[PATCHv2 2/4] x86/acpi: Replace manual page table initialization with kernel_ident_mapping_init()

Kirill A. Shutemov
2024-08-14T12:46:20Z

The function init_transition_pgtable() maps the page with
asm_acpi_mp_play_dead() into an identity mapping.

Replace manual page table initialization with kernel_ident_mapping_init()
to avoid code duplication. Use x86_mapping_info::offset to get the page
mapped at the correct location.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
---
arch/x86/kernel/acpi/madt_wakeup.c | 73 ++++++------------------------
1 file changed, 15 insertions(+), 58 deletions(-)

diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
index d5ef6215583b..78960b338be9 100644
--- a/arch/x86/kernel/acpi/madt_wakeup.c
+++ b/arch/x86/kernel/acpi/madt_wakeup.c
@@ -70,58 +70,6 @@ static void __init free_pgt_page(void *pgt, void *dummy)
return memblock_free(pgt, PAGE_SIZE);
}

-/*
- * Make sure asm_acpi_mp_play_dead() is present in the identity mapping at
- * the same place as in the kernel page tables. asm_acpi_mp_play_dead() switches
- * to the identity mapping and the function has be present at the same spot in
- * the virtual address space before and after switching page tables.
- */
-static int __init init_transition_pgtable(pgd_t *pgd)
-{
- pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
- unsigned long vaddr, paddr;
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
-
- vaddr = (unsigned long)asm_acpi_mp_play_dead;
- pgd += pgd_index(vaddr);
- if (!pgd_present(*pgd)) {
- p4d = (p4d_t *)alloc_pgt_page(NULL);
- if (!p4d)
- return -ENOMEM;
- set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
- }
- p4d = p4d_offset(pgd, vaddr);
- if (!p4d_present(*p4d)) {
- pud = (pud_t *)alloc_pgt_page(NULL);
- if (!pud)
- return -ENOMEM;
- set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
- }
- pud = pud_offset(p4d, vaddr);
- if (!pud_present(*pud)) {
- pmd = (pmd_t *)alloc_pgt_page(NULL);
- if (!pmd)
- return -ENOMEM;
- set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
- }
- pmd = pmd_offset(pud, vaddr);
- if (!pmd_present(*pmd)) {
- pte = (pte_t *)alloc_pgt_page(NULL);
- if (!pte)
- return -ENOMEM;
- set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
- }
- pte = pte_offset_kernel(pmd, vaddr);
-
- paddr = __pa(vaddr);
- set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
-
- return 0;
-}
-
static int __init acpi_mp_setup_reset(u64 reset_vector)
{
struct x86_mapping_info info = {
@@ -130,6 +78,7 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
.page_flag = __PAGE_KERNEL_LARGE_EXEC,
.kernpg_flag = _KERNPG_TABLE_NOENC,
};
+ unsigned long mstart, mend;
pgd_t *pgd;

pgd = alloc_pgt_page(NULL);
@@ -137,8 +86,6 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
return -ENOMEM;

for (int i = 0; i < nr_pfn_mapped; i++) {
- unsigned long mstart, mend;
-
mstart = pfn_mapped[i].start << PAGE_SHIFT;
mend = pfn_mapped[i].end << PAGE_SHIFT;
if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
@@ -147,14 +94,24 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
}
}

- if (kernel_ident_mapping_init(&info, pgd,
- PAGE_ALIGN_DOWN(reset_vector),
- PAGE_ALIGN(reset_vector + 1))) {
+ mstart = PAGE_ALIGN_DOWN(reset_vector);
+ mend = mstart + PAGE_SIZE;
+ if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
kernel_ident_mapping_free(&info, pgd);
return -ENOMEM;
}

- if (init_transition_pgtable(pgd)) {
+ /*
+ * Make sure asm_acpi_mp_play_dead() is present in the identity mapping
+ * at the same place as in the kernel page tables.
+ * asm_acpi_mp_play_dead() switches to the identity mapping and the
+ * function has be present at the same spot in the virtual address space
+ * before and after switching page tables.
+ */
+ info.offset = __START_KERNEL_map - phys_base;
+ mstart = PAGE_ALIGN_DOWN(__pa(asm_acpi_mp_play_dead));
+ mend = mstart + PAGE_SIZE;
+ if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
kernel_ident_mapping_free(&info, pgd);
return -ENOMEM;
}
--
2.43.0