From ef9257668e3199f9566dc4a31f5292838bd99b49 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 17 Apr 2008 17:40:45 +0200 Subject: [PATCH] x86: do kernel direct mapping at boot using GB pages The AMD Fam10h CPUs support new Gigabyte page table entry for mapping 1GB at a time. Use this for the kernel direct mapping. Only done for 64bit because i386 does not support GB page tables. This only applies to the data portion of the direct mapping; the kernel text mapping stays with 2MB pages because the AMD Fam10h microarchitecture does not support GB ITLBs and AMD recommends against using GB mappings for code. Can be disabled with disable_gbpages on the kernel command line [ tglx@linutronix.de: simplify enable code ] [ Yinghai Lu : boot fix on 256 GB RAM ] Signed-off-by: Andi Kleen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/mm/init_64.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 6e7d5a42a09a..ae66d8d4c58d 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -370,7 +370,14 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end) } if (pud_val(*pud)) { - phys_pmd_update(pud, addr, end); + if (!pud_large(*pud)) + phys_pmd_update(pud, addr, end); + continue; + } + + if (direct_gbpages) { + set_pte((pte_t *)pud, + pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE)); continue; } @@ -391,9 +398,11 @@ static void __init find_early_table_space(unsigned long end) unsigned long puds, pmds, tables, start; puds = (end + PUD_SIZE - 1) >> PUD_SHIFT; - pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT; - tables = round_up(puds * sizeof(pud_t), PAGE_SIZE) + - round_up(pmds * sizeof(pmd_t), PAGE_SIZE); + tables = round_up(puds * sizeof(pud_t), PAGE_SIZE); + if (!direct_gbpages) { + pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT; + tables += round_up(pmds * sizeof(pmd_t), PAGE_SIZE); + } /* * RED-PEN putting page tables only on node 0 could @@ -413,6 +422,14 @@ static void __init find_early_table_space(unsigned long end) (table_start << PAGE_SHIFT) + tables); } +static void __init init_gbpages(void) +{ + if (direct_gbpages && cpu_has_gbpages) + printk(KERN_INFO "Using GB pages for direct mapping\n"); + else + direct_gbpages = 0; +} + /* * Setup the direct mapping of the physical memory at PAGE_OFFSET. * This runs before bootmem is initialized and gets pages directly from @@ -431,8 +448,10 @@ void __init_refok init_memory_mapping(unsigned long start, unsigned long end) * memory mapped. Unfortunately this is done currently before the * nodes are discovered. */ - if (!after_bootmem) + if (!after_bootmem) { + init_gbpages(); find_early_table_space(end); + } start = (unsigned long)__va(start); end = (unsigned long)__va(end); -- 2.20.1