From 7ba6db2d688bdf83049a18c8e55b2d1e58e8b0bc Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 5 Apr 2014 20:05:02 +0200 Subject: uprobes/x86: Emulate unconditional relative jmp's Currently we always execute all insns out-of-line, including relative jmp's and call's. This assumes that even if regs->ip points to nowhere after the single-step, default_post_xol_op(UPROBE_FIX_IP) logic will update it correctly. However, this doesn't work if this regs->ip == xol_vaddr + insn_offset is not canonical. In this case CPU generates #GP and general_protection() kills the task which tries to execute this insn out-of-line. Now that we have uprobe_xol_ops we can teach uprobes to emulate these insns and solve the problem. This patch adds branch_xol_ops which has a single branch_emulate_op() hook, so far it can only handle rel8/32 relative jmp's. TODO: move ->fixup into the union along with rip_rela_target_address. Signed-off-by: Oleg Nesterov Reported-by: Jonathan Lebon Reviewed-by: Jim Keniston --- arch/x86/include/asm/uprobes.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'arch/x86/include/asm/uprobes.h') diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 9f8210bcbb49..e9fd4d5537ed 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -44,9 +44,15 @@ struct arch_uprobe { u16 fixups; const struct uprobe_xol_ops *ops; + union { #ifdef CONFIG_X86_64 - unsigned long rip_rela_target_address; + unsigned long rip_rela_target_address; #endif + struct { + s32 offs; + u8 ilen; + } branch; + }; }; struct arch_uprobe_task { -- cgit