irq handler for architectures which do no
+ *                           entry accounting themselves
+ * @regs:      Register file coming from the low-level handling code
+ */
+asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
+{
+       struct pt_regs *old_regs;
+
+       irq_enter();
+       old_regs = set_irq_regs(regs);
+       handle_arch_irq(regs);
+       set_irq_regs(old_regs);
+       irq_exit();
+}
 #endif
--

2.11.0

--
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel