x86: implement true end_pfn_mapped for 32bit

Even on 32bit 2MB pages can map more memory than is in the true
max_low_pfn if end_pfn is not highmem and not aligned to 2MB.
Add a end_pfn_map similar to x86-64 that accounts for this
fact. This is important for code that really needs to know about
all mapping aliases.

Signed-off-by: Andi Kleen <ak@suse.de>
Cc: andreas.herrmann3@amd.com
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 00168e65688a..73dd0601166a 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -51,6 +51,8 @@
 
 unsigned int __VMALLOC_RESERVE = 128 << 20;
 
+unsigned long end_pfn_map;
+
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 unsigned long highstart_pfn, highend_pfn;
 
@@ -194,6 +196,7 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
                                 set_pmd(pmd, pfn_pmd(pfn, prot));
 
                                 pfn += PTRS_PER_PTE;
+                                end_pfn_map = pfn;
                                 continue;
                         }
                         pte = one_page_table_init(pmd);
@@ -208,6 +211,7 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
 
                                 set_pte(pte, pfn_pte(pfn, prot));
                         }
+                        end_pfn_map = pfn;
                 }
         }
 }
diff --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index a05b2896492f..b734939916c4 100644
--- a/include/asm-x86/page.h
+++ b/include/asm-x86/page.h
@@ -36,7 +36,7 @@
 #define max_pfn_mapped          end_pfn_map
 #else
 #include <asm/page_32.h>
-#define max_pfn_mapped          max_low_pfn
+#define max_pfn_mapped          end_pfn_map
 #endif  /* CONFIG_X86_64 */
 
 #define PAGE_OFFSET             ((unsigned long)__PAGE_OFFSET)
@@ -50,6 +50,8 @@
 
 extern int page_is_ram(unsigned long pagenr);
 
+extern unsigned long end_pfn_map;
+
 struct page;
 
 static inline void clear_user_page(void *page, unsigned long vaddr,
diff --git a/include/asm-x86/page_64.h b/include/asm-x86/page_64.h
index f156778f707c..54d5db634858 100644
--- a/include/asm-x86/page_64.h
+++ b/include/asm-x86/page_64.h
@@ -59,7 +59,6 @@ void clear_page(void *page);
 void copy_page(void *to, void *from);
 
 extern unsigned long end_pfn;
-extern unsigned long end_pfn_map;
 extern unsigned long phys_base;
 
 extern unsigned long __phys_addr(unsigned long);