cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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idmap.c (3623B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/module.h>
      3#include <linux/kernel.h>
      4#include <linux/slab.h>
      5#include <linux/mm_types.h>
      6#include <linux/pgtable.h>
      7
      8#include <asm/cputype.h>
      9#include <asm/idmap.h>
     10#include <asm/hwcap.h>
     11#include <asm/pgalloc.h>
     12#include <asm/sections.h>
     13#include <asm/system_info.h>
     14
     15/*
     16 * Note: accesses outside of the kernel image and the identity map area
     17 * are not supported on any CPU using the idmap tables as its current
     18 * page tables.
     19 */
     20pgd_t *idmap_pgd __ro_after_init;
     21long long arch_phys_to_idmap_offset __ro_after_init;
     22
     23#ifdef CONFIG_ARM_LPAE
     24static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
     25	unsigned long prot)
     26{
     27	pmd_t *pmd;
     28	unsigned long next;
     29
     30	if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
     31		pmd = pmd_alloc_one(&init_mm, addr);
     32		if (!pmd) {
     33			pr_warn("Failed to allocate identity pmd.\n");
     34			return;
     35		}
     36		/*
     37		 * Copy the original PMD to ensure that the PMD entries for
     38		 * the kernel image are preserved.
     39		 */
     40		if (!pud_none(*pud))
     41			memcpy(pmd, pmd_offset(pud, 0),
     42			       PTRS_PER_PMD * sizeof(pmd_t));
     43		pud_populate(&init_mm, pud, pmd);
     44		pmd += pmd_index(addr);
     45	} else
     46		pmd = pmd_offset(pud, addr);
     47
     48	do {
     49		next = pmd_addr_end(addr, end);
     50		*pmd = __pmd((addr & PMD_MASK) | prot);
     51		flush_pmd_entry(pmd);
     52	} while (pmd++, addr = next, addr != end);
     53}
     54#else	/* !CONFIG_ARM_LPAE */
     55static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
     56	unsigned long prot)
     57{
     58	pmd_t *pmd = pmd_offset(pud, addr);
     59
     60	addr = (addr & PMD_MASK) | prot;
     61	pmd[0] = __pmd(addr);
     62	addr += SECTION_SIZE;
     63	pmd[1] = __pmd(addr);
     64	flush_pmd_entry(pmd);
     65}
     66#endif	/* CONFIG_ARM_LPAE */
     67
     68static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
     69	unsigned long prot)
     70{
     71	p4d_t *p4d = p4d_offset(pgd, addr);
     72	pud_t *pud = pud_offset(p4d, addr);
     73	unsigned long next;
     74
     75	do {
     76		next = pud_addr_end(addr, end);
     77		idmap_add_pmd(pud, addr, next, prot);
     78	} while (pud++, addr = next, addr != end);
     79}
     80
     81static void identity_mapping_add(pgd_t *pgd, const char *text_start,
     82				 const char *text_end, unsigned long prot)
     83{
     84	unsigned long addr, end;
     85	unsigned long next;
     86
     87	addr = virt_to_idmap(text_start);
     88	end = virt_to_idmap(text_end);
     89	pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
     90
     91	prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
     92
     93	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family())
     94		prot |= PMD_BIT4;
     95
     96	pgd += pgd_index(addr);
     97	do {
     98		next = pgd_addr_end(addr, end);
     99		idmap_add_pud(pgd, addr, next, prot);
    100	} while (pgd++, addr = next, addr != end);
    101}
    102
    103extern char  __idmap_text_start[], __idmap_text_end[];
    104
    105static int __init init_static_idmap(void)
    106{
    107	idmap_pgd = pgd_alloc(&init_mm);
    108	if (!idmap_pgd)
    109		return -ENOMEM;
    110
    111	identity_mapping_add(idmap_pgd, __idmap_text_start,
    112			     __idmap_text_end, 0);
    113
    114	/* Flush L1 for the hardware to see this page table content */
    115	if (!(elf_hwcap & HWCAP_LPAE))
    116		flush_cache_louis();
    117
    118	return 0;
    119}
    120early_initcall(init_static_idmap);
    121
    122/*
    123 * In order to soft-boot, we need to switch to a 1:1 mapping for the
    124 * cpu_reset functions. This will then ensure that we have predictable
    125 * results when turning off the mmu.
    126 */
    127void setup_mm_for_reboot(void)
    128{
    129	/* Switch to the identity mapping. */
    130	cpu_switch_mm(idmap_pgd, &init_mm);
    131	local_flush_bp_all();
    132
    133#ifdef CONFIG_CPU_HAS_ASID
    134	/*
    135	 * We don't have a clean ASID for the identity mapping, which
    136	 * may clash with virtual addresses of the previous page tables
    137	 * and therefore potentially in the TLB.
    138	 */
    139	local_flush_tlb_all();
    140#endif
    141}