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Subject[PATCH] powerpc/32s: Cleanup the mess in __set_pte_at()
Date
__set_pte_at() handles 3 main cases with #ifdefs plus the 'percpu'
subcase which leads to code duplication.

Rewrite the function using IS_ENABLED() to minimise the total number
of cases and remove duplicated code.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/book3s/32/pgtable.h | 77 ++++++++------------
1 file changed, 31 insertions(+), 46 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 40041ac713d9..2a0ca1f9a1ff 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -534,58 +534,43 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)


/* This low level function performs the actual PTE insertion
- * Setting the PTE depends on the MMU type and other factors. It's
- * an horrible mess that I'm not going to try to clean up now but
- * I'm keeping it in one place rather than spread around
+ * Setting the PTE depends on the MMU type and other factors.
+ *
+ * First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
+ * helper pte_update() which does an atomic update. We need to do that
+ * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
+ * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
+ * the hash bits instead (ie, same as the non-SMP case)
+ *
+ * Second case is 32-bit with 64-bit PTE. In this case, we
+ * can just store as long as we do the two halves in the right order
+ * with a barrier in between. This is possible because we take care,
+ * in the hash code, to pre-invalidate if the PTE was already hashed,
+ * which synchronizes us with any concurrent invalidation.
+ * In the percpu case, we also fallback to the simple update preserving
+ * the hash bits
+ *
+ * Third case is 32-bit hash table in UP mode, we need to preserve
+ * the _PAGE_HASHPTE bit since we may not have invalidated the previous
+ * translation in the hash yet (done in a subsequent flush_tlb_xxx())
+ * and see we need to keep track that this PTE needs invalidating
*/
static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte, int percpu)
{
-#if defined(CONFIG_SMP) && !defined(CONFIG_PTE_64BIT)
- /* First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
- * helper pte_update() which does an atomic update. We need to do that
- * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
- * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
- * the hash bits instead (ie, same as the non-SMP case)
- */
- if (percpu)
- *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
- | (pte_val(pte) & ~_PAGE_HASHPTE));
- else
- pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, pte_val(pte), 0);
+ if ((!IS_ENABLED(CONFIG_SMP) && !IS_ENABLED(CONFIG_PTE_64BIT)) || percpu) {
+ *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE) |
+ (pte_val(pte) & ~_PAGE_HASHPTE));
+ } else if (IS_ENABLED(CONFIG_PTE_64BIT)) {
+ if (pte_val(*ptep) & _PAGE_HASHPTE)
+ flush_hash_entry(mm, ptep, addr);

-#elif defined(CONFIG_PTE_64BIT)
- /* Second case is 32-bit with 64-bit PTE. In this case, we
- * can just store as long as we do the two halves in the right order
- * with a barrier in between. This is possible because we take care,
- * in the hash code, to pre-invalidate if the PTE was already hashed,
- * which synchronizes us with any concurrent invalidation.
- * In the percpu case, we also fallback to the simple update preserving
- * the hash bits
- */
- if (percpu) {
- *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
- | (pte_val(pte) & ~_PAGE_HASHPTE));
- return;
+ asm volatile("stw%X0 %2,%0; eieio; stw%X1 %L2,%1" :
+ "=m" (*ptep), "=m" (*((unsigned char *)ptep+4)) :
+ "r" (pte) : "memory");
+ } else {
+ pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, pte_val(pte), 0);
}
- if (pte_val(*ptep) & _PAGE_HASHPTE)
- flush_hash_entry(mm, ptep, addr);
- __asm__ __volatile__("\
- stw%X0 %2,%0\n\
- eieio\n\
- stw%X1 %L2,%1"
- : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
- : "r" (pte) : "memory");
-
-#else
- /* Third case is 32-bit hash table in UP mode, we need to preserve
- * the _PAGE_HASHPTE bit since we may not have invalidated the previous
- * translation in the hash yet (done in a subsequent flush_tlb_xxx())
- * and see we need to keep track that this PTE needs invalidating
- */
- *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
- | (pte_val(pte) & ~_PAGE_HASHPTE));
-#endif
}

/*
--
2.36.1
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