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Subject[PATCH v3 5/5] asm-generic/mm: stub out p{4,u}d_clear_bad() if __PAGETABLE_P{4,U}D_FOLDED
Date
This came up when removing __ARCH_HAS_5LEVEL_HACK for ARC as code bloat.
With this patch we see the following code reduction.

| bloat-o-meter2 vmlinux-D-elide-p4d_free_tlb vmlinux-E-elide-p?d_clear_bad
| add/remove: 0/2 grow/shrink: 0/0 up/down: 0/-40 (-40)
| function old new delta
| pud_clear_bad 20 - -20
| p4d_clear_bad 20 - -20
| Total: Before=4136930, After=4136890, chg -1.000000%

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
include/asm-generic/pgtable.h | 11 +++++++++++
mm/pgtable-generic.c | 9 +++++++++
2 files changed, 20 insertions(+)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 818691846c90..9cdcbc7c0b7b 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -558,8 +558,19 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
* Do the tests inline, but report and clear the bad entry in mm/memory.c.
*/
void pgd_clear_bad(pgd_t *);
+
+#ifndef __PAGETABLE_P4D_FOLDED
void p4d_clear_bad(p4d_t *);
+#else
+#define p4d_clear_bad(p4d) do { } while (0)
+#endif
+
+#ifndef __PAGETABLE_PUD_FOLDED
void pud_clear_bad(pud_t *);
+#else
+#define pud_clear_bad(p4d) do { } while (0)
+#endif
+
void pmd_clear_bad(pmd_t *);

static inline int pgd_none_or_clear_bad(pgd_t *pgd)
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 532c29276fce..3d7c01e76efc 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -24,18 +24,27 @@ void pgd_clear_bad(pgd_t *pgd)
pgd_clear(pgd);
}

+#ifndef __PAGETABLE_P4D_FOLDED
void p4d_clear_bad(p4d_t *p4d)
{
p4d_ERROR(*p4d);
p4d_clear(p4d);
}
+#endif

+#ifndef __PAGETABLE_PUD_FOLDED
void pud_clear_bad(pud_t *pud)
{
pud_ERROR(*pud);
pud_clear(pud);
}
+#endif

+/*
+ * Note that the pmd variant below can't be stub'ed out just as for p4d/pud
+ * above. pmd folding is special and typically pmd_* macros refer to upper
+ * level even when folded
+ */
void pmd_clear_bad(pmd_t *pmd)
{
pmd_ERROR(*pmd);
--
2.20.1
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