From 1eb0616c2df5b78c301eaa7bd2ee859f43915001 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 16 Nov 2020 11:32:53 -0800 Subject: xtensa/mm/highmem: Make generic kmap_atomic() work correctly The conversion to the generic kmap_atomic() implementation missed the fact that xtensa's fixmap works bottom up while all other implementations work top down. There is no real reason why xtensa needs to work that way. Cure it by: - Using the generic fix_to_virt()/virt_to_fix() functions which work top down - Adjusting the mapping defines - Using the generic index calculation for the non cache aliasing case - Making the cache colour offset reverse so the effective index is correct While at it, remove the outdated and misleading comment above the fixmap enum which originates from the initial copy&pasta of this code from i386. [ Max: Fixed the off by one in the index calculation ] Fixes: 629ed3f7dad2 ("xtensa/mm/highmem: Switch to generic kmap atomic") Reported-by: Max Filippov Signed-off-by: Thomas Gleixner Signed-off-by: Max Filippov Signed-off-by: Thomas Gleixner Tested-by: Max Filippov Link: https://lore.kernel.org/r/20201116193253.23875-1-jcmvbkbc@gmail.com --- arch/xtensa/include/asm/fixmap.h | 55 +++++---------------------------------- arch/xtensa/include/asm/highmem.h | 15 ++++++----- 2 files changed, 16 insertions(+), 54 deletions(-) (limited to 'arch/xtensa/include') diff --git a/arch/xtensa/include/asm/fixmap.h b/arch/xtensa/include/asm/fixmap.h index 92049b61c351..1c65dc1d3397 100644 --- a/arch/xtensa/include/asm/fixmap.h +++ b/arch/xtensa/include/asm/fixmap.h @@ -17,63 +17,22 @@ #include #include #include -#endif -/* - * Here we define all the compile-time 'special' virtual - * addresses. The point is to have a constant address at - * compile time, but to set the physical address only - * in the boot process. We allocate these special addresses - * from the start of the consistent memory region upwards. - * Also this lets us do fail-safe vmalloc(), we - * can guarantee that these special addresses and - * vmalloc()-ed addresses never overlap. - * - * these 'compile-time allocated' memory buffers are - * fixed-size 4k pages. (or larger if used with an increment - * higher than 1) use fixmap_set(idx,phys) to associate - * physical memory with fixmap indices. - */ +/* The map slots for temporary mappings via kmap_atomic/local(). */ enum fixed_addresses { -#ifdef CONFIG_HIGHMEM - /* reserved pte's for temporary kernel mappings */ FIX_KMAP_BEGIN, FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_MAX_IDX * NR_CPUS * DCACHE_N_COLORS) - 1, -#endif __end_of_fixed_addresses }; -#define FIXADDR_TOP (XCHAL_KSEG_CACHED_VADDR - PAGE_SIZE) +#define FIXADDR_END (XCHAL_KSEG_CACHED_VADDR - PAGE_SIZE) #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) -#define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK) +/* Enforce that FIXADDR_START is PMD aligned to handle cache aliasing */ +#define FIXADDR_START ((FIXADDR_END - FIXADDR_SIZE) & PMD_MASK) +#define FIXADDR_TOP (FIXADDR_START + FIXADDR_SIZE - PAGE_SIZE) -#define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT)) -#define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT) - -#ifndef __ASSEMBLY__ -/* - * 'index to address' translation. If anyone tries to use the idx - * directly without translation, we catch the bug with a NULL-deference - * kernel oops. Illegal ranges of incoming indices are caught too. - */ -static __always_inline unsigned long fix_to_virt(const unsigned int idx) -{ - /* Check if this memory layout is broken because fixmap overlaps page - * table. - */ - BUILD_BUG_ON(FIXADDR_START < - TLBTEMP_BASE_1 + TLBTEMP_SIZE); - BUILD_BUG_ON(idx >= __end_of_fixed_addresses); - return __fix_to_virt(idx); -} - -static inline unsigned long virt_to_fix(const unsigned long vaddr) -{ - BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); - return __virt_to_fix(vaddr); -} - -#endif +#include +#endif /* CONFIG_HIGHMEM */ #endif diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h index 0fc3b1cebc56..34b8b620e7f1 100644 --- a/arch/xtensa/include/asm/highmem.h +++ b/arch/xtensa/include/asm/highmem.h @@ -12,6 +12,7 @@ #ifndef _XTENSA_HIGHMEM_H #define _XTENSA_HIGHMEM_H +#ifdef CONFIG_HIGHMEM #include #include #include @@ -58,6 +59,13 @@ static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color) { return pkmap_map_wait_arr + color; } + +enum fixed_addresses kmap_local_map_idx(int type, unsigned long pfn); +#define arch_kmap_local_map_idx kmap_local_map_idx + +enum fixed_addresses kmap_local_unmap_idx(int type, unsigned long addr); +#define arch_kmap_local_unmap_idx kmap_local_unmap_idx + #endif extern pte_t *pkmap_page_table; @@ -67,15 +75,10 @@ static inline void flush_cache_kmaps(void) flush_cache_all(); } -enum fixed_addresses kmap_local_map_idx(int type, unsigned long pfn); -#define arch_kmap_local_map_idx kmap_local_map_idx - -enum fixed_addresses kmap_local_unmap_idx(int type, unsigned long addr); -#define arch_kmap_local_unmap_idx kmap_local_unmap_idx - #define arch_kmap_local_post_unmap(vaddr) \ local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE) void kmap_init(void); +#endif /* CONFIG_HIGHMEM */ #endif -- cgit v1.2.3