ARCH_SUPPORTS_DEBUG_PAGEALLOC provides a hook to map and unmap pages for debugging purposes. This requires memory be mapped with PAGE_SIZE mappings since breaking down larger mappings at runtime will lead to TLB conflicts. Check if debug_pagealloc is enabled at runtime and if so, map everyting with PAGE_SIZE pages. Implement the functions to actually map/unmap the pages at runtime.
Signed-off-by: Laura Abbott <[email protected]> --- arch/arm64/Kconfig | 3 +++ arch/arm64/mm/mmu.c | 25 +++++++++++++++++++++---- arch/arm64/mm/pageattr.c | 46 ++++++++++++++++++++++++++++++++++++---------- 3 files changed, 60 insertions(+), 14 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8cc6228..0f33218 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -537,6 +537,9 @@ config HOTPLUG_CPU source kernel/Kconfig.preempt source kernel/Kconfig.hz +config ARCH_SUPPORTS_DEBUG_PAGEALLOC + def_bool y + config ARCH_HAS_HOLES_MEMORYMODEL def_bool y if SPARSEMEM diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index ef0d66c..be81a59 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -180,8 +180,14 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end, pmd = pmd_set_fixmap_offset(pud, addr); do { next = pmd_addr_end(addr, end); - /* try section mapping first */ - if (((addr | next | phys) & ~SECTION_MASK) == 0) { + /* + * try a section mapping first + * + * See comment in use_1G_block for why we need the check + * for !pgtable_alloc with !debug_pagealloc + */ + if (((addr | next | phys) & ~SECTION_MASK) == 0 && + (!debug_pagealloc_enabled() || !pgtable_alloc)) { pmd_t old_pmd =*pmd; set_pmd(pmd, __pmd(phys | pgprot_val(mk_sect_prot(prot)))); @@ -208,8 +214,19 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end, } static inline bool use_1G_block(unsigned long addr, unsigned long next, - unsigned long phys) + unsigned long phys, phys_addr_t (*pgtable_alloc)(void)) { + /* + * If debug_page_alloc is enabled we don't want to be using sections + * since everything needs to be mapped with pages. The catch is + * that we only want to force pages if we can allocate the next + * layer of page tables. If there is no pgtable_alloc function, + * it's too early to allocate another layer and we should use + * section mappings. + */ + if (pgtable_alloc && debug_pagealloc_enabled()) + return false; + if (PAGE_SHIFT != 12) return false; @@ -241,7 +258,7 @@ static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end, /* * For 4K granule only, attempt to put down a 1GB block */ - if (use_1G_block(addr, next, phys)) { + if (use_1G_block(addr, next, phys, pgtable_alloc)) { pud_t old_pud = *pud; set_pud(pud, __pud(phys | pgprot_val(mk_sect_prot(prot)))); diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 1360a02..57877af 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -37,14 +37,31 @@ static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, return 0; } +/* + * This function assumes that the range is mapped with PAGE_SIZE pages. + */ +static int __change_memory_common(unsigned long start, unsigned long size, + pgprot_t set_mask, pgprot_t clear_mask) +{ + struct page_change_data data; + int ret; + + data.set_mask = set_mask; + data.clear_mask = clear_mask; + + ret = apply_to_page_range(&init_mm, start, size, change_page_range, + &data); + + flush_tlb_kernel_range(start, start+size); + return ret; +} + static int change_memory_common(unsigned long addr, int numpages, pgprot_t set_mask, pgprot_t clear_mask) { unsigned long start = addr; unsigned long size = PAGE_SIZE*numpages; unsigned long end = start + size; - int ret; - struct page_change_data data; struct vm_struct *area; if (!PAGE_ALIGNED(addr)) { @@ -72,14 +89,7 @@ static int change_memory_common(unsigned long addr, int numpages, !(area->flags & VM_ALLOC)) return -EINVAL; - data.set_mask = set_mask; - data.clear_mask = clear_mask; - - ret = apply_to_page_range(&init_mm, start, size, change_page_range, - &data); - - flush_tlb_kernel_range(start, end); - return ret; + return __change_memory_common(start, size, set_mask, clear_mask); } int set_memory_ro(unsigned long addr, int numpages) @@ -111,3 +121,19 @@ int set_memory_x(unsigned long addr, int numpages) __pgprot(PTE_PXN)); } EXPORT_SYMBOL_GPL(set_memory_x); + +#ifdef CONFIG_DEBUG_PAGEALLOC +void __kernel_map_pages(struct page *page, int numpages, int enable) +{ + unsigned long addr = (unsigned long) page_address(page); + + if (enable) + __change_memory_common(addr, PAGE_SIZE*numpages, + __pgprot(PTE_VALID), + __pgprot(0)); + else + __change_memory_common(addr, PAGE_SIZE*numpages, + __pgprot(0), + __pgprot(PTE_VALID)); +} +#endif -- 2.5.0
