From ef6e06b2ef87077104d1145a0fd452ff8dbbc4b7 Mon Sep 17 00:00:00 2001 From: Ira Weiny Date: Wed, 5 Oct 2022 21:05:55 -0700 Subject: [PATCH] highmem: fix kmap_to_page() for kmap_local_page() addresses kmap_to_page() is used to get the page for a virtual address which may be kmap'ed. Unfortunately, kmap_local_page() stores mappings in a thread local array separate from kmap(). These mappings were not checked by the call. Check the kmap_local_page() mappings and return the page if found. Because it is intended to remove kmap_to_page() add a warn on once to the kmap checks to flag potential issues early. NOTE Due to 32bit x86 use of kmap local in iomap atmoic, KMAP_LOCAL does not require HIGHMEM to be set. Therefore the support calls required a new KMAP_LOCAL section to fix 0day build errors. [akpm@linux-foundation.org: fix warning] Link: https://lkml.kernel.org/r/20221006040555.1502679-1-ira.weiny@intel.com Signed-off-by: Ira Weiny Reported-by: Al Viro Reported-by: kernel test robot Cc: "Fabio M. De Francesco" Cc: Thomas Gleixner Cc: Christoph Hellwig Signed-off-by: Andrew Morton --- mm/highmem.c | 43 +++++++++++++++++++++++++++++++------------ 1 file changed, 31 insertions(+), 12 deletions(-) diff --git a/mm/highmem.c b/mm/highmem.c index c707d7202d5f..db251e77f98f 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -30,6 +30,17 @@ #include #include +#ifdef CONFIG_KMAP_LOCAL +static inline int kmap_local_calc_idx(int idx) +{ + return idx + KM_MAX_IDX * smp_processor_id(); +} + +#ifndef arch_kmap_local_map_idx +#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx) +#endif +#endif /* CONFIG_KMAP_LOCAL */ + /* * Virtual_count is not a pure "count". * 0 means that it is not mapped, and has not been mapped @@ -142,12 +153,29 @@ pte_t *pkmap_page_table; struct page *__kmap_to_page(void *vaddr) { + unsigned long base = (unsigned long) vaddr & PAGE_MASK; + struct kmap_ctrl *kctrl = ¤t->kmap_ctrl; unsigned long addr = (unsigned long)vaddr; + int i; - if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) { - int i = PKMAP_NR(addr); + /* kmap() mappings */ + if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) && + addr < PKMAP_ADDR(LAST_PKMAP))) + return pte_page(pkmap_page_table[PKMAP_NR(addr)]); - return pte_page(pkmap_page_table[i]); + /* kmap_local_page() mappings */ + if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) && + base < __fix_to_virt(FIX_KMAP_BEGIN))) { + for (i = 0; i < kctrl->idx; i++) { + unsigned long base_addr; + int idx; + + idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); + base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + + if (base_addr == base) + return pte_page(kctrl->pteval[i]); + } } return virt_to_page(vaddr); @@ -462,10 +490,6 @@ static inline void kmap_local_idx_pop(void) # define arch_kmap_local_post_unmap(vaddr) do { } while (0) #endif -#ifndef arch_kmap_local_map_idx -#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx) -#endif - #ifndef arch_kmap_local_unmap_idx #define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx) #endif @@ -494,11 +518,6 @@ static inline bool kmap_high_unmap_local(unsigned long vaddr) return false; } -static inline int kmap_local_calc_idx(int idx) -{ - return idx + KM_MAX_IDX * smp_processor_id(); -} - static pte_t *__kmap_pte; static pte_t *kmap_get_pte(unsigned long vaddr, int idx)