From ed6f6a50dc5f183c53e7b3b7fed4794bc50d9aa7 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 23 Sep 2012 21:30:44 +0200 Subject: uprobes: Kill set_orig_insn()->is_swbp_at_addr() Unlike set_swbp(), set_orig_insn()->is_swbp_at_addr() makes sense, although it can't prevent all confusions. But the usage of is_swbp_at_addr() is equally confusing, and it adds the extra get_user_pages() we can avoid. This patch removes set_orig_insn()->is_swbp_at_addr() but changes write_opcode() to do the necessary checks before replace_page(). Perhaps it also makes sense to ensure PAGE_MAPPING_ANON in unregister case. find_active_uprobe() becomes the only user of is_swbp_at_addr(), we can change its semantics. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- kernel/events/uprobes.c | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index b6f0f716a88..9248ee76b4b 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -190,6 +190,25 @@ static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t kunmap_atomic(kaddr); } +static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) +{ + uprobe_opcode_t old_opcode; + bool is_swbp; + + copy_opcode(page, vaddr, &old_opcode); + is_swbp = is_swbp_insn(&old_opcode); + + if (is_swbp_insn(new_opcode)) { + if (is_swbp) /* register: already installed? */ + return 0; + } else { + if (!is_swbp) /* unregister: was it changed by us? */ + return -EINVAL; + } + + return 1; +} + /* * NOTE: * Expect the breakpoint instruction to be the smallest size instruction for @@ -226,6 +245,10 @@ retry: if (ret <= 0) return ret; + ret = verify_opcode(old_page, vaddr, &opcode); + if (ret <= 0) + goto put_old; + ret = -ENOMEM; new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); if (!new_page) @@ -311,15 +334,6 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned int __weak set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { - int result; - - result = is_swbp_at_addr(mm, vaddr); - if (!result) - return -EINVAL; - - if (result != 1) - return result; - return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); } -- cgit v1.2.3-18-g5258