[PATCH v5 15/18] powerpc/e500: Use contiguous PMD instead of hugepd

From: Christophe Leroy
Date: Mon Jun 10 2024 - 01:59:21 EST

e500 supports many page sizes among which the following size are
implemented in the kernel at the time being: 4M, 16M, 64M, 256M, 1G.

On e500, TLB miss for hugepages is exclusively handled by SW even
on e6500 which has HW assistance for 4k pages, so there are no
constraints like on the 8xx.

On e500/32, all are at PGD/PMD level and can be handled as
cont-PMD.

On e500/64, smaller ones are on PMD while bigger ones are on PUD.
Again, they can easily be handled as cont-PMD and cont-PUD instead
of hugepd.

On e500/32, use the pagesize bits in PTE to know if it is a PMD or
a leaf entry. This works because the pagesize bits are in the last
12 bits and page tables are 4k aligned.

On e500/64, use highest bit which is always 1 on PxD (Because PxD
contains virtual address of a kernel memory) and always 0 on PTEs
because not all bits of RPN are used/possible.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
v3: Add missing pmd_leaf_size() and pud_leaf_size()
v4: Rebased of v6.10-rc1 : pmd_huge() and pud_huge() are gone
v5:
- Define pte_huge_size() to reduce redundant and handle the case of mpc85xx with 32 bits PTE.
- Replace hard-coded page shift offset (10) with new macro _PAGE_PSIZE_SHIFT_OFFSET
- Use TSIZE encoding in SIZE field in PTE
- On 64 bits, use highest bit to know if it is a PUD/PMD or leaf entry. Avoids problem with page table alignment.
---
.../powerpc/include/asm/nohash/hugetlb-e500.h | 32 ++------------
arch/powerpc/include/asm/nohash/pgalloc.h | 2 -
arch/powerpc/include/asm/nohash/pgtable.h | 42 ++++++++++++++-----
arch/powerpc/include/asm/nohash/pte-e500.h | 33 +++++++++++++++
arch/powerpc/include/asm/page.h | 15 +------
arch/powerpc/kernel/head_85xx.S | 21 ++++------
arch/powerpc/mm/hugetlbpage.c | 2 -
arch/powerpc/mm/nohash/tlb_low_64e.S | 7 +---
arch/powerpc/mm/pgtable.c | 31 ++++++++++++++
arch/powerpc/platforms/Kconfig.cputype | 1 -
10 files changed, 107 insertions(+), 79 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/hugetlb-e500.h b/arch/powerpc/include/asm/nohash/hugetlb-e500.h
index c6a0938e86fd..812c71fc5eb1 100644
--- a/arch/powerpc/include/asm/nohash/hugetlb-e500.h
+++ b/arch/powerpc/include/asm/nohash/hugetlb-e500.h
@@ -2,38 +2,12 @@
#ifndef _ASM_POWERPC_NOHASH_HUGETLB_E500_H
#define _ASM_POWERPC_NOHASH_HUGETLB_E500_H

-static inline pte_t *hugepd_page(hugepd_t hpd)
-{
- if (WARN_ON(!hugepd_ok(hpd)))
- return NULL;
-
- return (pte_t *)((hpd_val(hpd) & ~HUGEPD_SHIFT_MASK) | PD_HUGE);
-}
-
-static inline unsigned int hugepd_shift(hugepd_t hpd)
-{
- return hpd_val(hpd) & HUGEPD_SHIFT_MASK;
-}
-
-static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
- unsigned int pdshift)
-{
- /*
- * On FSL BookE, we have multiple higher-level table entries that
- * point to the same hugepte. Just use the first one since they're all
- * identical. So for that case, idx=0.
- */
- return hugepd_page(hpd);
-}
+#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);

void flush_hugetlb_page(struct vm_area_struct *vma, unsigned long vmaddr);

-static inline void hugepd_populate(hugepd_t *hpdp, pte_t *new, unsigned int pshift)
-{
- /* We use the old format for PPC_E500 */
- *hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
-}
-
static inline int check_and_get_huge_psize(int shift)
{
if (shift & 1) /* Not a power of 4 */
diff --git a/arch/powerpc/include/asm/nohash/pgalloc.h b/arch/powerpc/include/asm/nohash/pgalloc.h
index 4b62376318e1..d06efac6d7aa 100644
--- a/arch/powerpc/include/asm/nohash/pgalloc.h
+++ b/arch/powerpc/include/asm/nohash/pgalloc.h
@@ -44,8 +44,6 @@ static inline void pgtable_free(void *table, int shift)
}
}

-#define get_hugepd_cache_index(x) (x)
-
static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
{
unsigned long pgf = (unsigned long)table;
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 90d6a0943b35..8d1f0b7062eb 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -31,6 +31,13 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p

extern int icache_44x_need_flush;

+#ifndef pte_huge_size
+static inline unsigned long pte_huge_size(pte_t pte)
+{
+ return PAGE_SIZE;
+}
+#endif
+
/*
* PTE updates. This function is called whenever an existing
* valid PTE is updated. This does -not- include set_pte_at()
@@ -52,11 +59,34 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
{
pte_basic_t old = pte_val(*p);
pte_basic_t new = (old & ~(pte_basic_t)clr) | set;
+ unsigned long sz;
+ unsigned long pdsize;
+ int i;

if (new == old)
return old;

- *p = __pte(new);
+ if (huge)
+ sz = pte_huge_size(__pte(old));
+ else
+ sz = PAGE_SIZE;
+
+ if (sz < PMD_SIZE)
+ pdsize = PAGE_SIZE;
+ else if (sz < PUD_SIZE)
+ pdsize = PMD_SIZE;
+ else if (sz < P4D_SIZE)
+ pdsize = PUD_SIZE;
+ else if (sz < PGDIR_SIZE)
+ pdsize = P4D_SIZE;
+ else
+ pdsize = PGDIR_SIZE;
+
+ for (i = 0; i < sz / pdsize; i++, p++) {
+ *p = __pte(new);
+ if (new)
+ new += (unsigned long long)(pdsize / PAGE_SIZE) << PTE_RPN_SHIFT;
+ }

if (IS_ENABLED(CONFIG_44x) && !is_kernel_addr(addr) && (old & _PAGE_EXEC))
icache_44x_need_flush = 1;
@@ -340,16 +370,6 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,

#define pgprot_writecombine pgprot_noncached_wc

-#ifdef CONFIG_ARCH_HAS_HUGEPD
-static inline int hugepd_ok(hugepd_t hpd)
-{
- /* We clear the top bit to indicate hugepd */
- return (hpd_val(hpd) && (hpd_val(hpd) & PD_HUGE) == 0);
-}
-
-#define is_hugepd(hpd) (hugepd_ok(hpd))
-#endif
-
int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
void unmap_kernel_page(unsigned long va);

diff --git a/arch/powerpc/include/asm/nohash/pte-e500.h b/arch/powerpc/include/asm/nohash/pte-e500.h
index 6dac1c0a6937..cb78392494da 100644
--- a/arch/powerpc/include/asm/nohash/pte-e500.h
+++ b/arch/powerpc/include/asm/nohash/pte-e500.h
@@ -101,6 +101,39 @@ static inline unsigned long pte_huge_size(pte_t pte)
}
#define pte_huge_size pte_huge_size

+static inline int pmd_leaf(pmd_t pmd)
+{
+ if (IS_ENABLED(CONFIG_PPC64))
+ return (long)pmd_val(pmd) > 0;
+ else
+ return pmd_val(pmd) & _PAGE_PSIZE_MSK;
+}
+#define pmd_leaf pmd_leaf
+
+static inline unsigned long pmd_leaf_size(pmd_t pmd)
+{
+ return pte_huge_size(__pte(pmd_val(pmd)));
+}
+#define pmd_leaf_size pmd_leaf_size
+
+#ifdef CONFIG_PPC64
+static inline int pud_leaf(pud_t pud)
+{
+ if (IS_ENABLED(CONFIG_PPC64))
+ return (long)pud_val(pud) > 0;
+ else
+ return pud_val(pud) & _PAGE_PSIZE_MSK;
+}
+#define pud_leaf pud_leaf
+
+static inline unsigned long pud_leaf_size(pud_t pud)
+{
+ return pte_huge_size(__pte(pud_val(pud)));
+}
+#define pud_leaf_size pud_leaf_size
+
+#endif
+
#endif /* __ASSEMBLY__ */

#endif /* __KERNEL__ */
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 018c3d55232c..7d3c3bc40e6a 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -269,20 +269,7 @@ static inline const void *pfn_to_kaddr(unsigned long pfn)
#define is_kernel_addr(x) ((x) >= TASK_SIZE)
#endif

-#ifndef CONFIG_PPC_BOOK3S_64
-/*
- * Use the top bit of the higher-level page table entries to indicate whether
- * the entries we point to contain hugepages. This works because we know that
- * the page tables live in kernel space. If we ever decide to support having
- * page tables at arbitrary addresses, this breaks and will have to change.
- */
-#ifdef CONFIG_PPC64
-#define PD_HUGE 0x8000000000000000UL
-#else
-#define PD_HUGE 0x80000000
-#endif
-
-#else /* CONFIG_PPC_BOOK3S_64 */
+#ifdef CONFIG_PPC_BOOK3S_64
/*
* Book3S 64 stores real addresses in the hugepd entries to
* avoid overlaps with _PAGE_PRESENT and _PAGE_PTE.
diff --git a/arch/powerpc/kernel/head_85xx.S b/arch/powerpc/kernel/head_85xx.S
index 226f88e77d6d..f9a73fae6464 100644
--- a/arch/powerpc/kernel/head_85xx.S
+++ b/arch/powerpc/kernel/head_85xx.S
@@ -311,16 +311,14 @@ set_ivor:
rlwinm r12, r13, 14, 18, 28; /* Compute pgdir/pmd offset */ \
add r12, r11, r12; \
lwz r11, 4(r12); /* Get pgd/pmd entry */ \
+ rlwinm. r10, r11, 32 - _PAGE_PSIZE_SHIFT, 0x1e; /* get tsize*/ \
+ bne 1000f; /* Huge page (leaf entry) */ \
rlwinm. r12, r11, 0, 0, 20; /* Extract pt base address */ \
- blt 1000f; /* Normal non-huge page */ \
beq 2f; /* Bail if no table */ \
- oris r11, r11, PD_HUGE@h; /* Put back address bit */ \
- andi. r10, r11, HUGEPD_SHIFT_MASK@l; /* extract size field */ \
- xor r12, r10, r11; /* drop size bits from pointer */ \
- b 1001f; \
-1000: rlwimi r12, r13, 23, 20, 28; /* Compute pte address */ \
+ rlwimi r12, r13, 23, 20, 28; /* Compute pte address */ \
li r10, 0; /* clear r10 */ \
-1001: lwz r11, 4(r12); /* Get pte entry */
+ lwz r11, 4(r12); /* Get pte entry */ \
+1000:
#else
#define FIND_PTE \
rlwinm r12, r13, 14, 18, 28; /* Compute pgdir/pmd offset */ \
@@ -735,17 +733,12 @@ finish_tlb_load:
lwz r15, 0(r14)
100: stw r15, 0(r17)

- /*
- * Calc MAS1_TSIZE from r10 (which has pshift encoded)
- * tlb_enc = (pshift - 10).
- */
- subi r15, r10, 10
mfspr r16, SPRN_MAS1
- rlwimi r16, r15, 7, 20, 24
+ rlwimi r16, r10, MAS1_TSIZE_SHIFT, MAS1_TSIZE_MASK
mtspr SPRN_MAS1, r16

/* copy the pshift for use later */
- mr r14, r10
+ addi r14, r10, _PAGE_PSIZE_SHIFT_OFFSET

/* fall through */

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 394846197974..9e692d96f9e1 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -625,8 +625,6 @@ static int __init hugetlbpage_init(void)
*/
if (pdshift > shift) {
pgtable_cache_add(pdshift - shift);
- } else if (IS_ENABLED(CONFIG_PPC_E500)) {
- pgtable_cache_add(PTE_T_ORDER);
}

configured = true;
diff --git a/arch/powerpc/mm/nohash/tlb_low_64e.S b/arch/powerpc/mm/nohash/tlb_low_64e.S
index a54e7d6c3d0b..de568297d5c5 100644
--- a/arch/powerpc/mm/nohash/tlb_low_64e.S
+++ b/arch/powerpc/mm/nohash/tlb_low_64e.S
@@ -450,11 +450,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_SMT)

tlb_miss_huge_e6500:
beq tlb_miss_fault_e6500
- li r10,1
- andi. r15,r14,HUGEPD_SHIFT_MASK@l /* r15 = psize */
- rldimi r14,r10,63,0 /* Set PD_HUGE */
- xor r14,r14,r15 /* Clear size bits */
- ldx r14,0,r14
+ rlwinm r15,r14,32-_PAGE_PSIZE_SHIFT,0x1e

/*
* Now we build the MAS for a huge page.
@@ -465,7 +461,6 @@ tlb_miss_huge_e6500:
* MAS 2,3+7: Needs to be redone similar to non-tablewalk handler
*/

- subi r15,r15,10 /* Convert psize to tsize */
mfspr r10,SPRN_MAS1
rlwinm r10,r10,0,~MAS1_IND
rlwimi r10,r15,MAS1_TSIZE_SHIFT,MAS1_TSIZE_MASK
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 294775c793ab..6498454959f3 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -331,6 +331,37 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
__set_huge_pte_at(pmdp, ptep, pte_val(pte));
}
}
+#elif defined(CONFIG_PPC_E500)
+void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+ pte_t pte, unsigned long sz)
+{
+ unsigned long pdsize;
+ int i;
+
+ pte = set_pte_filter(pte, addr);
+
+ /*
+ * Make sure hardware valid bit is not set. We don't do
+ * tlb flush for this update.
+ */
+ VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
+
+ if (sz < PMD_SIZE)
+ pdsize = PAGE_SIZE;
+ else if (sz < PUD_SIZE)
+ pdsize = PMD_SIZE;
+ else if (sz < P4D_SIZE)
+ pdsize = PUD_SIZE;
+ else if (sz < PGDIR_SIZE)
+ pdsize = P4D_SIZE;
+ else
+ pdsize = PGDIR_SIZE;
+
+ for (i = 0; i < sz / pdsize; i++, ptep++, addr += pdsize) {
+ __set_pte_at(mm, addr, ptep, pte, 0);
+ pte = __pte(pte_val(pte) + ((unsigned long long)pdsize / PAGE_SIZE << PFN_PTE_SHIFT));
+ }
+}
#endif
#endif /* CONFIG_HUGETLB_PAGE */

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index fa4bb096b3ae..30a78e99663e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -291,7 +291,6 @@ config PPC_BOOK3S
config PPC_E500
select FSL_EMB_PERFMON
bool
- select ARCH_HAS_HUGEPD if HUGETLB_PAGE
select ARCH_SUPPORTS_HUGETLBFS if PHYS_64BIT || PPC64
select PPC_SMP_MUXED_IPI
select PPC_DOORBELL
--
2.44.0