[RFC PATCH v2 20/21] riscv: mm: Adjust address space layout and init page table for 64K Page

Xu Lu
2024-12-05T10:45:13Z

arch/riscv/include/asm/page.h | 6 +++++-
arch/riscv/include/asm/pgtable.h | 12 +++++++++++
arch/riscv/mm/init.c | 36 +++++++++++++++++++++++---------
3 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 9bc908d94c7a..236b0106a1c9 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -40,8 +40,12 @@
* By default, CONFIG_PAGE_OFFSET value corresponds to SV57 address space so
* define the PAGE_OFFSET value for SV48 and SV39.
*/
+#ifdef CONFIG_RISCV_64K_PAGES
+#define PAGE_OFFSET_L4 _AC(0xffffa80000000000, UL)
+#else
#define PAGE_OFFSET_L4 _AC(0xffffaf8000000000, UL)
-#define PAGE_OFFSET_L3 _AC(0xffffffd600000000, UL)
+#endif /* CONFIG_RISCV_64K_PAGES */
+#define PAGE_OFFSET_L3 _AC(0xffffffd800000000, UL)
#else
#define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
#endif /* CONFIG_64BIT */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 9f347e5eefeb..fbc397c4e1c8 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -147,6 +147,18 @@ static inline unsigned long __page_val_to_pfn(unsigned long val);
#include <asm/pgtable-32.h>
#endif /* CONFIG_64BIT */

+#define __PMD_SHIFT (PMD_SHIFT - (PAGE_SHIFT - HW_PAGE_SHIFT))
+#define __PMD_SIZE (_AC(1, UL) << __PMD_SHIFT)
+
+#define __PUD_SHIFT (PUD_SHIFT - (PAGE_SHIFT - HW_PAGE_SHIFT))
+#define __PUD_SIZE (_AC(1, UL) << __PUD_SHIFT)
+
+#define __P4D_SHIFT (P4D_SHIFT - (PAGE_SHIFT - HW_PAGE_SHIFT))
+#define __P4D_SIZE (_AC(1, UL) << __P4D_SHIFT)
+
+#define __PGD_SHIFT (PGD_SHIFT - (PAGE_SHIFT - HW_PAGE_SHIFT))
+#define __PGD_SIZE (_AC(1, UL) << __PGD_SHIFT)
+
#include <linux/page_table_check.h>

#ifdef CONFIG_XIP_KERNEL
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 678b892b4ed8..2c6b7ea33009 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -695,15 +695,15 @@ static uintptr_t __meminit best_map_size(phys_addr_t pa, uintptr_t va, phys_addr
return PAGE_SIZE;

if (pgtable_l5_enabled &&
- !(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
+ !(pa & (__P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
return P4D_SIZE;

if (pgtable_l4_enabled &&
- !(pa & (PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
+ !(pa & (__PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
return PUD_SIZE;

if (IS_ENABLED(CONFIG_64BIT) &&
- !(pa & (PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
+ !(pa & (__PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
return PMD_SIZE;

return PAGE_SIZE;
@@ -937,17 +937,33 @@ static void __init create_kernel_page_table(pgd_t *pgdir,
PMD_SIZE, PAGE_KERNEL);
}
#else
+
+#ifdef CONFIG_RISCV_64K_PAGES
+/* TODO: better implementation */
+#define KERNEL_MAP_STEP PAGE_SIZE
+#else
+#define KERNEL_MAP_STEP PMD_SIZE
+#endif
+
static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
{
uintptr_t va, end_va;

end_va = kernel_map.virt_addr + kernel_map.size;
- for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
- create_pgd_mapping(pgdir, va,
- kernel_map.phys_addr + (va - kernel_map.virt_addr),
- PMD_SIZE,
- early ?
- PAGE_KERNEL_EXEC : pgprot_from_va(va));
+ if (early)
+ for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
+ create_pgd_mapping(pgdir, va,
+ kernel_map.phys_addr + (va - kernel_map.virt_addr),
+ PMD_SIZE,
+ early ?
+ PAGE_KERNEL_EXEC : pgprot_from_va(va));
+ else
+ for (va = kernel_map.virt_addr; va < end_va; va += KERNEL_MAP_STEP)
+ create_pgd_mapping(pgdir, va,
+ kernel_map.phys_addr + (va - kernel_map.virt_addr),
+ KERNEL_MAP_STEP,
+ early ?
+ PAGE_KERNEL_EXEC : pgprot_from_va(va));
}
#endif

@@ -1138,7 +1154,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)

/* Sanity check alignment and size */
BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
- BUG_ON((kernel_map.phys_addr % PMD_SIZE) != 0);
+ BUG_ON((kernel_map.phys_addr % __PMD_SIZE) != 0);

#ifdef CONFIG_64BIT
/*