mirror of https://gitee.com/openkylin/linux.git
x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce struct cpu_entry_area
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> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Link: https://lkml.kernel.org/r/20171204150605.563271721@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -60,17 +60,10 @@ static inline struct desc_struct *get_current_gdt_rw(void)
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return this_cpu_ptr(&gdt_page)->gdt;
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}
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/* Get the fixmap index for a specific processor */
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static inline unsigned int get_cpu_gdt_ro_index(int cpu)
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{
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return FIX_GDT_REMAP_END - cpu;
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}
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/* Provide the fixmap address of the remapped GDT */
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static inline struct desc_struct *get_cpu_gdt_ro(int cpu)
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{
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unsigned int idx = get_cpu_gdt_ro_index(cpu);
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return (struct desc_struct *)__fix_to_virt(idx);
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return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt;
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}
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/* Provide the current read-only GDT */
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@ -44,6 +44,19 @@ extern unsigned long __FIXADDR_TOP;
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PAGE_SIZE)
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#endif
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/*
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* cpu_entry_area is a percpu region in the fixmap that contains things
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* needed by the CPU and early entry/exit code. Real types aren't used
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* for all fields here to avoid circular header dependencies.
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*
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* Every field is a virtual alias of some other allocated backing store.
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* There is no direct allocation of a struct cpu_entry_area.
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*/
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struct cpu_entry_area {
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char gdt[PAGE_SIZE];
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};
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#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE)
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/*
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* Here we define all the compile-time 'special' virtual
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@ -101,8 +114,8 @@ enum fixed_addresses {
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FIX_LNW_VRTC,
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#endif
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/* Fixmap entries to remap the GDTs, one per processor. */
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FIX_GDT_REMAP_BEGIN,
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FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1,
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FIX_CPU_ENTRY_AREA_TOP,
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FIX_CPU_ENTRY_AREA_BOTTOM = FIX_CPU_ENTRY_AREA_TOP + (CPU_ENTRY_AREA_PAGES * NR_CPUS) - 1,
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#ifdef CONFIG_ACPI_APEI_GHES
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/* Used for GHES mapping from assorted contexts */
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@ -191,5 +204,25 @@ void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
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void __early_set_fixmap(enum fixed_addresses idx,
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phys_addr_t phys, pgprot_t flags);
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static inline unsigned int __get_cpu_entry_area_page_index(int cpu, int page)
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{
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BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0);
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return FIX_CPU_ENTRY_AREA_BOTTOM - cpu*CPU_ENTRY_AREA_PAGES - page;
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}
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#define __get_cpu_entry_area_offset_index(cpu, offset) ({ \
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BUILD_BUG_ON(offset % PAGE_SIZE != 0); \
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__get_cpu_entry_area_page_index(cpu, offset / PAGE_SIZE); \
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})
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#define get_cpu_entry_area_index(cpu, field) \
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__get_cpu_entry_area_offset_index((cpu), offsetof(struct cpu_entry_area, field))
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static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
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{
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return (struct cpu_entry_area *)__fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_FIXMAP_H */
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@ -466,12 +466,12 @@ void load_percpu_segment(int cpu)
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load_stack_canary_segment();
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}
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/* Setup the fixmap mapping only once per-processor */
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static inline void setup_fixmap_gdt(int cpu)
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/* Setup the fixmap mappings only once per-processor */
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static inline void setup_cpu_entry_area(int cpu)
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{
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#ifdef CONFIG_X86_64
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/* On 64-bit systems, we use a read-only fixmap GDT. */
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pgprot_t prot = PAGE_KERNEL_RO;
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pgprot_t gdt_prot = PAGE_KERNEL_RO;
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#else
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/*
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* On native 32-bit systems, the GDT cannot be read-only because
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@ -482,11 +482,11 @@ static inline void setup_fixmap_gdt(int cpu)
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* On Xen PV, the GDT must be read-only because the hypervisor requires
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* it.
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*/
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pgprot_t prot = boot_cpu_has(X86_FEATURE_XENPV) ?
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pgprot_t gdt_prot = boot_cpu_has(X86_FEATURE_XENPV) ?
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PAGE_KERNEL_RO : PAGE_KERNEL;
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#endif
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__set_fixmap(get_cpu_gdt_ro_index(cpu), get_cpu_gdt_paddr(cpu), prot);
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__set_fixmap(get_cpu_entry_area_index(cpu, gdt), get_cpu_gdt_paddr(cpu), gdt_prot);
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}
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/* Load the original GDT from the per-cpu structure */
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@ -1589,7 +1589,7 @@ void cpu_init(void)
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if (is_uv_system())
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uv_cpu_init();
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setup_fixmap_gdt(cpu);
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setup_cpu_entry_area(cpu);
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load_fixmap_gdt(cpu);
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}
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@ -1651,7 +1651,7 @@ void cpu_init(void)
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fpu__init_cpu();
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setup_fixmap_gdt(cpu);
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setup_cpu_entry_area(cpu);
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load_fixmap_gdt(cpu);
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}
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#endif
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@ -2272,7 +2272,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
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#endif
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case FIX_TEXT_POKE0:
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case FIX_TEXT_POKE1:
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case FIX_GDT_REMAP_BEGIN ... FIX_GDT_REMAP_END:
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case FIX_CPU_ENTRY_AREA_TOP ... FIX_CPU_ENTRY_AREA_BOTTOM:
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/* All local page mappings */
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pte = pfn_pte(phys, prot);
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break;
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