2013-01-21 00:43:10 +01:00
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#include <linux/module.h>
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2010-11-21 12:41:57 +01:00
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#include <linux/kernel.h>
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2013-01-21 00:43:10 +01:00
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#include <linux/slab.h>
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2010-11-21 12:41:57 +01:00
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#include <asm/cputype.h>
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2011-09-30 12:43:29 +02:00
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#include <asm/idmap.h>
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2010-11-21 12:41:57 +01:00
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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2011-09-30 12:43:29 +02:00
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#include <asm/sections.h>
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2012-03-28 19:30:01 +02:00
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#include <asm/system_info.h>
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2011-09-30 12:43:29 +02:00
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2014-07-29 13:18:34 +02:00
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/*
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* Note: accesses outside of the kernel image and the identity map area
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* are not supported on any CPU using the idmap tables as its current
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* page tables.
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*/
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2011-09-30 12:43:29 +02:00
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pgd_t *idmap_pgd;
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2013-07-31 18:44:42 +02:00
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phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
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2010-11-21 12:41:57 +01:00
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2011-11-22 18:30:32 +01:00
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#ifdef CONFIG_ARM_LPAE
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static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
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unsigned long prot)
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{
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pmd_t *pmd;
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unsigned long next;
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if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
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pmd = pmd_alloc_one(&init_mm, addr);
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if (!pmd) {
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2014-09-16 21:41:43 +02:00
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pr_warn("Failed to allocate identity pmd.\n");
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2011-11-22 18:30:32 +01:00
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return;
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}
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ARM: 8115/1: LPAE: reduce damage caused by idmap to virtual memory layout
On LPAE, each level 1 (pgd) page table entry maps 1GiB, and the level 2
(pmd) entries map 2MiB.
When the identity mapping is created on LPAE, the pgd pointers are copied
from the swapper_pg_dir. If we find that we need to modify the contents
of a pmd, we allocate a new empty pmd table and insert it into the
appropriate 1GB slot, before then filling it with the identity mapping.
However, if the 1GB slot covers the kernel lowmem mappings, we obliterate
those mappings.
When replacing a PMD, first copy the old PMD contents to the new PMD, so
that we preserve the existing mappings, particularly the mappings of the
kernel itself.
[rewrote commit message and added code comment -- rmk]
Fixes: ae2de101739c ("ARM: LPAE: Add identity mapping support for the 3-level page table format")
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-07-25 10:17:12 +02:00
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/*
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* Copy the original PMD to ensure that the PMD entries for
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* the kernel image are preserved.
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*/
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if (!pud_none(*pud))
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memcpy(pmd, pmd_offset(pud, 0),
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PTRS_PER_PMD * sizeof(pmd_t));
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2011-11-22 18:30:32 +01:00
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pud_populate(&init_mm, pud, pmd);
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pmd += pmd_index(addr);
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} else
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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*pmd = __pmd((addr & PMD_MASK) | prot);
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flush_pmd_entry(pmd);
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} while (pmd++, addr = next, addr != end);
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}
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#else /* !CONFIG_ARM_LPAE */
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2010-11-21 17:27:49 +01:00
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static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
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2010-11-21 12:48:16 +01:00
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unsigned long prot)
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{
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2010-11-21 17:27:49 +01:00
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pmd_t *pmd = pmd_offset(pud, addr);
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2010-11-21 12:48:16 +01:00
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addr = (addr & PMD_MASK) | prot;
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pmd[0] = __pmd(addr);
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addr += SECTION_SIZE;
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pmd[1] = __pmd(addr);
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flush_pmd_entry(pmd);
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}
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2011-11-22 18:30:32 +01:00
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#endif /* CONFIG_ARM_LPAE */
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2010-11-21 12:48:16 +01:00
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2010-11-21 17:27:49 +01:00
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static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
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unsigned long prot)
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{
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pud_t *pud = pud_offset(pgd, addr);
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unsigned long next;
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do {
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next = pud_addr_end(addr, end);
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idmap_add_pmd(pud, addr, next, prot);
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} while (pud++, addr = next, addr != end);
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}
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2013-01-21 00:43:10 +01:00
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static void identity_mapping_add(pgd_t *pgd, const char *text_start,
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const char *text_end, unsigned long prot)
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2010-11-21 12:41:57 +01:00
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{
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2013-01-21 00:43:10 +01:00
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unsigned long addr, end;
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unsigned long next;
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2013-07-31 18:44:42 +02:00
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addr = virt_to_idmap(text_start);
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end = virt_to_idmap(text_end);
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2013-07-31 18:44:43 +02:00
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pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
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2013-01-21 00:43:10 +01:00
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prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
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2010-11-21 12:41:57 +01:00
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if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
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prot |= PMD_BIT4;
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2010-11-21 12:48:16 +01:00
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pgd += pgd_index(addr);
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do {
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next = pgd_addr_end(addr, end);
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2010-11-21 17:27:49 +01:00
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idmap_add_pud(pgd, addr, next, prot);
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2010-11-21 12:48:16 +01:00
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} while (pgd++, addr = next, addr != end);
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2010-11-21 12:41:57 +01:00
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}
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2011-09-30 12:43:29 +02:00
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extern char __idmap_text_start[], __idmap_text_end[];
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static int __init init_static_idmap(void)
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{
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idmap_pgd = pgd_alloc(&init_mm);
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if (!idmap_pgd)
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return -ENOMEM;
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2013-01-21 00:43:10 +01:00
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identity_mapping_add(idmap_pgd, __idmap_text_start,
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__idmap_text_end, 0);
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2011-09-30 12:43:29 +02:00
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2012-11-08 19:46:07 +01:00
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/* Flush L1 for the hardware to see this page table content */
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flush_cache_louis();
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2013-04-12 20:12:03 +02:00
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return 0;
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2011-09-30 12:43:29 +02:00
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}
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2011-11-23 13:26:25 +01:00
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early_initcall(init_static_idmap);
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2011-09-30 12:43:29 +02:00
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2010-11-21 12:41:57 +01:00
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/*
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2011-06-08 16:53:34 +02:00
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* In order to soft-boot, we need to switch to a 1:1 mapping for the
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* cpu_reset functions. This will then ensure that we have predictable
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* results when turning off the mmu.
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2010-11-21 12:41:57 +01:00
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*/
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2011-11-01 11:15:27 +01:00
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void setup_mm_for_reboot(void)
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2010-11-21 12:41:57 +01:00
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{
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2011-06-08 16:53:34 +02:00
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/* Switch to the identity mapping. */
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cpu_switch_mm(idmap_pgd, &init_mm);
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2013-02-28 17:48:40 +01:00
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local_flush_bp_all();
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2011-06-08 16:53:34 +02:00
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2012-11-08 19:46:07 +01:00
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#ifdef CONFIG_CPU_HAS_ASID
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/*
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* We don't have a clean ASID for the identity mapping, which
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* may clash with virtual addresses of the previous page tables
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* and therefore potentially in the TLB.
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*/
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2010-11-21 12:41:57 +01:00
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local_flush_tlb_all();
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2012-11-08 19:46:07 +01:00
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#endif
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2010-11-21 12:41:57 +01:00
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}
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