Messages in this thread | | | Subject | Re: [PATCH 2/2] riscv: Use PUD/PGDIR entries for linear mapping when possible | From | Alex Ghiti <> | Date | Fri, 19 Jun 2020 00:28:16 -0400 |
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Hi Atish,
Le 6/18/20 à 8:47 PM, Atish Patra a écrit : > 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.
I'm not sure I understand: if pa starts at 0x8000_0000 and size is 2G, then pa will overflow in the last iteration, but remaining_size will then be equal to 0 right ?
And by the way, I realize that this loop only handles sizes that are aligned on map_size.
Thanks,
Alex
> >> -- >> 2.20.1 >> >> >
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