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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/arm/mm/idmap.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm/mm/idmap.c')
-rw-r--r-- | arch/arm/mm/idmap.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c new file mode 100644 index 000000000..448e57c6f --- /dev/null +++ b/arch/arm/mm/idmap.c @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/mm_types.h> +#include <linux/pgtable.h> + +#include <asm/cputype.h> +#include <asm/idmap.h> +#include <asm/hwcap.h> +#include <asm/pgalloc.h> +#include <asm/sections.h> +#include <asm/system_info.h> + +/* + * Note: accesses outside of the kernel image and the identity map area + * are not supported on any CPU using the idmap tables as its current + * page tables. + */ +pgd_t *idmap_pgd __ro_after_init; +long long arch_phys_to_idmap_offset __ro_after_init; + +#ifdef CONFIG_ARM_LPAE +static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end, + unsigned long prot) +{ + pmd_t *pmd; + unsigned long next; + + if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) { + pmd = pmd_alloc_one(&init_mm, addr); + if (!pmd) { + pr_warn("Failed to allocate identity pmd.\n"); + return; + } + /* + * Copy the original PMD to ensure that the PMD entries for + * the kernel image are preserved. + */ + if (!pud_none(*pud)) + memcpy(pmd, pmd_offset(pud, 0), + PTRS_PER_PMD * sizeof(pmd_t)); + pud_populate(&init_mm, pud, pmd); + pmd += pmd_index(addr); + } else + pmd = pmd_offset(pud, addr); + + do { + next = pmd_addr_end(addr, end); + *pmd = __pmd((addr & PMD_MASK) | prot); + flush_pmd_entry(pmd); + } while (pmd++, addr = next, addr != end); +} +#else /* !CONFIG_ARM_LPAE */ +static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end, + unsigned long prot) +{ + pmd_t *pmd = pmd_offset(pud, addr); + + addr = (addr & PMD_MASK) | prot; + pmd[0] = __pmd(addr); + addr += SECTION_SIZE; + pmd[1] = __pmd(addr); + flush_pmd_entry(pmd); +} +#endif /* CONFIG_ARM_LPAE */ + +static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end, + unsigned long prot) +{ + p4d_t *p4d = p4d_offset(pgd, addr); + pud_t *pud = pud_offset(p4d, addr); + unsigned long next; + + do { + next = pud_addr_end(addr, end); + idmap_add_pmd(pud, addr, next, prot); + } while (pud++, addr = next, addr != end); +} + +static void identity_mapping_add(pgd_t *pgd, const char *text_start, + const char *text_end, unsigned long prot) +{ + unsigned long addr, end; + unsigned long next; + + addr = virt_to_idmap(text_start); + end = virt_to_idmap(text_end); + pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end); + + prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF; + + if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family()) + prot |= PMD_BIT4; + + pgd += pgd_index(addr); + do { + next = pgd_addr_end(addr, end); + idmap_add_pud(pgd, addr, next, prot); + } while (pgd++, addr = next, addr != end); +} + +extern char __idmap_text_start[], __idmap_text_end[]; + +static int __init init_static_idmap(void) +{ + idmap_pgd = pgd_alloc(&init_mm); + if (!idmap_pgd) + return -ENOMEM; + + identity_mapping_add(idmap_pgd, __idmap_text_start, + __idmap_text_end, 0); + + /* Flush L1 for the hardware to see this page table content */ + if (!(elf_hwcap & HWCAP_LPAE)) + flush_cache_louis(); + + return 0; +} +early_initcall(init_static_idmap); + +/* + * In order to soft-boot, we need to switch to a 1:1 mapping for the + * cpu_reset functions. This will then ensure that we have predictable + * results when turning off the mmu. + */ +void setup_mm_for_reboot(void) +{ + /* Switch to the identity mapping. */ + cpu_switch_mm(idmap_pgd, &init_mm); + local_flush_bp_all(); + +#ifdef CONFIG_CPU_HAS_ASID + /* + * We don't have a clean ASID for the identity mapping, which + * may clash with virtual addresses of the previous page tables + * and therefore potentially in the TLB. + */ + local_flush_tlb_all(); +#endif +} |