Kill temp boot pmds From: Vivek Goyal Early in the boot process we need the ability to set up temporary mappings, before our normal mechanisms are initialized. Currently this is used to map pages that are part of the page tables we are building and pages during the dmi scan. The core problem is that we are using the user portion of the page tables to implement this. Which means that while this mechanism is active we cannot catch NULL pointer dereferences and we deviate from the normal ways of handling things. In this patch I modify early_ioremap to map pages into the kernel portion of address space, roughly where we will later put modules, and I make the discovery of which addresses we can use dynamic which removes all kinds of static limits and remove the dependencies on implementation details between different parts of the code. Now alloc_low_page() and unmap_low_page() use early_iomap() and early_iounmap() to allocate/map and unmap a page. Signed-off-by: Eric W. Biederman Signed-off-by: Vivek Goyal Signed-off-by: Andi Kleen --- arch/x86_64/kernel/head.S | 3 - arch/x86_64/mm/init.c | 100 ++++++++++++++++++++-------------------------- 2 files changed, 45 insertions(+), 58 deletions(-) Index: linux/arch/x86_64/kernel/head.S =================================================================== --- linux.orig/arch/x86_64/kernel/head.S +++ linux/arch/x86_64/kernel/head.S @@ -288,9 +288,6 @@ NEXT_PAGE(level2_ident_pgt) .quad i << 21 | 0x083 i = i + 1 .endr - /* Temporary mappings for the super early allocator in arch/x86_64/mm/init.c */ - .globl temp_boot_pmds -temp_boot_pmds: .fill 492,8,0 NEXT_PAGE(level2_kernel_pgt) Index: linux/arch/x86_64/mm/init.c =================================================================== --- linux.orig/arch/x86_64/mm/init.c +++ linux/arch/x86_64/mm/init.c @@ -167,23 +167,9 @@ __set_fixmap (enum fixed_addresses idx, unsigned long __initdata table_start, table_end; -extern pmd_t temp_boot_pmds[]; - -static struct temp_map { - pmd_t *pmd; - void *address; - int allocated; -} temp_mappings[] __initdata = { - { &temp_boot_pmds[0], (void *)(40UL * 1024 * 1024) }, - { &temp_boot_pmds[1], (void *)(42UL * 1024 * 1024) }, - {} -}; - -static __meminit void *alloc_low_page(int *index, unsigned long *phys) +static __meminit void *alloc_low_page(unsigned long *phys) { - struct temp_map *ti; - int i; - unsigned long pfn = table_end++, paddr; + unsigned long pfn = table_end++; void *adr; if (after_bootmem) { @@ -194,57 +180,63 @@ static __meminit void *alloc_low_page(in if (pfn >= end_pfn) panic("alloc_low_page: ran out of memory"); - for (i = 0; temp_mappings[i].allocated; i++) { - if (!temp_mappings[i].pmd) - panic("alloc_low_page: ran out of temp mappings"); - } - ti = &temp_mappings[i]; - paddr = (pfn << PAGE_SHIFT) & PMD_MASK; - set_pmd(ti->pmd, __pmd(paddr | _KERNPG_TABLE | _PAGE_PSE)); - ti->allocated = 1; - __flush_tlb(); - adr = ti->address + ((pfn << PAGE_SHIFT) & ~PMD_MASK); + + adr = early_ioremap(pfn * PAGE_SIZE, PAGE_SIZE); memset(adr, 0, PAGE_SIZE); - *index = i; - *phys = pfn * PAGE_SIZE; - return adr; -} + *phys = pfn * PAGE_SIZE; + return adr; +} -static __meminit void unmap_low_page(int i) +static __meminit void unmap_low_page(void *adr) { - struct temp_map *ti; if (after_bootmem) return; - ti = &temp_mappings[i]; - set_pmd(ti->pmd, __pmd(0)); - ti->allocated = 0; + early_iounmap(adr, PAGE_SIZE); } /* Must run before zap_low_mappings */ __init void *early_ioremap(unsigned long addr, unsigned long size) { - unsigned long map = round_down(addr, LARGE_PAGE_SIZE); - - /* actually usually some more */ - if (size >= LARGE_PAGE_SIZE) { - return NULL; + unsigned long vaddr; + pmd_t *pmd, *last_pmd; + int i, pmds; + + pmds = ((addr & ~PMD_MASK) + size + ~PMD_MASK) / PMD_SIZE; + vaddr = __START_KERNEL_map; + pmd = level2_kernel_pgt; + last_pmd = level2_kernel_pgt + PTRS_PER_PMD - 1; + for (; pmd <= last_pmd; pmd++, vaddr += PMD_SIZE) { + for (i = 0; i < pmds; i++) { + if (pmd_present(pmd[i])) + goto next; + } + vaddr += addr & ~PMD_MASK; + addr &= PMD_MASK; + for (i = 0; i < pmds; i++, addr += PMD_SIZE) + set_pmd(pmd + i,__pmd(addr | _KERNPG_TABLE | _PAGE_PSE)); + __flush_tlb(); + return (void *)vaddr; + next: + ; } - set_pmd(temp_mappings[0].pmd, __pmd(map | _KERNPG_TABLE | _PAGE_PSE)); - map += LARGE_PAGE_SIZE; - set_pmd(temp_mappings[1].pmd, __pmd(map | _KERNPG_TABLE | _PAGE_PSE)); - __flush_tlb(); - return temp_mappings[0].address + (addr & (LARGE_PAGE_SIZE-1)); + printk("early_ioremap(0x%lx, %lu) failed\n", addr, size); + return NULL; } /* To avoid virtual aliases later */ __init void early_iounmap(void *addr, unsigned long size) { - if ((void *)round_down((unsigned long)addr, LARGE_PAGE_SIZE) != temp_mappings[0].address) - printk("early_iounmap: bad address %p\n", addr); - set_pmd(temp_mappings[0].pmd, __pmd(0)); - set_pmd(temp_mappings[1].pmd, __pmd(0)); + unsigned long vaddr; + pmd_t *pmd; + int i, pmds; + + vaddr = (unsigned long)addr; + pmds = ((vaddr & ~PMD_MASK) + size + ~PMD_MASK) / PMD_SIZE; + pmd = level2_kernel_pgt + pmd_index(vaddr); + for (i = 0; i < pmds; i++) + pmd_clear(pmd + i); __flush_tlb(); } @@ -289,7 +281,6 @@ static void __meminit phys_pud_init(pud_ for (; i < PTRS_PER_PUD; i++, addr = (addr & PUD_MASK) + PUD_SIZE ) { - int map; unsigned long pmd_phys; pud_t *pud = pud_page + pud_index(addr); pmd_t *pmd; @@ -307,12 +298,12 @@ static void __meminit phys_pud_init(pud_ continue; } - pmd = alloc_low_page(&map, &pmd_phys); + pmd = alloc_low_page(&pmd_phys); spin_lock(&init_mm.page_table_lock); set_pud(pud, __pud(pmd_phys | _KERNPG_TABLE)); phys_pmd_init(pmd, addr, end); spin_unlock(&init_mm.page_table_lock); - unmap_low_page(map); + unmap_low_page(pmd); } __flush_tlb(); } @@ -364,7 +355,6 @@ void __meminit init_memory_mapping(unsig end = (unsigned long)__va(end); for (; start < end; start = next) { - int map; unsigned long pud_phys; pgd_t *pgd = pgd_offset_k(start); pud_t *pud; @@ -372,7 +362,7 @@ void __meminit init_memory_mapping(unsig if (after_bootmem) pud = pud_offset(pgd, start & PGDIR_MASK); else - pud = alloc_low_page(&map, &pud_phys); + pud = alloc_low_page(&pud_phys); next = start + PGDIR_SIZE; if (next > end) @@ -380,7 +370,7 @@ void __meminit init_memory_mapping(unsig phys_pud_init(pud, __pa(start), __pa(next)); if (!after_bootmem) set_pgd(pgd_offset_k(start), mk_kernel_pgd(pud_phys)); - unmap_low_page(map); + unmap_low_page(pud); } if (!after_bootmem)