Messages in this thread | | | From | Atish Patra <> | Date | Thu, 18 Jun 2020 17:47:30 -0700 | Subject | Re: [PATCH 2/2] riscv: Use PUD/PGDIR entries for linear mapping when possible |
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On Wed, Jun 3, 2020 at 8:38 AM Alexandre Ghiti <alex@ghiti.fr> wrote: > > Improve best_map_size so that PUD or PGDIR entries are used for linear > mapping when possible as it allows better TLB utilization. > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > --- > arch/riscv/mm/init.c | 45 +++++++++++++++++++++++++++++++++----------- > 1 file changed, 34 insertions(+), 11 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 9a5c97e091c1..d275f9f834cf 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -424,13 +424,29 @@ static void __init create_pgd_mapping(pgd_t *pgdp, > create_pgd_next_mapping(nextp, va, pa, sz, prot); > } > > -static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size) > +static bool is_map_size_ok(uintptr_t map_size, phys_addr_t base, > + uintptr_t base_virt, phys_addr_t size) > { > - /* Upgrade to PMD_SIZE mappings whenever possible */ > - if ((base & (PMD_SIZE - 1)) || (size & (PMD_SIZE - 1))) > - return PAGE_SIZE; > + return !((base & (map_size - 1)) || (base_virt & (map_size - 1)) || > + (size < map_size)); > +} > + > +static uintptr_t __init best_map_size(phys_addr_t base, uintptr_t base_virt, > + phys_addr_t size) > +{ > +#ifndef __PAGETABLE_PMD_FOLDED > + if (is_map_size_ok(PGDIR_SIZE, base, base_virt, size)) > + return PGDIR_SIZE; > + > + if (pgtable_l4_enabled) > + if (is_map_size_ok(PUD_SIZE, base, base_virt, size)) > + return PUD_SIZE; > +#endif > + > + if (is_map_size_ok(PMD_SIZE, base, base_virt, size)) > + return PMD_SIZE; > > - return PMD_SIZE; > + return PAGE_SIZE; > } > > /* > @@ -576,7 +592,7 @@ void create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size) > asmlinkage void __init setup_vm(uintptr_t dtb_pa) > { > uintptr_t va, end_va; > - uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE); > + uintptr_t map_size; > > load_pa = (uintptr_t)(&_start); > load_sz = (uintptr_t)(&_end) - load_pa; > @@ -587,6 +603,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) > > kernel_virt_addr = KERNEL_VIRT_ADDR; > > + map_size = best_map_size(load_pa, PAGE_OFFSET, MAX_EARLY_MAPPING_SIZE); > va_pa_offset = PAGE_OFFSET - load_pa; > va_kernel_pa_offset = kernel_virt_addr - load_pa; > pfn_base = PFN_DOWN(load_pa); > @@ -700,6 +717,8 @@ static void __init setup_vm_final(void) > > /* Map all memory banks */ > for_each_memblock(memory, reg) { > + uintptr_t remaining_size; > + > start = reg->base; > end = start + reg->size; > > @@ -707,15 +726,19 @@ static void __init setup_vm_final(void) > break; > if (memblock_is_nomap(reg)) > continue; > - if (start <= __pa(PAGE_OFFSET) && > - __pa(PAGE_OFFSET) < end) > - start = __pa(PAGE_OFFSET); > > - map_size = best_map_size(start, end - start); > - for (pa = start; pa < end; pa += map_size) { > + pa = start; > + remaining_size = reg->size; > + > + while (remaining_size) { > va = (uintptr_t)__va(pa); > + map_size = best_map_size(pa, va, remaining_size); > + > create_pgd_mapping(swapper_pg_dir, va, pa, > map_size, PAGE_KERNEL); > + > + pa += map_size; > + remaining_size -= map_size; > } > } >
This may not work in the RV32 with 2G memory and if the map_size is determined to be a page size for the last memblock. Both pa & remaining_size will overflow and the loop will try to map memory from zero again.
> -- > 2.20.1 > >
-- Regards, Atish
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