[tip:x86/asm] x86: Lift restriction on the location of FIX_BTMAP_*
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From: tip-bot for Jan Beulich on 30 Dec 2009 07:30 Commit-ID: 499a5f1efa0b0ac56ec5d060412aed84ae68e63e Gitweb: http://git.kernel.org/tip/499a5f1efa0b0ac56ec5d060412aed84ae68e63e Author: Jan Beulich <JBeulich(a)novell.com> AuthorDate: Fri, 18 Dec 2009 16:05:51 +0000 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Wed, 30 Dec 2009 11:57:30 +0100 x86: Lift restriction on the location of FIX_BTMAP_* The early ioremap fixmap entries cover half (or for 32-bit non-PAE, a quarter) of a page table, yet they got uncondtitionally aligned so far to a 256-entry boundary. This is not necessary if the range of page table entries anyway falls into a single page table. This buys back, for (theoretically) 50% of all configurations (25% of all non-PAE ones), at least some of the lowmem necessarily lost with commit e621bd18958ef5dbace3129ebe17a0a475e127d9. Signed-off-by: Jan Beulich <jbeulich(a)novell.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> LKML-Reference: <4B2BB66F0200007800026AD6(a)vpn.id2.novell.com> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- arch/x86/include/asm/fixmap.h | 16 +++++++++++----- arch/x86/mm/ioremap.c | 4 ++++ 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index 14f9890..635f03b 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -118,14 +118,20 @@ enum fixed_addresses { * 256 temporary boot-time mappings, used by early_ioremap(), * before ioremap() is functional. * - * We round it up to the next 256 pages boundary so that we - * can have a single pgd entry and a single pte table: + * If necessary we round it up to the next 256 pages boundary so + * that we can have a single pgd entry and a single pte table: */ #define NR_FIX_BTMAPS 64 #define FIX_BTMAPS_SLOTS 4 - FIX_BTMAP_END = __end_of_permanent_fixed_addresses + 256 - - (__end_of_permanent_fixed_addresses & 255), - FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_SLOTS - 1, +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS) + FIX_BTMAP_END = + (__end_of_permanent_fixed_addresses ^ + (__end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS - 1)) & + -PTRS_PER_PTE + ? __end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS - + (__end_of_permanent_fixed_addresses & (TOTAL_FIX_BTMAPS - 1)) + : __end_of_permanent_fixed_addresses, + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1, #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT FIX_OHCI1394_BASE, #endif diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index c246d25..03c75ff 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -422,6 +422,10 @@ void __init early_ioremap_init(void) * The boot-ioremap range spans multiple pmds, for which * we are not prepared: */ +#define __FIXADDR_TOP (-PAGE_SIZE) + BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) + != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); +#undef __FIXADDR_TOP if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) { WARN_ON(1); printk(KERN_WARNING "pmd %p != %p\n", -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |