On 2024-03-07 22:43:07 Thu, Michael Ellerman wrote: > > diff --git a/arch/powerpc/include/asm/interrupt.h > > b/arch/powerpc/include/asm/interrupt.h > > index a4196ab1d0167..0b96464ff0339 100644 > > --- a/arch/powerpc/include/asm/interrupt.h > > +++ b/arch/powerpc/include/asm/interrupt.h > > @@ -336,6 +336,14 @@ static inline void interrupt_nmi_enter_prepare(struct > > pt_regs *regs, struct inte > > if (IS_ENABLED(CONFIG_KASAN)) > > return; > > > > + /* > > + * Likewise, do not use it in real mode if percpu first chunk is not > > + * embedded. With CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there > > + * are chances where percpu allocation can come from vmalloc area. > > + */ > > + if (IS_ENABLED(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) && > > !is_embed_first_chunk) > > I think this would be clearer if it was inverted, eg: > > if (percpu_first_chunk_is_paged) > return;
Agree. > > That way you shouldn't need to check CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK > here. > Instead it can be part of the ifdef in the header. > > > @@ -351,6 +359,8 @@ static inline void interrupt_nmi_exit_prepare(struct > > pt_regs *regs, struct inter > > // no nmi_exit for a pseries hash guest taking a real mode > > exception > > } else if (IS_ENABLED(CONFIG_KASAN)) { > > // no nmi_exit for KASAN in real mode > > + } else if (IS_ENABLED(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) && > > !is_embed_first_chunk) { > > + // no nmi_exit if percpu first chunk is not embedded > > } else { > > nmi_exit(); > > } > > diff --git a/arch/powerpc/include/asm/percpu.h > > b/arch/powerpc/include/asm/percpu.h > > index 8e5b7d0b851c6..e24063eb0b33b 100644 > > --- a/arch/powerpc/include/asm/percpu.h > > +++ b/arch/powerpc/include/asm/percpu.h > > @@ -15,6 +15,16 @@ > > #endif /* CONFIG_SMP */ > > #endif /* __powerpc64__ */ > > > > +#ifdef CONFIG_PPC64 > > +#include <linux/jump_label.h> > > +DECLARE_STATIC_KEY_FALSE(__percpu_embed_first_chunk); > > + > > +#define is_embed_first_chunk \ > > + (static_key_enabled(&__percpu_embed_first_chunk.key)) > > +#else > > +#define is_embed_first_chunk true > > +#endif /* CONFIG_PPC64 */ > > + > > Something like: > > #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK > #include <linux/jump_label.h> > DECLARE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); > > #define percpu_first_chunk_is_paged \ > (static_key_enabled(&__percpu_first_chunk_is_paged.key)) > #else > #define percpu_first_chunk_is_paged false > #endif /* CONFIG_PPC64 */ Sure, will fix it. > > > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > > index 2f19d5e944852..e04f0ff69d4b6 100644 > > --- a/arch/powerpc/kernel/setup_64.c > > +++ b/arch/powerpc/kernel/setup_64.c > > @@ -834,6 +834,7 @@ static __init int pcpu_cpu_to_node(int cpu) > > > > unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; > > EXPORT_SYMBOL(__per_cpu_offset); > > +DEFINE_STATIC_KEY_FALSE(__percpu_embed_first_chunk); > > > > void __init setup_per_cpu_areas(void) > > { > > @@ -869,6 +870,8 @@ void __init setup_per_cpu_areas(void) > > pr_warn("PERCPU: %s allocator failed (%d), " > > "falling back to page size\n", > > pcpu_fc_names[pcpu_chosen_fc], rc); > > + else > > + static_key_enable(&__percpu_embed_first_chunk.key); > > } > > > > if (rc < 0) > > Finally, the current patch breaks the microwatt build: > > $ make microwatt_defconfig ; make -s -j (nproc) > make[1]: Entering directory '/home/michael/linux/.build' > GEN Makefile > # > # configuration written to .config > # > make[1]: Leaving directory '/home/michael/linux/.build' > ld: arch/powerpc/kernel/traps.o:(.toc+0x0): undefined reference to > `__percpu_embed_first_chunk' > ld: arch/powerpc/kernel/mce.o:(.toc+0x0): undefined reference to > `__percpu_embed_first_chunk' > make[3]: *** [../scripts/Makefile.vmlinux:37: vmlinux] Error 1 > > I guess because it has CONFIG_JUMP_LABEL=n? Even with CONFIG_JUMP_LABEL=n it should still work. Let me take look and fix this for microwatt build. Thanks for your review. -Mahesh. > > cheers -- Mahesh J Salgaonkar