From: Matt Fleming <matt.fleming@xxxxxxxxx> There are various pieces of code in arch/x86 that require a page table with an identity mapping. Make trampoline_pgd a proper kernel page table, it currently only includes the kernel text and module space mapping. One new feature of trampoline_pgd is that it now has mappings for the physical I/O device addresses, which are inserted at ioremap() time. Some broken implementations of EFI firmware require these mappings to always be around. Acked-by: Jan Beulich <jbeulich@xxxxxxxx> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> --- arch/x86/mm/init_64.c | 9 +++- arch/x86/mm/ioremap.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/realmode/init.c | 17 +++++++- 3 files changed, 128 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 2b6b4a3..fd4404f 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -108,13 +108,13 @@ void sync_global_pgds(unsigned long start, unsigned long end) for (address = start; address <= end; address += PGDIR_SIZE) { const pgd_t *pgd_ref = pgd_offset_k(address); struct page *page; + pgd_t *pgd; if (pgd_none(*pgd_ref)) continue; spin_lock(&pgd_lock); list_for_each_entry(page, &pgd_list, lru) { - pgd_t *pgd; spinlock_t *pgt_lock; pgd = (pgd_t *)page_address(page) + pgd_index(address); @@ -130,6 +130,13 @@ void sync_global_pgds(unsigned long start, unsigned long end) spin_unlock(pgt_lock); } + + pgd = __va(real_mode_header->trampoline_pgd); + pgd += pgd_index(address); + + if (pgd_none(*pgd)) + set_pgd(pgd, *pgd_ref); + spin_unlock(&pgd_lock); } } diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 78fe3f1..e190f7b 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -50,6 +50,107 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size, return err; } +#ifdef CONFIG_X86_64 +static void ident_pte_range(unsigned long paddr, unsigned long vaddr, + pmd_t *ppmd, pmd_t *vpmd, unsigned long end) +{ + pte_t *ppte = pte_offset_kernel(ppmd, paddr); + pte_t *vpte = pte_offset_kernel(vpmd, vaddr); + + do { + set_pte(ppte, *vpte); + } while (ppte++, vpte++, vaddr += PAGE_SIZE, vaddr != end); +} + +static int ident_pmd_range(unsigned long paddr, unsigned long vaddr, + pud_t *ppud, pud_t *vpud, unsigned long end) +{ + pmd_t *ppmd = pmd_offset(ppud, paddr); + pmd_t *vpmd = pmd_offset(vpud, vaddr); + unsigned long next; + + do { + next = pmd_addr_end(vaddr, end); + + if (!pmd_present(*ppmd)) { + pte_t *ppte = (pte_t *)get_zeroed_page(GFP_KERNEL); + if (!ppte) + return 1; + + set_pmd(ppmd, __pmd(_KERNPG_TABLE | __pa(ppte))); + } + + ident_pte_range(paddr, vaddr, ppmd, vpmd, next); + } while (ppmd++, vpmd++, vaddr = next, vaddr != end); + + return 0; +} + +static int ident_pud_range(unsigned long paddr, unsigned long vaddr, + pgd_t *ppgd, pgd_t *vpgd, unsigned long end) +{ + pud_t *ppud = pud_offset(ppgd, paddr); + pud_t *vpud = pud_offset(vpgd, vaddr); + unsigned long next; + + do { + next = pud_addr_end(vaddr, end); + + if (!pud_present(*ppud)) { + pmd_t *ppmd = (pmd_t *)get_zeroed_page(GFP_KERNEL); + if (!ppmd) + return 1; + + set_pud(ppud, __pud(_KERNPG_TABLE | __pa(ppmd))); + } + + if (ident_pmd_range(paddr, vaddr, ppud, vpud, next)) + return 1; + } while (ppud++, vpud++, vaddr = next, vaddr != end); + + return 0; +} + +static int insert_identity_mapping(resource_size_t paddr, unsigned long vaddr, + unsigned long size) +{ + unsigned long end = vaddr + size; + unsigned long next; + pgd_t *vpgd, *ppgd; + + /* Don't map over the guard hole. */ + if (paddr >= 0x800000000000 || paddr + size > 0x800000000000) + return 1; + + ppgd = __va(real_mode_header->trampoline_pgd) + pgd_index(paddr); + + vpgd = pgd_offset_k(vaddr); + do { + next = pgd_addr_end(vaddr, end); + + if (!pgd_present(*ppgd)) { + pud_t *ppud = (pud_t *)get_zeroed_page(GFP_KERNEL); + if (!ppud) + return 1; + + set_pgd(ppgd, __pgd(_KERNPG_TABLE | __pa(ppud))); + } + + if (ident_pud_range(paddr, vaddr, ppgd, vpgd, next)) + return 1; + } while (ppgd++, vpgd++, vaddr = next, vaddr != end); + + return 0; +} +#else +static inline int insert_identity_mapping(resource_size_t paddr, + unsigned long vaddr, + unsigned long size) +{ + return 0; +} +#endif /* CONFIG_X86_64 */ + /* * Remap an arbitrary physical address space into the kernel virtual * address space. Needed when the kernel wants to access high addresses @@ -163,6 +264,10 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, ret_addr = (void __iomem *) (vaddr + offset); mmiotrace_ioremap(unaligned_phys_addr, unaligned_size, ret_addr); + if (insert_identity_mapping(phys_addr, vaddr, size)) + printk(KERN_WARNING "ioremap: unable to map 0x%llx in identity pagetable\n", + (unsigned long long)phys_addr); + /* * Check if the request spans more than any BAR in the iomem resource * tree. diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index cbca565..8e6ab61 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -78,8 +78,21 @@ void __init setup_real_mode(void) *trampoline_cr4_features = read_cr4(); trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); - trampoline_pgd[0] = __pa(level3_ident_pgt) + _KERNPG_TABLE; - trampoline_pgd[511] = __pa(level3_kernel_pgt) + _KERNPG_TABLE; + + /* + * Create an identity mapping for all of physical memory. + */ + for (i = 0; i <= pgd_index(max_pfn << PAGE_SHIFT); i++) { + int index = pgd_index(PAGE_OFFSET) + i; + + trampoline_pgd[i] = (u64)pgd_val(swapper_pg_dir[index]); + } + + /* + * Copy the upper-half of the kernel pages tables. + */ + for (i = pgd_index(PAGE_OFFSET); i < PTRS_PER_PGD; i++) + trampoline_pgd[i] = (u64)pgd_val(swapper_pg_dir[i]); #endif } -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html