This is inine with similar patches for nopud [1] and nop4d [2] cases.
However I'm not really sure I understand clearly how the nopmd code is
supposed to work (for a 2 tier paging system) - hence the RFC.
Consider free_pmd_range() simplified/annotated below
free_pmd_range
...
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) => *pmd_bad()/pmd_clear_bad() [a]*
continue;
free_pte_range(tlb, pmd, addr);
} while (pmd++, addr = next, addr != end);
...
*pmd_free_tlb(tlb, pmd, start); => [b]*
For ARC/nopmd case [a] is actually checking pgd and consequently
pmd_clear_bad() can't be stubbed out for PMD_FOLDED case. However it seems
case [b] can be stubbed out (hence this patch) along same lines as [1] and [2]
| bloat-o-meter2 vmlinux-E-elide-p?d_clear_bad vmlinux-F-elide-pmd_free_tlb
| add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-112 (-112)
| function old new delta
| free_pgd_range 422 310 -112
| Total: Before=4137002, After=4136890, chg -1.000000%
[1] http://lists.infradead.org/pipermail/linux-snps-arc/2019-October/006266.html
[2] http://lists.infradead.org/pipermail/linux-snps-arc/2019-October/006265.html
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
include/asm-generic/tlb.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index f3dad87f4ecc..a1edad7d4170 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -574,6 +574,7 @@ static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vm
} while (0)
#endif
+#ifndef __PAGETABLE_PMD_FOLDED
#ifndef pmd_free_tlb
#define pmd_free_tlb(tlb, pmdp, address) \
do { \
@@ -583,6 +584,9 @@ static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vm
__pmd_free_tlb(tlb, pmdp, address); \
} while (0)
#endif
+#else
+#define pmd_free_tlb(tlb, pmdp, address) do { } while (0)
+#endif
#ifndef __PAGETABLE_PUD_FOLDED
#ifndef pud_free_tlb
--
2.20.1
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