cregit-Linux how code gets into the kernel

Release 4.11 arch/arm/mm/idmap.c

Directory: arch/arm/mm
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm_types.h>

#include <asm/cputype.h>
#include <asm/idmap.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.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;

long long arch_phys_to_idmap_offset;

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Catalin Marinas14382.66%133.33%
Konstantin Khlebnikov2916.76%133.33%
Joe Perches10.58%133.33%
Total173100.00%3100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Russell King72100.00%3100.00%
Total72100.00%3100.00%

#endif /* CONFIG_ARM_LPAE */
static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end, unsigned long prot) { pud_t *pud = pud_offset(pgd, addr); unsigned long next; do { next = pud_addr_end(addr, end); idmap_add_pmd(pud, addr, next, prot); } while (pud++, addr = next, addr != end); }

Contributors

PersonTokensPropCommitsCommitProp
Russell King74100.00%1100.00%
Total74100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Russell King8165.32%333.33%
Christoffer Dall2822.58%111.11%
Santosh Shilimkar118.87%222.22%
Catalin Marinas21.61%111.11%
Arnd Bergmann10.81%111.11%
Will Deacon10.81%111.11%
Total124100.00%9100.00%

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 */ flush_cache_louis(); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Will Deacon3579.55%125.00%
Nico Pitre49.09%125.00%
Christoffer Dall49.09%125.00%
Marc Zyngier12.27%125.00%
Total44100.00%4100.00%

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 }

Contributors

PersonTokensPropCommitsCommitProp
Russell King1450.00%240.00%
Will Deacon828.57%240.00%
Nico Pitre621.43%120.00%
Total28100.00%5100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Russell King25744.54%731.82%
Catalin Marinas15426.69%14.55%
Will Deacon6811.79%418.18%
Christoffer Dall386.59%14.55%
Konstantin Khlebnikov295.03%14.55%
Santosh Shilimkar122.08%29.09%
Nico Pitre101.73%14.55%
David Howells30.52%14.55%
Ingo Molnar30.52%14.55%
Arnd Bergmann10.17%14.55%
Marc Zyngier10.17%14.55%
Joe Perches10.17%14.55%
Total577100.00%22100.00%
Directory: arch/arm/mm
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