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Diffstat (limited to 'arch/x86/boot/compressed/pagetable.c')
-rw-r--r--arch/x86/boot/compressed/pagetable.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c
index 1d78f1739087..28029be47fbb 100644
--- a/arch/x86/boot/compressed/pagetable.c
+++ b/arch/x86/boot/compressed/pagetable.c
@@ -63,7 +63,7 @@ static void *alloc_pgt_page(void *context)
static struct alloc_pgt_data pgt_data;
/* The top level page table entry pointer. */
-static unsigned long level4p;
+static unsigned long top_level_pgt;
/*
* Mapping information structure passed to kernel_ident_mapping_init().
@@ -91,9 +91,15 @@ void initialize_identity_maps(void)
* If we came here via startup_32(), cr3 will be _pgtable already
* and we must append to the existing area instead of entirely
* overwriting it.
+ *
+ * With 5-level paging, we use '_pgtable' to allocate the p4d page table,
+ * the top-level page table is allocated separately.
+ *
+ * p4d_offset(top_level_pgt, 0) would cover both the 4- and 5-level
+ * cases. On 4-level paging it's equal to 'top_level_pgt'.
*/
- level4p = read_cr3();
- if (level4p == (unsigned long)_pgtable) {
+ top_level_pgt = read_cr3_pa();
+ if (p4d_offset((pgd_t *)top_level_pgt, 0) == (p4d_t *)_pgtable) {
debug_putstr("booted via startup_32()\n");
pgt_data.pgt_buf = _pgtable + BOOT_INIT_PGT_SIZE;
pgt_data.pgt_buf_size = BOOT_PGT_SIZE - BOOT_INIT_PGT_SIZE;
@@ -103,7 +109,7 @@ void initialize_identity_maps(void)
pgt_data.pgt_buf = _pgtable;
pgt_data.pgt_buf_size = BOOT_PGT_SIZE;
memset(pgt_data.pgt_buf, 0, pgt_data.pgt_buf_size);
- level4p = (unsigned long)alloc_pgt_page(&pgt_data);
+ top_level_pgt = (unsigned long)alloc_pgt_page(&pgt_data);
}
}
@@ -123,7 +129,7 @@ void add_identity_map(unsigned long start, unsigned long size)
return;
/* Build the mapping. */
- kernel_ident_mapping_init(&mapping_info, (pgd_t *)level4p,
+ kernel_ident_mapping_init(&mapping_info, (pgd_t *)top_level_pgt,
start, end);
}
@@ -134,5 +140,5 @@ void add_identity_map(unsigned long start, unsigned long size)
*/
void finalize_identity_maps(void)
{
- write_cr3(level4p);
+ write_cr3(top_level_pgt);
}