Merge "arm: Allow remapping lowmem as 4K pages"

	      8 - SIGSEGV faults

	     16 - SIGBUS faults

config FORCE_PAGES

	bool "Force lowmem to be mapped with 4K pages"

        help

          There are some advanced debug features that can only be done when

          memory is mapped with pages instead of sections. Enable this option

          to always map lowmem pages with pages. This may have a performance

          cost due to increased TLB pressure.

          If unsure say N.

# These options are only for real kernel hackers who want to get their hands dirty.

config DEBUG_LL

	bool "Kernel low-level debugging functions (read help!)"

	unsigned long size = PAGE_SIZE*numpages; \

	unsigned end = start + size; \

\

	if (!IS_ENABLED(CONFIG_FORCE_PAGES)) { \

		if (start < MODULES_VADDR || start >= MODULES_END) \

			return -EINVAL;\

\

		if (end < MODULES_VADDR || end >= MODULES_END) \

			return -EINVAL; \

	} \

\

	apply_to_page_range(&init_mm, start, size, callback, NULL); \

	flush_tlb_kernel_range(start, end); \

	}

}

#ifdef CONFIG_FORCE_PAGES

/*

 * remap a PMD into pages

 * We split a single pmd here none of this two pmd nonsense

 */

static noinline void split_pmd(pmd_t *pmd, unsigned long addr,

				unsigned long end, unsigned long pfn,

				const struct mem_type *type)

{

	pte_t *pte, *start_pte;

	start_pte = early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);

	pte = start_pte;

	do {

		set_pte_ext(pte, pfn_pte(pfn, type->prot_pte), 0);

		pfn++;

	} while (pte++, addr += PAGE_SIZE, addr != end);

	*pmd = __pmd((__pa(start_pte) + PTE_HWTABLE_OFF) | type->prot_l1);

	mb();

	flush_pmd_entry(pmd);

	flush_tlb_all();

}

/*

 * It's significantly easier to remap as pages later after all memory is

 * mapped. Everything is sections so all we have to do is split

 */

static void __init remap_pages(void)

{

	struct memblock_region *reg;

	for_each_memblock(memory, reg) {

		phys_addr_t phys_start = reg->base;

		phys_addr_t phys_end = reg->base + reg->size;

		unsigned long addr = (unsigned long)__va(phys_start);

		unsigned long end = (unsigned long)__va(phys_end);

		pmd_t *pmd = NULL;

		unsigned long next;

		unsigned long pfn = __phys_to_pfn(phys_start);

		bool fixup = false;

		unsigned long saved_start = addr;

		if (phys_end > arm_lowmem_limit)

			end = (unsigned long)__va(arm_lowmem_limit);

		if (phys_start >= phys_end)

			break;

		pmd = pmd_offset(

			pud_offset(pgd_offset(&init_mm, addr), addr), addr);

#ifndef	CONFIG_ARM_LPAE

		if (addr & SECTION_SIZE) {

			fixup = true;

			pmd_empty_section_gap((addr - SECTION_SIZE) & PMD_MASK);

			pmd++;

		}

		if (end & SECTION_SIZE)

			pmd_empty_section_gap(end);

#endif

		do {

			next = addr + SECTION_SIZE;

			if (pmd_none(*pmd) || pmd_bad(*pmd))

				split_pmd(pmd, addr, next, pfn,

						&mem_types[MT_MEMORY]);

			pmd++;

			pfn += SECTION_SIZE >> PAGE_SHIFT;

		} while (addr = next, addr < end);

		if (fixup) {

			/*

			 * Put a faulting page table here to avoid detecting no

			 * pmd when accessing an odd section boundary. This

			 * needs to be faulting to help catch errors and avoid

			 * speculation

			 */

			pmd = pmd_off_k(saved_start);

			pmd[0] = pmd[1] & ~1;

		}

	}

}

#else

static void __init remap_pages(void)

{

}

#endif

/*

 * paging_init() sets up the page tables, initialises the zone memory

 * maps, and sets up the zero page, bad page and bad page tables.

	prepare_page_table();

	map_lowmem();

	dma_contiguous_remap();

	remap_pages();

	devicemaps_init(mdesc);

	kmap_init();

	tcm_init();