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powerpc/e500: use contiguous PMD instead of hugepd

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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.

Link: https://lkml.kernel.org/r/dd085987816ed2a0c70adb7e34966cb833fc03e1.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Christophe Leroy
2024-07-02 15:51:32 +02:00
committed by Andrew Morton
parent dc0aa538a9
commit 7c44202e36
10 changed files with 107 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
arch/powerpc/include/asm/nohash/pgtable.h
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@@ -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);