x86: construct 32-bit boot time page tables in native format.

Specifically the boot time page tables in a CONFIG_X86_PAE=y enabled
kernel are in PAE format.

early_ioremap is updated to use the standard page table accessors.

Clear any mappings beyond max_low_pfn from the boot page tables in
native_pagetable_setup_start because the initial mappings can extend
beyond the range of physical memory and into the vmalloc area.

Derived from patches by Eric Biederman and H. Peter Anvin.

[ jeremy@goop.org: PAE swapper_pg_dir needs to be page-sized fix ]

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Mika Penttilä <mika.penttila@kolumbus.fi>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 178 insertions, 104 deletions

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 5d8c5730686b..74ef4a41f224 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -19,6 +19,10 @@
 #include <asm/thread_info.h>
 #include <asm/asm-offsets.h>
 #include <asm/setup.h>
+#include <asm/processor-flags.h>
+
+/* Physical address */
+#define pa(X) ((X) - __PAGE_OFFSET)
 
 /*
  * References to members of the new_cpu_data structure.
@@ -80,10 +84,6 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_
  */
 .section .text.head,"ax",@progbits
 ENTRY(startup_32)
-        /* check to see if KEEP_SEGMENTS flag is meaningful */
-        cmpw $0x207, BP_version(%esi)
-        jb 1f
-
         /* test KEEP_SEGMENTS flag to see if the bootloader is asking
                 us to not reload segments */
         testb $(1<<6), BP_loadflags(%esi)
@@ -92,7 +92,7 @@ ENTRY(startup_32)
 /*
  * Set segments to known values.
  */
-1:      lgdt boot_gdt_descr - __PAGE_OFFSET
+        lgdt pa(boot_gdt_descr)
         movl $(__BOOT_DS),%eax
         movl %eax,%ds
         movl %eax,%es
@@ -105,8 +105,8 @@ ENTRY(startup_32)
  */
         cld
         xorl %eax,%eax
-        movl $__bss_start - __PAGE_OFFSET,%edi
-        movl $__bss_stop - __PAGE_OFFSET,%ecx
+        movl $pa(__bss_start),%edi
+        movl $pa(__bss_stop),%ecx
         subl %edi,%ecx
         shrl $2,%ecx
         rep ; stosl
@@ -118,31 +118,32 @@ ENTRY(startup_32)
  * (kexec on panic case). Hence copy out the parameters before initializing
  * page tables.
  */
-        movl $(boot_params - __PAGE_OFFSET),%edi
+        movl $pa(boot_params),%edi
         movl $(PARAM_SIZE/4),%ecx
         cld
         rep
         movsl
-        movl boot_params - __PAGE_OFFSET + NEW_CL_POINTER,%esi
+        movl pa(boot_params) + NEW_CL_POINTER,%esi
         andl %esi,%esi
         jz 1f                   # No comand line
-        movl $(boot_command_line - __PAGE_OFFSET),%edi
+        movl $pa(boot_command_line),%edi
         movl $(COMMAND_LINE_SIZE/4),%ecx
         rep
         movsl
 1:
 
 #ifdef CONFIG_PARAVIRT
-        cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)
+        /* This is can only trip for a broken bootloader... */
+        cmpw $0x207, pa(boot_params + BP_version)
         jb default_entry
 
         /* Paravirt-compatible boot parameters.  Look to see what architecture
                 we're booting under. */
-        movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax
+        movl pa(boot_params + BP_hardware_subarch), %eax
         cmpl $num_subarch_entries, %eax
         jae bad_subarch
 
-        movl subarch_entries - __PAGE_OFFSET(,%eax,4), %eax
+        movl pa(subarch_entries)(,%eax,4), %eax
         subl $__PAGE_OFFSET, %eax
         jmp *%eax
 
@@ -170,17 +171,68 @@ num_subarch_entries = (. - subarch_entries) / 4
  * Mappings are created both at virtual address 0 (identity mapping)
  * and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END.
  *
- * Warning: don't use %esi or the stack in this code.  However, %esp
- * can be used as a GPR if you really need it...
+ * Note that the stack is not yet set up!
  */
-page_pde_offset = (__PAGE_OFFSET >> 20);
+#define PTE_ATTR        0x007           /* PRESENT+RW+USER */
+#define PDE_ATTR        0x067           /* PRESENT+RW+USER+DIRTY+ACCESSED */
+#define PGD_ATTR        0x001           /* PRESENT (no other attributes) */
 
 default_entry:
-        movl $(pg0 - __PAGE_OFFSET), %edi
-        movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
-        movl $0x007, %eax                       /* 0x007 = PRESENT+RW+USER */
+#ifdef CONFIG_X86_PAE
+
+        /*
+         * In PAE mode swapper_pg_dir is statically defined to contain enough
+         * entries to cover the VMSPLIT option (that is the top 1, 2 or 3
+         * entries). The identity mapping is handled by pointing two PGD
+         * entries to the first kernel PMD.
+         *
+         * Note the upper half of each PMD or PTE are always zero at
+         * this stage.
+         */
+
+#define KPMDS ((0x100000000-__PAGE_OFFSET) >> 30) /* Number of kernel PMDs */
+
+        xorl %ebx,%ebx                          /* %ebx is kept at zero */
+
+        movl $pa(pg0), %edi
+        movl $pa(swapper_pg_pmd), %edx
+        movl $PTE_ATTR, %eax
+10:
+        leal PDE_ATTR(%edi),%ecx                /* Create PMD entry */
+        movl %ecx,(%edx)                        /* Store PMD entry */
+                                                /* Upper half already zero */
+        addl $8,%edx
+        movl $512,%ecx
+11:
+        stosl
+        xchgl %eax,%ebx
+        stosl
+        xchgl %eax,%ebx
+        addl $0x1000,%eax
+        loop 11b
+
+        /*
+         * End condition: we must map up to and including INIT_MAP_BEYOND_END
+         * bytes beyond the end of our own page tables.
+         */
+        leal (INIT_MAP_BEYOND_END+PTE_ATTR)(%edi),%ebp
+        cmpl %ebp,%eax
+        jb 10b
+1:
+        movl %edi,pa(init_pg_tables_end)
+
+        /* Do early initialization of the fixmap area */
+        movl $pa(swapper_pg_fixmap)+PDE_ATTR,%eax
+        movl %eax,pa(swapper_pg_pmd+0x1000*KPMDS-8)
+#else   /* Not PAE */
+
+page_pde_offset = (__PAGE_OFFSET >> 20);
+
+        movl $pa(pg0), %edi
+        movl $pa(swapper_pg_dir), %edx
+        movl $PTE_ATTR, %eax
 10:
-        leal 0x007(%edi),%ecx                   /* Create PDE entry */
+        leal PDE_ATTR(%edi),%ecx                /* Create PDE entry */
         movl %ecx,(%edx)                        /* Store identity PDE entry */
         movl %ecx,page_pde_offset(%edx)         /* Store kernel PDE entry */
         addl $4,%edx
@@ -189,19 +241,20 @@ default_entry:
         stosl
         addl $0x1000,%eax
         loop 11b
-        /* End condition: we must map up to and including INIT_MAP_BEYOND_END */
-        /* bytes beyond the end of our own page tables; the +0x007 is the attribute bits */
-        leal (INIT_MAP_BEYOND_END+0x007)(%edi),%ebp
+        /*
+         * End condition: we must map up to and including INIT_MAP_BEYOND_END
+         * bytes beyond the end of our own page tables; the +0x007 is
+         * the attribute bits
+         */
+        leal (INIT_MAP_BEYOND_END+PTE_ATTR)(%edi),%ebp
         cmpl %ebp,%eax
         jb 10b
-        movl %edi,(init_pg_tables_end - __PAGE_OFFSET)
-
-        /* Do an early initialization of the fixmap area */
-        movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
-        movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
-        addl $0x67, %eax                        /* 0x67 == _PAGE_TABLE */
-        movl %eax, 4092(%edx)
+        movl %edi,pa(init_pg_tables_end)
 
+        /* Do early initialization of the fixmap area */
+        movl $pa(swapper_pg_fixmap)+PDE_ATTR,%eax
+        movl %eax,pa(swapper_pg_dir+0xffc)
+#endif
         jmp 3f
 /*
  * Non-boot CPU entry point; entered from trampoline.S
@@ -241,7 +294,7 @@ ENTRY(startup_32_smp)
  *      NOTE! We have to correct for the fact that we're
  *      not yet offset PAGE_OFFSET..
  */
-#define cr4_bits mmu_cr4_features-__PAGE_OFFSET
+#define cr4_bits pa(mmu_cr4_features)
         movl cr4_bits,%edx
         andl %edx,%edx
         jz 6f
@@ -276,10 +329,10 @@ ENTRY(startup_32_smp)
 /*
  * Enable paging
  */
-        movl $swapper_pg_dir-__PAGE_OFFSET,%eax
+        movl $pa(swapper_pg_dir),%eax
         movl %eax,%cr3          /* set the page table pointer.. */
         movl %cr0,%eax
-        orl $0x80000000,%eax
+        orl  $X86_CR0_PG,%eax
         movl %eax,%cr0          /* ..and set paging (PG) bit */
         ljmp $__BOOT_CS,$1f     /* Clear prefetch and normalize %eip */
 1:
@@ -552,16 +605,44 @@ ENTRY(_stext)
  */
 .section ".bss.page_aligned","wa"
         .align PAGE_SIZE_asm
+#ifdef CONFIG_X86_PAE
+ENTRY(swapper_pg_pmd)
+        .fill 1024*KPMDS,4,0
+#else
 ENTRY(swapper_pg_dir)
         .fill 1024,4,0
-ENTRY(swapper_pg_pmd)
+#endif
+ENTRY(swapper_pg_fixmap)
         .fill 1024,4,0
 ENTRY(empty_zero_page)
         .fill 4096,1,0
-
 /*
  * This starts the data section.
  */
+#ifdef CONFIG_X86_PAE
+.section ".data.page_aligned","wa"
+        /* Page-aligned for the benefit of paravirt? */
+        .align PAGE_SIZE_asm
+ENTRY(swapper_pg_dir)
+        .long   pa(swapper_pg_pmd+PGD_ATTR),0           /* low identity map */
+# if KPMDS == 3
+        .long   pa(swapper_pg_pmd+PGD_ATTR),0
+        .long   pa(swapper_pg_pmd+PGD_ATTR+0x1000),0
+        .long   pa(swapper_pg_pmd+PGD_ATTR+0x2000),0
+# elif KPMDS == 2
+        .long   0,0
+        .long   pa(swapper_pg_pmd+PGD_ATTR),0
+        .long   pa(swapper_pg_pmd+PGD_ATTR+0x1000),0
+# elif KPMDS == 1
+        .long   0,0
+        .long   0,0
+        .long   pa(swapper_pg_pmd+PGD_ATTR),0
+# else
+#  error "Kernel PMDs should be 1, 2 or 3"
+# endif
+        .align PAGE_SIZE_asm            /* needs to be page-sized too */
+#endif
+
 .data
 ENTRY(stack_start)
         .long init_thread_union+THREAD_SIZE
diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index d1d8c347cc0b..691ab4cb167b 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -154,7 +154,11 @@ struct cpuinfo_x86 new_cpu_data __cpuinitdata = { 0, 0, 0, 0, -1, 1, 0, 0, -1 };
 struct cpuinfo_x86 boot_cpu_data __read_mostly = { 0, 0, 0, 0, -1, 1, 0, 0, -1 };
 EXPORT_SYMBOL(boot_cpu_data);
 
+#ifndef CONFIG_X86_PAE
 unsigned long mmu_cr4_features;
+#else
+unsigned long mmu_cr4_features = X86_CR4_PAE;
+#endif
 
 /* for MCA, but anyone else can use it if they want */
 unsigned int machine_id;
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index d1bc04006d16..54aba3cf9efe 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -46,6 +46,7 @@
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
 #include <asm/paravirt.h>
+#include <asm/setup.h>
 
 unsigned int __VMALLOC_RESERVE = 128 << 20;
 
@@ -328,44 +329,38 @@ pteval_t __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
 
 void __init native_pagetable_setup_start(pgd_t *base)
 {
-#ifdef CONFIG_X86_PAE
-        int i;
+        unsigned long pfn, va;
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
 
         /*
-         * Init entries of the first-level page table to the
-         * zero page, if they haven't already been set up.
-         *
-         * In a normal native boot, we'll be running on a
-         * pagetable rooted in swapper_pg_dir, but not in PAE
-         * mode, so this will end up clobbering the mappings
-         * for the lower 24Mbytes of the address space,
-         * without affecting the kernel address space.
+         * Remove any mappings which extend past the end of physical
+         * memory from the boot time page table:
          */
-        for (i = 0; i < USER_PTRS_PER_PGD; i++)
-                set_pgd(&base[i],
-                        __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
-
-        /* Make sure kernel address space is empty so that a pagetable
-           will be allocated for it. */
-        memset(&base[USER_PTRS_PER_PGD], 0,
-               KERNEL_PGD_PTRS * sizeof(pgd_t));
-#else
+        for (pfn = max_low_pfn + 1; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
+                va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
+                pgd = base + pgd_index(va);
+                if (!pgd_present(*pgd))
+                        break;
+
+                pud = pud_offset(pgd, va);
+                pmd = pmd_offset(pud, va);
+                if (!pmd_present(*pmd))
+                        break;
+
+                pte = pte_offset_kernel(pmd, va);
+                if (!pte_present(*pte))
+                        break;
+
+                pte_clear(NULL, va, pte);
+        }
         paravirt_alloc_pd(&init_mm, __pa(base) >> PAGE_SHIFT);
-#endif
 }
 
 void __init native_pagetable_setup_done(pgd_t *base)
 {
-#ifdef CONFIG_X86_PAE
-        /*
-         * Add low memory identity-mappings - SMP needs it when
-         * starting up on an AP from real-mode. In the non-PAE
-         * case we already have these mappings through head.S.
-         * All user-space mappings are explicitly cleared after
-         * SMP startup.
-         */
-        set_pgd(&base[0], base[USER_PTRS_PER_PGD]);
-#endif
 }
 
 /*
@@ -374,9 +369,8 @@ void __init native_pagetable_setup_done(pgd_t *base)
  * the boot process.
  *
  * If we're booting on native hardware, this will be a pagetable
- * constructed in arch/i386/kernel/head.S, and not running in PAE mode
- * (even if we'll end up running in PAE).  The root of the pagetable
- * will be swapper_pg_dir.
+ * constructed in arch/x86/kernel/head_32.S.  The root of the
+ * pagetable will be swapper_pg_dir.
  *
  * If we're booting paravirtualized under a hypervisor, then there are
  * more options: we may already be running PAE, and the pagetable may
@@ -537,14 +531,6 @@ void __init paging_init(void)
 
         load_cr3(swapper_pg_dir);
 
-#ifdef CONFIG_X86_PAE
-        /*
-         * We will bail out later - printk doesn't work right now so
-         * the user would just see a hanging kernel.
-         */
-        if (cpu_has_pae)
-                set_in_cr4(X86_CR4_PAE);
-#endif
         __flush_tlb_all();
 
         kmap_init();
@@ -675,10 +661,6 @@ void __init mem_init(void)
         BUG_ON((unsigned long)high_memory               > VMALLOC_START);
 #endif /* double-sanity-check paranoia */
 
-#ifdef CONFIG_X86_PAE
-        if (!cpu_has_pae)
-                panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
-#endif
         if (boot_cpu_data.wp_works_ok < 0)
                 test_wp_bit();
 
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index ee6648fe6b15..1106b7f477bd 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -260,41 +260,46 @@ static int __init early_ioremap_debug_setup(char *str)
 early_param("early_ioremap_debug", early_ioremap_debug_setup);
 
 static __initdata int after_paging_init;
-static __initdata unsigned long bm_pte[1024]
+static __initdata pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)]
                                 __attribute__((aligned(PAGE_SIZE)));
 
-static inline unsigned long * __init early_ioremap_pgd(unsigned long addr)
+static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
 {
-        return (unsigned long *)swapper_pg_dir + ((addr >> 22) & 1023);
+        pgd_t *pgd = &swapper_pg_dir[pgd_index(addr)];
+        pud_t *pud = pud_offset(pgd, addr);
+        pmd_t *pmd = pmd_offset(pud, addr);
+
+        return pmd;
 }
 
-static inline unsigned long * __init early_ioremap_pte(unsigned long addr)
+static inline pte_t * __init early_ioremap_pte(unsigned long addr)
 {
-        return bm_pte + ((addr >> PAGE_SHIFT) & 1023);
+        return &bm_pte[pte_index(addr)];
 }
 
 void __init early_ioremap_init(void)
 {
-        unsigned long *pgd;
+        pmd_t *pmd;
 
         if (early_ioremap_debug)
                 printk(KERN_INFO "early_ioremap_init()\n");
 
-        pgd = early_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
-        *pgd = __pa(bm_pte) | _PAGE_TABLE;
+        pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
         memset(bm_pte, 0, sizeof(bm_pte));
+        set_pmd(pmd, __pmd(__pa(bm_pte) | _PAGE_TABLE));
+
         /*
-         * The boot-ioremap range spans multiple pgds, for which
+         * The boot-ioremap range spans multiple pmds, for which
          * we are not prepared:
          */
-        if (pgd != early_ioremap_pgd(fix_to_virt(FIX_BTMAP_END))) {
+        if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
                 WARN_ON(1);
-                printk(KERN_WARNING "pgd %p != %p\n",
-                       pgd, early_ioremap_pgd(fix_to_virt(FIX_BTMAP_END)));
+                printk(KERN_WARNING "pmd %p != %p\n",
+                       pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
-                       fix_to_virt(FIX_BTMAP_BEGIN));
+                        fix_to_virt(FIX_BTMAP_BEGIN));
                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_END):   %08lx\n",
-                       fix_to_virt(FIX_BTMAP_END));
+                        fix_to_virt(FIX_BTMAP_END));
 
                 printk(KERN_WARNING "FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
                 printk(KERN_WARNING "FIX_BTMAP_BEGIN:     %d\n",
@@ -304,28 +309,29 @@ void __init early_ioremap_init(void)
 
 void __init early_ioremap_clear(void)
 {
-        unsigned long *pgd;
+        pmd_t *pmd;
 
         if (early_ioremap_debug)
                 printk(KERN_INFO "early_ioremap_clear()\n");
 
-        pgd = early_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
-        *pgd = 0;
-        paravirt_release_pt(__pa(pgd) >> PAGE_SHIFT);
+        pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+        pmd_clear(pmd);
+        paravirt_release_pt(__pa(pmd) >> PAGE_SHIFT);
         __flush_tlb_all();
 }
 
 void __init early_ioremap_reset(void)
 {
         enum fixed_addresses idx;
-        unsigned long *pte, phys, addr;
+        unsigned long addr, phys;
+        pte_t *pte;
 
         after_paging_init = 1;
         for (idx = FIX_BTMAP_BEGIN; idx >= FIX_BTMAP_END; idx--) {
                 addr = fix_to_virt(idx);
                 pte = early_ioremap_pte(addr);
-                if (*pte & _PAGE_PRESENT) {
-                        phys = *pte & PAGE_MASK;
+                if (pte_present(*pte)) {
+                        phys = pte_val(*pte) & PAGE_MASK;
                         set_fixmap(idx, phys);
                 }
         }
@@ -334,7 +340,8 @@ void __init early_ioremap_reset(void)
 static void __init __early_set_fixmap(enum fixed_addresses idx,
                                    unsigned long phys, pgprot_t flags)
 {
-        unsigned long *pte, addr = __fix_to_virt(idx);
+        unsigned long addr = __fix_to_virt(idx);
+        pte_t *pte;
 
         if (idx >= __end_of_fixed_addresses) {
                 BUG();
@@ -342,9 +349,9 @@ static void __init __early_set_fixmap(enum fixed_addresses idx,
         }
         pte = early_ioremap_pte(addr);
         if (pgprot_val(flags))
-                *pte = (phys & PAGE_MASK) | pgprot_val(flags);
+                set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
         else
-                *pte = 0;
+                pte_clear(NULL, addr, pte);
         __flush_tlb_one(addr);
 }