diff options
| -rw-r--r-- | arch/arm/mm/Kconfig | 4 | ||||
| -rw-r--r-- | arch/arm/mm/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm/mm/mmu.c | 124 | ||||
| -rw-r--r-- | arch/arm/mm/pv-fixup-asm.S | 88 |
4 files changed, 133 insertions, 84 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index b4f92b9a13ac..4dc661e2d3a6 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -624,6 +624,10 @@ config ARM_LPAE If unsure, say N. +config ARM_PV_FIXUP + def_bool y + depends on ARM_LPAE && ARM_PATCH_PHYS_VIRT && ARCH_KEYSTONE + config ARCH_PHYS_ADDR_T_64BIT def_bool ARM_LPAE diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile index d3afdf9eb65a..4cc1ec9f6bb0 100644 --- a/arch/arm/mm/Makefile +++ b/arch/arm/mm/Makefile @@ -18,6 +18,7 @@ obj-$(CONFIG_MODULES) += proc-syms.o obj-$(CONFIG_ALIGNMENT_TRAP) += alignment.o obj-$(CONFIG_HIGHMEM) += highmem.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o +obj-$(CONFIG_ARM_PV_FIXUP) += pv-fixup-asm.o obj-$(CONFIG_CPU_ABRT_NOMMU) += abort-nommu.o obj-$(CONFIG_CPU_ABRT_EV4) += abort-ev4.o diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 0e5ed87221dd..a5d3180a6886 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1387,7 +1387,11 @@ static void __init map_lowmem(void) } } -#if defined(CONFIG_ARM_LPAE) && defined(CONFIG_ARM_PATCH_PHYS_VIRT) +#ifdef CONFIG_ARM_PV_FIXUP +extern unsigned long __atags_pointer; +typedef void pgtables_remap(long long offset, unsigned long pgd, void *bdata); +pgtables_remap lpae_pgtables_remap_asm; + /* * early_paging_init() recreates boot time page table setup, allowing machines * to switch over to a high (>4G) address space on LPAE systems @@ -1395,35 +1399,30 @@ static void __init map_lowmem(void) void __init early_paging_init(const struct machine_desc *mdesc, struct proc_info_list *procinfo) { - pmdval_t pmdprot = procinfo->__cpu_mm_mmu_flags; - unsigned long map_start, map_end; + pgtables_remap *lpae_pgtables_remap; + unsigned long pa_pgd; + unsigned int cr, ttbcr; long long offset; - pgd_t *pgd0, *pgdk; - pud_t *pud0, *pudk, *pud_start; - pmd_t *pmd0, *pmdk; - phys_addr_t phys; - int i; + void *boot_data; if (!mdesc->pv_fixup) return; - /* remap kernel code and data */ - map_start = init_mm.start_code & PMD_MASK; - map_end = ALIGN(init_mm.brk, PMD_SIZE); - - /* get a handle on things... */ - pgd0 = pgd_offset_k(0); - pud_start = pud0 = pud_offset(pgd0, 0); - pmd0 = pmd_offset(pud0, 0); - - pgdk = pgd_offset_k(map_start); - pudk = pud_offset(pgdk, map_start); - pmdk = pmd_offset(pudk, map_start); - offset = mdesc->pv_fixup(); if (offset == 0) return; + /* + * Get the address of the remap function in the 1:1 identity + * mapping setup by the early page table assembly code. We + * must get this prior to the pv update. The following barrier + * ensures that this is complete before we fixup any P:V offsets. + */ + lpae_pgtables_remap = (pgtables_remap *)(unsigned long)__pa(lpae_pgtables_remap_asm); + pa_pgd = __pa(swapper_pg_dir); + boot_data = __va(__atags_pointer); + barrier(); + pr_info("Switching physical address space to 0x%08llx\n", (u64)PHYS_OFFSET + offset); @@ -1436,75 +1435,32 @@ void __init early_paging_init(const struct machine_desc *mdesc, (&__pv_table_end - &__pv_table_begin) << 2); /* - * Cache cleaning operations for self-modifying code - * We should clean the entries by MVA but running a - * for loop over every pv_table entry pointer would - * just complicate the code. - */ - flush_cache_louis(); - dsb(ishst); - isb(); - - /* - * FIXME: This code is not architecturally compliant: we modify - * the mappings in-place, indeed while they are in use by this - * very same code. This may lead to unpredictable behaviour of - * the CPU. - * - * Even modifying the mappings in a separate page table does - * not resolve this. - * - * The architecture strongly recommends that when a mapping is - * changed, that it is changed by first going via an invalid - * mapping and back to the new mapping. This is to ensure that - * no TLB conflicts (caused by the TLB having more than one TLB - * entry match a translation) can occur. However, doing that - * here will result in unmapping the code we are running. - */ - pr_warn("WARNING: unsafe modification of in-place page tables - tainting kernel\n"); - add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); - - /* - * Remap level 1 table. This changes the physical addresses - * used to refer to the level 2 page tables to the high - * physical address alias, leaving everything else the same. - */ - for (i = 0; i < PTRS_PER_PGD; pud0++, i++) { - set_pud(pud0, - __pud(__pa(pmd0) | PMD_TYPE_TABLE | L_PGD_SWAPPER)); - pmd0 += PTRS_PER_PMD; - } - - /* - * Remap the level 2 table, pointing the mappings at the high - * physical address alias of these pages. - */ - phys = __pa(map_start); - do { - *pmdk++ = __pmd(phys | pmdprot); - phys += PMD_SIZE; - } while (phys < map_end); - - /* - * Ensure that the above updates are flushed out of the cache. - * This is not strictly correct; on a system where the caches - * are coherent with each other, but the MMU page table walks - * may not be coherent, flush_cache_all() may be a no-op, and - * this will fail. + * We changing not only the virtual to physical mapping, but also + * the physical addresses used to access memory. We need to flush + * all levels of cache in the system with caching disabled to + * ensure that all data is written back, and nothing is prefetched + * into the caches. We also need to prevent the TLB walkers + * allocating into the caches too. Note that this is ARMv7 LPAE + * specific. */ + cr = get_cr(); + set_cr(cr & ~(CR_I | CR_C)); + asm("mrc p15, 0, %0, c2, c0, 2" : "=r" (ttbcr)); + asm volatile("mcr p15, 0, %0, c2, c0, 2" + : : "r" (ttbcr & ~(3 << 8 | 3 << 10))); flush_cache_all(); /* - * Re-write the TTBR values to point them at the high physical - * alias of the page tables. We expect __va() will work on - * cpu_get_pgd(), which returns the value of TTBR0. + * Fixup the page tables - this must be in the idmap region as + * we need to disable the MMU to do this safely, and hence it + * needs to be assembly. It's fairly simple, as we're using the + * temporary tables setup by the initial assembly code. */ - cpu_switch_mm(pgd0, &init_mm); - cpu_set_ttbr(1, __pa(pgd0) + TTBR1_OFFSET); + lpae_pgtables_remap(offset, pa_pgd, boot_data); - /* Finally flush any stale TLB values. */ - local_flush_bp_all(); - local_flush_tlb_all(); + /* Re-enable the caches and cacheable TLB walks */ + asm volatile("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr)); + set_cr(cr); } #else diff --git a/arch/arm/mm/pv-fixup-asm.S b/arch/arm/mm/pv-fixup-asm.S new file mode 100644 index 000000000000..1867f3e43016 --- /dev/null +++ b/arch/arm/mm/pv-fixup-asm.S @@ -0,0 +1,88 @@ +/* + * Copyright (C) 2015 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This assembly is required to safely remap the physical address space + * for Keystone 2 + */ +#include <linux/linkage.h> +#include <asm/asm-offsets.h> +#include <asm/cp15.h> +#include <asm/memory.h> +#include <asm/pgtable.h> + + .section ".idmap.text", "ax" + +#define L1_ORDER 3 +#define L2_ORDER 3 + +ENTRY(lpae_pgtables_remap_asm) + stmfd sp!, {r4-r8, lr} + + mrc p15, 0, r8, c1, c0, 0 @ read control reg + bic ip, r8, #CR_M @ disable caches and MMU + mcr p15, 0, ip, c1, c0, 0 + dsb + isb + + /* Update level 2 entries covering the kernel */ + ldr r6, =(_end - 1) + add r7, r2, #0x1000 + add r6, r7, r6, lsr #SECTION_SHIFT - L2_ORDER + add r7, r7, #PAGE_OFFSET >> (SECTION_SHIFT - L2_ORDER) +1: ldrd r4, [r7] + adds r4, r4, r0 + adc r5, r5, r1 + strd r4, [r7], #1 << L2_ORDER + cmp r7, r6 + bls 1b + + /* Update level 2 entries for the boot data */ + add r7, r2, #0x1000 + add r7, r7, r3, lsr #SECTION_SHIFT - L2_ORDER + bic r7, r7, #(1 << L2_ORDER) - 1 + ldrd r4, [r7] + adds r4, r4, r0 + adc r5, r5, r1 + strd r4, [r7], #1 << L2_ORDER + ldrd r4, [r7] + adds r4, r4, r0 + adc r5, r5, r1 + strd r4, [r7] + + /* Update level 1 entries */ + mov r6, #4 + mov r7, r2 +2: ldrd r4, [r7] + adds r4, r4, r0 + adc r5, r5, r1 + strd r4, [r7], #1 << L1_ORDER + subs r6, r6, #1 + bne 2b + + mrrc p15, 0, r4, r5, c2 @ read TTBR0 + adds r4, r4, r0 @ update physical address + adc r5, r5, r1 + mcrr p15, 0, r4, r5, c2 @ write back TTBR0 + mrrc p15, 1, r4, r5, c2 @ read TTBR1 + adds r4, r4, r0 @ update physical address + adc r5, r5, r1 + mcrr p15, 1, r4, r5, c2 @ write back TTBR1 + + dsb + + mov ip, #0 + mcr p15, 0, ip, c7, c5, 0 @ I+BTB cache invalidate + mcr p15, 0, ip, c8, c7, 0 @ local_flush_tlb_all() + dsb + isb + + mcr p15, 0, r8, c1, c0, 0 @ re-enable MMU + dsb + isb + + ldmfd sp!, {r4-r8, pc} +ENDPROC(lpae_pgtables_remap_asm) |