From 55f49fcb879fbeebf2a8c1ac7c9e6d90df55f798 Mon Sep 17 00:00:00 2001 From: William Grant Date: Tue, 30 Jan 2018 22:22:55 +1100 Subject: [PATCH] x86/mm: Fix overlap of i386 CPU_ENTRY_AREA with FIX_BTMAP Since commit 92a0f81d8957 ("x86/cpu_entry_area: Move it out of the fixmap"), i386's CPU_ENTRY_AREA has been mapped to the memory area just below FIXADDR_START. But already immediately before FIXADDR_START is the FIX_BTMAP area, which means that early_ioremap can collide with the entry area. It's especially bad on PAE where FIX_BTMAP_BEGIN gets aligned to exactly match CPU_ENTRY_AREA_BASE, so the first early_ioremap slot clobbers the IDT and causes interrupts during early boot to reset the system. The overlap wasn't a problem before the CPU entry area was introduced, as the fixmap has classically been preceded by the pkmap or vmalloc areas, neither of which is used until early_ioremap is out of the picture. Relocate CPU_ENTRY_AREA to below FIX_BTMAP, not just below the permanent fixmap area. Fixes: commit 92a0f81d8957 ("x86/cpu_entry_area: Move it out of the fixmap") Signed-off-by: William Grant Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/7041d181-a019-e8b9-4e4e-48215f841e2c@canonical.com --- arch/x86/include/asm/fixmap.h | 6 ++++-- arch/x86/include/asm/pgtable_32_types.h | 5 +++-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index 64c4a30e0d39..e203169931c7 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -137,8 +137,10 @@ enum fixed_addresses { extern void reserve_top_address(unsigned long reserve); -#define FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT) -#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) +#define FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT) +#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) +#define FIXADDR_TOT_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) +#define FIXADDR_TOT_START (FIXADDR_TOP - FIXADDR_TOT_SIZE) extern int fixmaps_set; diff --git a/arch/x86/include/asm/pgtable_32_types.h b/arch/x86/include/asm/pgtable_32_types.h index ce245b0cdfca..0777e18a1d23 100644 --- a/arch/x86/include/asm/pgtable_32_types.h +++ b/arch/x86/include/asm/pgtable_32_types.h @@ -44,8 +44,9 @@ extern bool __vmalloc_start_set; /* set once high_memory is set */ */ #define CPU_ENTRY_AREA_PAGES (NR_CPUS * 40) -#define CPU_ENTRY_AREA_BASE \ - ((FIXADDR_START - PAGE_SIZE * (CPU_ENTRY_AREA_PAGES + 1)) & PMD_MASK) +#define CPU_ENTRY_AREA_BASE \ + ((FIXADDR_TOT_START - PAGE_SIZE * (CPU_ENTRY_AREA_PAGES + 1)) \ + & PMD_MASK) #define PKMAP_BASE \ ((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK)