Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ef8813ab authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

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: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent aaeed3ae

arch/x86/include/asm/desc.h

+1 −8
Original line number Diff line number Diff line
@@ -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 */

arch/x86/include/asm/fixmap.h

+35 −2
Original line number Diff line number Diff line
@@ -44,6 +44,19 @@ 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 avoid circular header dependencies.

 *

 * Every field is a virtual alias of some other allocated backing store.

 * There is no direct allocation of a struct cpu_entry_area.

 */

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 +114,8 @@ 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 +204,25 @@ 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);



	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))



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));

}



#endif /* !__ASSEMBLY__ */

#endif /* _ASM_X86_FIXMAP_H */

arch/x86/kernel/cpu/common.c

+7 −7
Original line number Diff line number Diff line
@@ -466,12 +466,12 @@ void load_percpu_segment(int cpu) 
	load_stack_canary_segment();

}



/* Setup the fixmap mapping only once per-processor */

static inline void setup_fixmap_gdt(int cpu)

/* Setup the fixmap mappings only once per-processor */

static inline void setup_cpu_entry_area(int cpu)

{

#ifdef CONFIG_X86_64

	/* On 64-bit systems, we use a read-only fixmap GDT. */

	pgprot_t prot = PAGE_KERNEL_RO;

	pgprot_t gdt_prot = PAGE_KERNEL_RO;

#else

	/*

	 * On native 32-bit systems, the GDT cannot be read-only because
@@ -482,11 +482,11 @@ static inline void setup_fixmap_gdt(int cpu) 
	 * On Xen PV, the GDT must be read-only because the hypervisor requires

	 * it.

	 */

	pgprot_t prot = boot_cpu_has(X86_FEATURE_XENPV) ?

	pgprot_t gdt_prot = boot_cpu_has(X86_FEATURE_XENPV) ?

		PAGE_KERNEL_RO : PAGE_KERNEL;

#endif



	__set_fixmap(get_cpu_gdt_ro_index(cpu), get_cpu_gdt_paddr(cpu), prot);

	__set_fixmap(get_cpu_entry_area_index(cpu, gdt), get_cpu_gdt_paddr(cpu), gdt_prot);

}



/* Load the original GDT from the per-cpu structure */
@@ -1589,7 +1589,7 @@ void cpu_init(void) 
	if (is_uv_system())

		uv_cpu_init();



	setup_fixmap_gdt(cpu);

	setup_cpu_entry_area(cpu);

	load_fixmap_gdt(cpu);

}
@@ -1651,7 +1651,7 @@ void cpu_init(void) 


	fpu__init_cpu();



	setup_fixmap_gdt(cpu);

	setup_cpu_entry_area(cpu);

	load_fixmap_gdt(cpu);

}

#endif

arch/x86/xen/mmu_pv.c

+1 −1
Original line number Diff line number Diff line
@@ -2272,7 +2272,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) 
#endif

	case FIX_TEXT_POKE0:

	case FIX_TEXT_POKE1:

	case FIX_GDT_REMAP_BEGIN ... FIX_GDT_REMAP_END:

	case FIX_CPU_ENTRY_AREA_TOP ... FIX_CPU_ENTRY_AREA_BOTTOM:

		/* All local page mappings */

		pte = pfn_pte(phys, prot);

		break;