[PATCH V5 3/3] powerpc/mm: Switch to generic RCU get_user_pages_fast

From: Aneesh Kumar K.V
Date: Wed Nov 05 2014 - 11:29:32 EST

This patch switch the ppc arch to use the generic RCU based
gup implementation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/hugetlb.h | 8 +-
arch/powerpc/include/asm/page.h | 3 +-
arch/powerpc/include/asm/pgtable-ppc64.h | 1 -
arch/powerpc/include/asm/pgtable.h | 6 +-
arch/powerpc/mm/Makefile | 2 +-
arch/powerpc/mm/gup.c | 235 -------------------------------
arch/powerpc/mm/hugetlbpage.c | 33 ++---
8 files changed, 22 insertions(+), 267 deletions(-)
delete mode 100644 arch/powerpc/mm/gup.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 88eace4e28c3..7af887dc6aed 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -148,6 +148,7 @@ config PPC
select HAVE_ARCH_AUDITSYSCALL
select ARCH_SUPPORTS_ATOMIC_RMW
select DCACHE_WORD_ACCESS if PPC64 && CPU_LITTLE_ENDIAN
+ select HAVE_GENERIC_RCU_GUP

config GENERIC_CSUM
def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 766b77d527ac..1d53a65b4ec1 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -48,7 +48,7 @@ static inline unsigned int hugepd_shift(hugepd_t hpd)
#endif /* CONFIG_PPC_BOOK3S_64 */


-static inline pte_t *hugepte_offset(hugepd_t *hpdp, unsigned long addr,
+static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
unsigned pdshift)
{
/*
@@ -58,9 +58,9 @@ static inline pte_t *hugepte_offset(hugepd_t *hpdp, unsigned long addr,
*/
unsigned long idx = 0;

- pte_t *dir = hugepd_page(*hpdp);
+ pte_t *dir = hugepd_page(hpd);
#ifndef CONFIG_PPC_FSL_BOOK3E
- idx = (addr & ((1UL << pdshift) - 1)) >> hugepd_shift(*hpdp);
+ idx = (addr & ((1UL << pdshift) - 1)) >> hugepd_shift(hpd);
#endif

return dir + idx;
@@ -193,7 +193,7 @@ static inline void flush_hugetlb_page(struct vm_area_struct *vma,
}

#define hugepd_shift(x) 0
-static inline pte_t *hugepte_offset(hugepd_t *hpdp, unsigned long addr,
+static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
unsigned pdshift)
{
return 0;
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index f973fce73a43..69c059887a2c 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -379,13 +379,14 @@ static inline int hugepd_ok(hugepd_t hpd)
}
#endif

-#define is_hugepd(pdep) (hugepd_ok(*((hugepd_t *)(pdep))))
+#define is_hugepd(hpd) (hugepd_ok(hpd))
#define pgd_huge pgd_huge
int pgd_huge(pgd_t pgd);
#else /* CONFIG_HUGETLB_PAGE */
#define is_hugepd(pdep) 0
#define pgd_huge(pgd) 0
#endif /* CONFIG_HUGETLB_PAGE */
+#define __hugepd(x) ((hugepd_t) { (x) })

struct page;
extern void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index d12092420560..5600e434332f 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -600,6 +600,5 @@ static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
*/
return true;
}
-
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_PGTABLE_PPC64_H_ */
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 316f9a5da173..a8805fee0df9 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -274,11 +274,9 @@ extern void paging_init(void);
*/
extern void update_mmu_cache(struct vm_area_struct *, unsigned long, pte_t *);

-extern int gup_hugepd(hugepd_t *hugepd, unsigned pdshift, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr);
-
extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr);
+ unsigned long end, int write,
+ struct page **pages, int *nr);
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_large(pmd) 0
#define has_transparent_hugepage() 0
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 325e861616a1..438dcd3fd0d1 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -6,7 +6,7 @@ subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror

ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)

-obj-y := fault.o mem.o pgtable.o gup.o mmap.o \
+obj-y := fault.o mem.o pgtable.o mmap.o \
init_$(CONFIG_WORD_SIZE).o \
pgtable_$(CONFIG_WORD_SIZE).o
obj-$(CONFIG_PPC_MMU_NOHASH) += mmu_context_nohash.o tlb_nohash.o \
diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
deleted file mode 100644
index d8746684f606..000000000000
--- a/arch/powerpc/mm/gup.c
+++ /dev/null
@@ -1,235 +0,0 @@
-/*
- * Lockless get_user_pages_fast for powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-#undef DEBUG
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/hugetlb.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-
-#ifdef __HAVE_ARCH_PTE_SPECIAL
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr)
-{
- unsigned long mask, result;
- pte_t *ptep;
-
- result = _PAGE_PRESENT|_PAGE_USER;
- if (write)
- result |= _PAGE_RW;
- mask = result | _PAGE_SPECIAL;
-
- ptep = pte_offset_kernel(&pmd, addr);
- do {
- pte_t pte = ACCESS_ONCE(*ptep);
- struct page *page;
- /*
- * Similar to the PMD case, NUMA hinting must take slow path
- */
- if (pte_numa(pte))
- return 0;
-
- if ((pte_val(pte) & mask) != result)
- return 0;
- VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
- page = pte_page(pte);
- if (!page_cache_get_speculative(page))
- return 0;
- if (unlikely(pte_val(pte) != pte_val(*ptep))) {
- put_page(page);
- return 0;
- }
- pages[*nr] = page;
- (*nr)++;
-
- } while (ptep++, addr += PAGE_SIZE, addr != end);
-
- return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
- int write, struct page **pages, int *nr)
-{
- unsigned long next;
- pmd_t *pmdp;
-
- pmdp = pmd_offset(&pud, addr);
- do {
- pmd_t pmd = ACCESS_ONCE(*pmdp);
-
- next = pmd_addr_end(addr, end);
- /*
- * If we find a splitting transparent hugepage we
- * return zero. That will result in taking the slow
- * path which will call wait_split_huge_page()
- * if the pmd is still in splitting state
- */
- if (pmd_none(pmd) || pmd_trans_splitting(pmd))
- return 0;
- if (pmd_huge(pmd) || pmd_large(pmd)) {
- /*
- * NUMA hinting faults need to be handled in the GUP
- * slowpath for accounting purposes and so that they
- * can be serialised against THP migration.
- */
- if (pmd_numa(pmd))
- return 0;
-
- if (!gup_hugepte((pte_t *)pmdp, PMD_SIZE, addr, next,
- write, pages, nr))
- return 0;
- } else if (is_hugepd(pmdp)) {
- if (!gup_hugepd((hugepd_t *)pmdp, PMD_SHIFT,
- addr, next, write, pages, nr))
- return 0;
- } else if (!gup_pte_range(pmd, addr, next, write, pages, nr))
- return 0;
- } while (pmdp++, addr = next, addr != end);
-
- return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
- int write, struct page **pages, int *nr)
-{
- unsigned long next;
- pud_t *pudp;
-
- pudp = pud_offset(&pgd, addr);
- do {
- pud_t pud = ACCESS_ONCE(*pudp);
-
- next = pud_addr_end(addr, end);
- if (pud_none(pud))
- return 0;
- if (pud_huge(pud)) {
- if (!gup_hugepte((pte_t *)pudp, PUD_SIZE, addr, next,
- write, pages, nr))
- return 0;
- } else if (is_hugepd(pudp)) {
- if (!gup_hugepd((hugepd_t *)pudp, PUD_SHIFT,
- addr, next, write, pages, nr))
- return 0;
- } else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
- return 0;
- } while (pudp++, addr = next, addr != end);
-
- return 1;
-}
-
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
- struct page **pages)
-{
- struct mm_struct *mm = current->mm;
- unsigned long addr, len, end;
- unsigned long next;
- unsigned long flags;
- pgd_t *pgdp;
- int nr = 0;
-
- pr_devel("%s(%lx,%x,%s)\n", __func__, start, nr_pages, write ? "write" : "read");
-
- start &= PAGE_MASK;
- addr = start;
- len = (unsigned long) nr_pages << PAGE_SHIFT;
- end = start + len;
-
- if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
- start, len)))
- return 0;
-
- pr_devel(" aligned: %lx .. %lx\n", start, end);
-
- /*
- * XXX: batch / limit 'nr', to avoid large irq off latency
- * needs some instrumenting to determine the common sizes used by
- * important workloads (eg. DB2), and whether limiting the batch size
- * will decrease performance.
- *
- * It seems like we're in the clear for the moment. Direct-IO is
- * the main guy that batches up lots of get_user_pages, and even
- * they are limited to 64-at-a-time which is not so many.
- */
- /*
- * This doesn't prevent pagetable teardown, but does prevent
- * the pagetables from being freed on powerpc.
- *
- * So long as we atomically load page table pointers versus teardown,
- * we can follow the address down to the the page and take a ref on it.
- */
- local_irq_save(flags);
-
- pgdp = pgd_offset(mm, addr);
- do {
- pgd_t pgd = ACCESS_ONCE(*pgdp);
-
- pr_devel(" %016lx: normal pgd %p\n", addr,
- (void *)pgd_val(pgd));
- next = pgd_addr_end(addr, end);
- if (pgd_none(pgd))
- break;
- if (pgd_huge(pgd)) {
- if (!gup_hugepte((pte_t *)pgdp, PGDIR_SIZE, addr, next,
- write, pages, &nr))
- break;
- } else if (is_hugepd(pgdp)) {
- if (!gup_hugepd((hugepd_t *)pgdp, PGDIR_SHIFT,
- addr, next, write, pages, &nr))
- break;
- } else if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
- break;
- } while (pgdp++, addr = next, addr != end);
-
- local_irq_restore(flags);
-
- return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages, int write,
- struct page **pages)
-{
- struct mm_struct *mm = current->mm;
- int nr, ret;
-
- start &= PAGE_MASK;
- nr = __get_user_pages_fast(start, nr_pages, write, pages);
- ret = nr;
-
- if (nr < nr_pages) {
- pr_devel(" slow path ! nr = %d\n", nr);
-
- /* Try to get the remaining pages with get_user_pages */
- start += nr << PAGE_SHIFT;
- pages += nr;
-
- down_read(&mm->mmap_sem);
- ret = get_user_pages(current, mm, start,
- nr_pages - nr, write, 0, pages, NULL);
- up_read(&mm->mmap_sem);
-
- /* Have to be a bit careful with return values */
- if (nr > 0) {
- if (ret < 0)
- ret = nr;
- else
- ret += nr;
- }
- }
-
- return ret;
-}
-
-#endif /* __HAVE_ARCH_PTE_SPECIAL */
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 2e35b9a82929..d54d74ccdc5a 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -233,7 +233,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
return NULL;

- return hugepte_offset(hpdp, addr, pdshift);
+ return hugepte_offset(*hpdp, addr, pdshift);
}

#else
@@ -273,7 +273,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
return NULL;

- return hugepte_offset(hpdp, addr, pdshift);
+ return hugepte_offset(*hpdp, addr, pdshift);
}
#endif

@@ -541,7 +541,7 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
do {
pmd = pmd_offset(pud, addr);
next = pmd_addr_end(addr, end);
- if (!is_hugepd(pmd)) {
+ if (!is_hugepd(__hugepd(pmd_val(*pmd)))) {
/*
* if it is not hugepd pointer, we should already find
* it cleared.
@@ -590,7 +590,7 @@ static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
do {
pud = pud_offset(pgd, addr);
next = pud_addr_end(addr, end);
- if (!is_hugepd(pud)) {
+ if (!is_hugepd(__hugepd(pud_val(*pud)))) {
if (pud_none_or_clear_bad(pud))
continue;
hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
@@ -656,7 +656,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
do {
next = pgd_addr_end(addr, end);
pgd = pgd_offset(tlb->mm, addr);
- if (!is_hugepd(pgd)) {
+ if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
if (pgd_none_or_clear_bad(pgd))
continue;
hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
@@ -716,12 +716,11 @@ static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
return (__boundary - 1 < end - 1) ? __boundary : end;
}

-int gup_hugepd(hugepd_t *hugepd, unsigned pdshift,
- unsigned long addr, unsigned long end,
- int write, struct page **pages, int *nr)
+int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
+ unsigned long end, int write, struct page **pages, int *nr)
{
pte_t *ptep;
- unsigned long sz = 1UL << hugepd_shift(*hugepd);
+ unsigned long sz = 1UL << hugepd_shift(hugepd);
unsigned long next;

ptep = hugepte_offset(hugepd, addr, pdshift);
@@ -964,7 +963,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift
else if (pgd_huge(pgd)) {
ret_pte = (pte_t *) pgdp;
goto out;
- } else if (is_hugepd(&pgd))
+ } else if (is_hugepd(__hugepd(pgd_val(pgd))))
hpdp = (hugepd_t *)&pgd;
else {
/*
@@ -981,7 +980,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift
else if (pud_huge(pud)) {
ret_pte = (pte_t *) pudp;
goto out;
- } else if (is_hugepd(&pud))
+ } else if (is_hugepd(__hugepd(pud_val(pud))))
hpdp = (hugepd_t *)&pud;
else {
pdshift = PMD_SHIFT;
@@ -1002,7 +1001,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift
if (pmd_huge(pmd) || pmd_large(pmd)) {
ret_pte = (pte_t *) pmdp;
goto out;
- } else if (is_hugepd(&pmd))
+ } else if (is_hugepd(__hugepd(pmd_val(pmd))))
hpdp = (hugepd_t *)&pmd;
else
return pte_offset_kernel(&pmd, ea);
@@ -1011,7 +1010,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift
if (!hpdp)
return NULL;

- ret_pte = hugepte_offset(hpdp, ea, pdshift);
+ ret_pte = hugepte_offset(*hpdp, ea, pdshift);
pdshift = hugepd_shift(*hpdp);
out:
if (shift)
@@ -1041,14 +1040,6 @@ int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
if ((pte_val(pte) & mask) != mask)
return 0;

-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- /*
- * check for splitting here
- */
- if (pmd_trans_splitting(pte_pmd(pte)))
- return 0;
-#endif
-
/* hugepages are never "special" */
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));

--
2.1.0

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