path: root/freed-ora/tags/f16/3.5.0-1.fc16.gnu/uprobes-backport.patch

Hello,

Test build: http://koji.fedoraproject.org/koji/taskinfo?taskID=4490824
This also fixes: https://bugzilla.redhat.com/show_bug.cgi?id=849364

The split-out series is available in the git repository at:
  http://fedorapeople.org/cgit/aarapov/public_git/kernel-uprobes.git/log/?h=f17_uprobes_out
  (Just @jistone's patch is not upstream that exports functions.)

Ananth N Mavinakayanahalli (1):
      uprobes: Pass probed vaddr to arch_uprobe_analyze_insn()

Josh Stone (1):
      uprobes: add exports necessary for uprobes use by modules

Oleg Nesterov (52):
      uprobes: Optimize is_swbp_at_addr() for current->mm
      uprobes: Change read_opcode() to use FOLL_FORCE
      uprobes: Introduce find_active_uprobe() helper
      uprobes: Teach find_active_uprobe() to provide the "is_swbp" info
      uprobes: Change register_for_each_vma() to take mm->mmap_sem for writing
      uprobes: Teach handle_swbp() to rely on "is_swbp" rather than uprobes_srcu
      uprobes: Kill uprobes_srcu/uprobe_srcu_id
      uprobes: Valid_vma() should reject VM_HUGETLB
      uprobes: __copy_insn() should ensure a_ops->readpage != NULL
      uprobes: Write_opcode()->__replace_page() can race with try_to_unmap()
      uprobes: Install_breakpoint() should fail if is_swbp_insn() == T
      uprobes: Rework register_for_each_vma() to make it O(n)
      uprobes: Change build_map_info() to try kmalloc(GFP_NOWAIT) first
      uprobes: Copy_insn() shouldn't depend on mm/vma/vaddr
      uprobes: Copy_insn() should not return -ENOMEM if __copy_insn() fails
      uprobes: No need to re-check vma_address() in write_opcode()
      uprobes: Move BUG_ON(UPROBE_SWBP_INSN_SIZE) from write_opcode() to install_breakpoint()
      uprobes: Simplify the usage of uprobe->pending_list
      uprobes: Don't use loff_t for the valid virtual address
      uprobes: __copy_insn() needs "loff_t offset"
      uprobes: Remove the unnecessary initialization in add_utask()
      uprobes: Don't recheck vma/f_mapping in write_opcode()
      uprobes: __replace_page() should not use page_address_in_vma()
      uprobes: Kill write_opcode()->lock_page(new_page)
      uprobes: Clean up and document write_opcode()->lock_page(old_page)
      uprobes: Uprobe_mmap/munmap needs list_for_each_entry_safe()
      uprobes: Suppress uprobe_munmap() from mmput()
      uprobes: Fix overflow in vma_address()/find_active_uprobe()
      uprobes: Remove copy_vma()->uprobe_mmap()
      uprobes: Remove insert_vm_struct()->uprobe_mmap()
      uprobes: Teach build_probe_list() to consider the range
      uprobes: Introduce vaddr_to_offset(vma, vaddr)
      uprobes: Fix register_for_each_vma()->vma_address() check
      uprobes: Rename vma_address() and make it return "unsigned long"
      uprobes: __replace_page() needs munlock_vma_page()
      uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails
      uprobes: Kill uprobes_state->count
      uprobes: Kill dup_mmap()->uprobe_mmap(), simplify uprobe_mmap/munmap
      uprobes: Change uprobe_mmap() to ignore the errors but check fatal_signal_pending()
      uprobes: Do not use -EEXIST in install_breakpoint() paths
      uprobes: Introduce MMF_HAS_UPROBES
      uprobes: Fold uprobe_reset_state() into uprobe_dup_mmap()
      uprobes: Remove "verify" argument from set_orig_insn()
      uprobes: uprobes_treelock should not disable irqs
      uprobes: Introduce MMF_RECALC_UPROBES
      uprobes: Teach find_active_uprobe() to clear MMF_HAS_UPROBES
      ptrace/x86: Introduce set_task_blockstep() helper
      ptrace/x86: Partly fix set_task_blockstep()->update_debugctlmsr() logic
      uprobes/x86: Do not (ab)use TIF_SINGLESTEP/user_*_single_step() for single-stepping
      uprobes/x86: Xol should send SIGTRAP if X86_EFLAGS_TF was set
      uprobes/x86: Fix arch_uprobe_disable_step() && UTASK_SSTEP_TRAPPED interaction
      uprobes: Make arch_uprobe_task->saved_trap_nr "unsigned int"

Peter Zijlstra (1):
      uprobes: Document uprobe_register() vs uprobe_mmap() race

Sebastian Andrzej Siewior (4):
      uprobes: Remove check for uprobe variable in handle_swbp()
      uprobes: Don't put NULL pointer in uprobe_register()
      uprobes: Introduce arch_uprobe_enable/disable_step()
      uprobes/x86: Implement x86 specific arch_uprobe_*_step

Srikar Dronamraju (1):
      uprobes: Remove redundant lock_page/unlock_page

Signed-off-by: Anton Arapov <anton@redhat.com>
---
 arch/x86/include/asm/processor.h |   2 +
 arch/x86/include/asm/uprobes.h   |   5 +-
 arch/x86/kernel/step.c           |  53 ++-
 arch/x86/kernel/uprobes.c        |  55 ++-
 include/linux/sched.h            |   4 +-
 include/linux/uprobes.h          |  15 +-
 kernel/events/uprobes.c          | 819 +++++++++++++++++++--------------------
 kernel/fork.c                    |   6 +-
 kernel/ptrace.c                  |   6 +
 mm/mmap.c                        |  11 +-
 10 files changed, 505 insertions(+), 471 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 39bc577..2f9f8ca 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -746,6 +746,8 @@ static inline void update_debugctlmsr(unsigned long debugctlmsr)
 	wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctlmsr);
 }
 
+extern void set_task_blockstep(struct task_struct *task, bool on);
+
 /*
  * from system description table in BIOS. Mostly for MCA use, but
  * others may find it useful:
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 1e9bed1..8ff8be7 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -42,13 +42,14 @@ struct arch_uprobe {
 };
 
 struct arch_uprobe_task {
-	unsigned long			saved_trap_nr;
 #ifdef CONFIG_X86_64
 	unsigned long			saved_scratch_register;
 #endif
+	unsigned int			saved_trap_nr;
+	unsigned int			saved_tf;
 };
 
-extern int  arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm);
+extern int  arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
 extern int  arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
 extern int  arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
 extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index c346d11..cd3b243 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -157,6 +157,33 @@ static int enable_single_step(struct task_struct *child)
 	return 1;
 }
 
+void set_task_blockstep(struct task_struct *task, bool on)
+{
+	unsigned long debugctl;
+
+	/*
+	 * Ensure irq/preemption can't change debugctl in between.
+	 * Note also that both TIF_BLOCKSTEP and debugctl should
+	 * be changed atomically wrt preemption.
+	 * FIXME: this means that set/clear TIF_BLOCKSTEP is simply
+	 * wrong if task != current, SIGKILL can wakeup the stopped
+	 * tracee and set/clear can play with the running task, this
+	 * can confuse the next __switch_to_xtra().
+	 */
+	local_irq_disable();
+	debugctl = get_debugctlmsr();
+	if (on) {
+		debugctl |= DEBUGCTLMSR_BTF;
+		set_tsk_thread_flag(task, TIF_BLOCKSTEP);
+	} else {
+		debugctl &= ~DEBUGCTLMSR_BTF;
+		clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
+	}
+	if (task == current)
+		update_debugctlmsr(debugctl);
+	local_irq_enable();
+}
+
 /*
  * Enable single or block step.
  */
@@ -169,19 +196,10 @@ static void enable_step(struct task_struct *child, bool block)
 	 * So no one should try to use debugger block stepping in a program
 	 * that uses user-mode single stepping itself.
 	 */
-	if (enable_single_step(child) && block) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl |= DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-		set_tsk_thread_flag(child, TIF_BLOCKSTEP);
-	} else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl &= ~DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-		clear_tsk_thread_flag(child, TIF_BLOCKSTEP);
-	}
+	if (enable_single_step(child) && block)
+		set_task_blockstep(child, true);
+	else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))
+		set_task_blockstep(child, false);
 }
 
 void user_enable_single_step(struct task_struct *child)
@@ -199,13 +217,8 @@ void user_disable_single_step(struct task_struct *child)
 	/*
 	 * Make sure block stepping (BTF) is disabled.
 	 */
-	if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl &= ~DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-		clear_tsk_thread_flag(child, TIF_BLOCKSTEP);
-	}
+	if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))
+		set_task_blockstep(child, false);
 
 	/* Always clear TIF_SINGLESTEP... */
 	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index dc4e910..9538f00 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -41,6 +41,9 @@
 /* Adjust the return address of a call insn */
 #define UPROBE_FIX_CALL	0x2
 
+/* Instruction will modify TF, don't change it */
+#define UPROBE_FIX_SETF	0x4
+
 #define UPROBE_FIX_RIP_AX	0x8000
 #define UPROBE_FIX_RIP_CX	0x4000
 
@@ -239,6 +242,10 @@ static void prepare_fixups(struct arch_uprobe *auprobe, struct insn *insn)
 	insn_get_opcode(insn);	/* should be a nop */
 
 	switch (OPCODE1(insn)) {
+	case 0x9d:
+		/* popf */
+		auprobe->fixups |= UPROBE_FIX_SETF;
+		break;
 	case 0xc3:		/* ret/lret */
 	case 0xcb:
 	case 0xc2:
@@ -409,9 +416,10 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
  * arch_uprobe_analyze_insn - instruction analysis including validity and fixups.
  * @mm: the probed address space.
  * @arch_uprobe: the probepoint information.
+ * @addr: virtual address at which to install the probepoint
  * Return 0 on success or a -ve number on error.
  */
-int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm)
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long addr)
 {
 	int ret;
 	struct insn insn;
@@ -645,7 +653,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
  * Skip these instructions as per the currently known x86 ISA.
  * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 }
  */
-bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
 	int i;
 
@@ -672,3 +680,46 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 	}
 	return false;
 }
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+	bool ret = __skip_sstep(auprobe, regs);
+	if (ret && (regs->flags & X86_EFLAGS_TF))
+		send_sig(SIGTRAP, current, 0);
+	return ret;
+}
+
+void arch_uprobe_enable_step(struct arch_uprobe *auprobe)
+{
+	struct task_struct *task = current;
+	struct arch_uprobe_task	*autask	= &task->utask->autask;
+	struct pt_regs *regs = task_pt_regs(task);
+
+	autask->saved_tf = !!(regs->flags & X86_EFLAGS_TF);
+
+	regs->flags |= X86_EFLAGS_TF;
+	if (test_tsk_thread_flag(task, TIF_BLOCKSTEP))
+		set_task_blockstep(task, false);
+}
+
+void arch_uprobe_disable_step(struct arch_uprobe *auprobe)
+{
+	struct task_struct *task = current;
+	struct arch_uprobe_task	*autask	= &task->utask->autask;
+	bool trapped = (task->utask->state == UTASK_SSTEP_TRAPPED);
+	struct pt_regs *regs = task_pt_regs(task);
+	/*
+	 * The state of TIF_BLOCKSTEP was not saved so we can get an extra
+	 * SIGTRAP if we do not clear TF. We need to examine the opcode to
+	 * make it right.
+	 */
+	if (unlikely(trapped)) {
+		if (!autask->saved_tf)
+			regs->flags &= ~X86_EFLAGS_TF;
+	} else {
+		if (autask->saved_tf)
+			send_sig(SIGTRAP, task, 0);
+		else if (!(auprobe->fixups & UPROBE_FIX_SETF))
+			regs->flags &= ~X86_EFLAGS_TF;
+	}
+}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4a1f493..864054f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -441,6 +441,9 @@ extern int get_dumpable(struct mm_struct *mm);
 #define MMF_VM_HUGEPAGE		17	/* set when VM_HUGEPAGE is set on vma */
 #define MMF_EXE_FILE_CHANGED	18	/* see prctl_set_mm_exe_file() */
 
+#define MMF_HAS_UPROBES		19	/* has uprobes */
+#define MMF_RECALC_UPROBES	20	/* MMF_HAS_UPROBES can be wrong */
+
 #define MMF_INIT_MASK		(MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
 
 struct sighand_struct {
@@ -1581,7 +1584,6 @@ struct task_struct {
 #endif
 #ifdef CONFIG_UPROBES
 	struct uprobe_task *utask;
-	int uprobe_srcu_id;
 #endif
 };
 
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index efe4b33..e6f0331 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -99,25 +99,27 @@ struct xol_area {
 
 struct uprobes_state {
 	struct xol_area		*xol_area;
-	atomic_t		count;
 };
+
 extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
-extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm,  unsigned long vaddr, bool verify);
+extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
 extern bool __weak is_swbp_insn(uprobe_opcode_t *insn);
 extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
 extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
 extern int uprobe_mmap(struct vm_area_struct *vma);
 extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
+extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
 extern void uprobe_free_utask(struct task_struct *t);
 extern void uprobe_copy_process(struct task_struct *t);
 extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs);
+extern void __weak arch_uprobe_enable_step(struct arch_uprobe *arch);
+extern void __weak arch_uprobe_disable_step(struct arch_uprobe *arch);
 extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
 extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
 extern void uprobe_notify_resume(struct pt_regs *regs);
 extern bool uprobe_deny_signal(void);
 extern bool __weak arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
 extern void uprobe_clear_state(struct mm_struct *mm);
-extern void uprobe_reset_state(struct mm_struct *mm);
 #else /* !CONFIG_UPROBES */
 struct uprobes_state {
 };
@@ -138,6 +140,10 @@ static inline void
 uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
 {
 }
+static inline void
+uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
+{
+}
 static inline void uprobe_notify_resume(struct pt_regs *regs)
 {
 }
@@ -158,8 +164,5 @@ static inline void uprobe_copy_process(struct task_struct *t)
 static inline void uprobe_clear_state(struct mm_struct *mm)
 {
 }
-static inline void uprobe_reset_state(struct mm_struct *mm)
-{
-}
 #endif /* !CONFIG_UPROBES */
 #endif	/* _LINUX_UPROBES_H */
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 985be4d..f8a97e7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -27,24 +27,42 @@
 #include <linux/pagemap.h>	/* read_mapping_page */
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/export.h>
 #include <linux/rmap.h>		/* anon_vma_prepare */
 #include <linux/mmu_notifier.h>	/* set_pte_at_notify */
 #include <linux/swap.h>		/* try_to_free_swap */
 #include <linux/ptrace.h>	/* user_enable_single_step */
 #include <linux/kdebug.h>	/* notifier mechanism */
+#include "../../mm/internal.h"	/* munlock_vma_page */
 
 #include <linux/uprobes.h>
 
 #define UINSNS_PER_PAGE			(PAGE_SIZE/UPROBE_XOL_SLOT_BYTES)
 #define MAX_UPROBE_XOL_SLOTS		UINSNS_PER_PAGE
 
-static struct srcu_struct uprobes_srcu;
 static struct rb_root uprobes_tree = RB_ROOT;
 
 static DEFINE_SPINLOCK(uprobes_treelock);	/* serialize rbtree access */
 
 #define UPROBES_HASH_SZ	13
 
+/*
+ * We need separate register/unregister and mmap/munmap lock hashes because
+ * of mmap_sem nesting.
+ *
+ * uprobe_register() needs to install probes on (potentially) all processes
+ * and thus needs to acquire multiple mmap_sems (consequtively, not
+ * concurrently), whereas uprobe_mmap() is called while holding mmap_sem
+ * for the particular process doing the mmap.
+ *
+ * uprobe_register()->register_for_each_vma() needs to drop/acquire mmap_sem
+ * because of lock order against i_mmap_mutex. This means there's a hole in
+ * the register vma iteration where a mmap() can happen.
+ *
+ * Thus uprobe_register() can race with uprobe_mmap() and we can try and
+ * install a probe where one is already installed.
+ */
+
 /* serialize (un)register */
 static struct mutex uprobes_mutex[UPROBES_HASH_SZ];
 
@@ -61,17 +79,6 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
  */
 static atomic_t uprobe_events = ATOMIC_INIT(0);
 
-/*
- * Maintain a temporary per vma info that can be used to search if a vma
- * has already been handled. This structure is introduced since extending
- * vm_area_struct wasnt recommended.
- */
-struct vma_info {
-	struct list_head	probe_list;
-	struct mm_struct	*mm;
-	loff_t			vaddr;
-};
-
 struct uprobe {
 	struct rb_node		rb_node;	/* node in the rb tree */
 	atomic_t		ref;
@@ -100,20 +107,21 @@ static bool valid_vma(struct vm_area_struct *vma, bool is_register)
 	if (!is_register)
 		return true;
 
-	if ((vma->vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) == (VM_READ|VM_EXEC))
+	if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED))
+				== (VM_READ|VM_EXEC))
 		return true;
 
 	return false;
 }
 
-static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
+static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
 {
-	loff_t vaddr;
-
-	vaddr = vma->vm_start + offset;
-	vaddr -= vma->vm_pgoff << PAGE_SHIFT;
+	return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+}
 
-	return vaddr;
+static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
+{
+	return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start);
 }
 
 /**
@@ -121,41 +129,27 @@ static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
  * based on replace_page in mm/ksm.c
  *
  * @vma:      vma that holds the pte pointing to page
+ * @addr:     address the old @page is mapped at
  * @page:     the cowed page we are replacing by kpage
  * @kpage:    the modified page we replace page by
  *
  * Returns 0 on success, -EFAULT on failure.
  */
-static int __replace_page(struct vm_area_struct *vma, struct page *page, struct page *kpage)
+static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
+				struct page *page, struct page *kpage)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *ptep;
 	spinlock_t *ptl;
-	unsigned long addr;
-	int err = -EFAULT;
-
-	addr = page_address_in_vma(page, vma);
-	if (addr == -EFAULT)
-		goto out;
-
-	pgd = pgd_offset(mm, addr);
-	if (!pgd_present(*pgd))
-		goto out;
-
-	pud = pud_offset(pgd, addr);
-	if (!pud_present(*pud))
-		goto out;
+	pte_t *ptep;
+	int err;
 
-	pmd = pmd_offset(pud, addr);
-	if (!pmd_present(*pmd))
-		goto out;
+	/* For try_to_free_swap() and munlock_vma_page() below */
+	lock_page(page);
 
-	ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	err = -EAGAIN;
+	ptep = page_check_address(page, mm, addr, &ptl, 0);
 	if (!ptep)
-		goto out;
+		goto unlock;
 
 	get_page(kpage);
 	page_add_new_anon_rmap(kpage, vma, addr);
@@ -172,11 +166,15 @@ static int __replace_page(struct vm_area_struct *vma, struct page *page, struct
 	page_remove_rmap(page);
 	if (!page_mapped(page))
 		try_to_free_swap(page);
-	put_page(page);
 	pte_unmap_unlock(ptep, ptl);
-	err = 0;
 
-out:
+	if (vma->vm_flags & VM_LOCKED)
+		munlock_vma_page(page);
+	put_page(page);
+
+	err = 0;
+ unlock:
+	unlock_page(page);
 	return err;
 }
 
@@ -218,79 +216,46 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 			unsigned long vaddr, uprobe_opcode_t opcode)
 {
 	struct page *old_page, *new_page;
-	struct address_space *mapping;
 	void *vaddr_old, *vaddr_new;
 	struct vm_area_struct *vma;
-	struct uprobe *uprobe;
-	loff_t addr;
 	int ret;
 
+retry:
 	/* Read the page with vaddr into memory */
 	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
 	if (ret <= 0)
 		return ret;
 
-	ret = -EINVAL;
-
-	/*
-	 * We are interested in text pages only. Our pages of interest
-	 * should be mapped for read and execute only. We desist from
-	 * adding probes in write mapped pages since the breakpoints
-	 * might end up in the file copy.
-	 */
-	if (!valid_vma(vma, is_swbp_insn(&opcode)))
-		goto put_out;
-
-	uprobe = container_of(auprobe, struct uprobe, arch);
-	mapping = uprobe->inode->i_mapping;
-	if (mapping != vma->vm_file->f_mapping)
-		goto put_out;
-
-	addr = vma_address(vma, uprobe->offset);
-	if (vaddr != (unsigned long)addr)
-		goto put_out;
-
 	ret = -ENOMEM;
 	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 	if (!new_page)
-		goto put_out;
+		goto put_old;
 
 	__SetPageUptodate(new_page);
 
-	/*
-	 * lock page will serialize against do_wp_page()'s
-	 * PageAnon() handling
-	 */
-	lock_page(old_page);
 	/* copy the page now that we've got it stable */
 	vaddr_old = kmap_atomic(old_page);
 	vaddr_new = kmap_atomic(new_page);
 
 	memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
-
-	/* poke the new insn in, ASSUMES we don't cross page boundary */
-	vaddr &= ~PAGE_MASK;
-	BUG_ON(vaddr + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
-	memcpy(vaddr_new + vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
+	memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE);
 
 	kunmap_atomic(vaddr_new);
 	kunmap_atomic(vaddr_old);
 
 	ret = anon_vma_prepare(vma);
 	if (ret)
-		goto unlock_out;
+		goto put_new;
 
-	lock_page(new_page);
-	ret = __replace_page(vma, old_page, new_page);
-	unlock_page(new_page);
+	ret = __replace_page(vma, vaddr, old_page, new_page);
 
-unlock_out:
-	unlock_page(old_page);
+put_new:
 	page_cache_release(new_page);
-
-put_out:
+put_old:
 	put_page(old_page);
 
+	if (unlikely(ret == -EAGAIN))
+		goto retry;
 	return ret;
 }
 
@@ -312,16 +277,14 @@ static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_
 	void *vaddr_new;
 	int ret;
 
-	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &page, NULL);
+	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
 	if (ret <= 0)
 		return ret;
 
-	lock_page(page);
 	vaddr_new = kmap_atomic(page);
 	vaddr &= ~PAGE_MASK;
 	memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE);
 	kunmap_atomic(vaddr_new);
-	unlock_page(page);
 
 	put_page(page);
 
@@ -333,10 +296,20 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
 	uprobe_opcode_t opcode;
 	int result;
 
+	if (current->mm == mm) {
+		pagefault_disable();
+		result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
+								sizeof(opcode));
+		pagefault_enable();
+
+		if (likely(result == 0))
+			goto out;
+	}
+
 	result = read_opcode(mm, vaddr, &opcode);
 	if (result)
 		return result;
-
+out:
 	if (is_swbp_insn(&opcode))
 		return 1;
 
@@ -355,10 +328,12 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
 int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 {
 	int result;
-
+	/*
+	 * See the comment near uprobes_hash().
+	 */
 	result = is_swbp_at_addr(mm, vaddr);
 	if (result == 1)
-		return -EEXIST;
+		return 0;
 
 	if (result)
 		return result;
@@ -371,24 +346,22 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned
  * @mm: the probed process address space.
  * @auprobe: arch specific probepoint information.
  * @vaddr: the virtual address to insert the opcode.
- * @verify: if true, verify existance of breakpoint instruction.
  *
  * For mm @mm, restore the original opcode (opcode) at @vaddr.
  * Return 0 (success) or a negative errno.
  */
 int __weak
-set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify)
+set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 {
-	if (verify) {
-		int result;
+	int result;
 
-		result = is_swbp_at_addr(mm, vaddr);
-		if (!result)
-			return -EINVAL;
+	result = is_swbp_at_addr(mm, vaddr);
+	if (!result)
+		return -EINVAL;
+
+	if (result != 1)
+		return result;
 
-		if (result != 1)
-			return result;
-	}
 	return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
 }
 
@@ -439,11 +412,10 @@ static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
 static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
 {
 	struct uprobe *uprobe;
-	unsigned long flags;
 
-	spin_lock_irqsave(&uprobes_treelock, flags);
+	spin_lock(&uprobes_treelock);
 	uprobe = __find_uprobe(inode, offset);
-	spin_unlock_irqrestore(&uprobes_treelock, flags);
+	spin_unlock(&uprobes_treelock);
 
 	return uprobe;
 }
@@ -490,12 +462,11 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
  */
 static struct uprobe *insert_uprobe(struct uprobe *uprobe)
 {
-	unsigned long flags;
 	struct uprobe *u;
 
-	spin_lock_irqsave(&uprobes_treelock, flags);
+	spin_lock(&uprobes_treelock);
 	u = __insert_uprobe(uprobe);
-	spin_unlock_irqrestore(&uprobes_treelock, flags);
+	spin_unlock(&uprobes_treelock);
 
 	/* For now assume that the instruction need not be single-stepped */
 	uprobe->flags |= UPROBE_SKIP_SSTEP;
@@ -520,7 +491,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
 	uprobe->inode = igrab(inode);
 	uprobe->offset = offset;
 	init_rwsem(&uprobe->consumer_rwsem);
-	INIT_LIST_HEAD(&uprobe->pending_list);
 
 	/* add to uprobes_tree, sorted on inode:offset */
 	cur_uprobe = insert_uprobe(uprobe);
@@ -588,20 +558,22 @@ static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
 }
 
 static int
-__copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *insn,
-			unsigned long nbytes, unsigned long offset)
+__copy_insn(struct address_space *mapping, struct file *filp, char *insn,
+			unsigned long nbytes, loff_t offset)
 {
-	struct file *filp = vma->vm_file;
 	struct page *page;
 	void *vaddr;
-	unsigned long off1;
-	unsigned long idx;
+	unsigned long off;
+	pgoff_t idx;
 
 	if (!filp)
 		return -EINVAL;
 
-	idx = (unsigned long)(offset >> PAGE_CACHE_SHIFT);
-	off1 = offset &= ~PAGE_MASK;
+	if (!mapping->a_ops->readpage)
+		return -EIO;
+
+	idx = offset >> PAGE_CACHE_SHIFT;
+	off = offset & ~PAGE_MASK;
 
 	/*
 	 * Ensure that the page that has the original instruction is
@@ -612,22 +584,20 @@ __copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *ins
 		return PTR_ERR(page);
 
 	vaddr = kmap_atomic(page);
-	memcpy(insn, vaddr + off1, nbytes);
+	memcpy(insn, vaddr + off, nbytes);
 	kunmap_atomic(vaddr);
 	page_cache_release(page);
 
 	return 0;
 }
 
-static int
-copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr)
+static int copy_insn(struct uprobe *uprobe, struct file *filp)
 {
 	struct address_space *mapping;
 	unsigned long nbytes;
 	int bytes;
 
-	addr &= ~PAGE_MASK;
-	nbytes = PAGE_SIZE - addr;
+	nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK);
 	mapping = uprobe->inode->i_mapping;
 
 	/* Instruction at end of binary; copy only available bytes */
@@ -638,13 +608,13 @@ copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr)
 
 	/* Instruction at the page-boundary; copy bytes in second page */
 	if (nbytes < bytes) {
-		if (__copy_insn(mapping, vma, uprobe->arch.insn + nbytes,
-				bytes - nbytes, uprobe->offset + nbytes))
-			return -ENOMEM;
-
+		int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes,
+				bytes - nbytes, uprobe->offset + nbytes);
+		if (err)
+			return err;
 		bytes = nbytes;
 	}
-	return __copy_insn(mapping, vma, uprobe->arch.insn, bytes, uprobe->offset);
+	return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
 }
 
 /*
@@ -672,9 +642,9 @@ copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr)
  */
 static int
 install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
-			struct vm_area_struct *vma, loff_t vaddr)
+			struct vm_area_struct *vma, unsigned long vaddr)
 {
-	unsigned long addr;
+	bool first_uprobe;
 	int ret;
 
 	/*
@@ -685,204 +655,194 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 	 * Hence behave as if probe already existed.
 	 */
 	if (!uprobe->consumers)
-		return -EEXIST;
-
-	addr = (unsigned long)vaddr;
+		return 0;
 
 	if (!(uprobe->flags & UPROBE_COPY_INSN)) {
-		ret = copy_insn(uprobe, vma, addr);
+		ret = copy_insn(uprobe, vma->vm_file);
 		if (ret)
 			return ret;
 
 		if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn))
-			return -EEXIST;
+			return -ENOTSUPP;
 
-		ret = arch_uprobe_analyze_insn(&uprobe->arch, mm);
+		ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
 		if (ret)
 			return ret;
 
+		/* write_opcode() assumes we don't cross page boundary */
+		BUG_ON((uprobe->offset & ~PAGE_MASK) +
+				UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
+
 		uprobe->flags |= UPROBE_COPY_INSN;
 	}
 
 	/*
-	 * Ideally, should be updating the probe count after the breakpoint
-	 * has been successfully inserted. However a thread could hit the
-	 * breakpoint we just inserted even before the probe count is
-	 * incremented. If this is the first breakpoint placed, breakpoint
-	 * notifier might ignore uprobes and pass the trap to the thread.
-	 * Hence increment before and decrement on failure.
+	 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
+	 * the task can hit this breakpoint right after __replace_page().
 	 */
-	atomic_inc(&mm->uprobes_state.count);
-	ret = set_swbp(&uprobe->arch, mm, addr);
-	if (ret)
-		atomic_dec(&mm->uprobes_state.count);
+	first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags);
+	if (first_uprobe)
+		set_bit(MMF_HAS_UPROBES, &mm->flags);
+
+	ret = set_swbp(&uprobe->arch, mm, vaddr);
+	if (!ret)
+		clear_bit(MMF_RECALC_UPROBES, &mm->flags);
+	else if (first_uprobe)
+		clear_bit(MMF_HAS_UPROBES, &mm->flags);
 
 	return ret;
 }
 
 static void
-remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, loff_t vaddr)
+remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
 {
-	if (!set_orig_insn(&uprobe->arch, mm, (unsigned long)vaddr, true))
-		atomic_dec(&mm->uprobes_state.count);
+	/* can happen if uprobe_register() fails */
+	if (!test_bit(MMF_HAS_UPROBES, &mm->flags))
+		return;
+
+	set_bit(MMF_RECALC_UPROBES, &mm->flags);
+	set_orig_insn(&uprobe->arch, mm, vaddr);
 }
 
 /*
- * There could be threads that have hit the breakpoint and are entering the
- * notifier code and trying to acquire the uprobes_treelock. The thread
- * calling delete_uprobe() that is removing the uprobe from the rb_tree can
- * race with these threads and might acquire the uprobes_treelock compared
- * to some of the breakpoint hit threads. In such a case, the breakpoint
- * hit threads will not find the uprobe. The current unregistering thread
- * waits till all other threads have hit a breakpoint, to acquire the
- * uprobes_treelock before the uprobe is removed from the rbtree.
+ * There could be threads that have already hit the breakpoint. They
+ * will recheck the current insn and restart if find_uprobe() fails.
+ * See find_active_uprobe().
  */
 static void delete_uprobe(struct uprobe *uprobe)
 {
-	unsigned long flags;
-
-	synchronize_srcu(&uprobes_srcu);
-	spin_lock_irqsave(&uprobes_treelock, flags);
+	spin_lock(&uprobes_treelock);
 	rb_erase(&uprobe->rb_node, &uprobes_tree);
-	spin_unlock_irqrestore(&uprobes_treelock, flags);
+	spin_unlock(&uprobes_treelock);
 	iput(uprobe->inode);
 	put_uprobe(uprobe);
 	atomic_dec(&uprobe_events);
 }
 
-static struct vma_info *
-__find_next_vma_info(struct address_space *mapping, struct list_head *head,
-			struct vma_info *vi, loff_t offset, bool is_register)
+struct map_info {
+	struct map_info *next;
+	struct mm_struct *mm;
+	unsigned long vaddr;
+};
+
+static inline struct map_info *free_map_info(struct map_info *info)
+{
+	struct map_info *next = info->next;
+	kfree(info);
+	return next;
+}
+
+static struct map_info *
+build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
 {
+	unsigned long pgoff = offset >> PAGE_SHIFT;
 	struct prio_tree_iter iter;
 	struct vm_area_struct *vma;
-	struct vma_info *tmpvi;
-	unsigned long pgoff;
-	int existing_vma;
-	loff_t vaddr;
-
-	pgoff = offset >> PAGE_SHIFT;
+	struct map_info *curr = NULL;
+	struct map_info *prev = NULL;
+	struct map_info *info;
+	int more = 0;
 
+ again:
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		if (!valid_vma(vma, is_register))
 			continue;
 
-		existing_vma = 0;
-		vaddr = vma_address(vma, offset);
-
-		list_for_each_entry(tmpvi, head, probe_list) {
-			if (tmpvi->mm == vma->vm_mm && tmpvi->vaddr == vaddr) {
-				existing_vma = 1;
-				break;
-			}
+		if (!prev && !more) {
+			/*
+			 * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through
+			 * reclaim. This is optimistic, no harm done if it fails.
+			 */
+			prev = kmalloc(sizeof(struct map_info),
+					GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
+			if (prev)
+				prev->next = NULL;
 		}
-
-		/*
-		 * Another vma needs a probe to be installed. However skip
-		 * installing the probe if the vma is about to be unlinked.
-		 */
-		if (!existing_vma && atomic_inc_not_zero(&vma->vm_mm->mm_users)) {
-			vi->mm = vma->vm_mm;
-			vi->vaddr = vaddr;
-			list_add(&vi->probe_list, head);
-
-			return vi;
+		if (!prev) {
+			more++;
+			continue;
 		}
-	}
-
-	return NULL;
-}
 
-/*
- * Iterate in the rmap prio tree  and find a vma where a probe has not
- * yet been inserted.
- */
-static struct vma_info *
-find_next_vma_info(struct address_space *mapping, struct list_head *head,
-		loff_t offset, bool is_register)
-{
-	struct vma_info *vi, *retvi;
+		if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
+			continue;
 
-	vi = kzalloc(sizeof(struct vma_info), GFP_KERNEL);
-	if (!vi)
-		return ERR_PTR(-ENOMEM);
+		info = prev;
+		prev = prev->next;
+		info->next = curr;
+		curr = info;
 
-	mutex_lock(&mapping->i_mmap_mutex);
-	retvi = __find_next_vma_info(mapping, head, vi, offset, is_register);
+		info->mm = vma->vm_mm;
+		info->vaddr = offset_to_vaddr(vma, offset);
+	}
 	mutex_unlock(&mapping->i_mmap_mutex);
 
-	if (!retvi)
-		kfree(vi);
+	if (!more)
+		goto out;
+
+	prev = curr;
+	while (curr) {
+		mmput(curr->mm);
+		curr = curr->next;
+	}
 
-	return retvi;
+	do {
+		info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
+		if (!info) {
+			curr = ERR_PTR(-ENOMEM);
+			goto out;
+		}
+		info->next = prev;
+		prev = info;
+	} while (--more);
+
+	goto again;
+ out:
+	while (prev)
+		prev = free_map_info(prev);
+	return curr;
 }
 
 static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 {
-	struct list_head try_list;
-	struct vm_area_struct *vma;
-	struct address_space *mapping;
-	struct vma_info *vi, *tmpvi;
-	struct mm_struct *mm;
-	loff_t vaddr;
-	int ret;
+	struct map_info *info;
+	int err = 0;
 
-	mapping = uprobe->inode->i_mapping;
-	INIT_LIST_HEAD(&try_list);
+	info = build_map_info(uprobe->inode->i_mapping,
+					uprobe->offset, is_register);
+	if (IS_ERR(info))
+		return PTR_ERR(info);
 
-	ret = 0;
+	while (info) {
+		struct mm_struct *mm = info->mm;
+		struct vm_area_struct *vma;
 
-	for (;;) {
-		vi = find_next_vma_info(mapping, &try_list, uprobe->offset, is_register);
-		if (!vi)
-			break;
+		if (err)
+			goto free;
 
-		if (IS_ERR(vi)) {
-			ret = PTR_ERR(vi);
-			break;
-		}
+		down_write(&mm->mmap_sem);
+		vma = find_vma(mm, info->vaddr);
+		if (!vma || !valid_vma(vma, is_register) ||
+		    vma->vm_file->f_mapping->host != uprobe->inode)
+			goto unlock;
 
-		mm = vi->mm;
-		down_read(&mm->mmap_sem);
-		vma = find_vma(mm, (unsigned long)vi->vaddr);
-		if (!vma || !valid_vma(vma, is_register)) {
-			list_del(&vi->probe_list);
-			kfree(vi);
-			up_read(&mm->mmap_sem);
-			mmput(mm);
-			continue;
-		}
-		vaddr = vma_address(vma, uprobe->offset);
-		if (vma->vm_file->f_mapping->host != uprobe->inode ||
-						vaddr != vi->vaddr) {
-			list_del(&vi->probe_list);
-			kfree(vi);
-			up_read(&mm->mmap_sem);
-			mmput(mm);
-			continue;
-		}
+		if (vma->vm_start > info->vaddr ||
+		    vaddr_to_offset(vma, info->vaddr) != uprobe->offset)
+			goto unlock;
 
 		if (is_register)
-			ret = install_breakpoint(uprobe, mm, vma, vi->vaddr);
+			err = install_breakpoint(uprobe, mm, vma, info->vaddr);
 		else
-			remove_breakpoint(uprobe, mm, vi->vaddr);
+			remove_breakpoint(uprobe, mm, info->vaddr);
 
-		up_read(&mm->mmap_sem);
+ unlock:
+		up_write(&mm->mmap_sem);
+ free:
 		mmput(mm);
-		if (is_register) {
-			if (ret && ret == -EEXIST)
-				ret = 0;
-			if (ret)
-				break;
-		}
-	}
-
-	list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) {
-		list_del(&vi->probe_list);
-		kfree(vi);
+		info = free_map_info(info);
 	}
 
-	return ret;
+	return err;
 }
 
 static int __uprobe_register(struct uprobe *uprobe)
@@ -941,10 +901,12 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
 	}
 
 	mutex_unlock(uprobes_hash(inode));
-	put_uprobe(uprobe);
+	if (uprobe)
+		put_uprobe(uprobe);
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(uprobe_register);
 
 /*
  * uprobe_unregister - unregister a already registered probe.
@@ -976,81 +938,81 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
 	if (uprobe)
 		put_uprobe(uprobe);
 }
+EXPORT_SYMBOL_GPL(uprobe_unregister);
 
-/*
- * Of all the nodes that correspond to the given inode, return the node
- * with the least offset.
- */
-static struct rb_node *find_least_offset_node(struct inode *inode)
+static struct rb_node *
+find_node_in_range(struct inode *inode, loff_t min, loff_t max)
 {
-	struct uprobe u = { .inode = inode, .offset = 0};
 	struct rb_node *n = uprobes_tree.rb_node;
-	struct rb_node *close_node = NULL;
-	struct uprobe *uprobe;
-	int match;
 
 	while (n) {
-		uprobe = rb_entry(n, struct uprobe, rb_node);
-		match = match_uprobe(&u, uprobe);
-
-		if (uprobe->inode == inode)
-			close_node = n;
-
-		if (!match)
-			return close_node;
+		struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
 
-		if (match < 0)
+		if (inode < u->inode) {
 			n = n->rb_left;
-		else
+		} else if (inode > u->inode) {
 			n = n->rb_right;
+		} else {
+			if (max < u->offset)
+				n = n->rb_left;
+			else if (min > u->offset)
+				n = n->rb_right;
+			else
+				break;
+		}
 	}
 
-	return close_node;
+	return n;
 }
 
 /*
- * For a given inode, build a list of probes that need to be inserted.
+ * For a given range in vma, build a list of probes that need to be inserted.
  */
-static void build_probe_list(struct inode *inode, struct list_head *head)
+static void build_probe_list(struct inode *inode,
+				struct vm_area_struct *vma,
+				unsigned long start, unsigned long end,
+				struct list_head *head)
 {
-	struct uprobe *uprobe;
-	unsigned long flags;
-	struct rb_node *n;
-
-	spin_lock_irqsave(&uprobes_treelock, flags);
-
-	n = find_least_offset_node(inode);
+	loff_t min, max;
+	struct rb_node *n, *t;
+	struct uprobe *u;
 
-	for (; n; n = rb_next(n)) {
-		uprobe = rb_entry(n, struct uprobe, rb_node);
-		if (uprobe->inode != inode)
-			break;
+	INIT_LIST_HEAD(head);
+	min = vaddr_to_offset(vma, start);
+	max = min + (end - start) - 1;
 
-		list_add(&uprobe->pending_list, head);
-		atomic_inc(&uprobe->ref);
+	spin_lock(&uprobes_treelock);
+	n = find_node_in_range(inode, min, max);
+	if (n) {
+		for (t = n; t; t = rb_prev(t)) {
+			u = rb_entry(t, struct uprobe, rb_node);
+			if (u->inode != inode || u->offset < min)
+				break;
+			list_add(&u->pending_list, head);
+			atomic_inc(&u->ref);
+		}
+		for (t = n; (t = rb_next(t)); ) {
+			u = rb_entry(t, struct uprobe, rb_node);
+			if (u->inode != inode || u->offset > max)
+				break;
+			list_add(&u->pending_list, head);
+			atomic_inc(&u->ref);
+		}
 	}
-
-	spin_unlock_irqrestore(&uprobes_treelock, flags);
+	spin_unlock(&uprobes_treelock);
 }
 
 /*
- * Called from mmap_region.
- * called with mm->mmap_sem acquired.
- *
- * Return -ve no if we fail to insert probes and we cannot
- * bail-out.
- * Return 0 otherwise. i.e:
+ * Called from mmap_region/vma_adjust with mm->mmap_sem acquired.
  *
- *	- successful insertion of probes
- *	- (or) no possible probes to be inserted.
- *	- (or) insertion of probes failed but we can bail-out.
+ * Currently we ignore all errors and always return 0, the callers
+ * can't handle the failure anyway.
  */
 int uprobe_mmap(struct vm_area_struct *vma)
 {
 	struct list_head tmp_list;
 	struct uprobe *uprobe, *u;
 	struct inode *inode;
-	int ret, count;
 
 	if (!atomic_read(&uprobe_events) || !valid_vma(vma, true))
 		return 0;
@@ -1059,54 +1021,38 @@ int uprobe_mmap(struct vm_area_struct *vma)
 	if (!inode)
 		return 0;
 
-	INIT_LIST_HEAD(&tmp_list);
 	mutex_lock(uprobes_mmap_hash(inode));
-	build_probe_list(inode, &tmp_list);
-
-	ret = 0;
-	count = 0;
+	build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
 
 	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
-		loff_t vaddr;
-
-		list_del(&uprobe->pending_list);
-		if (!ret) {
-			vaddr = vma_address(vma, uprobe->offset);
-
-			if (vaddr < vma->vm_start || vaddr >= vma->vm_end) {
-				put_uprobe(uprobe);
-				continue;
-			}
-
-			ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
-
-			/* Ignore double add: */
-			if (ret == -EEXIST) {
-				ret = 0;
-
-				if (!is_swbp_at_addr(vma->vm_mm, vaddr))
-					continue;
-
-				/*
-				 * Unable to insert a breakpoint, but
-				 * breakpoint lies underneath. Increment the
-				 * probe count.
-				 */
-				atomic_inc(&vma->vm_mm->uprobes_state.count);
-			}
-
-			if (!ret)
-				count++;
+		if (!fatal_signal_pending(current)) {
+			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
+			install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
 		}
 		put_uprobe(uprobe);
 	}
-
 	mutex_unlock(uprobes_mmap_hash(inode));
 
-	if (ret)
-		atomic_sub(count, &vma->vm_mm->uprobes_state.count);
+	return 0;
+}
 
-	return ret;
+static bool
+vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
+{
+	loff_t min, max;
+	struct inode *inode;
+	struct rb_node *n;
+
+	inode = vma->vm_file->f_mapping->host;
+
+	min = vaddr_to_offset(vma, start);
+	max = min + (end - start) - 1;
+
+	spin_lock(&uprobes_treelock);
+	n = find_node_in_range(inode, min, max);
+	spin_unlock(&uprobes_treelock);
+
+	return !!n;
 }
 
 /*
@@ -1114,41 +1060,18 @@ int uprobe_mmap(struct vm_area_struct *vma)
  */
 void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
 {
-	struct list_head tmp_list;
-	struct uprobe *uprobe, *u;
-	struct inode *inode;
-
 	if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))
 		return;
 
-	if (!atomic_read(&vma->vm_mm->uprobes_state.count))
+	if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
 		return;
 
-	inode = vma->vm_file->f_mapping->host;
-	if (!inode)
+	if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
+	     test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
 		return;
 
-	INIT_LIST_HEAD(&tmp_list);
-	mutex_lock(uprobes_mmap_hash(inode));
-	build_probe_list(inode, &tmp_list);
-
-	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
-		loff_t vaddr;
-
-		list_del(&uprobe->pending_list);
-		vaddr = vma_address(vma, uprobe->offset);
-
-		if (vaddr >= start && vaddr < end) {
-			/*
-			 * An unregister could have removed the probe before
-			 * unmap. So check before we decrement the count.
-			 */
-			if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1)
-				atomic_dec(&vma->vm_mm->uprobes_state.count);
-		}
-		put_uprobe(uprobe);
-	}
-	mutex_unlock(uprobes_mmap_hash(inode));
+	if (vma_has_uprobes(vma, start, end))
+		set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
 }
 
 /* Slot allocation for XOL */
@@ -1250,13 +1173,15 @@ void uprobe_clear_state(struct mm_struct *mm)
 	kfree(area);
 }
 
-/*
- * uprobe_reset_state - Free the area allocated for slots.
- */
-void uprobe_reset_state(struct mm_struct *mm)
+void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
 {
-	mm->uprobes_state.xol_area = NULL;
-	atomic_set(&mm->uprobes_state.count, 0);
+	newmm->uprobes_state.xol_area = NULL;
+
+	if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
+		set_bit(MMF_HAS_UPROBES, &newmm->flags);
+		/* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
+		set_bit(MMF_RECALC_UPROBES, &newmm->flags);
+	}
 }
 
 /*
@@ -1378,9 +1303,6 @@ void uprobe_free_utask(struct task_struct *t)
 {
 	struct uprobe_task *utask = t->utask;
 
-	if (t->uprobe_srcu_id != -1)
-		srcu_read_unlock_raw(&uprobes_srcu, t->uprobe_srcu_id);
-
 	if (!utask)
 		return;
 
@@ -1398,7 +1320,6 @@ void uprobe_free_utask(struct task_struct *t)
 void uprobe_copy_process(struct task_struct *t)
 {
 	t->utask = NULL;
-	t->uprobe_srcu_id = -1;
 }
 
 /*
@@ -1417,7 +1338,6 @@ static struct uprobe_task *add_utask(void)
 	if (unlikely(!utask))
 		return NULL;
 
-	utask->active_uprobe = NULL;
 	current->utask = utask;
 	return utask;
 }
@@ -1479,41 +1399,93 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
 	return false;
 }
 
+static void mmf_recalc_uprobes(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (!valid_vma(vma, false))
+			continue;
+		/*
+		 * This is not strictly accurate, we can race with
+		 * uprobe_unregister() and see the already removed
+		 * uprobe if delete_uprobe() was not yet called.
+		 */
+		if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
+			return;
+	}
+
+	clear_bit(MMF_HAS_UPROBES, &mm->flags);
+}
+
+static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
+{
+	struct mm_struct *mm = current->mm;
+	struct uprobe *uprobe = NULL;
+	struct vm_area_struct *vma;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, bp_vaddr);
+	if (vma && vma->vm_start <= bp_vaddr) {
+		if (valid_vma(vma, false)) {
+			struct inode *inode = vma->vm_file->f_mapping->host;
+			loff_t offset = vaddr_to_offset(vma, bp_vaddr);
+
+			uprobe = find_uprobe(inode, offset);
+		}
+
+		if (!uprobe)
+			*is_swbp = is_swbp_at_addr(mm, bp_vaddr);
+	} else {
+		*is_swbp = -EFAULT;
+	}
+
+	if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags))
+		mmf_recalc_uprobes(mm);
+	up_read(&mm->mmap_sem);
+
+	return uprobe;
+}
+
+void __weak arch_uprobe_enable_step(struct arch_uprobe *arch)
+{
+	user_enable_single_step(current);
+}
+
+void __weak arch_uprobe_disable_step(struct arch_uprobe *arch)
+{
+	user_disable_single_step(current);
+}
+
 /*
  * Run handler and ask thread to singlestep.
  * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
  */
 static void handle_swbp(struct pt_regs *regs)
 {
-	struct vm_area_struct *vma;
 	struct uprobe_task *utask;
 	struct uprobe *uprobe;
-	struct mm_struct *mm;
 	unsigned long bp_vaddr;
+	int uninitialized_var(is_swbp);
 
-	uprobe = NULL;
 	bp_vaddr = uprobe_get_swbp_addr(regs);
-	mm = current->mm;
-	down_read(&mm->mmap_sem);
-	vma = find_vma(mm, bp_vaddr);
-
-	if (vma && vma->vm_start <= bp_vaddr && valid_vma(vma, false)) {
-		struct inode *inode;
-		loff_t offset;
-
-		inode = vma->vm_file->f_mapping->host;
-		offset = bp_vaddr - vma->vm_start;
-		offset += (vma->vm_pgoff << PAGE_SHIFT);
-		uprobe = find_uprobe(inode, offset);
-	}
-
-	srcu_read_unlock_raw(&uprobes_srcu, current->uprobe_srcu_id);
-	current->uprobe_srcu_id = -1;
-	up_read(&mm->mmap_sem);
+	uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
 
 	if (!uprobe) {
-		/* No matching uprobe; signal SIGTRAP. */
-		send_sig(SIGTRAP, current, 0);
+		if (is_swbp > 0) {
+			/* No matching uprobe; signal SIGTRAP. */
+			send_sig(SIGTRAP, current, 0);
+		} else {
+			/*
+			 * Either we raced with uprobe_unregister() or we can't
+			 * access this memory. The latter is only possible if
+			 * another thread plays with our ->mm. In both cases
+			 * we can simply restart. If this vma was unmapped we
+			 * can pretend this insn was not executed yet and get
+			 * the (correct) SIGSEGV after restart.
+			 */
+			instruction_pointer_set(regs, bp_vaddr);
+		}
 		return;
 	}
 
@@ -1531,7 +1503,7 @@ static void handle_swbp(struct pt_regs *regs)
 
 	utask->state = UTASK_SSTEP;
 	if (!pre_ssout(uprobe, regs, bp_vaddr)) {
-		user_enable_single_step(current);
+		arch_uprobe_enable_step(&uprobe->arch);
 		return;
 	}
 
@@ -1540,17 +1512,15 @@ cleanup_ret:
 		utask->active_uprobe = NULL;
 		utask->state = UTASK_RUNNING;
 	}
-	if (uprobe) {
-		if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
+	if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
 
-			/*
-			 * cannot singlestep; cannot skip instruction;
-			 * re-execute the instruction.
-			 */
-			instruction_pointer_set(regs, bp_vaddr);
+		/*
+		 * cannot singlestep; cannot skip instruction;
+		 * re-execute the instruction.
+		 */
+		instruction_pointer_set(regs, bp_vaddr);
 
-		put_uprobe(uprobe);
-	}
+	put_uprobe(uprobe);
 }
 
 /*
@@ -1569,10 +1539,10 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
 	else
 		WARN_ON_ONCE(1);
 
+	arch_uprobe_disable_step(&uprobe->arch);
 	put_uprobe(uprobe);
 	utask->active_uprobe = NULL;
 	utask->state = UTASK_RUNNING;
-	user_disable_single_step(current);
 	xol_free_insn_slot(current);
 
 	spin_lock_irq(&current->sighand->siglock);
@@ -1611,8 +1581,7 @@ int uprobe_pre_sstep_notifier(struct pt_regs *regs)
 {
 	struct uprobe_task *utask;
 
-	if (!current->mm || !atomic_read(&current->mm->uprobes_state.count))
-		/* task is currently not uprobed */
+	if (!current->mm || !test_bit(MMF_HAS_UPROBES, &current->mm->flags))
 		return 0;
 
 	utask = current->utask;
@@ -1620,7 +1589,6 @@ int uprobe_pre_sstep_notifier(struct pt_regs *regs)
 		utask->state = UTASK_BP_HIT;
 
 	set_thread_flag(TIF_UPROBE);
-	current->uprobe_srcu_id = srcu_read_lock_raw(&uprobes_srcu);
 
 	return 1;
 }
@@ -1655,7 +1623,6 @@ static int __init init_uprobes(void)
 		mutex_init(&uprobes_mutex[i]);
 		mutex_init(&uprobes_mmap_mutex[i]);
 	}
-	init_srcu_struct(&uprobes_srcu);
 
 	return register_die_notifier(&uprobe_exception_nb);
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 7a1d634..5d0137c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -355,6 +355,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 
 	down_write(&oldmm->mmap_sem);
 	flush_cache_dup_mm(oldmm);
+	uprobe_dup_mmap(oldmm, mm);
 	/*
 	 * Not linked in yet - no deadlock potential:
 	 */
@@ -843,8 +841,6 @@ struct mm_struct *dup_mm(struct task_struct *tsk)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	mm->pmd_huge_pte = NULL;
 #endif
-	uprobe_reset_state(mm);
-
 	if (!mm_init(mm, tsk))
 		goto fail_nomem;
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a232bb5..764fcd1 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -33,6 +33,12 @@ static int ptrace_trapping_sleep_fn(void *flags)
 }
 
 /*
+ * This is declared in linux/regset.h and defined in machine-dependent
+ * code.  We put the export here to ensure no machine forgets it.
+ */
+EXPORT_SYMBOL_GPL(task_user_regset_view);
+
+/*
  * ptrace a task: make the debugger its new parent and
  * move it to the ptrace list.
  *
diff --git a/mm/mmap.c b/mm/mmap.c
index 3edfcdf..f25fd3f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2345,9 +2344,6 @@ int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
 	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
 		return -ENOMEM;
 
-	if (vma->vm_file && uprobe_mmap(vma))
-		return -EINVAL;
-
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 	return 0;
 }
@@ -2418,9 +2414,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 			if (new_vma->vm_file) {
 				get_file(new_vma->vm_file);
 
-				if (uprobe_mmap(new_vma))
-					goto out_free_mempol;
-
 				if (vma->vm_flags & VM_EXECUTABLE)
 					added_exe_file_vma(mm);
 			}
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