[PATCH v5 09/14] riscv: Fix accessing pfn bits in PTEs for non-32bit variants

Heiko Stuebner
2022-01-21T16:37:43Z

On rv32 the PFN part of PTEs is defined to use bits [xlen-1:10]
while on rv64 it is defined to use bits [53:10], leaving [63:54]
as reserved.

With upcoming optional extensions like svpbmt these previously
reserved bits will get used so simply right-shifting the PTE
to get the PFN won't be enough.

So introduce a _PAGE_PFN_MASK constant to mask the correct bits
for both rv32 and rv64 before shifting.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
arch/riscv/include/asm/pgtable-32.h | 8 ++++++++
arch/riscv/include/asm/pgtable-64.h | 14 +++++++++++---
arch/riscv/include/asm/pgtable-bits.h | 6 ------
arch/riscv/include/asm/pgtable.h | 6 +++---
4 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable-32.h b/arch/riscv/include/asm/pgtable-32.h
index 5b2e79e5bfa5..e266a4fe7f43 100644
--- a/arch/riscv/include/asm/pgtable-32.h
+++ b/arch/riscv/include/asm/pgtable-32.h
@@ -7,6 +7,7 @@
#define _ASM_RISCV_PGTABLE_32_H

#include <asm-generic/pgtable-nopmd.h>
+#include <linux/bits.h>
#include <linux/const.h>

/* Size of region mapped by a page global directory */
@@ -16,4 +17,11 @@

#define MAX_POSSIBLE_PHYSMEM_BITS 34

+/*
+ * rv32 PTE format:
+ * | XLEN-1 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
+ * PFN reserved for SW D A G U X W R V
+ */
+#define _PAGE_PFN_MASK GENMASK(31, 10)
+
#endif /* _ASM_RISCV_PGTABLE_32_H */
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 228261aa9628..706f0897437d 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -6,6 +6,7 @@
#ifndef _ASM_RISCV_PGTABLE_64_H
#define _ASM_RISCV_PGTABLE_64_H

+#include <linux/bits.h>
#include <linux/const.h>

#define PGDIR_SHIFT 30
@@ -28,6 +29,13 @@ typedef struct {

#define PTRS_PER_PMD (PAGE_SIZE / sizeof(pmd_t))

+/*
+ * rv64 PTE format:
+ * | 63 | 62 61 | 60 54 | 53 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
+ * N MT RSV PFN reserved for SW D A G U X W R V
+ */
+#define _PAGE_PFN_MASK GENMASK(53, 10)
+
static inline int pud_present(pud_t pud)
{
return (pud_val(pud) & _PAGE_PRESENT);
@@ -61,12 +69,12 @@ static inline void pud_clear(pud_t *pudp)

static inline pmd_t *pud_pgtable(pud_t pud)
{
- return (pmd_t *)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT);
+ return (pmd_t *)pfn_to_virt((pud_val(pud) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT);
}

static inline struct page *pud_page(pud_t pud)
{
- return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT);
+ return pfn_to_page((pud_val(pud) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT);
}

static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
@@ -76,7 +84,7 @@ static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)

static inline unsigned long _pmd_pfn(pmd_t pmd)
{
- return pmd_val(pmd) >> _PAGE_PFN_SHIFT;
+ return (pmd_val(pmd) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT;
}

#define mk_pmd(page, prot) pfn_pmd(page_to_pfn(page), prot)
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index 2ee413912926..4831122d559d 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -6,12 +6,6 @@
#ifndef _ASM_RISCV_PGTABLE_BITS_H
#define _ASM_RISCV_PGTABLE_BITS_H

-/*
- * PTE format:
- * | XLEN-1 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
- * PFN reserved for SW D A G U X W R V
- */
-
#define _PAGE_ACCESSED_OFFSET 6

#define _PAGE_PRESENT (1 << 0)
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index bf204e7c1f74..5cf7465a96c5 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -232,12 +232,12 @@ static inline unsigned long _pgd_pfn(pgd_t pgd)

static inline struct page *pmd_page(pmd_t pmd)
{
- return pfn_to_page(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+ return pfn_to_page((pmd_val(pmd) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT);
}

static inline unsigned long pmd_page_vaddr(pmd_t pmd)
{
- return (unsigned long)pfn_to_virt(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
+ return (unsigned long)pfn_to_virt((pmd_val(pmd) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT);
}

static inline pte_t pmd_pte(pmd_t pmd)
@@ -253,7 +253,7 @@ static inline pte_t pud_pte(pud_t pud)
/* Yields the page frame number (PFN) of a page table entry */
static inline unsigned long pte_pfn(pte_t pte)
{
- return (pte_val(pte) >> _PAGE_PFN_SHIFT);
+ return ((pte_val(pte) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT);
}

#define pte_page(x) pfn_to_page(pte_pfn(x))
--
2.30.2