[PATCH kernel] powerpc: Make vmalloc_to_phys() public

[Alexey Kardashevskiy]

This makes vmalloc_to_phys() public as there will be another user
(in-kernel VFIO acceleration) for it soon.

As a part of future little optimization, this changes the helper to call
vmalloc_to_pfn() instead of vmalloc_to_page() as the size of the
struct page may not be power-of-two aligned which will make gcc use
multiply instructions instead of shifts.

Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
---

A couple of notes:

1. real_vmalloc_addr() will be reworked later by Paul separately;

2. the optimization note it not valid at the moment as
vmalloc_to_pfn() calls vmalloc_to_page() which does the actual
search; these helpers functionality will be swapped later
(also, by Paul).

---
 arch/powerpc/include/asm/pgtable.h | 3 +++
 arch/powerpc/mm/pgtable.c          | 8 ++++++++
 arch/powerpc/perf/hv-24x7.c        | 8 --------
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index ac9fb11..47897a3 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -78,6 +78,9 @@ static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
 	}
 	return __find_linux_pte_or_hugepte(pgdir, ea, is_thp, shift);
 }
+
+unsigned long vmalloc_to_phys(void *vmalloc_addr);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_PGTABLE_H */
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 83dfd79..de37ff4 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -243,3 +243,11 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
 }
 #endif /* CONFIG_DEBUG_VM */
 
+unsigned long vmalloc_to_phys(void *va)
+{
+	unsigned long pfn = vmalloc_to_pfn(va);
+
+	BUG_ON(!pfn);
+	return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va);
+}
+EXPORT_SYMBOL_GPL(vmalloc_to_phys);
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 9f9dfda..3b09ecf 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -493,14 +493,6 @@ static size_t event_to_attr_ct(struct hv_24x7_event_data *event)
 	}
 }
 
-static unsigned long vmalloc_to_phys(void *v)
-{
-	struct page *p = vmalloc_to_page(v);
-
-	BUG_ON(!p);
-	return page_to_phys(p) + offset_in_page(v);
-}
-
 /* */
 struct event_uniq {
 	struct rb_node node;
-- 
2.5.0.rc3