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ARM: 9016/2: Initialize the mapping of KASan shadow memory
This patch initializes KASan shadow region's page table and memory. There are two stage for KASan initializing: 1. At early boot stage the whole shadow region is mapped to just one physical page (kasan_zero_page). It is finished by the function kasan_early_init which is called by __mmap_switched(arch/arm/kernel/ head-common.S) 2. After the calling of paging_init, we use kasan_zero_page as zero shadow for some memory that KASan does not need to track, and we allocate a new shadow space for the other memory that KASan need to track. These issues are finished by the function kasan_init which is call by setup_arch. When using KASan we also need to increase the THREAD_SIZE_ORDER from 1 to 2 as the extra calls for shadow memory uses quite a bit of stack. As we need to make a temporary copy of the PGD when setting up shadow memory we create a helpful PGD_SIZE definition for both LPAE and non-LPAE setups. The KASan core code unconditionally calls pud_populate() so this needs to be changed from BUG() to do {} while (0) when building with KASan enabled. After the initial development by Andre Ryabinin several modifications have been made to this code: Abbott Liu <[email protected]> - Add support ARM LPAE: If LPAE is enabled, KASan shadow region's mapping table need be copied in the pgd_alloc() function. - Change kasan_pte_populate,kasan_pmd_populate,kasan_pud_populate, kasan_pgd_populate from .meminit.text section to .init.text section. Reported by Florian Fainelli <[email protected]> Linus Walleij <[email protected]>: - Drop the custom mainpulation of TTBR0 and just use cpu_switch_mm() to switch the pgd table. - Adopt to handle 4th level page tabel folding. - Rewrite the entire page directory and page entry initialization sequence to be recursive based on ARM64:s kasan_init.c. Ard Biesheuvel <[email protected]>: - Necessary underlying fixes. - Crucial bug fixes to the memory set-up code. Co-developed-by: Andrey Ryabinin <[email protected]> Co-developed-by: Abbott Liu <[email protected]> Co-developed-by: Ard Biesheuvel <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: [email protected] Cc: Mike Rapoport <[email protected]> Acked-by: Mike Rapoport <[email protected]> Reviewed-by: Ard Biesheuvel <[email protected]> Tested-by: Ard Biesheuvel <[email protected]> # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli <[email protected]> # Brahma SoCs Tested-by: Ahmad Fatoum <[email protected]> # i.MX6Q Reported-by: Russell King - ARM Linux <[email protected]> Reported-by: Florian Fainelli <[email protected]> Signed-off-by: Andrey Ryabinin <[email protected]> Signed-off-by: Abbott Liu <[email protected]> Signed-off-by: Florian Fainelli <[email protected]> Signed-off-by: Ard Biesheuvel <[email protected]> Signed-off-by: Linus Walleij <[email protected]> Signed-off-by: Russell King <[email protected]>
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