x86/cpu_entry_area: Move it to a separate unit

Separate the cpu_entry_area code out of cpu/common.c and the fixmap.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/common.c

@@ -482,102 +482,8 @@ static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
 	  [0 ... N_EXCEPTION_STACKS - 1]	= EXCEPTION_STKSZ,
 	  [DEBUG_STACK - 1]			= DEBUG_STKSZ
 };
-
-static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
-	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
 #endif
 
-static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page,
-				   entry_stack_storage);
-
-static void __init
-set_percpu_fixmap_pages(int idx, void *ptr, int pages, pgprot_t prot)
-{
-	for ( ; pages; pages--, idx--, ptr += PAGE_SIZE)
-		__set_fixmap(idx, per_cpu_ptr_to_phys(ptr), prot);
-}
-
-/* Setup the fixmap mappings only once per-processor */
-static void __init setup_cpu_entry_area(int cpu)
-{
-#ifdef CONFIG_X86_64
-	extern char _entry_trampoline[];
-
-	/* On 64-bit systems, we use a read-only fixmap GDT and TSS. */
-	pgprot_t gdt_prot = PAGE_KERNEL_RO;
-	pgprot_t tss_prot = PAGE_KERNEL_RO;
-#else
-	/*
-	 * On native 32-bit systems, the GDT cannot be read-only because
-	 * our double fault handler uses a task gate, and entering through
-	 * a task gate needs to change an available TSS to busy.  If the
-	 * GDT is read-only, that will triple fault.  The TSS cannot be
-	 * read-only because the CPU writes to it on task switches.
-	 *
-	 * On Xen PV, the GDT must be read-only because the hypervisor
-	 * requires it.
-	 */
-	pgprot_t gdt_prot = boot_cpu_has(X86_FEATURE_XENPV) ?
-		PAGE_KERNEL_RO : PAGE_KERNEL;
-	pgprot_t tss_prot = PAGE_KERNEL;
-#endif
-
-	__set_fixmap(get_cpu_entry_area_index(cpu, gdt), get_cpu_gdt_paddr(cpu), gdt_prot);
-	set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, entry_stack_page),
-				per_cpu_ptr(&entry_stack_storage, cpu), 1,
-				PAGE_KERNEL);
-
-	/*
-	 * The Intel SDM says (Volume 3, 7.2.1):
-	 *
-	 *  Avoid placing a page boundary in the part of the TSS that the
-	 *  processor reads during a task switch (the first 104 bytes). The
-	 *  processor may not correctly perform address translations if a
-	 *  boundary occurs in this area. During a task switch, the processor
-	 *  reads and writes into the first 104 bytes of each TSS (using
-	 *  contiguous physical addresses beginning with the physical address
-	 *  of the first byte of the TSS). So, after TSS access begins, if
-	 *  part of the 104 bytes is not physically contiguous, the processor
-	 *  will access incorrect information without generating a page-fault
-	 *  exception.
-	 *
-	 * There are also a lot of errata involving the TSS spanning a page
-	 * boundary.  Assert that we're not doing that.
-	 */
-	BUILD_BUG_ON((offsetof(struct tss_struct, x86_tss) ^
-		      offsetofend(struct tss_struct, x86_tss)) & PAGE_MASK);
-	BUILD_BUG_ON(sizeof(struct tss_struct) % PAGE_SIZE != 0);
-	set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, tss),
-				&per_cpu(cpu_tss_rw, cpu),
-				sizeof(struct tss_struct) / PAGE_SIZE,
-				tss_prot);
-
-#ifdef CONFIG_X86_32
-	per_cpu(cpu_entry_area, cpu) = get_cpu_entry_area(cpu);
-#endif
-
-#ifdef CONFIG_X86_64
-	BUILD_BUG_ON(sizeof(exception_stacks) % PAGE_SIZE != 0);
-	BUILD_BUG_ON(sizeof(exception_stacks) !=
-		     sizeof(((struct cpu_entry_area *)0)->exception_stacks));
-	set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, exception_stacks),
-				&per_cpu(exception_stacks, cpu),
-				sizeof(exception_stacks) / PAGE_SIZE,
-				PAGE_KERNEL);
-
-	__set_fixmap(get_cpu_entry_area_index(cpu, entry_trampoline),
-		     __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX);
-#endif
-}
-
-void __init setup_cpu_entry_areas(void)
-{
-	unsigned int cpu;
-
-	for_each_possible_cpu(cpu)
-		setup_cpu_entry_area(cpu);
-}
-
 /* Load the original GDT from the per-cpu structure */
 void load_direct_gdt(int cpu)
 {

arch/x86/kernel/traps.c

@@ -52,6 +52,7 @@
 #include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/fpu/internal.h>
+#include <asm/cpu_entry_area.h>
 #include <asm/mce.h>
 #include <asm/fixmap.h>
 #include <asm/mach_traps.h>