From c1090bb10d5e15906d296936e64317e35c43f21d Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 10 Nov 2020 19:05:11 +0100 Subject: [PATCH] arm64: mm: don't assume struct page is always 64 bytes Commit 8c96400d6a39be7 simplified the page-to-virt and virt-to-page conversions, based on the assumption that struct page is always 64 bytes in size, in which case we can use a single signed shift to perform the conversion (provided that the vmemmap array is placed appropriately in the kernel VA space) Unfortunately, this assumption turns out not to hold, and so we need to revert part of this commit, and go back to an affine transformation. Given that all the quantities involved are compile time constants, this should not make any practical difference. Fixes: 8c96400d6a39 ("arm64: mm: make vmemmap region a projection of the linear region") Reported-by: Geert Uytterhoeven Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20201110180511.29083-1-ardb@kernel.org Tested-by: Geert Uytterhoeven Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/memory.h | 8 +++++--- arch/arm64/mm/init.c | 2 -- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 03e9b112bd949..556cb2d62b5bb 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -308,13 +308,15 @@ static inline void *phys_to_virt(phys_addr_t x) #else #define page_to_virt(x) ({ \ __typeof__(x) __page = x; \ - u64 __addr = (u64)__page << VMEMMAP_SHIFT; \ + u64 __idx = ((u64)__page - VMEMMAP_START) / sizeof(struct page);\ + u64 __addr = PAGE_OFFSET + (__idx * PAGE_SIZE); \ (void *)__tag_set((const void *)__addr, page_kasan_tag(__page));\ }) #define virt_to_page(x) ({ \ - u64 __addr = __tag_reset((u64)(x)) & PAGE_MASK; \ - (struct page *)((s64)__addr >> VMEMMAP_SHIFT); \ + u64 __idx = (__tag_reset((u64)x) - PAGE_OFFSET) / PAGE_SIZE; \ + u64 __addr = VMEMMAP_START + (__idx * sizeof(struct page)); \ + (struct page *)__addr; \ }) #endif /* !CONFIG_SPARSEMEM_VMEMMAP || CONFIG_DEBUG_VIRTUAL */ diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 3a5e9f9298e96..7e15d92836d8a 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -502,8 +502,6 @@ static void __init free_unused_memmap(void) */ void __init mem_init(void) { - BUILD_BUG_ON(!is_power_of_2(sizeof(struct page))); - if (swiotlb_force == SWIOTLB_FORCE || max_pfn > PFN_DOWN(arm64_dma_phys_limit ? : arm64_dma32_phys_limit)) swiotlb_init(1); -- 2.30.2