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Subject[PATCH v2 2/2] riscv: Introduce huge page support for 32/64bit kernel
Date
This patch implements both 4MB huge page support for 32bit kernel
and 2MB/1GB huge pages support for 64bit kernel.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
arch/riscv/Kconfig | 8 ++++++
arch/riscv/include/asm/hugetlb.h | 18 +++++++++++++
arch/riscv/include/asm/page.h | 10 ++++++++
arch/riscv/include/asm/pgtable.h | 8 ++++--
arch/riscv/mm/Makefile | 2 ++
arch/riscv/mm/hugetlbpage.c | 44 ++++++++++++++++++++++++++++++++
6 files changed, 88 insertions(+), 2 deletions(-)
create mode 100644 arch/riscv/include/asm/hugetlb.h
create mode 100644 arch/riscv/mm/hugetlbpage.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index eb56c82d8aa1..a400d4b4e1b3 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -49,6 +49,8 @@ config RISCV
select GENERIC_IRQ_MULTI_HANDLER
select ARCH_HAS_PTE_SPECIAL
select HAVE_EBPF_JIT if 64BIT
+ select ARCH_HAS_GIGANTIC_PAGE
+ select ARCH_WANT_HUGE_PMD_SHARE if 64BIT

config MMU
def_bool y
@@ -63,6 +65,12 @@ config PAGE_OFFSET
default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB

+config ARCH_WANT_GENERAL_HUGETLB
+ def_bool y
+
+config SYS_SUPPORTS_HUGETLBFS
+ def_bool y
+
config STACKTRACE_SUPPORT
def_bool y

diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
new file mode 100644
index 000000000000..728a5db66597
--- /dev/null
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_HUGETLB_H
+#define _ASM_RISCV_HUGETLB_H
+
+#include <asm-generic/hugetlb.h>
+#include <asm/page.h>
+
+static inline int is_hugepage_only_range(struct mm_struct *mm,
+ unsigned long addr,
+ unsigned long len) {
+ return 0;
+}
+
+static inline void arch_clear_hugepage_flags(struct page *page)
+{
+}
+
+#endif /* _ASM_RISCV_HUGETLB_H */
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 2a546a52f02a..4ef2936295aa 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -24,6 +24,16 @@
#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE - 1))

+#ifdef CONFIG_64BIT
+#define HUGE_MAX_HSTATE 2
+#else
+#define HUGE_MAX_HSTATE 1
+#endif
+#define HPAGE_SHIFT PMD_SHIFT
+#define HPAGE_SIZE (_AC(1, UL) << HPAGE_SHIFT)
+#define HPAGE_MASK (~(HPAGE_SIZE - 1))
+#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
+
/*
* PAGE_OFFSET -- the first address of the first page of memory.
* When not using MMU this corresponds to the first free page in
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 1141364d990e..f3456fcdff92 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -121,7 +121,6 @@ static inline void pmd_clear(pmd_t *pmdp)
set_pmd(pmdp, __pmd(0));
}

-
static inline pgd_t pfn_pgd(unsigned long pfn, pgprot_t prot)
{
return __pgd((pfn << _PAGE_PFN_SHIFT) | pgprot_val(prot));
@@ -258,6 +257,11 @@ static inline pte_t pte_mkspecial(pte_t pte)
return __pte(pte_val(pte) | _PAGE_SPECIAL);
}

+static inline pte_t pte_mkhuge(pte_t pte)
+{
+ return pte;
+}
+
/* Modify page protection bits */
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
@@ -417,7 +421,7 @@ static inline void pgtable_cache_init(void)
#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)

/*
- * Task size is 0x40000000000 for RV64 or 0xb800000 for RV32.
+ * Task size is 0x4000000000 for RV64 or 0xb800000 for RV32.
* Note that PGDIR_SIZE must evenly divide TASK_SIZE.
*/
#ifdef CONFIG_64BIT
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index b68aac701803..7bbe533d92f5 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -9,3 +9,5 @@ obj-y += fault.o
obj-y += extable.o
obj-y += ioremap.o
obj-y += cacheflush.o
+
+obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
new file mode 100644
index 000000000000..0d4747e9d5b5
--- /dev/null
+++ b/arch/riscv/mm/hugetlbpage.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/hugetlb.h>
+#include <linux/err.h>
+
+int pud_huge(pud_t pud)
+{
+ return pud_present(pud) &&
+ (pud_val(pud) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
+}
+
+int pmd_huge(pmd_t pmd)
+{
+ return pmd_present(pmd) &&
+ (pmd_val(pmd) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
+}
+
+static __init int setup_hugepagesz(char *opt)
+{
+ unsigned long ps = memparse(opt, &opt);
+
+ if (ps == HPAGE_SIZE) {
+ hugetlb_add_hstate(HPAGE_SHIFT - PAGE_SHIFT);
+ } else if (IS_ENABLED(CONFIG_64BIT) && ps == PUD_SIZE) {
+ hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+ } else {
+ hugetlb_bad_size();
+ pr_err("hugepagesz: Unsupported page size %lu M\n", ps >> 20);
+ return 0;
+ }
+
+ return 1;
+}
+__setup("hugepagesz=", setup_hugepagesz);
+
+#ifdef CONFIG_CONTIG_ALLOC
+static __init int gigantic_pages_init(void)
+{
+ /* With CONTIG_ALLOC, we can allocate gigantic pages at runtime */
+ if (IS_ENABLED(CONFIG_64BIT) && !size_to_hstate(1UL << PUD_SHIFT))
+ hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+ return 0;
+}
+arch_initcall(gigantic_pages_init);
+#endif
--
2.20.1
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