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>

1 files changed, 4 insertions, 0 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;
                 }
         }
 }