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-rw-r--r--arch/x86/kernel/head64.c3
-rw-r--r--arch/x86/kernel/head_64.S7
-rw-r--r--arch/x86/mm/init_64.c27
-rw-r--r--include/asm-x86/pgtable_64.h1
4 files changed, 37 insertions, 1 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 24dbf56..ad24408 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -88,6 +88,9 @@ void __init x86_64_start_kernel(char * real_mode_data)
/* Make NULL pointers segfault */
zap_identity_mappings();
+ /* Cleanup the over mapped high alias */
+ cleanup_highmap();
+
for (i = 0; i < IDT_ENTRIES; i++) {
#ifdef CONFIG_EARLY_PRINTK
set_intr_gate(i, &early_idt_handlers[i]);
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 09b38d5..53e5820 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -107,8 +107,13 @@ startup_64:
movq %rdx, 0(%rbx, %rax, 8)
ident_complete:
- /* Fixup the kernel text+data virtual addresses
+ /*
+ * Fixup the kernel text+data virtual addresses. Note that
+ * we might write invalid pmds, when the kernel is relocated
+ * cleanup_highmap() fixes this up along with the mappings
+ * beyond _end.
*/
+
leaq level2_kernel_pgt(%rip), %rdi
leaq 4096(%rdi), %r8
/* See if it is a valid page table entry */
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index a4a9ccc..bb652f5 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -171,6 +171,33 @@ set_pte_phys(unsigned long vaddr, unsigned long phys, pgprot_t prot)
__flush_tlb_one(vaddr);
}
+/*
+ * The head.S code sets up the kernel high mapping from:
+ * __START_KERNEL_map to __START_KERNEL_map + KERNEL_TEXT_SIZE
+ *
+ * phys_addr holds the negative offset to the kernel, which is added
+ * to the compile time generated pmds. This results in invalid pmds up
+ * to the point where we hit the physaddr 0 mapping.
+ *
+ * We limit the mappings to the region from _text to _end. _end is
+ * rounded up to the 2MB boundary. This catches the invalid pmds as
+ * well, as they are located before _text:
+ */
+void __init cleanup_highmap(void)
+{
+ unsigned long vaddr = __START_KERNEL_map;
+ unsigned long end = round_up((unsigned long)_end, PMD_SIZE) - 1;
+ pmd_t *pmd = level2_kernel_pgt;
+ pmd_t *last_pmd = pmd + PTRS_PER_PMD;
+
+ for (; pmd < last_pmd; pmd++, vaddr += PMD_SIZE) {
+ if (!pmd_present(*pmd))
+ continue;
+ if (vaddr < (unsigned long) _text || vaddr > end)
+ set_pmd(pmd, __pmd(0));
+ }
+}
+
/* NOTE: this is meant to be run only at boot */
void __init
__set_fixmap(enum fixed_addresses idx, unsigned long phys, pgprot_t prot)
diff --git a/include/asm-x86/pgtable_64.h b/include/asm-x86/pgtable_64.h
index bd4740a..7fd5e0e 100644
--- a/include/asm-x86/pgtable_64.h
+++ b/include/asm-x86/pgtable_64.h
@@ -246,6 +246,7 @@ static inline int pud_large(pud_t pte)
#define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val })
extern int kern_addr_valid(unsigned long addr);
+extern void cleanup_highmap(void);
#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
remap_pfn_range(vma, vaddr, pfn, size, prot)