x86-64: Fix accounting in kernel_physical_mapping_init()

When finding a present and acceptable 2M/1G mapping, the number
of pages mapped this way shouldn't be incremented (as it was
already incremented when the earlier part of the mapping was
established). Instead, last_map_addr needs to be updated in this
case.

Further, address increments were wrong in one place each in both
phys_pmd_init() and phys_pud_init() (lacking the aligning down
to the respective page boundary).

As we're now doing the same calculation several times, fold it
into a single instance using a local variable (matching how
kernel_physical_mapping_init() itself does it at the PGD level).

Observed during code inspection, not because of an actual
problem.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FB3C27202000078000841A0@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 436a0309db33..f9476a0f8cb6 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -408,12 +408,12 @@ static unsigned long __meminit
 phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
               unsigned long page_size_mask, pgprot_t prot)
 {
-        unsigned long pages = 0;
+        unsigned long pages = 0, next;
         unsigned long last_map_addr = end;
 
         int i = pmd_index(address);
 
-        for (; i < PTRS_PER_PMD; i++, address += PMD_SIZE) {
+        for (; i < PTRS_PER_PMD; i++, address = next) {
                 unsigned long pte_phys;
                 pmd_t *pmd = pmd_page + pmd_index(address);
                 pte_t *pte;
@@ -427,6 +427,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                         break;
                 }
 
+                next = (address & PMD_MASK) + PMD_SIZE;
+
                 if (pmd_val(*pmd)) {
                         if (!pmd_large(*pmd)) {
                                 spin_lock(&init_mm.page_table_lock);
@@ -450,7 +452,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                          * attributes.
                          */
                         if (page_size_mask & (1 << PG_LEVEL_2M)) {
-                                pages++;
+                                last_map_addr = next;
                                 continue;
                         }
                         new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
@@ -463,7 +465,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
                                 pfn_pte(address >> PAGE_SHIFT,
                                         __pgprot(pgprot_val(prot) | _PAGE_PSE)));
                         spin_unlock(&init_mm.page_table_lock);
-                        last_map_addr = (address & PMD_MASK) + PMD_SIZE;
+                        last_map_addr = next;
                         continue;
                 }
 
@@ -483,11 +485,11 @@ static unsigned long __meminit
 phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                          unsigned long page_size_mask)
 {
-        unsigned long pages = 0;
+        unsigned long pages = 0, next;
         unsigned long last_map_addr = end;
         int i = pud_index(addr);
 
-        for (; i < PTRS_PER_PUD; i++, addr = (addr & PUD_MASK) + PUD_SIZE) {
+        for (; i < PTRS_PER_PUD; i++, addr = next) {
                 unsigned long pmd_phys;
                 pud_t *pud = pud_page + pud_index(addr);
                 pmd_t *pmd;
@@ -496,8 +498,9 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                 if (addr >= end)
                         break;
 
-                if (!after_bootmem &&
-                                !e820_any_mapped(addr, addr+PUD_SIZE, 0)) {
+                next = (addr & PUD_MASK) + PUD_SIZE;
+
+                if (!after_bootmem && !e820_any_mapped(addr, next, 0)) {
                         set_pud(pud, __pud(0));
                         continue;
                 }
@@ -524,7 +527,7 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                          * attributes.
                          */
                         if (page_size_mask & (1 << PG_LEVEL_1G)) {
-                                pages++;
+                                last_map_addr = next;
                                 continue;
                         }
                         prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
@@ -536,7 +539,7 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
                         set_pte((pte_t *)pud,
                                 pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
                         spin_unlock(&init_mm.page_table_lock);
-                        last_map_addr = (addr & PUD_MASK) + PUD_SIZE;
+                        last_map_addr = next;
                         continue;
                 }