The split-out series is available in the git repository at:

git://fedorapeople.org/home/fedora/aarapov/public_git/kernel-uprobes.git tags/f17_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 (36): 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: mmap_region() corrupts mm->mm_rb if uprobe_mmap() fails

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

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

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 | 5 +- include/linux/sched.h | 1 - kernel/events/uprobes.c | 624 ++++++++++++++++++++--------------------- kernel/fork.c | 4 +- mm/mmap.c | 11 +- 7 files changed, 314 insertions(+), 339 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..ad9faf1 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; @@ -626,6 +627,7 @@ int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,

return ret; } +EXPORT_SYMBOL_GPL(uprobe_register);

/* * This function gets called when XOL instruction either gets trapped or @@ -640,6 +642,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) handle_riprel_post_xol(auprobe, regs, NULL); instruction_pointer_set(regs, utask->vaddr); } +EXPORT_SYMBOL_GPL(uprobe_unregister);

/* * Skip these instructions as per the currently known x86 ISA. diff --git a/include/linux/sched.h b/include/linux/sched.h index 4a1f493..64d9df5 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..7cff24c 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -32,19 +32,36 @@ #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 +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; @@ -100,20 +106,21 @@ 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 +128,27 @@ 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 +165,15 @@ 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 +215,46 @@ 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 +276,14 @@ 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 +295,20 @@ 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 +327,9 @@ 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 +494,6 @@ 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 +561,22 @@ 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 +587,20 @@ __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 +611,13 @@ 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 +645,8 @@ 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 +659,22 @@ 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 +687,7 @@ 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 +695,21 @@ 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 +718,136 @@ 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 = 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 (is_register) - ret = install_breakpoint(uprobe, mm, vma, vi->vaddr); - else - remove_breakpoint(uprobe, mm, vi->vaddr); + if (vma->vm_start > info->vaddr || + vaddr_to_offset(vma, info->vaddr) != uprobe->offset) + 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) @@ -977,59 +942,66 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume put_uprobe(uprobe); }

-/* - * 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); + struct uprobe *u = rb_entry(n, struct uprobe, rb_node);

- if (uprobe->inode == inode) - close_node = n; - - if (!match) - return close_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; + loff_t min, max; unsigned long flags; - struct rb_node *n; - - spin_lock_irqsave(&uprobes_treelock, flags); - - n = find_least_offset_node(inode); + 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_irqsave(&uprobes_treelock, flags); + 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); }

@@ -1059,28 +1031,21 @@ 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); + build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);

ret = 0; count = 0;

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; - } + unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);

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;

@@ -1121,6 +1086,9 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) return;

+ if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ + return; + if (!atomic_read(&vma->vm_mm->uprobes_state.count)) return;

@@ -1128,24 +1096,17 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon if (!inode) return;

- INIT_LIST_HEAD(&tmp_list); mutex_lock(uprobes_mmap_hash(inode)); - build_probe_list(inode, &tmp_list); + build_probe_list(inode, vma, start, end, &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); - } + unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); + /* + * 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)); @@ -1378,9 +1339,6 @@ 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 +1356,6 @@ 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 +1374,6 @@ static struct uprobe_task *add_utask(void) if (unlikely(!utask)) return NULL;

- utask->active_uprobe = NULL; current->utask = utask; return utask; } @@ -1479,41 +1435,61 @@ 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 = 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; + } + 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 +1596,6 @@ 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 +1630,6 @@ 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..7a02280 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -459,8 +459,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) if (retval) goto out;

- if (file && uprobe_mmap(tmp)) - goto out; + if (file) + uprobe_mmap(tmp); } /* a new mm has just been created */ arch_dup_mmap(oldmm, mm); diff --git a/mm/mmap.c b/mm/mmap.c index 3edfcdf..f25fd3f 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1355,9 +1355,8 @@ out: } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) make_pages_present(addr, addr + len);

- if (file && uprobe_mmap(vma)) - /* matching probes but cannot insert */ - goto unmap_and_free_vma; + if (file) + uprobe_mmap(vma);

return addr;

@@ -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); }