x86/mm: Update physical mapping variable names

Change the variable names in kernel_physical_mapping_init() and related
functions to correctly reflect physical and virtual memory addresses.
Also add comments on each function to describe usage and alignment
constraints.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1466556426-32664-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 96 insertions, 66 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index bce2e5d9edd4..6714712bd5da 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -328,22 +328,30 @@ void __init cleanup_highmap(void)
         }
 }
 
+/*
+ * Create PTE level page table mapping for physical addresses.
+ * It returns the last physical address mapped.
+ */
 static unsigned long __meminit
-phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
+phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
               pgprot_t prot)
 {
-        unsigned long pages = 0, next;
-        unsigned long last_map_addr = end;
+        unsigned long pages = 0, paddr_next;
+        unsigned long paddr_last = paddr_end;
+        pte_t *pte;
         int i;
 
-        pte_t *pte = pte_page + pte_index(addr);
+        pte = pte_page + pte_index(paddr);
+        i = pte_index(paddr);
 
-        for (i = pte_index(addr); i < PTRS_PER_PTE; i++, addr = next, pte++) {
-                next = (addr & PAGE_MASK) + PAGE_SIZE;
-                if (addr >= end) {
+        for (; i < PTRS_PER_PTE; i++, paddr = paddr_next, pte++) {
+                paddr_next = (paddr & PAGE_MASK) + PAGE_SIZE;
+                if (paddr >= paddr_end) {
                         if (!after_bootmem &&
-                            !e820_any_mapped(addr & PAGE_MASK, next, E820_RAM) &&
-                            !e820_any_mapped(addr & PAGE_MASK, next, E820_RESERVED_KERN))
+                            !e820_any_mapped(paddr & PAGE_MASK, paddr_next,
+                                             E820_RAM) &&
+                            !e820_any_mapped(paddr & PAGE_MASK, paddr_next,
+                                             E820_RESERVED_KERN))
                                 set_pte(pte, __pte(0));
                         continue;
                 }
@@ -361,37 +369,44 @@ phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
                 }
 
                 if (0)
-                        printk("   pte=%p addr=%lx pte=%016lx\n",
-                               pte, addr, pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL).pte);
+                        pr_info("   pte=%p addr=%lx pte=%016lx\n", pte, paddr,
+                                pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL).pte);
                 pages++;
-                set_pte(pte, pfn_pte(addr >> PAGE_SHIFT, prot));
-                last_map_addr = (addr & PAGE_MASK) + PAGE_SIZE;
+                set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
+                paddr_last = (paddr & PAGE_MASK) + PAGE_SIZE;
         }
 
         update_page_count(PG_LEVEL_4K, pages);
 
-        return last_map_addr;
+        return paddr_last;
 }
 
+/*
+ * Create PMD level page table mapping for physical addresses. The virtual
+ * and physical address have to be aligned at this level.
+ * It returns the last physical address mapped.
+ */
 static unsigned long __meminit
-phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
+phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
               unsigned long page_size_mask, pgprot_t prot)
 {
-        unsigned long pages = 0, next;
-        unsigned long last_map_addr = end;
+        unsigned long pages = 0, paddr_next;
+        unsigned long paddr_last = paddr_end;
 
-        int i = pmd_index(address);
+        int i = pmd_index(paddr);
 
-        for (; i < PTRS_PER_PMD; i++, address = next) {
-                pmd_t *pmd = pmd_page + pmd_index(address);
+        for (; i < PTRS_PER_PMD; i++, paddr = paddr_next) {
+                pmd_t *pmd = pmd_page + pmd_index(paddr);
                 pte_t *pte;
                 pgprot_t new_prot = prot;
 
-                next = (address & PMD_MASK) + PMD_SIZE;
-                if (address >= end) {
+                paddr_next = (paddr & PMD_MASK) + PMD_SIZE;
+                if (paddr >= paddr_end) {
                         if (!after_bootmem &&
-                            !e820_any_mapped(address & PMD_MASK, next, E820_RAM) &&
-                            !e820_any_mapped(address & PMD_MASK, next, E820_RESERVED_KERN))
+                            !e820_any_mapped(paddr & PMD_MASK, paddr_next,
+                                             E820_RAM) &&
+                            !e820_any_mapped(paddr & PMD_MASK, paddr_next,
+                                             E820_RESERVED_KERN))
                                 set_pmd(pmd, __pmd(0));
                         continue;
                 }
@@ -400,8 +415,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                         if (!pmd_large(*pmd)) {
                                 spin_lock(&init_mm.page_table_lock);
                                 pte = (pte_t *)pmd_page_vaddr(*pmd);
-                                last_map_addr = phys_pte_init(pte, address,
-                                                                end, prot);
+                                paddr_last = phys_pte_init(pte, paddr,
+                                                           paddr_end, prot);
                                 spin_unlock(&init_mm.page_table_lock);
                                 continue;
                         }
@@ -420,7 +435,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                         if (page_size_mask & (1 << PG_LEVEL_2M)) {
                                 if (!after_bootmem)
                                         pages++;
-                                last_map_addr = next;
+                                paddr_last = paddr_next;
                                 continue;
                         }
                         new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
@@ -430,42 +445,49 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                         pages++;
                         spin_lock(&init_mm.page_table_lock);
                         set_pte((pte_t *)pmd,
-                                pfn_pte((address & PMD_MASK) >> PAGE_SHIFT,
+                                pfn_pte((paddr & PMD_MASK) >> PAGE_SHIFT,
                                         __pgprot(pgprot_val(prot) | _PAGE_PSE)));
                         spin_unlock(&init_mm.page_table_lock);
-                        last_map_addr = next;
+                        paddr_last = paddr_next;
                         continue;
                 }
 
                 pte = alloc_low_page();
-                last_map_addr = phys_pte_init(pte, address, end, new_prot);
+                paddr_last = phys_pte_init(pte, paddr, paddr_end, new_prot);
 
                 spin_lock(&init_mm.page_table_lock);
                 pmd_populate_kernel(&init_mm, pmd, pte);
                 spin_unlock(&init_mm.page_table_lock);
         }
         update_page_count(PG_LEVEL_2M, pages);
-        return last_map_addr;
+        return paddr_last;
 }
 
+/*
+ * Create PUD level page table mapping for physical addresses. The virtual
+ * and physical address have to be aligned at this level.
+ * It returns the last physical address mapped.
+ */
 static unsigned long __meminit
-phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
-                         unsigned long page_size_mask)
+phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
+              unsigned long page_size_mask)
 {
-        unsigned long pages = 0, next;
-        unsigned long last_map_addr = end;
-        int i = pud_index(addr);
+        unsigned long pages = 0, paddr_next;
+        unsigned long paddr_last = paddr_end;
+        int i = pud_index(paddr);
 
-        for (; i < PTRS_PER_PUD; i++, addr = next) {
-                pud_t *pud = pud_page + pud_index(addr);
+        for (; i < PTRS_PER_PUD; i++, paddr = paddr_next) {
+                pud_t *pud = pud_page + pud_index(paddr);
                 pmd_t *pmd;
                 pgprot_t prot = PAGE_KERNEL;
 
-                next = (addr & PUD_MASK) + PUD_SIZE;
-                if (addr >= end) {
+                paddr_next = (paddr & PUD_MASK) + PUD_SIZE;
+                if (paddr >= paddr_end) {
                         if (!after_bootmem &&
-                            !e820_any_mapped(addr & PUD_MASK, next, E820_RAM) &&
-                            !e820_any_mapped(addr & PUD_MASK, next, E820_RESERVED_KERN))
+                            !e820_any_mapped(paddr & PUD_MASK, paddr_next,
+                                             E820_RAM) &&
+                            !e820_any_mapped(paddr & PUD_MASK, paddr_next,
+                                             E820_RESERVED_KERN))
                                 set_pud(pud, __pud(0));
                         continue;
                 }
@@ -473,8 +495,10 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                 if (pud_val(*pud)) {
                         if (!pud_large(*pud)) {
                                 pmd = pmd_offset(pud, 0);
-                                last_map_addr = phys_pmd_init(pmd, addr, end,
-                                                         page_size_mask, prot);
+                                paddr_last = phys_pmd_init(pmd, paddr,
+                                                           paddr_end,
+                                                           page_size_mask,
+                                                           prot);
                                 __flush_tlb_all();
                                 continue;
                         }
@@ -493,7 +517,7 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                         if (page_size_mask & (1 << PG_LEVEL_1G)) {
                                 if (!after_bootmem)
                                         pages++;
-                                last_map_addr = next;
+                                paddr_last = paddr_next;
                                 continue;
                         }
                         prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
@@ -503,16 +527,16 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                         pages++;
                         spin_lock(&init_mm.page_table_lock);
                         set_pte((pte_t *)pud,
-                                pfn_pte((addr & PUD_MASK) >> PAGE_SHIFT,
+                                pfn_pte((paddr & PUD_MASK) >> PAGE_SHIFT,
                                         PAGE_KERNEL_LARGE));
                         spin_unlock(&init_mm.page_table_lock);
-                        last_map_addr = next;
+                        paddr_last = paddr_next;
                         continue;
                 }
 
                 pmd = alloc_low_page();
-                last_map_addr = phys_pmd_init(pmd, addr, end, page_size_mask,
-                                              prot);
+                paddr_last = phys_pmd_init(pmd, paddr, paddr_end,
+                                           page_size_mask, prot);
 
                 spin_lock(&init_mm.page_table_lock);
                 pud_populate(&init_mm, pud, pmd);
@@ -522,38 +546,44 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
 
         update_page_count(PG_LEVEL_1G, pages);
 
-        return last_map_addr;
+        return paddr_last;
 }
 
+/*
+ * Create page table mapping for the physical memory for specific physical
+ * addresses. The virtual and physical addresses have to be aligned on PUD level
+ * down. It returns the last physical address mapped.
+ */
 unsigned long __meminit
-kernel_physical_mapping_init(unsigned long start,
-                             unsigned long end,
+kernel_physical_mapping_init(unsigned long paddr_start,
+                             unsigned long paddr_end,
                              unsigned long page_size_mask)
 {
         bool pgd_changed = false;
-        unsigned long next, last_map_addr = end;
-        unsigned long addr;
+        unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;
 
-        start = (unsigned long)__va(start);
-        end = (unsigned long)__va(end);
-        addr = start;
+        paddr_last = paddr_end;
+        vaddr = (unsigned long)__va(paddr_start);
+        vaddr_end = (unsigned long)__va(paddr_end);
+        vaddr_start = vaddr;
 
-        for (; start < end; start = next) {
-                pgd_t *pgd = pgd_offset_k(start);
+        for (; vaddr < vaddr_end; vaddr = vaddr_next) {
+                pgd_t *pgd = pgd_offset_k(vaddr);
                 pud_t *pud;
 
-                next = (start & PGDIR_MASK) + PGDIR_SIZE;
+                vaddr_next = (vaddr & PGDIR_MASK) + PGDIR_SIZE;
 
                 if (pgd_val(*pgd)) {
                         pud = (pud_t *)pgd_page_vaddr(*pgd);
-                        last_map_addr = phys_pud_init(pud, __pa(start),
-                                                 __pa(end), page_size_mask);
+                        paddr_last = phys_pud_init(pud, __pa(vaddr),
+                                                   __pa(vaddr_end),
+                                                   page_size_mask);
                         continue;
                 }
 
                 pud = alloc_low_page();
-                last_map_addr = phys_pud_init(pud, __pa(start), __pa(end),
-                                                 page_size_mask);
+                paddr_last = phys_pud_init(pud, __pa(vaddr), __pa(vaddr_end),
+                                           page_size_mask);
 
                 spin_lock(&init_mm.page_table_lock);
                 pgd_populate(&init_mm, pgd, pud);
@@ -562,11 +592,11 @@ kernel_physical_mapping_init(unsigned long start,
         }
 
         if (pgd_changed)
-                sync_global_pgds(addr, end - 1, 0);
+                sync_global_pgds(vaddr_start, vaddr_end - 1, 0);
 
         __flush_tlb_all();
 
-        return last_map_addr;
+        return paddr_last;
 }
 
 #ifndef CONFIG_NUMA