| Message ID | 20191015191926.9281-2-vgupta@synopsys.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | eldie generated code for folded p4d/pud | expand |
On Tue, Oct 15, 2019 at 12:19 PM Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote: > > This is a non-functional change anyways since ARC has software page walker > with 2 lookup levels (pgd -> pte) Could we encourage other architectures to do the same, and get rid of all uses of __ARCH_USE_5LEVEL_HACK? Linus
On 10/15/19 2:48 PM, Linus Torvalds wrote: > On Tue, Oct 15, 2019 at 12:19 PM Vineet Gupta > <Vineet.Gupta1@synopsys.com> wrote: >> This is a non-functional change anyways since ARC has software page walker >> with 2 lookup levels (pgd -> pte) > > Could we encourage other architectures to do the same, and get rid of > all uses of __ARCH_USE_5LEVEL_HACK? IMHO this should have been done at the onset. The actual changes don't seem that difficult, just need to add the missing p4d calls although I can sympathize with hassles of coordinating/building/testing/yadi yada cross arch. OTOH, the [45]LEVEL_HACK seem like a nice way to "fold" the levels: the skipped/folded level vanishes completely. Among others it does things like #define p4d_t pgd_t On ARC 2-level code: free_pte_range pmd_pgtable(*pmd); ((((((*pmd).pud).pgd))) & PAGE_MASK)); <-- 5LEVEL_HACK vs. ((((((((*pmd).pud).p4d).pgd)))) & PAGE_MASK )); <-- w/o 5LEVEL_HACK pmd_clear(pmd); *(pmd)).pud).pgd)))) = 0 vs. *(pmd)).pud).p4d).pgd)))) = 0 So we may not be able to fix all he historical misgivigs, but this might alleviate the pain a bit. I'll try to dabble a bit. Thx for taking a look and te ACKs. -Vineet
diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h index 7addd0301c51..b917b596f7fb 100644 --- a/arch/arc/include/asm/pgtable.h +++ b/arch/arc/include/asm/pgtable.h @@ -33,7 +33,6 @@ #define _ASM_ARC_PGTABLE_H #include <linux/bits.h> -#define __ARCH_USE_5LEVEL_HACK #include <asm-generic/pgtable-nopmd.h> #include <asm/page.h> #include <asm/mmu.h> /* to propagate CONFIG_ARC_MMU_VER <n> */ diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index 3861543b66a0..fb86bc3e9b35 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -30,6 +30,7 @@ noinline static int handle_kernel_vaddr_fault(unsigned long address) * with the 'reference' page table. */ pgd_t *pgd, *pgd_k; + p4d_t *p4d, *p4d_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; @@ -39,8 +40,13 @@ noinline static int handle_kernel_vaddr_fault(unsigned long address) if (!pgd_present(*pgd_k)) goto bad_area; - pud = pud_offset(pgd, address); - pud_k = pud_offset(pgd_k, address); + p4d = p4d_offset(pgd, address); + p4d_k = p4d_offset(pgd_k, address); + if (!p4d_present(*p4d_k)) + goto bad_area; + + pud = pud_offset(p4d, address); + pud_k = pud_offset(p4d_k, address); if (!pud_present(*pud_k)) goto bad_area; diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c index a4856bfaedf3..fc8849e4f72e 100644 --- a/arch/arc/mm/highmem.c +++ b/arch/arc/mm/highmem.c @@ -111,12 +111,14 @@ EXPORT_SYMBOL(__kunmap_atomic); static noinline pte_t * __init alloc_kmap_pgtable(unsigned long kvaddr) { pgd_t *pgd_k; + p4d_t *p4d_k; pud_t *pud_k; pmd_t *pmd_k; pte_t *pte_k; pgd_k = pgd_offset_k(kvaddr); - pud_k = pud_offset(pgd_k, kvaddr); + p4d_k = p4d_offset(pgd_k, kvaddr); + pud_k = pud_offset(p4d_k, kvaddr); pmd_k = pmd_offset(pud_k, kvaddr); pte_k = (pte_t *)memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
Add the intermedivmlinux-A-baseline vmlinux-B-elide-ARCH_USE_5LEVEL_HACK This is a non-functional change anyways since ARC has software page walker with 2 lookup levels (pgd -> pte) There is slight code bloat due to pulling in needless p*d_free_tlb() macros which needs to be addressed seperately. | bloat-o-meter2 vmlinux-with-5LEVEL_HACK vmlinux-patched | add/remove: 0/0 grow/shrink: 2/0 up/down: 128/0 (128) | function old new delta | free_pgd_range 546 656 +110 | p4d_clear_bad 2 20 +18 | Total: Before=4137148, After=4137276, chg 0.000000% Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- arch/arc/include/asm/pgtable.h | 1 - arch/arc/mm/fault.c | 10 ++++++++-- arch/arc/mm/highmem.c | 4 +++- 3 files changed, 11 insertions(+), 4 deletions(-)