From d701fda8601fe267fbd3648f108f0e751305101b Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 30 Jan 2008 13:33:48 +0100 Subject: [PATCH] x86: fix early_ioremap()/btmap fix a long-standing weakness of the early-ioremap allocator: it uses a single pgd entry for the boot mappings, and was not properly protecting itself against crossing a 2MB (4MB) boundary. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- include/asm-x86/fixmap_32.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/asm-x86/fixmap_32.h b/include/asm-x86/fixmap_32.h index 46bedb7b5426..fde140fd6d95 100644 --- a/include/asm-x86/fixmap_32.h +++ b/include/asm-x86/fixmap_32.h @@ -90,10 +90,18 @@ enum fixed_addresses { FIX_PARAVIRT_BOOTMAP, #endif __end_of_permanent_fixed_addresses, - /* temporary boot-time mappings, used before ioremap() is functional */ + /* + * 256 temporary boot-time mappings, used by early_ioremap(), + * before ioremap() is functional. + * + * We round it up to the next 512 pages boundary so that we + * can have a single pgd entry and a single pte table: + */ #define NR_FIX_BTMAPS 64 #define FIX_BTMAPS_NESTING 4 - FIX_BTMAP_END = __end_of_permanent_fixed_addresses, + FIX_BTMAP_END = + __end_of_permanent_fixed_addresses + 512 - + (__end_of_permanent_fixed_addresses & 511), FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_NESTING - 1, FIX_WP_TEST, __end_of_fixed_addresses -- 2.20.1