2024-03-25 16:45:14

by Christophe Leroy

[permalink] [raw]
Subject: [RFC PATCH 8/8] powerpc/8xx: Add back support for 8M pages using contiguous PTE entries

In order to fit better with standard Linux page tables layout, add
support for 8M pages using contiguous PTE entries in a standard
page table. Page tables will then be populated with 1024 similar
entries and two PMD entries will point to that page table.

The PMD entries also get a flag to tell it is addressing an 8M page,
this is required for the HW tablewalk assistance.

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/include/asm/hugetlb.h | 11 ++++-
.../include/asm/nohash/32/hugetlb-8xx.h | 28 +++++++++++-
arch/powerpc/include/asm/nohash/32/pgalloc.h | 2 +
arch/powerpc/include/asm/nohash/32/pte-8xx.h | 43 +++++++++++++++++--
arch/powerpc/include/asm/pgtable.h | 1 +
arch/powerpc/kernel/head_8xx.S | 1 +
arch/powerpc/mm/hugetlbpage.c | 12 +++++-
arch/powerpc/mm/nohash/8xx.c | 31 ++++++++++---
arch/powerpc/mm/nohash/tlb.c | 3 ++
arch/powerpc/mm/pgtable.c | 24 +++++++----
arch/powerpc/mm/pgtable_32.c | 2 +-
11 files changed, 134 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index a05657e5701b..bd60ea134f8e 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -41,7 +41,16 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
- return __pte(pte_update(mm, addr, ptep, ~0UL, 0, 1));
+ pmd_t *pmdp = (pmd_t *)ptep;
+ pte_t pte;
+
+ if (pmdp == pmd_off(mm, ALIGN_DOWN(addr, SZ_8M))) {
+ pte = __pte(pte_update(mm, addr, pte_offset_kernel(pmdp, 0), ~0UL, 0, 1));
+ pte_update(mm, addr, pte_offset_kernel(pmdp + 1, 0), ~0UL, 0, 1);
+ } else {
+ pte = __pte(pte_update(mm, addr, ptep, ~0UL, 0, 1));
+ }
+ return pte;
}

#define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
index 178ed9fdd353..1414cfd28987 100644
--- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
@@ -15,6 +15,16 @@ static inline int check_and_get_huge_psize(int shift)
return shift_to_mmu_psize(shift);
}

+#define __HAVE_ARCH_HUGE_PTEP_GET
+static inline pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+ pmd_t *pmdp = (pmd_t *)ptep;
+
+ if (pmdp == pmd_off(mm, ALIGN_DOWN(addr, SZ_8M)))
+ ptep = pte_offset_kernel(pmdp, 0);
+ return ptep_get(ptep);
+}
+
#define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
pte_t pte, unsigned long sz);
@@ -23,7 +33,14 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, unsigned long sz)
{
- pte_update(mm, addr, ptep, ~0UL, 0, 1);
+ pmd_t *pmdp = (pmd_t *)ptep;
+
+ if (pmdp == pmd_off(mm, ALIGN_DOWN(addr, SZ_8M))) {
+ pte_update(mm, addr, pte_offset_kernel(pmdp, 0), ~0UL, 0, 1);
+ pte_update(mm, addr, pte_offset_kernel(pmdp + 1, 0), ~0UL, 0, 1);
+ } else {
+ pte_update(mm, addr, ptep, ~0UL, 0, 1);
+ }
}

#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT
@@ -33,7 +50,14 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
unsigned long clr = ~pte_val(pte_wrprotect(__pte(~0)));
unsigned long set = pte_val(pte_wrprotect(__pte(0)));

- pte_update(mm, addr, ptep, clr, set, 1);
+ pmd_t *pmdp = (pmd_t *)ptep;
+
+ if (pmdp == pmd_off(mm, ALIGN_DOWN(addr, SZ_8M))) {
+ pte_update(mm, addr, pte_offset_kernel(pmdp, 0), clr, set, 1);
+ pte_update(mm, addr, pte_offset_kernel(pmdp + 1, 0), clr, set, 1);
+ } else {
+ pte_update(mm, addr, ptep, clr, set, 1);
+ }
}

#ifdef CONFIG_PPC_4K_PAGES
diff --git a/arch/powerpc/include/asm/nohash/32/pgalloc.h b/arch/powerpc/include/asm/nohash/32/pgalloc.h
index 11eac371e7e0..ff4f90cfb461 100644
--- a/arch/powerpc/include/asm/nohash/32/pgalloc.h
+++ b/arch/powerpc/include/asm/nohash/32/pgalloc.h
@@ -14,6 +14,7 @@
#define __pmd_free_tlb(tlb,x,a) do { } while (0)
/* #define pgd_populate(mm, pmd, pte) BUG() */

+#ifndef CONFIG_PPC_8xx
static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp,
pte_t *pte)
{
@@ -31,5 +32,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp,
else
*pmdp = __pmd(__pa(pte_page) | _PMD_USER | _PMD_PRESENT);
}
+#endif

#endif /* _ASM_POWERPC_PGALLOC_32_H */
diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
index 004d7e825af2..b05cc4f87713 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
@@ -129,14 +129,23 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
}
#define ptep_set_wrprotect ptep_set_wrprotect

+static pmd_t *pmd_off(struct mm_struct *mm, unsigned long addr);
+static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address);
+
static inline void __ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep,
pte_t entry, unsigned long address, int psize)
{
unsigned long set = pte_val(entry) & (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_EXEC);
unsigned long clr = ~pte_val(entry) & _PAGE_RO;
int huge = psize > mmu_virtual_psize ? 1 : 0;
+ pmd_t *pmdp = (pmd_t *)ptep;

- pte_update(vma->vm_mm, address, ptep, clr, set, huge);
+ if (pmdp == pmd_off(vma->vm_mm, ALIGN_DOWN(address, SZ_8M))) {
+ pte_update(vma->vm_mm, address, pte_offset_kernel(pmdp, 0), clr, set, huge);
+ pte_update(vma->vm_mm, address, pte_offset_kernel(pmdp + 1, 0), clr, set, huge);
+ } else {
+ pte_update(vma->vm_mm, address, ptep, clr, set, huge);
+ }

flush_tlb_page(vma, address);
}
@@ -146,6 +155,8 @@ static inline unsigned long pte_leaf_size(pmd_t pmd, pte_t pte)
{
pte_basic_t val = pte_val(pte);

+ if (pmd_val(pmd) & _PMD_PAGE_8M)
+ return SZ_8M;
if (val & _PAGE_HUGE)
return SZ_512K;
if (val & _PAGE_SPS)
@@ -159,14 +170,16 @@ static inline unsigned long pte_leaf_size(pmd_t pmd, pte_t pte)
* On the 8xx, the page tables are a bit special. For 16k pages, we have
* 4 identical entries. For 512k pages, we have 128 entries as if it was
* 4k pages, but they are flagged as 512k pages for the hardware.
- * For other page sizes, we have a single entry in the table.
+ * For 8M pages, we have 1024 entries as if it was
+ * 4M pages, but they are flagged as 8M pages for the hardware.
+ * For 4k pages, we have a single entry in the table.
*/
-static pmd_t *pmd_off(struct mm_struct *mm, unsigned long addr);
-
static inline int number_of_cells_per_pte(pmd_t *pmd, pte_basic_t val, int huge)
{
if (!huge)
return PAGE_SIZE / SZ_4K;
+ else if ((pmd_val(*pmd) & _PMD_PAGE_MASK) == _PMD_PAGE_8M)
+ return SZ_4M / SZ_4K;
else if (IS_ENABLED(CONFIG_PPC_4K_PAGES) && !(val & _PAGE_HUGE))
return SZ_16K / SZ_4K;
else
@@ -209,6 +222,28 @@ static inline pte_t ptep_get(pte_t *ptep)
}
#endif /* CONFIG_PPC_16K_PAGES */

+static inline void pmd_populate_kernel_size(struct mm_struct *mm, pmd_t *pmdp,
+ pte_t *pte, unsigned long sz)
+{
+ if (sz == SZ_8M)
+ *pmdp = __pmd(__pa(pte) | _PMD_PRESENT | _PMD_PAGE_8M);
+ else
+ *pmdp = __pmd(__pa(pte) | _PMD_PRESENT);
+}
+
+static inline void pmd_populate_size(struct mm_struct *mm, pmd_t *pmdp,
+ pgtable_t pte_page, unsigned long sz)
+{
+ if (sz == SZ_8M)
+ *pmdp = __pmd(__pa(pte_page) | _PMD_USER | _PMD_PRESENT | _PMD_PAGE_8M);
+ else
+ *pmdp = __pmd(__pa(pte_page) | _PMD_USER | _PMD_PRESENT);
+}
+#define pmd_populate_size pmd_populate_size
+
+#define pmd_populate(mm, pmdp, pte) pmd_populate_size(mm, pmdp, pte, PAGE_SIZE)
+#define pmd_populate_kernel(mm, pmdp, pte) pmd_populate_kernel_size(mm, pmdp, pte, PAGE_SIZE)
+
#endif

#endif /* __KERNEL__ */
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 239709a2f68e..005dad336565 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -106,6 +106,7 @@ unsigned long vmalloc_to_phys(void *vmalloc_addr);

void pgtable_cache_add(unsigned int shift);

+void __init *early_alloc_pgtable(unsigned long size);
pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va);

#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_PPC32)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index b53af565b132..43919ae0bd11 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -415,6 +415,7 @@ FixupDAR:/* Entry point for dcbx workaround. */
oris r11, r11, (swapper_pg_dir - PAGE_OFFSET)@ha
3:
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
+ rlwinm r11, r11, 0, ~_PMD_PAGE_8M
mtspr SPRN_MD_TWC, r11
mfspr r11, SPRN_MD_TWC
lwz r11, 0(r11) /* Get the pte */
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 4e9fbd5b895d..dd29845ce0ce 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -195,7 +195,17 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
- return pte_alloc_huge(mm, pmd_off(mm, addr), addr, sz);
+ pmd_t *pmd = pmd_off(mm, addr);
+
+ if (sz == SZ_512M)
+ return pte_alloc_huge(mm, pmd, addr, sz);
+ if (sz != SZ_8M)
+ return NULL;
+ if (!pte_alloc_huge(mm, pmd, addr, sz))
+ return NULL;
+ if (!pte_alloc_huge(mm, pmd + 1, addr, sz))
+ return NULL;
+ return (pte_t *)pmd;
}
#endif

diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index fc10e08bcb85..b416bfc161d4 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -54,25 +54,40 @@ static int __ref __early_map_kernel_hugepage(unsigned long va, phys_addr_t pa,
pmd_t *pmdp = pmd_off_k(va);
pte_t *ptep;

- if (WARN_ON(psize != MMU_PAGE_512K))
+ if (WARN_ON(psize != MMU_PAGE_512K && psize != MMU_PAGE_8M))
return -EINVAL;

if (new) {
if (WARN_ON(slab_is_available()))
return -EINVAL;

- ptep = early_pte_alloc_kernel(pmdp, va);
+ if (psize == MMU_PAGE_8M) {
+ if (WARN_ON(!pmd_none(*pmdp) || !pmd_none(*(pmdp + 1))))
+ return -EINVAL;
+
+ ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
+ pmd_populate_kernel_size(&init_mm, pmdp, ptep, SZ_8M);
+
+ ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
+ pmd_populate_kernel_size(&init_mm, pmdp + 1, ptep, SZ_8M);
+
+ ptep = (pte_t *)pmdp;
+ } else {
+ ptep = early_pte_alloc_kernel(pmdp, va);
+ /* The PTE should never be already present */
+ if (WARN_ON(pte_present(*ptep) && pgprot_val(prot)))
+ return -EINVAL;
+ }
} else {
- ptep = pte_offset_kernel(pmdp, va);
+ if (psize == MMU_PAGE_8M)
+ ptep = (pte_t *)pmdp;
+ else
+ ptep = pte_offset_kernel(pmdp, va);
}

if (WARN_ON(!ptep))
return -ENOMEM;

- /* The PTE should never be already present */
- if (new && WARN_ON(pte_present(*ptep) && pgprot_val(prot)))
- return -EINVAL;
-
set_huge_pte_at(&init_mm, va, ptep,
pte_mkhuge(pfn_pte(pa >> PAGE_SHIFT, prot)),
1UL << mmu_psize_to_shift(psize));
@@ -110,6 +125,8 @@ static void mmu_mapin_ram_chunk(unsigned long offset, unsigned long top,

for (; p < ALIGN(p, SZ_8M) && p < top; p += SZ_512K, v += SZ_512K)
__early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
+ for (; p < ALIGN_DOWN(top, SZ_8M) && p < top; p += SZ_8M, v += SZ_8M)
+ __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_8M, new);
for (; p < ALIGN_DOWN(top, SZ_512K) && p < top; p += SZ_512K, v += SZ_512K)
__early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);

diff --git a/arch/powerpc/mm/nohash/tlb.c b/arch/powerpc/mm/nohash/tlb.c
index cb2afe39cee5..5ffa0af4328a 100644
--- a/arch/powerpc/mm/nohash/tlb.c
+++ b/arch/powerpc/mm/nohash/tlb.c
@@ -104,6 +104,9 @@ struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
[MMU_PAGE_512K] = {
.shift = 19,
},
+ [MMU_PAGE_8M] = {
+ .shift = 23,
+ },
};
#endif

diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index acdf64c9b93e..59f0d7706d2f 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -297,11 +297,8 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
}

#if defined(CONFIG_PPC_8xx)
-void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
- pte_t pte, unsigned long sz)
+static void __set_huge_pte_at(pmd_t *pmd, pte_t *ptep, pte_basic_t val)
{
- pmd_t *pmd = pmd_off(mm, addr);
- pte_basic_t val;
pte_basic_t *entry = (pte_basic_t *)ptep;
int num, i;

@@ -311,15 +308,26 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
*/
VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));

- pte = set_pte_filter(pte, addr);
-
- val = pte_val(pte);
-
num = number_of_cells_per_pte(pmd, val, 1);

for (i = 0; i < num; i++, entry++, val += SZ_4K)
*entry = val;
}
+
+void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+ pte_t pte, unsigned long sz)
+{
+ pmd_t *pmdp = pmd_off(mm, addr);
+
+ pte = set_pte_filter(pte, addr);
+
+ if (sz == SZ_8M) {
+ __set_huge_pte_at(pmdp, pte_offset_kernel(pmdp, 0), pte_val(pte));
+ __set_huge_pte_at(pmdp, pte_offset_kernel(pmdp + 1, 0), pte_val(pte) + SZ_4M);
+ } else {
+ __set_huge_pte_at(pmdp, ptep, pte_val(pte));
+ }
+}
#endif
#endif /* CONFIG_HUGETLB_PAGE */

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index face94977cb2..0b1d68ef87cd 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -48,7 +48,7 @@ notrace void __init early_ioremap_init(void)
early_ioremap_setup();
}

-static void __init *early_alloc_pgtable(unsigned long size)
+void __init *early_alloc_pgtable(unsigned long size)
{
void *ptr = memblock_alloc(size, size);

--
2.43.0