Merge branch 'x86-irq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 irq updates from Ingo Molnar:
 "Here are the main changes in this tree:

   - Introduce x86-64 IRQ/exception/debug stack guard pages to detect
     stack overflows immediately and deterministically.

   - Clean up over a decade worth of cruft accumulated.

  The outcome of this should be more clear-cut faults/crashes when any
  of the low level x86 CPU stacks overflow, instead of silent memory
  corruption and sporadic failures much later on"

* 'x86-irq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  x86/irq: Fix outdated comments
  x86/irq/64: Remove stack overflow debug code
  x86/irq/64: Remap the IRQ stack with guard pages
  x86/irq/64: Split the IRQ stack into its own pages
  x86/irq/64: Init hardirq_stack_ptr during CPU hotplug
  x86/irq/32: Handle irq stack allocation failure proper
  x86/irq/32: Invoke irq_ctx_init() from init_IRQ()
  x86/irq/64: Rename irq_stack_ptr to hardirq_stack_ptr
  x86/irq/32: Rename hard/softirq_stack to hard/softirq_stack_ptr
  x86/irq/32: Make irq stack a character array
  x86/irq/32: Define IRQ_STACK_SIZE
  x86/dumpstack/64: Speedup in_exception_stack()
  x86/exceptions: Split debug IST stack
  x86/exceptions: Enable IST guard pages
  x86/exceptions: Disconnect IST index and stack order
  x86/cpu: Remove orig_ist array
  x86/cpu: Prepare TSS.IST setup for guard pages
  x86/dumpstack/64: Use cpu_entry_area instead of orig_ist
  x86/irq/64: Use cpu entry area instead of orig_ist
  x86/traps: Use cpu_entry_area instead of orig_ist
  ...

2 files changed, 47 insertions, 20 deletions

diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
index 19c6abf9ea31..752ad11d6868 100644
--- a/arch/x86/mm/cpu_entry_area.c
+++ b/arch/x86/mm/cpu_entry_area.c
@@ -13,8 +13,8 @@
 static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page, entry_stack_storage);
 
 #ifdef CONFIG_X86_64
-static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
-	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
+static DEFINE_PER_CPU_PAGE_ALIGNED(struct exception_stacks, exception_stacks);
+DEFINE_PER_CPU(struct cea_exception_stacks*, cea_exception_stacks);
 #endif
 
 struct cpu_entry_area *get_cpu_entry_area(int cpu)
@@ -52,10 +52,10 @@ cea_map_percpu_pages(void *cea_vaddr, void *ptr, int pages, pgprot_t prot)
 		cea_set_pte(cea_vaddr, per_cpu_ptr_to_phys(ptr), prot);
 }
 
-static void __init percpu_setup_debug_store(int cpu)
+static void __init percpu_setup_debug_store(unsigned int cpu)
 {
 #ifdef CONFIG_CPU_SUP_INTEL
-	int npages;
+	unsigned int npages;
 	void *cea;
 
 	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
@@ -78,9 +78,43 @@ static void __init percpu_setup_debug_store(int cpu)
 #endif
 }
 
+#ifdef CONFIG_X86_64
+
+#define cea_map_stack(name) do {					\
+	npages = sizeof(estacks->name## _stack) / PAGE_SIZE;		\
+	cea_map_percpu_pages(cea->estacks.name## _stack,		\
+			estacks->name## _stack, npages, PAGE_KERNEL);	\
+	} while (0)
+
+static void __init percpu_setup_exception_stacks(unsigned int cpu)
+{
+	struct exception_stacks *estacks = per_cpu_ptr(&exception_stacks, cpu);
+	struct cpu_entry_area *cea = get_cpu_entry_area(cpu);
+	unsigned int npages;
+
+	BUILD_BUG_ON(sizeof(exception_stacks) % PAGE_SIZE != 0);
+
+	per_cpu(cea_exception_stacks, cpu) = &cea->estacks;
+
+	/*
+	 * The exceptions stack mappings in the per cpu area are protected
+	 * by guard pages so each stack must be mapped separately. DB2 is
+	 * not mapped; it just exists to catch triple nesting of #DB.
+	 */
+	cea_map_stack(DF);
+	cea_map_stack(NMI);
+	cea_map_stack(DB1);
+	cea_map_stack(DB);
+	cea_map_stack(MCE);
+}
+#else
+static inline void percpu_setup_exception_stacks(unsigned int cpu) {}
+#endif
+
 /* Setup the fixmap mappings only once per-processor */
-static void __init setup_cpu_entry_area(int cpu)
+static void __init setup_cpu_entry_area(unsigned int cpu)
 {
+	struct cpu_entry_area *cea = get_cpu_entry_area(cpu);
 #ifdef CONFIG_X86_64
 	/* On 64-bit systems, we use a read-only fixmap GDT and TSS. */
 	pgprot_t gdt_prot = PAGE_KERNEL_RO;
@@ -101,10 +135,9 @@ static void __init setup_cpu_entry_area(int cpu)
 	pgprot_t tss_prot = PAGE_KERNEL;
 #endif
 
-	cea_set_pte(&get_cpu_entry_area(cpu)->gdt, get_cpu_gdt_paddr(cpu),
-		    gdt_prot);
+	cea_set_pte(&cea->gdt, get_cpu_gdt_paddr(cpu), gdt_prot);
 
-	cea_map_percpu_pages(&get_cpu_entry_area(cpu)->entry_stack_page,
+	cea_map_percpu_pages(&cea->entry_stack_page,
 			     per_cpu_ptr(&entry_stack_storage, cpu), 1,
 			     PAGE_KERNEL);
 
@@ -128,22 +161,15 @@ static void __init setup_cpu_entry_area(int cpu)
 	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);
-	cea_map_percpu_pages(&get_cpu_entry_area(cpu)->tss,
-			     &per_cpu(cpu_tss_rw, cpu),
+	cea_map_percpu_pages(&cea->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);
+	per_cpu(cpu_entry_area, cpu) = cea;
 #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));
-	cea_map_percpu_pages(&get_cpu_entry_area(cpu)->exception_stacks,
-			     &per_cpu(exception_stacks, cpu),
-			     sizeof(exception_stacks) / PAGE_SIZE, PAGE_KERNEL);
-#endif
+	percpu_setup_exception_stacks(cpu);
+
 	percpu_setup_debug_store(cpu);
 }
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 667f1da36208..06c089513d39 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -28,6 +28,7 @@
 #include <asm/mmu_context.h>		/* vma_pkey()			*/
 #include <asm/efi.h>			/* efi_recover_from_page_fault()*/
 #include <asm/desc.h>			/* store_idt(), ...		*/
+#include <asm/cpu_entry_area.h>		/* exception stack		*/
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/exceptions.h>
@@ -793,7 +794,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 	if (is_vmalloc_addr((void *)address) &&
 	    (((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
 	     address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
-		unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_STACK]) - sizeof(void *);
+		unsigned long stack = __this_cpu_ist_top_va(DF) - sizeof(void *);
 		/*
 		 * We're likely to be running with very little stack space
 		 * left.  It's plausible that we'd hit this condition but