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[PATCH 4.4 019/117] parisc: Protect huge page pte changes with spinlocks

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.4 019/117] parisc: Protect huge page pte changes with spinlocks
Date 2016-02-15 01:50 +0100
Message-ID <r2fwu-1Sa-1@gated-at.bofh.it> (permalink)
References <r2dl0-tX-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Helge Deller <deller@gmx.de>

commit b0e551313ebde17764f3a5ed273df524d1e7e690 upstream.

PA-RISC doesn't have atomic instructions to modify page table entries, so it
takes spinlock in the TLB handler and modifies the page table entry
non-atomically. If you modify the page table entry without the spinlock, you
may race with TLB handler on another CPU and your modification may be lost.
Protect against that with usage of purge_tlb_start() and purge_tlb_end() which
handles the TLB spinlock.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/parisc/include/asm/hugetlb.h |   20 ++----------
 arch/parisc/mm/hugetlbpage.c      |   60 ++++++++++++++++++++++++++++++--------
 2 files changed, 52 insertions(+), 28 deletions(-)

--- a/arch/parisc/include/asm/hugetlb.h
+++ b/arch/parisc/include/asm/hugetlb.h
@@ -54,24 +54,12 @@ static inline pte_t huge_pte_wrprotect(p
 	return pte_wrprotect(pte);
 }
 
-static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
-					   unsigned long addr, pte_t *ptep)
-{
-	pte_t old_pte = *ptep;
-	set_huge_pte_at(mm, addr, ptep, pte_wrprotect(old_pte));
-}
+void huge_ptep_set_wrprotect(struct mm_struct *mm,
+					   unsigned long addr, pte_t *ptep);
 
-static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 					     unsigned long addr, pte_t *ptep,
-					     pte_t pte, int dirty)
-{
-	int changed = !pte_same(*ptep, pte);
-	if (changed) {
-		set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
-		flush_tlb_page(vma, addr);
-	}
-	return changed;
-}
+					     pte_t pte, int dirty);
 
 static inline pte_t huge_ptep_get(pte_t *ptep)
 {
--- a/arch/parisc/mm/hugetlbpage.c
+++ b/arch/parisc/mm/hugetlbpage.c
@@ -105,15 +105,13 @@ static inline void purge_tlb_entries_hug
 	addr |= _HUGE_PAGE_SIZE_ENCODING_DEFAULT;
 
 	for (i = 0; i < (1 << (HPAGE_SHIFT-REAL_HPAGE_SHIFT)); i++) {
-		mtsp(mm->context, 1);
-		pdtlb(addr);
-		if (unlikely(split_tlb))
-			pitlb(addr);
+		purge_tlb_entries(mm, addr);
 		addr += (1UL << REAL_HPAGE_SHIFT);
 	}
 }
 
-void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+/* __set_huge_pte_at() must be called holding the pa_tlb_lock. */
+static void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 		     pte_t *ptep, pte_t entry)
 {
 	unsigned long addr_start;
@@ -123,14 +121,9 @@ void set_huge_pte_at(struct mm_struct *m
 	addr_start = addr;
 
 	for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
-		/* Directly write pte entry.  We could call set_pte_at(mm, addr, ptep, entry)
-		 * instead, but then we get double locking on pa_tlb_lock. */
-		*ptep = entry;
+		set_pte(ptep, entry);
 		ptep++;
 
-		/* Drop the PAGE_SIZE/non-huge tlb entry */
-		purge_tlb_entries(mm, addr);
-
 		addr += PAGE_SIZE;
 		pte_val(entry) += PAGE_SIZE;
 	}
@@ -138,18 +131,61 @@ void set_huge_pte_at(struct mm_struct *m
 	purge_tlb_entries_huge(mm, addr_start);
 }
 
+void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+		     pte_t *ptep, pte_t entry)
+{
+	unsigned long flags;
+
+	purge_tlb_start(flags);
+	__set_huge_pte_at(mm, addr, ptep, entry);
+	purge_tlb_end(flags);
+}
+
 
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep)
 {
+	unsigned long flags;
 	pte_t entry;
 
+	purge_tlb_start(flags);
 	entry = *ptep;
-	set_huge_pte_at(mm, addr, ptep, __pte(0));
+	__set_huge_pte_at(mm, addr, ptep, __pte(0));
+	purge_tlb_end(flags);
 
 	return entry;
 }
 
+
+void huge_ptep_set_wrprotect(struct mm_struct *mm,
+				unsigned long addr, pte_t *ptep)
+{
+	unsigned long flags;
+	pte_t old_pte;
+
+	purge_tlb_start(flags);
+	old_pte = *ptep;
+	__set_huge_pte_at(mm, addr, ptep, pte_wrprotect(old_pte));
+	purge_tlb_end(flags);
+}
+
+int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+				unsigned long addr, pte_t *ptep,
+				pte_t pte, int dirty)
+{
+	unsigned long flags;
+	int changed;
+
+	purge_tlb_start(flags);
+	changed = !pte_same(*ptep, pte);
+	if (changed) {
+		__set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+	}
+	purge_tlb_end(flags);
+	return changed;
+}
+
+
 int pmd_huge(pmd_t pmd)
 {
 	return 0;

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[PATCH 4.4 000/117] 4.4.2-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 042/117] ALSA: pcm: Fix potential deadlock in OSS emulation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 077/117] iommu/io-pgtable-arm: Ensure we free the final level on teardown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 074/117] tty: Wait interruptibly for tty lock on reopen Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 004/117] ocfs2: NFS hangs in __ocfs2_cluster_lock due to race with ocfs2_unblock_lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 046/117] ALSA: seq: Fix lockdep warnings due to double mutex locks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 069/117] usb: cdc-acm: send zero packet for intel 7260 modem Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 005/117] HID: usbhid: fix recursive deadlock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 065/117] USB: cp210x: add ID for IAI USB to RS485 adaptor Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 040/117] ALSA: hda/realtek - Support headset mode for ALC225 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 070/117] usb: phy: msm: fix error handling in probe. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 041/117] ALSA: hda/realtek - Support Dell headset mode for ALC225 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 007/117] block: fix bio splitting on max sectors Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 056/117] ALSA: hda - Fix speaker output from VAIO AiO machines Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 009/117] ocfs2/dlm: ignore cleaning the migration mle that is inuse Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 072/117] usb: xhci: apply XHCI_PME_STUCK_QUIRK to Intel Broxton-M platforms Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 057/117] ALSA: hda - Fix bad dereference of jack object Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 044/117] ALSA: seq: Fix yet another races among ALSA timer accesses Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:40 +0100
  [PATCH 4.4 019/117] parisc: Protect huge page pte changes with spinlocks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 016/117] tracing: Fix stacktrace skip depth in trace_buffer_unlock_commit_regs() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 002/117] NFSv4.1/pnfs: Fixup an lo->plh_block_lgets imbalance in layoutreturn Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 037/117] ALSA: rawmidi: Remove kernel WARNING for NULL user-space buffer check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 031/117] ALSA: hda - disable dynamic clock gating on Broxton before reset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 020/117] parisc: Fix __ARCH_SI_PREAMBLE_SIZE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 022/117] md/raid: only permit hot-add of compatible integrity profiles Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 023/117] hrtimer: Handle remaining time proper for TIME_LOW_RES Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 030/117] ALSA: Add missing dependency on CONFIG_SND_TIMER Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
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  [PATCH 4.4 021/117] [media] media: i2c: Dont export ir-kbd-i2c module alias Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 017/117] tracing/stacktrace: Show entire trace if passed in function not found Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 033/117] ALSA: dummy: Disable switching timer backend via sysfs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 034/117] ALSA: seq: Fix incorrect sanity check at snd_seq_oss_synth_cleanup() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 035/117] ALSA: seq: Degrade the error message for too many opens Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 006/117] base/platform: Fix platform drivers with no probe callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 018/117] printk: do cond_resched() between lines while outputting to consoles Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 036/117] ALSA: rawmidi: Make snd_rawmidi_transmit() race-free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 028/117] ALSA: usb-audio: avoid freeing umidi object twice Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 026/117] ALSA: usb-audio: Fix OPPO HA-1 vendor ID Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
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  [PATCH 4.4 039/117] ALSA: hda/realtek - New codec support of ALC225 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 027/117] ALSA: usb-audio: Add native DSD support for PS Audio NuWave DAC Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 015/117] PCI: Fix minimum allocation address overwrite Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 010/117] ocfs2/dlm: clear refmap bit of recovery lock while doing local recovery cleanup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 032/117] ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 025/117] ALSA: usb-audio: Add quirk for Microsoft LifeCam HD-6000 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
  [PATCH 4.4 013/117] mtd: nand: assign reasonable default name for NAND drivers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 01:50 +0100
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  Re: [PATCH 4.4 000/117] 4.4.2-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-02-15 18:10 +0100

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