[PATCH v2 1/3] powerpc/mm: Rename find_linux_pte_or_hugepte
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Fri Jun 2 00:33:33 AEST 2017
Add newer helpers to make the usage simpler. It is always recommended to use
find_current_mm_pte() for walking the page table. If cannot used, it should
be documented why the said usage of __find_linux_pte() is safe against a
parallel THP split.
For now we have KVM code use __find_linux_pte(). This is because kvm code ends
up calling __find_linux_pte() in real mode with MSR_EE=0 but PACA soft_enabled =
1. We may want to fix that later and make sure we keep the MSR_EE and PACA
soft_enabled in sync. When we do that we can switch kvm to use find_linux_pte().
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
arch/powerpc/include/asm/pgtable.h | 10 +--------
arch/powerpc/include/asm/pte-walk.h | 38 ++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/eeh.c | 4 ++--
arch/powerpc/kernel/io-workarounds.c | 5 +++--
arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 +++--
arch/powerpc/kvm/book3s_64_mmu_radix.c | 28 ++++++++++++-------------
arch/powerpc/kvm/book3s_64_vio_hv.c | 12 ++++++++++-
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 18 ++++++++--------
arch/powerpc/kvm/e500_mmu_host.c | 3 ++-
arch/powerpc/mm/hash_utils_64.c | 5 +++--
arch/powerpc/mm/hugetlbpage.c | 24 ++++++++++++---------
arch/powerpc/mm/tlb_hash64.c | 6 ++++--
arch/powerpc/perf/callchain.c | 3 ++-
13 files changed, 106 insertions(+), 55 deletions(-)
create mode 100644 arch/powerpc/include/asm/pte-walk.h
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index dd01212935ac..9fa263ad7cb3 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -66,16 +66,8 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_large(pmd) 0
#endif
-pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
- bool *is_thp, unsigned *shift);
-static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
- bool *is_thp, unsigned *shift)
-{
- VM_WARN(!arch_irqs_disabled(),
- "%s called with irq enabled\n", __func__);
- return __find_linux_pte_or_hugepte(pgdir, ea, is_thp, shift);
-}
+/* can we use this in kvm */
unsigned long vmalloc_to_phys(void *vmalloc_addr);
void pgtable_cache_add(unsigned shift, void (*ctor)(void *));
diff --git a/arch/powerpc/include/asm/pte-walk.h b/arch/powerpc/include/asm/pte-walk.h
new file mode 100644
index 000000000000..3a5a391a4c6d
--- /dev/null
+++ b/arch/powerpc/include/asm/pte-walk.h
@@ -0,0 +1,38 @@
+#ifndef _ASM_POWERPC_PTE_WALK_H
+#define _ASM_POWERPC_PTE_WALK_H
+
+#ifndef __ASSEMBLY__
+#include <linux/sched.h>
+
+/* Don't use this directly */
+extern pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
+ bool *is_thp, unsigned *hshift);
+
+static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea,
+ bool *is_thp, unsigned *hshift)
+{
+ VM_WARN(!arch_irqs_disabled(),
+ "%s called with irq enabled\n", __func__);
+ return __find_linux_pte(pgdir, ea, is_thp, hshift);
+}
+
+static inline pte_t *find_init_mm_pte(unsigned long ea, unsigned *hshift)
+{
+ pgd_t *pgdir = init_mm.pgd;
+ return __find_linux_pte(pgdir, ea, NULL, hshift);
+}
+/*
+ * This is what we should always use. Any other lockless page table lookup needs
+ * careful audit against THP split.
+ */
+static inline pte_t *find_current_mm_pte(pgd_t *pgdir, unsigned long ea,
+ bool *is_thp, unsigned *hshift)
+{
+ VM_WARN(!arch_irqs_disabled(),
+ "%s called with irq enabled\n", __func__);
+ VM_WARN(pgdir != current->mm->pgd,
+ "%s lock less page table lookup called on wrong mm\n", __func__);
+ return __find_linux_pte(pgdir, ea, is_thp, hshift);
+}
+#endif
+#endif
diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 63992b2d8e15..5e6887c40528 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -44,6 +44,7 @@
#include <asm/machdep.h>
#include <asm/ppc-pci.h>
#include <asm/rtas.h>
+#include <asm/pte-walk.h>
/** Overview:
@@ -352,8 +353,7 @@ static inline unsigned long eeh_token_to_phys(unsigned long token)
* worried about _PAGE_SPLITTING/collapse. Also we will not hit
* page table free, because of init_mm.
*/
- ptep = __find_linux_pte_or_hugepte(init_mm.pgd, token,
- NULL, &hugepage_shift);
+ ptep = find_init_mm_pte(token, &hugepage_shift);
if (!ptep)
return token;
WARN_ON(hugepage_shift);
diff --git a/arch/powerpc/kernel/io-workarounds.c b/arch/powerpc/kernel/io-workarounds.c
index a582e0d42525..bbe85f5aea71 100644
--- a/arch/powerpc/kernel/io-workarounds.c
+++ b/arch/powerpc/kernel/io-workarounds.c
@@ -19,6 +19,8 @@
#include <asm/pgtable.h>
#include <asm/ppc-pci.h>
#include <asm/io-workarounds.h>
+#include <asm/pte-walk.h>
+
#define IOWA_MAX_BUS 8
@@ -75,8 +77,7 @@ struct iowa_bus *iowa_mem_find_bus(const PCI_IO_ADDR addr)
* We won't find huge pages here (iomem). Also can't hit
* a page table free due to init_mm
*/
- ptep = __find_linux_pte_or_hugepte(init_mm.pgd, vaddr,
- NULL, &hugepage_shift);
+ ptep = find_init_mm_pte(vaddr, &hugepage_shift);
if (ptep == NULL)
paddr = 0;
else {
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 710e491206ed..fdf3c4846117 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -37,6 +37,7 @@
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>
+#include <asm/pte-walk.h>
#include "trace_hv.h"
@@ -597,8 +598,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
* hugepage split and collapse.
*/
local_irq_save(flags);
- ptep = find_linux_pte_or_hugepte(current->mm->pgd,
- hva, NULL, NULL);
+ ptep = find_current_mm_pte(current->mm->pgd,
+ hva, NULL, NULL);
if (ptep) {
pte = kvmppc_read_update_linux_pte(ptep, 1);
if (__pte_write(pte))
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index f6b3e67c5762..7d719c8aa0bb 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -17,6 +17,7 @@
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
+#include <asm/pte-walk.h>
/*
* Supported radix tree geometry.
@@ -359,8 +360,7 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
if (writing)
pgflags |= _PAGE_DIRTY;
local_irq_save(flags);
- ptep = __find_linux_pte_or_hugepte(current->mm->pgd, hva,
- NULL, NULL);
+ ptep = find_current_mm_pte(current->mm->pgd, hva, NULL, NULL);
if (ptep) {
pte = READ_ONCE(*ptep);
if (pte_present(pte) &&
@@ -374,8 +374,12 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
spin_unlock(&kvm->mmu_lock);
return RESUME_GUEST;
}
- ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable,
- gpa, NULL, &shift);
+ /*
+ * We are walking the secondary page table here. We can do this
+ * without disabling irq.
+ */
+ ptep = __find_linux_pte(kvm->arch.pgtable,
+ gpa, NULL, &shift);
if (ptep && pte_present(*ptep)) {
kvmppc_radix_update_pte(kvm, ptep, 0, pgflags,
gpa, shift);
@@ -427,8 +431,8 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
pgflags |= _PAGE_WRITE;
} else {
local_irq_save(flags);
- ptep = __find_linux_pte_or_hugepte(current->mm->pgd,
- hva, NULL, NULL);
+ ptep = find_current_mm_pte(current->mm->pgd,
+ hva, NULL, NULL);
if (ptep && pte_write(*ptep) && pte_dirty(*ptep))
pgflags |= _PAGE_WRITE;
local_irq_restore(flags);
@@ -499,8 +503,7 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
unsigned long old;
- ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
- NULL, &shift);
+ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep)) {
old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_PRESENT, 0,
gpa, shift);
@@ -525,8 +528,7 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
int ref = 0;
- ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
- NULL, &shift);
+ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
gpa, shift);
@@ -545,8 +547,7 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
int ref = 0;
- ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
- NULL, &shift);
+ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep))
ref = 1;
return ref;
@@ -562,8 +563,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
unsigned int shift;
int ret = 0;
- ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
- NULL, &shift);
+ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
ret = 1;
if (shift)
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
index 3adfd2f5301c..c32e9bfe75b1 100644
--- a/arch/powerpc/kvm/book3s_64_vio_hv.c
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -39,6 +39,7 @@
#include <asm/udbg.h>
#include <asm/iommu.h>
#include <asm/tce.h>
+#include <asm/pte-walk.h>
#ifdef CONFIG_BUG
@@ -353,7 +354,16 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
pte_t *ptep, pte;
unsigned shift = 0;
- ptep = __find_linux_pte_or_hugepte(vcpu->arch.pgdir, ua, NULL, &shift);
+ /*
+ * Called in real mode with MSR_EE = 0. We are safe here.
+ * It is ok to do the lookup with arch.pgdir here, because
+ * we are doing this on secondary cpus and current task there
+ * is not the hypervisor. Also this is safe against THP in the
+ * host, because an IPI to primary thread will wait for the secondary
+ * to exit which will agains result in the below page table walk
+ * to finish.
+ */
+ ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift);
if (!ptep || !pte_present(*ptep))
return -ENXIO;
pte = *ptep;
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index ce6f2121fffe..e19228556bba 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -21,6 +21,7 @@
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
+#include <asm/pte-walk.h>
/* Translate address of a vmalloc'd thing to a linear map address */
static void *real_vmalloc_addr(void *x)
@@ -30,9 +31,9 @@ static void *real_vmalloc_addr(void *x)
/*
* assume we don't have huge pages in vmalloc space...
* So don't worry about THP collapse/split. Called
- * Only in realmode, hence won't need irq_save/restore.
+ * Only in realmode with MSR_EE = 0, hence won't need irq_save/restore.
*/
- p = __find_linux_pte_or_hugepte(swapper_pg_dir, addr, NULL, NULL);
+ p = find_init_mm_pte(addr, NULL);
if (!p || !pte_present(*p))
return NULL;
addr = (pte_pfn(*p) << PAGE_SHIFT) | (addr & ~PAGE_MASK);
@@ -229,14 +230,13 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
* If we had a page table table change after lookup, we would
* retry via mmu_notifier_retry.
*/
- if (realmode)
- ptep = __find_linux_pte_or_hugepte(pgdir, hva, NULL,
- &hpage_shift);
- else {
+ if (!realmode)
local_irq_save(irq_flags);
- ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL,
- &hpage_shift);
- }
+ /*
+ * If called in real mode we have MSR_EE = 0. Otherwise
+ * we disable irq above.
+ */
+ ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift);
if (ptep) {
pte_t pte;
unsigned int host_pte_size;
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 77fd043b3ecc..c6c734424c70 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -30,6 +30,7 @@
#include <linux/vmalloc.h>
#include <linux/hugetlb.h>
#include <asm/kvm_ppc.h>
+#include <asm/pte-walk.h>
#include "e500.h"
#include "timing.h"
@@ -476,7 +477,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
* can't run hence pfn won't change.
*/
local_irq_save(flags);
- ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL, NULL);
+ ptep = find_linux_pte(pgdir, hva, NULL, NULL);
if (ptep) {
pte_t pte = READ_ONCE(*ptep);
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index c4b04c4aac86..6e1a3ee3e846 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -61,6 +61,7 @@
#include <asm/tm.h>
#include <asm/trace.h>
#include <asm/ps3.h>
+#include <asm/pte-walk.h>
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
@@ -1295,7 +1296,7 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
#endif /* CONFIG_PPC_64K_PAGES */
/* Get PTE and page size from page tables */
- ptep = __find_linux_pte_or_hugepte(pgdir, ea, &is_thp, &hugeshift);
+ ptep = find_linux_pte(pgdir, ea, &is_thp, &hugeshift);
if (ptep == NULL || !pte_present(*ptep)) {
DBG_LOW(" no PTE !\n");
rc = 1;
@@ -1524,7 +1525,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
* THP pages use update_mmu_cache_pmd. We don't do
* hash preload there. Hence can ignore THP here
*/
- ptep = find_linux_pte_or_hugepte(pgdir, ea, NULL, &hugepage_shift);
+ ptep = find_current_mm_pte(pgdir, ea, NULL, &hugepage_shift);
if (!ptep)
goto out_exit;
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 2bcb7e5b2ab6..11178845226a 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -24,6 +24,8 @@
#include <asm/tlb.h>
#include <asm/setup.h>
#include <asm/hugetlb.h>
+#include <asm/pte-walk.h>
+
#ifdef CONFIG_HUGETLB_PAGE
@@ -39,8 +41,11 @@ unsigned int HPAGE_SHIFT;
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
- /* Only called for hugetlbfs pages, hence can ignore THP */
- return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL, NULL);
+ /*
+ * Only called for hugetlbfs pages, hence can ignore THP and the
+ * irq disabled walk.
+ */
+ return __find_linux_pte(mm->pgd, addr, NULL, NULL);
}
static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
@@ -748,9 +753,8 @@ void flush_dcache_icache_hugepage(struct page *page)
* This function need to be called with interrupts disabled. We use this variant
* when we have MSR[EE] = 0 but the paca->soft_enabled = 1
*/
-
-pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
- bool *is_thp, unsigned *shift)
+pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
+ bool *is_thp, unsigned *hpage_shift)
{
pgd_t pgd, *pgdp;
pud_t pud, *pudp;
@@ -759,8 +763,8 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
hugepd_t *hpdp = NULL;
unsigned pdshift = PGDIR_SHIFT;
- if (shift)
- *shift = 0;
+ if (hpage_shift)
+ *hpage_shift = 0;
if (is_thp)
*is_thp = false;
@@ -830,11 +834,11 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
ret_pte = hugepte_offset(*hpdp, ea, pdshift);
pdshift = hugepd_shift(*hpdp);
out:
- if (shift)
- *shift = pdshift;
+ if (hpage_shift)
+ *hpage_shift = pdshift;
return ret_pte;
}
-EXPORT_SYMBOL_GPL(__find_linux_pte_or_hugepte);
+EXPORT_SYMBOL_GPL(__find_linux_pte);
int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
diff --git a/arch/powerpc/mm/tlb_hash64.c b/arch/powerpc/mm/tlb_hash64.c
index 4517aa43a8b1..b3e6116b4317 100644
--- a/arch/powerpc/mm/tlb_hash64.c
+++ b/arch/powerpc/mm/tlb_hash64.c
@@ -29,6 +29,8 @@
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/bug.h>
+#include <asm/pte-walk.h>
+
#include <trace/events/thp.h>
@@ -209,8 +211,8 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
local_irq_save(flags);
arch_enter_lazy_mmu_mode();
for (; start < end; start += PAGE_SIZE) {
- pte_t *ptep = find_linux_pte_or_hugepte(mm->pgd, start, &is_thp,
- &hugepage_shift);
+ pte_t *ptep = find_current_mm_pte(mm->pgd, start, &is_thp,
+ &hugepage_shift);
unsigned long pte;
if (ptep == NULL)
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index 0fc26714780a..0af051a1974e 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -22,6 +22,7 @@
#ifdef CONFIG_PPC64
#include "../kernel/ppc32.h"
#endif
+#include <asm/pte-walk.h>
/*
@@ -127,7 +128,7 @@ static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
return -EFAULT;
local_irq_save(flags);
- ptep = find_linux_pte_or_hugepte(pgdir, addr, NULL, &shift);
+ ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
if (!ptep)
goto err_out;
if (!shift)
--
2.7.4
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