From 6aae3425aa9ca776e8201a93494a4a482353d2c3 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Sat, 30 Nov 2019 17:51:06 -0800 Subject: ARC: mm: remove __ARCH_USE_5LEVEL_HACK Patch series "elide extraneous generated code for folded p4d/pud/pmd", v3. This series came out of seemingly benign excursion into understanding/removing __ARCH_USE_5LEVEL_HACK from ARC port showing some extraneous code being generated despite folded p4d/pud/pmd | bloat-o-meter2 vmlinux-[AB]* | add/remove: 0/0 grow/shrink: 3/0 up/down: 130/0 (130) | function old new delta | free_pgd_range 548 660 +112 | p4d_clear_bad 2 20 +18 The patches here address that | bloat-o-meter2 vmlinux-[BF]* | add/remove: 0/2 grow/shrink: 0/1 up/down: 0/-386 (-386) | function old new delta | pud_clear_bad 20 - -20 | p4d_clear_bad 20 - -20 | free_pgd_range 660 314 -346 The code savings are not a whole lot, but still worthwhile IMHO. This patch (of 5): With paging code made 5-level compliant, this is no longer needed. ARC has software page walker with 2 lookup levels (pgd -> pte) This was expected to be non functional change but ended with slight code bloat due to needless inclusions of p*d_free_tlb() macros which will be addressed in further patches. | bloat-o-meter2 vmlinux-[AB]* | 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% Link: http://lkml.kernel.org/r/20191016162400.14796-2-vgupta@synopsys.com Signed-off-by: Vineet Gupta Acked-by: Kirill A. Shutemov Cc: "Aneesh Kumar K . V" Cc: Arnd Bergmann Cc: Nick Piggin Cc: Peter Zijlstra Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arc/mm/fault.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'arch/arc/mm/fault.c') 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; -- cgit