From 7b2d81d48a2d8e37efb6ce7b4d5ef58822b30d89 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 17 Feb 2012 09:27:41 +0100 Subject: uprobes/core: Clean up, refactor and improve the code Make the uprobes code readable to me: - improve the Kconfig text so that a mere mortal gets some idea what CONFIG_UPROBES=y is really about - do trivial renames to standardize around the uprobes_*() namespace - clean up and simplify various code flow details - separate basic blocks of functionality - line break artifact and white space related removal - use standard local varible definition blocks - use vertical spacing to make things more readable - remove unnecessary volatile - restructure comment blocks to make them more uniform and more readable in general Cc: Srikar Dronamraju Cc: Jim Keniston Cc: Peter Zijlstra Cc: Oleg Nesterov Cc: Masami Hiramatsu Cc: Arnaldo Carvalho de Melo Cc: Anton Arapov Cc: Ananth N Mavinakayanahalli Link: http://lkml.kernel.org/n/tip-ewbwhb8o6navvllsauu7k07p@git.kernel.org Signed-off-by: Ingo Molnar --- kernel/uprobes.c | 219 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 127 insertions(+), 92 deletions(-) (limited to 'kernel') diff --git a/kernel/uprobes.c b/kernel/uprobes.c index 72e8bb3b52cd..884817f1b0d3 100644 --- a/kernel/uprobes.c +++ b/kernel/uprobes.c @@ -1,5 +1,5 @@ /* - * Userspace Probes (UProbes) + * User-space Probes (UProbes) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -29,24 +29,26 @@ #include /* anon_vma_prepare */ #include /* set_pte_at_notify */ #include /* try_to_free_swap */ + #include static struct rb_root uprobes_tree = RB_ROOT; + static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ #define UPROBES_HASH_SZ 13 + /* serialize (un)register */ static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; -#define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) %\ - UPROBES_HASH_SZ]) + +#define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) /* serialize uprobe->pending_list */ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; -#define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) %\ - UPROBES_HASH_SZ]) +#define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) /* - * uprobe_events allows us to skip the mmap_uprobe if there are no uprobe + * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe * events active at this time. Probably a fine grained per inode count is * better? */ @@ -58,9 +60,9 @@ static atomic_t uprobe_events = ATOMIC_INIT(0); * vm_area_struct wasnt recommended. */ struct vma_info { - struct list_head probe_list; - struct mm_struct *mm; - loff_t vaddr; + struct list_head probe_list; + struct mm_struct *mm; + loff_t vaddr; }; /* @@ -79,8 +81,7 @@ 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_READ|VM_WRITE|VM_EXEC|VM_SHARED)) == (VM_READ|VM_EXEC)) return true; return false; @@ -92,6 +93,7 @@ static loff_t vma_address(struct vm_area_struct *vma, loff_t offset) vaddr = vma->vm_start + offset; vaddr -= vma->vm_pgoff << PAGE_SHIFT; + return vaddr; } @@ -105,8 +107,7 @@ static loff_t vma_address(struct vm_area_struct *vma, loff_t offset) * * 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, struct page *page, struct page *kpage) { struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; @@ -163,7 +164,7 @@ out: */ bool __weak is_bkpt_insn(uprobe_opcode_t *insn) { - return (*insn == UPROBES_BKPT_INSN); + return *insn == UPROBES_BKPT_INSN; } /* @@ -203,6 +204,7 @@ static int write_opcode(struct mm_struct *mm, struct uprobe *uprobe, ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); if (ret <= 0) return ret; + ret = -EINVAL; /* @@ -239,6 +241,7 @@ static int write_opcode(struct mm_struct *mm, struct uprobe *uprobe, 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_opcode_sz > PAGE_SIZE); @@ -260,7 +263,8 @@ unlock_out: page_cache_release(new_page); put_out: - put_page(old_page); /* we did a get_page in the beginning */ + put_page(old_page); + return ret; } @@ -276,8 +280,7 @@ put_out: * For mm @mm, read the opcode at @vaddr and store it in @opcode. * Return 0 (success) or a negative errno. */ -static int read_opcode(struct mm_struct *mm, unsigned long vaddr, - uprobe_opcode_t *opcode) +static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) { struct page *page; void *vaddr_new; @@ -293,15 +296,18 @@ static int read_opcode(struct mm_struct *mm, unsigned long vaddr, memcpy(opcode, vaddr_new + vaddr, uprobe_opcode_sz); kunmap_atomic(vaddr_new); unlock_page(page); - put_page(page); /* we did a get_user_pages in the beginning */ + + put_page(page); + return 0; } static int is_bkpt_at_addr(struct mm_struct *mm, unsigned long vaddr) { uprobe_opcode_t opcode; - int result = read_opcode(mm, vaddr, &opcode); + int result; + result = read_opcode(mm, vaddr, &opcode); if (result) return result; @@ -320,11 +326,11 @@ static int is_bkpt_at_addr(struct mm_struct *mm, unsigned long vaddr) * For mm @mm, store the breakpoint instruction at @vaddr. * Return 0 (success) or a negative errno. */ -int __weak set_bkpt(struct mm_struct *mm, struct uprobe *uprobe, - unsigned long vaddr) +int __weak set_bkpt(struct mm_struct *mm, struct uprobe *uprobe, unsigned long vaddr) { - int result = is_bkpt_at_addr(mm, vaddr); + int result; + result = is_bkpt_at_addr(mm, vaddr); if (result == 1) return -EEXIST; @@ -344,35 +350,35 @@ int __weak set_bkpt(struct mm_struct *mm, struct uprobe *uprobe, * For mm @mm, restore the original opcode (opcode) at @vaddr. * Return 0 (success) or a negative errno. */ -int __weak set_orig_insn(struct mm_struct *mm, struct uprobe *uprobe, - unsigned long vaddr, bool verify) +int __weak +set_orig_insn(struct mm_struct *mm, struct uprobe *uprobe, unsigned long vaddr, bool verify) { if (verify) { - int result = is_bkpt_at_addr(mm, vaddr); + int result; + result = is_bkpt_at_addr(mm, vaddr); if (!result) return -EINVAL; if (result != 1) return result; } - return write_opcode(mm, uprobe, vaddr, - *(uprobe_opcode_t *)uprobe->insn); + return write_opcode(mm, uprobe, vaddr, *(uprobe_opcode_t *)uprobe->insn); } static int match_uprobe(struct uprobe *l, struct uprobe *r) { if (l->inode < r->inode) return -1; + if (l->inode > r->inode) return 1; - else { - if (l->offset < r->offset) - return -1; - if (l->offset > r->offset) - return 1; - } + if (l->offset < r->offset) + return -1; + + if (l->offset > r->offset) + return 1; return 0; } @@ -391,6 +397,7 @@ static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) atomic_inc(&uprobe->ref); return uprobe; } + if (match < 0) n = n->rb_left; else @@ -411,6 +418,7 @@ static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) spin_lock_irqsave(&uprobes_treelock, flags); uprobe = __find_uprobe(inode, offset); spin_unlock_irqrestore(&uprobes_treelock, flags); + return uprobe; } @@ -436,16 +444,18 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe) p = &parent->rb_right; } + u = NULL; rb_link_node(&uprobe->rb_node, parent, p); rb_insert_color(&uprobe->rb_node, &uprobes_tree); /* get access + creation ref */ atomic_set(&uprobe->ref, 2); + return u; } /* - * Acquires uprobes_treelock. + * Acquire uprobes_treelock. * Matching uprobe already exists in rbtree; * increment (access refcount) and return the matching uprobe. * @@ -460,6 +470,7 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe) spin_lock_irqsave(&uprobes_treelock, flags); u = __insert_uprobe(uprobe); spin_unlock_irqrestore(&uprobes_treelock, flags); + return u; } @@ -490,19 +501,22 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) kfree(uprobe); uprobe = cur_uprobe; iput(inode); - } else + } else { atomic_inc(&uprobe_events); + } + return uprobe; } /* Returns the previous consumer */ -static struct uprobe_consumer *add_consumer(struct uprobe *uprobe, - struct uprobe_consumer *consumer) +static struct uprobe_consumer * +consumer_add(struct uprobe *uprobe, struct uprobe_consumer *consumer) { down_write(&uprobe->consumer_rwsem); consumer->next = uprobe->consumers; uprobe->consumers = consumer; up_write(&uprobe->consumer_rwsem); + return consumer->next; } @@ -511,8 +525,7 @@ static struct uprobe_consumer *add_consumer(struct uprobe *uprobe, * Return true if the @consumer is deleted successfully * or return false. */ -static bool del_consumer(struct uprobe *uprobe, - struct uprobe_consumer *consumer) +static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *consumer) { struct uprobe_consumer **con; bool ret = false; @@ -526,6 +539,7 @@ static bool del_consumer(struct uprobe *uprobe, } } up_write(&uprobe->consumer_rwsem); + return ret; } @@ -557,15 +571,15 @@ static int __copy_insn(struct address_space *mapping, memcpy(insn, vaddr + off1, 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 vm_area_struct *vma, unsigned long addr) { struct address_space *mapping; - int bytes; unsigned long nbytes; + int bytes; addr &= ~PAGE_MASK; nbytes = PAGE_SIZE - addr; @@ -605,6 +619,7 @@ static int install_breakpoint(struct mm_struct *mm, struct uprobe *uprobe, return -EEXIST; addr = (unsigned long)vaddr; + if (!(uprobe->flags & UPROBES_COPY_INSN)) { ret = copy_insn(uprobe, vma, addr); if (ret) @@ -613,7 +628,7 @@ static int install_breakpoint(struct mm_struct *mm, struct uprobe *uprobe, if (is_bkpt_insn((uprobe_opcode_t *)uprobe->insn)) return -EEXIST; - ret = analyze_insn(mm, uprobe); + ret = arch_uprobes_analyze_insn(mm, uprobe); if (ret) return ret; @@ -624,8 +639,7 @@ static int install_breakpoint(struct mm_struct *mm, struct uprobe *uprobe, return ret; } -static void remove_breakpoint(struct mm_struct *mm, struct uprobe *uprobe, - loff_t vaddr) +static void remove_breakpoint(struct mm_struct *mm, struct uprobe *uprobe, loff_t vaddr) { set_orig_insn(mm, uprobe, (unsigned long)vaddr, true); } @@ -649,9 +663,11 @@ static struct vma_info *__find_next_vma_info(struct list_head *head, struct prio_tree_iter iter; struct vm_area_struct *vma; struct vma_info *tmpvi; - loff_t vaddr; - unsigned long pgoff = offset >> PAGE_SHIFT; + unsigned long pgoff; int existing_vma; + loff_t vaddr; + + pgoff = offset >> PAGE_SHIFT; vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { if (!valid_vma(vma, is_register)) @@ -659,6 +675,7 @@ static struct vma_info *__find_next_vma_info(struct list_head *head, 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; @@ -670,14 +687,15 @@ static struct vma_info *__find_next_vma_info(struct list_head *head, * 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)) { + 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; } } + return NULL; } @@ -685,11 +703,12 @@ static struct vma_info *__find_next_vma_info(struct list_head *head, * 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 list_head *head, - loff_t offset, struct address_space *mapping, - bool is_register) +static struct vma_info * +find_next_vma_info(struct list_head *head, loff_t offset, struct address_space *mapping, + bool is_register) { struct vma_info *vi, *retvi; + vi = kzalloc(sizeof(struct vma_info), GFP_KERNEL); if (!vi) return ERR_PTR(-ENOMEM); @@ -700,6 +719,7 @@ static struct vma_info *find_next_vma_info(struct list_head *head, if (!retvi) kfree(vi); + return retvi; } @@ -711,16 +731,23 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) struct vma_info *vi, *tmpvi; struct mm_struct *mm; loff_t vaddr; - int ret = 0; + int ret; mapping = uprobe->inode->i_mapping; INIT_LIST_HEAD(&try_list); - while ((vi = find_next_vma_info(&try_list, uprobe->offset, - mapping, is_register)) != NULL) { + + ret = 0; + + for (;;) { + vi = find_next_vma_info(&try_list, uprobe->offset, mapping, is_register); + if (!vi) + break; + if (IS_ERR(vi)) { ret = PTR_ERR(vi); break; } + mm = vi->mm; down_read(&mm->mmap_sem); vma = find_vma(mm, (unsigned long)vi->vaddr); @@ -755,19 +782,21 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) break; } } + list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) { list_del(&vi->probe_list); kfree(vi); } + return ret; } -static int __register_uprobe(struct uprobe *uprobe) +static int __uprobe_register(struct uprobe *uprobe) { return register_for_each_vma(uprobe, true); } -static void __unregister_uprobe(struct uprobe *uprobe) +static void __uprobe_unregister(struct uprobe *uprobe) { if (!register_for_each_vma(uprobe, false)) delete_uprobe(uprobe); @@ -776,15 +805,15 @@ static void __unregister_uprobe(struct uprobe *uprobe) } /* - * register_uprobe - register a probe + * uprobe_register - register a probe * @inode: the file in which the probe has to be placed. * @offset: offset from the start of the file. * @consumer: information on howto handle the probe.. * - * Apart from the access refcount, register_uprobe() takes a creation + * Apart from the access refcount, uprobe_register() takes a creation * refcount (thro alloc_uprobe) if and only if this @uprobe is getting * inserted into the rbtree (i.e first consumer for a @inode:@offset - * tuple). Creation refcount stops unregister_uprobe from freeing the + * tuple). Creation refcount stops uprobe_unregister from freeing the * @uprobe even before the register operation is complete. Creation * refcount is released when the last @consumer for the @uprobe * unregisters. @@ -792,28 +821,29 @@ static void __unregister_uprobe(struct uprobe *uprobe) * Return errno if it cannot successully install probes * else return 0 (success) */ -int register_uprobe(struct inode *inode, loff_t offset, - struct uprobe_consumer *consumer) +int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *consumer) { struct uprobe *uprobe; - int ret = -EINVAL; + int ret; if (!inode || !consumer || consumer->next) - return ret; + return -EINVAL; if (offset > i_size_read(inode)) - return ret; + return -EINVAL; ret = 0; mutex_lock(uprobes_hash(inode)); uprobe = alloc_uprobe(inode, offset); - if (uprobe && !add_consumer(uprobe, consumer)) { - ret = __register_uprobe(uprobe); + + if (uprobe && !consumer_add(uprobe, consumer)) { + ret = __uprobe_register(uprobe); if (ret) { uprobe->consumers = NULL; - __unregister_uprobe(uprobe); - } else + __uprobe_unregister(uprobe); + } else { uprobe->flags |= UPROBES_RUN_HANDLER; + } } mutex_unlock(uprobes_hash(inode)); @@ -823,15 +853,14 @@ int register_uprobe(struct inode *inode, loff_t offset, } /* - * unregister_uprobe - unregister a already registered probe. + * uprobe_unregister - unregister a already registered probe. * @inode: the file in which the probe has to be removed. * @offset: offset from the start of the file. * @consumer: identify which probe if multiple probes are colocated. */ -void unregister_uprobe(struct inode *inode, loff_t offset, - struct uprobe_consumer *consumer) +void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *consumer) { - struct uprobe *uprobe = NULL; + struct uprobe *uprobe; if (!inode || !consumer) return; @@ -841,15 +870,14 @@ void unregister_uprobe(struct inode *inode, loff_t offset, return; mutex_lock(uprobes_hash(inode)); - if (!del_consumer(uprobe, consumer)) - goto unreg_out; - if (!uprobe->consumers) { - __unregister_uprobe(uprobe); - uprobe->flags &= ~UPROBES_RUN_HANDLER; + if (consumer_del(uprobe, consumer)) { + if (!uprobe->consumers) { + __uprobe_unregister(uprobe); + uprobe->flags &= ~UPROBES_RUN_HANDLER; + } } -unreg_out: mutex_unlock(uprobes_hash(inode)); if (uprobe) put_uprobe(uprobe); @@ -870,6 +898,7 @@ static struct rb_node *find_least_offset_node(struct inode *inode) while (n) { uprobe = rb_entry(n, struct uprobe, rb_node); match = match_uprobe(&u, uprobe); + if (uprobe->inode == inode) close_node = n; @@ -881,6 +910,7 @@ static struct rb_node *find_least_offset_node(struct inode *inode) else n = n->rb_right; } + return close_node; } @@ -890,11 +920,13 @@ static struct rb_node *find_least_offset_node(struct inode *inode) static void build_probe_list(struct inode *inode, struct list_head *head) { struct uprobe *uprobe; - struct rb_node *n; unsigned long flags; + struct rb_node *n; spin_lock_irqsave(&uprobes_treelock, flags); + n = find_least_offset_node(inode); + for (; n; n = rb_next(n)) { uprobe = rb_entry(n, struct uprobe, rb_node); if (uprobe->inode != inode) @@ -903,6 +935,7 @@ static void build_probe_list(struct inode *inode, struct list_head *head) list_add(&uprobe->pending_list, head); atomic_inc(&uprobe->ref); } + spin_unlock_irqrestore(&uprobes_treelock, flags); } @@ -912,42 +945,44 @@ static void build_probe_list(struct inode *inode, struct list_head *head) * * Return -ve no if we fail to insert probes and we cannot * bail-out. - * Return 0 otherwise. i.e : + * Return 0 otherwise. i.e: + * * - successful insertion of probes * - (or) no possible probes to be inserted. * - (or) insertion of probes failed but we can bail-out. */ -int mmap_uprobe(struct vm_area_struct *vma) +int uprobe_mmap(struct vm_area_struct *vma) { struct list_head tmp_list; struct uprobe *uprobe, *u; struct inode *inode; - int ret = 0; + int ret; if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) - return ret; /* Bail-out */ + return 0; inode = vma->vm_file->f_mapping->host; if (!inode) - return ret; + return 0; INIT_LIST_HEAD(&tmp_list); mutex_lock(uprobes_mmap_hash(inode)); build_probe_list(inode, &tmp_list); + + ret = 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; + if (vaddr >= vma->vm_start && vaddr < vma->vm_end) { + ret = install_breakpoint(vma->vm_mm, uprobe, vma, vaddr); + /* Ignore double add: */ + if (ret == -EEXIST) + ret = 0; } - ret = install_breakpoint(vma->vm_mm, uprobe, vma, - vaddr); - if (ret == -EEXIST) - ret = 0; } put_uprobe(uprobe); } -- cgit v1.2.3