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SubjectRe: [PATCH v5] powerpc/irq: inline call_do_irq() and call_do_softirq() on PPC32
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Hi Michael,

Le 07/12/2019 à 18:20, Christophe Leroy a écrit :
> call_do_irq() and call_do_softirq() are simple enough to be
> worth inlining.
>
> Inlining them avoids an mflr/mtlr pair plus a save/reload on stack.
> It also allows GCC to keep the saved ksp_limit in an nonvolatile reg.
>
> This is inspired from S390 arch. Several other arches do more or
> less the same. The way sparc arch does seems odd thought.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>

Anything more I need to do for this patch to get merged ?

Thanks
Christophe


>
> ---
> v2: no change.
> v3: no change.
> v4:
> - comment reminding the purpose of the inline asm block.
> - added r2 as clobbered reg
> v5:
> - Limiting the change to PPC32 for now.
> - removed r2 from the clobbered regs list (on PPC32 r2 points to current all the time)
> - Removed patch 1 and merged ksp_limit handling in here.
> ---
> arch/powerpc/include/asm/irq.h | 2 ++
> arch/powerpc/kernel/irq.c | 48 ++++++++++++++++++++++++++++++++++++++++++
> arch/powerpc/kernel/misc_32.S | 39 ----------------------------------
> 3 files changed, 50 insertions(+), 39 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
> index 814dfab7e392..e4a92f0b4ad4 100644
> --- a/arch/powerpc/include/asm/irq.h
> +++ b/arch/powerpc/include/asm/irq.h
> @@ -56,8 +56,10 @@ extern void *mcheckirq_ctx[NR_CPUS];
> extern void *hardirq_ctx[NR_CPUS];
> extern void *softirq_ctx[NR_CPUS];
>
> +#ifdef CONFIG_PPC64
> void call_do_softirq(void *sp);
> void call_do_irq(struct pt_regs *regs, void *sp);
> +#endif
> extern void do_IRQ(struct pt_regs *regs);
> extern void __init init_IRQ(void);
> extern void __do_irq(struct pt_regs *regs);
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index 5645bc9cbc09..240eca12c71d 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -611,6 +611,54 @@ static inline void check_stack_overflow(void)
> #endif
> }
>
> +#ifdef CONFIG_PPC32
> +static inline void call_do_softirq(const void *sp)
> +{
> + register unsigned long ret asm("r3");
> + unsigned long limit = current->thread.ksp_limit;
> +
> + /* Adjust the stack limit */
> + current->thread.ksp_limit = (unsigned long)sp;
> +
> + /* Temporarily switch r1 to sp, call __do_softirq() then restore r1. */
> + asm volatile(
> + " "PPC_STLU" 1, %2(%1);\n"
> + " mr 1, %1;\n"
> + " bl %3;\n"
> + " "PPC_LL" 1, 0(1);\n" :
> + "=r"(ret) :
> + "b"(sp), "i"(THREAD_SIZE - STACK_FRAME_OVERHEAD), "i"(__do_softirq) :
> + "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6", "cr7",
> + "r0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
> +
> + /* Restore stack limit */
> + current->thread.ksp_limit = limit;
> +}
> +
> +static inline void call_do_irq(struct pt_regs *regs, void *sp)
> +{
> + register unsigned long r3 asm("r3") = (unsigned long)regs;
> + unsigned long limit = current->thread.ksp_limit;
> +
> + /* Adjust the stack limit */
> + current->thread.ksp_limit = (unsigned long)sp;
> +
> + /* Temporarily switch r1 to sp, call __do_irq() then restore r1 */
> + asm volatile(
> + " "PPC_STLU" 1, %2(%1);\n"
> + " mr 1, %1;\n"
> + " bl %3;\n"
> + " "PPC_LL" 1, 0(1);\n" :
> + "+r"(r3) :
> + "b"(sp), "i"(THREAD_SIZE - STACK_FRAME_OVERHEAD), "i"(__do_irq) :
> + "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6", "cr7",
> + "r0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
> +
> + /* Restore stack limit */
> + current->thread.ksp_limit = limit;
> +}
> +#endif
> +
> void __do_irq(struct pt_regs *regs)
> {
> unsigned int irq;
> diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
> index d80212be8698..341a3cd199cb 100644
> --- a/arch/powerpc/kernel/misc_32.S
> +++ b/arch/powerpc/kernel/misc_32.S
> @@ -28,45 +28,6 @@
> .text
>
> /*
> - * We store the saved ksp_limit in the unused part
> - * of the STACK_FRAME_OVERHEAD
> - */
> -_GLOBAL(call_do_softirq)
> - mflr r0
> - stw r0,4(r1)
> - lwz r10,THREAD+KSP_LIMIT(r2)
> - stw r3, THREAD+KSP_LIMIT(r2)
> - stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
> - mr r1,r3
> - stw r10,8(r1)
> - bl __do_softirq
> - lwz r10,8(r1)
> - lwz r1,0(r1)
> - lwz r0,4(r1)
> - stw r10,THREAD+KSP_LIMIT(r2)
> - mtlr r0
> - blr
> -
> -/*
> - * void call_do_irq(struct pt_regs *regs, void *sp);
> - */
> -_GLOBAL(call_do_irq)
> - mflr r0
> - stw r0,4(r1)
> - lwz r10,THREAD+KSP_LIMIT(r2)
> - stw r4, THREAD+KSP_LIMIT(r2)
> - stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4)
> - mr r1,r4
> - stw r10,8(r1)
> - bl __do_irq
> - lwz r10,8(r1)
> - lwz r1,0(r1)
> - lwz r0,4(r1)
> - stw r10,THREAD+KSP_LIMIT(r2)
> - mtlr r0
> - blr
> -
> -/*
> * This returns the high 64 bits of the product of two 64-bit numbers.
> */
> _GLOBAL(mulhdu)
>

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