Messages in this thread Patch in this message | | | Date | Wed, 22 Nov 2017 16:33:38 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 05/18] x86/fixmap: Generalize the GDT fixmap mechanism |
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On Tue, Nov 21, 2017 at 08:44:00PM -0800, Andy Lutomirski wrote: > Currently, the GDT is an ad-hoc array of pages, one per CPU, in the > fixmap. Generalize it to be an array of a new struct cpu_entry_area > so that we can cleanly add new things to it. > > Signed-off-by: Andy Lutomirski <luto@kernel.org> > --- > arch/x86/include/asm/desc.h | 9 +-------- > arch/x86/include/asm/fixmap.h | 36 ++++++++++++++++++++++++++++++++++-- > arch/x86/kernel/cpu/common.c | 14 +++++++------- > arch/x86/xen/mmu_pv.c | 2 +- > 4 files changed, 43 insertions(+), 18 deletions(-) > > diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h > index 95cd95eb7285..194ffab00ebe 100644 > --- a/arch/x86/include/asm/desc.h > +++ b/arch/x86/include/asm/desc.h > @@ -60,17 +60,10 @@ static inline struct desc_struct *get_current_gdt_rw(void) > return this_cpu_ptr(&gdt_page)->gdt; > } > > -/* Get the fixmap index for a specific processor */ > -static inline unsigned int get_cpu_gdt_ro_index(int cpu) > -{ > - return FIX_GDT_REMAP_END - cpu; > -} > - > /* 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..038b8474c7f8 100644 > --- a/arch/x86/include/asm/fixmap.h > +++ b/arch/x86/include/asm/fixmap.h
Btw, the whole cpu_entry_area machinery looks like it should belong more in asm/processor.h and not in 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 > + * needed by the CPU and early entry/exit code. Real types aren't used > + * for all fields here to about circular header dependencies.
s/about/avoid/
> + */ > +struct cpu_entry_area > +{
ERROR: open brace '{' following struct go on the same line #67: FILE: arch/x86/include/asm/fixmap.h:53: +struct cpu_entry_area +{
> + char gdt[PAGE_SIZE]; > +}; > + > +#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE) > > /* > * Here we define all the compile-time 'special' virtual > @@ -101,8 +112,8 @@ enum fixed_addresses { > FIX_LNW_VRTC, > #endif > /* Fixmap entries to remap the GDTs, one per processor. */ > - FIX_GDT_REMAP_BEGIN, > - FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1, > + FIX_CPU_ENTRY_AREA_TOP, > + FIX_CPU_ENTRY_AREA_BOTTOM = FIX_CPU_ENTRY_AREA_TOP + (CPU_ENTRY_AREA_PAGES * NR_CPUS) - 1, > > #ifdef CONFIG_ACPI_APEI_GHES > /* Used for GHES mapping from assorted contexts */ > @@ -191,5 +202,26 @@ void __init *early_memremap_decrypted_wp(resource_size_t phys_addr, > void __early_set_fixmap(enum fixed_addresses idx, > phys_addr_t phys, pgprot_t flags); > > +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);
BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE);
> + > + 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); \
BUILD_BUG_ON(offset % PAGE_SIZE);
> + __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)) > + > +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));
Just let it stick out. -- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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