From 1dc76e6eacef271230d9ff6fd0f91824bda03f44 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 25 Apr 2014 18:06:19 +0200 Subject: [PATCH] uprobes/x86: Kill adjust_ret_addr(), simplify UPROBE_FIX_CALL logic The only insn which could have both UPROBE_FIX_IP and UPROBE_FIX_CALL was 0xe8 "call relative", and now it is handled by branch_xol_ops. So we can change default_post_xol_op(UPROBE_FIX_CALL) to simply push the address of next insn == utask->vaddr + insn.length, just we need to record insn.length into the new auprobe->def.ilen member. Note: if/when we teach branch_xol_ops to support jcxz/loopz we can remove the "correction" logic, UPROBE_FIX_IP can use the same address. Signed-off-by: Oleg Nesterov --- arch/x86/include/asm/uprobes.h | 1 + arch/x86/kernel/uprobes.c | 24 +++--------------------- 2 files changed, 4 insertions(+), 21 deletions(-) diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 9ce25ce04fee..a040d493a4f9 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -54,6 +54,7 @@ struct arch_uprobe { long riprel_target; #endif u8 fixups; + u8 ilen; } def; }; }; diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index df75913acfc0..5bcce852628a 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -418,24 +418,6 @@ static int push_ret_address(struct pt_regs *regs, unsigned long ip) return 0; } -/* - * Adjust the return address pushed by a call insn executed out of line. - */ -static int adjust_ret_addr(unsigned long sp, long correction) -{ - int rasize = sizeof_long(); - long ra; - - if (copy_from_user(&ra, (void __user *)sp, rasize)) - return -EFAULT; - - ra += correction; - if (copy_to_user((void __user *)sp, &ra, rasize)) - return -EFAULT; - - return 0; -} - static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs) { struct uprobe_task *utask = current->utask; @@ -446,10 +428,9 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs regs->ip += correction; if (auprobe->def.fixups & UPROBE_FIX_CALL) { - if (adjust_ret_addr(regs->sp, correction)) { - regs->sp += sizeof_long(); + regs->sp += sizeof_long(); + if (push_ret_address(regs, utask->vaddr + auprobe->def.ilen)) return -ERESTART; - } } /* popf; tell the caller to not touch TF */ if (auprobe->def.fixups & UPROBE_FIX_SETF) @@ -687,6 +668,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, handle_riprel_insn(auprobe, &insn); } + auprobe->def.ilen = insn.length; if (fix_ip) auprobe->def.fixups |= UPROBE_FIX_IP; if (fix_call) -- 2.30.2