[RFC, PATCHv1 12/28] x86/kexec: support p4d_t

[Kirill A. Shutemov]

Handle additional page table level in kexec code.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/kexec.h       |  1 +
 arch/x86/kernel/machine_kexec_32.c |  4 +++-
 arch/x86/kernel/machine_kexec_64.c | 12 +++++++++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index d2434c1cad05..5fed4cc96028 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -164,6 +164,7 @@ struct kimage_arch {
 };
 #else
 struct kimage_arch {
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index 469b23d6acc2..5f43cec296c5 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -103,6 +103,7 @@ static void machine_kexec_page_table_set_one(
 	pgd_t *pgd, pmd_t *pmd, pte_t *pte,
 	unsigned long vaddr, unsigned long paddr)
 {
+	p4d_t *p4d;
 	pud_t *pud;
 
 	pgd += pgd_index(vaddr);
@@ -110,7 +111,8 @@ static void machine_kexec_page_table_set_one(
 	if (!(pgd_val(*pgd) & _PAGE_PRESENT))
 		set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
 #endif
-	pud = pud_offset(pgd, vaddr);
+	p4d = p4d_offset(pgd, vaddr);
+	pud = pud_offset(p4d, vaddr);
 	pmd = pmd_offset(pud, vaddr);
 	if (!(pmd_val(*pmd) & _PAGE_PRESENT))
 		set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 5a294e48b185..0a44cf20f939 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -36,6 +36,7 @@ static struct kexec_file_ops *kexec_file_loaders[] = {
 
 static void free_transition_pgtable(struct kimage *image)
 {
+	free_page((unsigned long)image->arch.p4d);
 	free_page((unsigned long)image->arch.pud);
 	free_page((unsigned long)image->arch.pmd);
 	free_page((unsigned long)image->arch.pte);
@@ -43,6 +44,7 @@ static void free_transition_pgtable(struct kimage *image)
 
 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 {
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -59,7 +61,15 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 		image->arch.pud = pud;
 		set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
 	}
-	pud = pud_offset(pgd, vaddr);
+	p4d = p4d_offset(pgd, vaddr);
+	if (!p4d_present(*p4d)) {
+		p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
+		if (!p4d)
+			goto err;
+		image->arch.p4d = p4d;
+		set_p4d(p4d, __p4d(__pa(p4d) | _KERNPG_TABLE));
+	}
+	pud = pud_offset(p4d, vaddr);
 	if (!pud_present(*pud)) {
 		pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 		if (!pmd)
-- 
2.10.2