The split-out series is available in the git repository at:
git://fedorapeople.org/home/fedora/aarapov/public_git/kernel-uprobes.git tags/rawhide_exported
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 (21):
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: 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: Move BUG_ON(UPROBE_SWBP_INSN_SIZE) from write_opcode() to install_breakpoint()
Peter Zijlstra (1):
uprobes: Document uprobe_register() vs uprobe_mmap() race
Signed-off-by: Anton Arapov <anton@redhat.com>
---
arch/x86/include/asm/uprobes.h | 2 +-
arch/x86/kernel/ptrace.c | 6 +
arch/x86/kernel/uprobes.c | 3 +-
include/linux/sched.h | 1 -
kernel/events/uprobes.c | 464 ++++++++++++++++++++--------------------
5 files changed, 240 insertions(+), 236 deletions(-)
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 1e9bed1..f3971bb 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -48,7 +48,7 @@ struct arch_uprobe_task {
#endif
};
-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/ptrace.c b/arch/x86/kernel/ptrace.c
index c4c6a5c..a6a6871 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1415,6 +1415,12 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
#endif
}
+/*
+ * 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);
+
static void fill_sigtrap_info(struct task_struct *tsk,
struct pt_regs *regs,
int error_code, int si_code,
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index dc4e910..36fd420 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -409,9 +409,10 @@ 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;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4059c0f..c7cfa69 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1581,7 +1581,6 @@ struct task_struct {
#endif
#ifdef CONFIG_UPROBES
struct uprobe_task *utask;
- int uprobe_srcu_id;
#endif
};
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 985be4d..d9e5ba5 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -34,17 +34,34 @@
#include <linux/kdebug.h> /* notifier mechanism */
#include <linux/uprobes.h>
+#include <linux/export.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 +78,6 @@ 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;
@@ -100,7 +106,8 @@ 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;
@@ -129,33 +136,17 @@ static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
static int __replace_page(struct vm_area_struct *vma, 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;
+ spinlock_t *ptl;
+ pte_t *ptep;
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;
-
- pmd = pmd_offset(pud, addr);
- if (!pmd_present(*pmd))
- goto out;
+ return -EFAULT;
- ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ ptep = page_check_address(page, mm, addr, &ptl, 0);
if (!ptep)
- goto out;
+ return -EAGAIN;
get_page(kpage);
page_add_new_anon_rmap(kpage, vma, addr);
@@ -174,10 +165,8 @@ static int __replace_page(struct vm_area_struct *vma, struct page *page, struct
try_to_free_swap(page);
put_page(page);
pte_unmap_unlock(ptep, ptl);
- err = 0;
-out:
- return err;
+ return 0;
}
/**
@@ -222,9 +211,8 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
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)
@@ -246,10 +234,6 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
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)
@@ -267,11 +251,7 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
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);
@@ -291,6 +271,8 @@ unlock_out:
put_out:
put_page(old_page);
+ if (unlikely(ret == -EAGAIN))
+ goto retry;
return ret;
}
@@ -312,7 +294,7 @@ 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;
@@ -333,10 +315,20 @@ 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;
@@ -355,7 +347,9 @@ 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;
@@ -520,7 +514,6 @@ 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 +581,22 @@ 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 +607,20 @@ __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 +631,13 @@ 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 +665,8 @@ 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;
int ret;
/*
@@ -687,20 +679,22 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
if (!uprobe->consumers)
return -EEXIST;
- addr = (unsigned long)vaddr;
-
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;
}
@@ -713,7 +707,7 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
* Hence increment before and decrement on failure.
*/
atomic_inc(&mm->uprobes_state.count);
- ret = set_swbp(&uprobe->arch, mm, addr);
+ ret = set_swbp(&uprobe->arch, mm, vaddr);
if (ret)
atomic_dec(&mm->uprobes_state.count);
@@ -721,27 +715,21 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
}
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))
+ if (!set_orig_insn(&uprobe->arch, mm, vaddr, true))
atomic_dec(&mm->uprobes_state.count);
}
/*
- * 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);
rb_erase(&uprobe->rb_node, &uprobes_tree);
spin_unlock_irqrestore(&uprobes_treelock, flags);
@@ -750,139 +738,135 @@ static void delete_uprobe(struct 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 = vma_address(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, (unsigned long)info->vaddr);
+ if (!vma || !valid_vma(vma, is_register))
+ 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 (is_register)
- ret = install_breakpoint(uprobe, mm, vma, vi->vaddr);
- else
- remove_breakpoint(uprobe, mm, vi->vaddr);
+ vma_address(vma, uprobe->offset) != info->vaddr)
+ goto unlock;
- up_read(&mm->mmap_sem);
- mmput(mm);
if (is_register) {
- if (ret && ret == -EEXIST)
- ret = 0;
- if (ret)
- break;
+ err = install_breakpoint(uprobe, mm, vma, info->vaddr);
+ /*
+ * We can race against uprobe_mmap(), see the
+ * comment near uprobe_hash().
+ */
+ if (err == -EEXIST)
+ err = 0;
+ } else {
+ remove_breakpoint(uprobe, mm, info->vaddr);
}
+ unlock:
+ up_write(&mm->mmap_sem);
+ free:
+ mmput(mm);
+ info = free_map_info(info);
}
- list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) {
- list_del(&vi->probe_list);
- kfree(vi);
- }
-
- return ret;
+ return err;
}
static int __uprobe_register(struct uprobe *uprobe)
@@ -945,6 +929,7 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
return ret;
}
+EXPORT_SYMBOL_GPL(uprobe_register);
/*
* uprobe_unregister - unregister a already registered probe.
@@ -976,6 +961,7 @@ 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
@@ -1048,7 +1034,7 @@ static void build_probe_list(struct inode *inode, struct list_head *head)
int uprobe_mmap(struct vm_area_struct *vma)
{
struct list_head tmp_list;
- struct uprobe *uprobe, *u;
+ struct uprobe *uprobe;
struct inode *inode;
int ret, count;
@@ -1066,12 +1052,9 @@ int uprobe_mmap(struct vm_area_struct *vma)
ret = 0;
count = 0;
- list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
- loff_t vaddr;
-
- list_del(&uprobe->pending_list);
+ list_for_each_entry(uprobe, &tmp_list, pending_list) {
if (!ret) {
- vaddr = vma_address(vma, uprobe->offset);
+ loff_t vaddr = vma_address(vma, uprobe->offset);
if (vaddr < vma->vm_start || vaddr >= vma->vm_end) {
put_uprobe(uprobe);
@@ -1079,8 +1062,10 @@ int uprobe_mmap(struct vm_area_struct *vma)
}
ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
-
- /* Ignore double add: */
+ /*
+ * We can race against uprobe_register(), see the
+ * comment near uprobe_hash().
+ */
if (ret == -EEXIST) {
ret = 0;
@@ -1115,7 +1100,7 @@ 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 uprobe *uprobe;
struct inode *inode;
if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))
@@ -1132,11 +1117,8 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
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);
+ list_for_each_entry(uprobe, &tmp_list, pending_list) {
+ loff_t vaddr = vma_address(vma, uprobe->offset);
if (vaddr >= start && vaddr < end) {
/*
@@ -1378,9 +1360,6 @@ 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 +1377,6 @@ 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 +1395,6 @@ static struct uprobe_task *add_utask(void)
if (unlikely(!utask))
return NULL;
- utask->active_uprobe = NULL;
current->utask = utask;
return utask;
}
@@ -1479,41 +1456,64 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
return false;
}
+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;
+ 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);
+ }
+
+ if (!uprobe)
+ *is_swbp = is_swbp_at_addr(mm, bp_vaddr);
+ } else {
+ *is_swbp = -EFAULT;
+ }
+ up_read(&mm->mmap_sem);
+
+ return uprobe;
+}
+
/*
* 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;
}
@@ -1620,7 +1620,6 @@ 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 +1654,6 @@ 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);
}