| Message ID | 1399043829-9036-1-git-send-email-steve.capper@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 02, 2014 at 04:17:09PM +0100, Steve Capper wrote: > We have the capability to map 1GB level 1 blocks when using a 4K > granule. > > This patch adjusts the create_mapping logic s.t. when mapping physical > memory on boot, we attempt to use a 1GB block if both the VA and PA > start and end are 1GB aligned. This both reduces the levels of lookup > required to resolve a kernel logical address, as well as reduces TLB > pressure on cores that support 1GB TLB entries. > > Signed-off-by: Steve Capper <steve.capper@linaro.org> I think you need to patch kern_addr_valid as well for this (we recently pushed a patch to detect pmd block mappings).
On Tue, May 06, 2014 at 10:58:53AM +0100, Catalin Marinas wrote: > On Fri, May 02, 2014 at 04:17:09PM +0100, Steve Capper wrote: > > We have the capability to map 1GB level 1 blocks when using a 4K > > granule. > > > > This patch adjusts the create_mapping logic s.t. when mapping physical > > memory on boot, we attempt to use a 1GB block if both the VA and PA > > start and end are 1GB aligned. This both reduces the levels of lookup > > required to resolve a kernel logical address, as well as reduces TLB > > pressure on cores that support 1GB TLB entries. > > > > Signed-off-by: Steve Capper <steve.capper@linaro.org> > > I think you need to patch kern_addr_valid as well for this (we recently > pushed a patch to detect pmd block mappings). Ahh, I see it, thanks. I will amend the logic. Cheers,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 4d29332..2ced5f6 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -234,7 +234,30 @@ static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr, pud = pud_offset(pgd, addr); do { next = pud_addr_end(addr, end); - alloc_init_pmd(pud, addr, next, phys); + + /* + * For 4K granule only, attempt to put down a 1GB block + */ + if ((PAGE_SHIFT == 12) && + ((addr | next | phys) & ~PUD_MASK) == 0) { + pud_t old_pud = *pud; + set_pud(pud, __pud(phys | prot_sect_kernel)); + + /* + * If we have an old value for a pud, it will + * be pointing to a pmd table that we no longer + * need (from swapper_pg_dir). + * + * Look up the old pmd table and free it. + */ + if (!pud_none(old_pud)) { + phys_addr_t table = __pa(pmd_offset(&old_pud, 0)); + memblock_free(table, PAGE_SIZE); + flush_tlb_all(); + } + } else { + alloc_init_pmd(pud, addr, next, phys); + } phys += next - addr; } while (pud++, addr = next, addr != end); }
We have the capability to map 1GB level 1 blocks when using a 4K granule. This patch adjusts the create_mapping logic s.t. when mapping physical memory on boot, we attempt to use a 1GB block if both the VA and PA start and end are 1GB aligned. This both reduces the levels of lookup required to resolve a kernel logical address, as well as reduces TLB pressure on cores that support 1GB TLB entries. Signed-off-by: Steve Capper <steve.capper@linaro.org> --- Changed in V2: free the original pmd table from swapper_pg_dir if we replace it with a block pud entry. Catalin, pud_pfn would give us the pud pointed to by a huge pud. (so will resolve to a gigabyte aligned address when << PAGE_SHIFTed). What we want is the pointer to the pmd table. I've opted to go for pmd_offset as it's easier to gauge intent. (I know we convert from PA->VA->PA, but this will probably compile out, and is done once on boot...). I've tested this with 3 and 4 levels on the Model (and a load of debug printing that I've removed from the patch). Cheers,