On Mon, Nov 20, 2017 at 2:01 PM, Thomas Gleixner <t...@linutronix.de> wrote: > On Mon, 20 Nov 2017, Andy Lutomirski wrote: > > Just a few nits. > >> /* Provide the fixmap address of the remapped GDT */ >> static inline struct desc_struct *get_cpu_gdt_ro(int cpu) >> { >> - unsigned int idx = get_cpu_gdt_ro_index(cpu); >> - return (struct desc_struct *)__fix_to_virt(idx); >> + return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt; >> } >> >> /* Provide the current read-only GDT */ >> diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h >> index b0c505fe9a95..5ff8e251772a 100644 >> --- a/arch/x86/include/asm/fixmap.h >> +++ b/arch/x86/include/asm/fixmap.h >> @@ -44,6 +44,17 @@ extern unsigned long __FIXADDR_TOP; >> PAGE_SIZE) >> #endif >> >> +/* >> + * cpu_entry_area is a percpu region in the fixmap that contains things >> + * need by the CPU and early entry/exit code. Real types aren't used here > > s/need/needed/
Yeah, fixed > >> + * to avoid circular header dependencies. > > :( Hmm. I could probably fix this, but it involves (at least) moving a struct definition and adding several new includes, and I'm not sure it'll actually converge to something working. > >> + */ >> +struct cpu_entry_area >> +{ >> + char gdt[PAGE_SIZE]; >> +}; >> + >> +#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE) > >> +static inline unsigned int __get_cpu_entry_area_page_index(int cpu, int >> page) >> +{ >> + BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0); >> + >> + return FIX_CPU_ENTRY_AREA_BOTTOM - cpu*CPU_ENTRY_AREA_PAGES - page; >> +} >> + >> +#define __get_cpu_entry_area_offset_index(cpu, offset) ({ \ >> + BUILD_BUG_ON(offset % PAGE_SIZE != 0); \ >> + __get_cpu_entry_area_page_index(cpu, offset / PAGE_SIZE); \ >> + }) >> + >> +#define get_cpu_entry_area_index(cpu, field) \ >> + __get_cpu_entry_area_offset_index((cpu), offsetof(struct >> cpu_entry_area, field)) > > Any reason why those need to be macros? The former is a macro because I doubt that BUILD_BUG_ON is valid in that context in a function. The latter is a macro because 'field' is a name, not a value. > >> +static inline struct cpu_entry_area *get_cpu_entry_area(int cpu) >> +{ >> + return (struct cpu_entry_area *) >> + __fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0)); >> +} >> + > > Thanks, > > tglx >