commit 34e7317d6ae8f6111ac449444f22e14f4a14ebfd
author Oleg Nesterov <oleg@redhat.com> Mon Mar 31 19:38:09 2014 +0200
committer Oleg Nesterov <oleg@redhat.com> Thu Apr 17 21:58:18 2014 +0200
tree 06a98d253f4c9de9ae8f4af73209727ec2a1589e
parent d20737c07a1063d681fe9fb86f3da369da1edab7

uprobes/x86: move the UPROBE_FIX_{RIP,IP,CALL} code at the end of pre/post hooks

No functional changes. Preparation to simplify the review of the next
change. Just reorder the code in arch_uprobe_pre/post_xol() functions
so that UPROBE_FIX_{RIP_*,IP,CALL} logic goes to the end.

Also change arch_uprobe_pre_xol() to use utask instead of autask, to
make the code more symmetrical with arch_uprobe_post_xol().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

arch/x86/kernel/uprobes.c

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index c52c30f..3bb4198 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -474,19 +474,18 @@
  */
 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
-	struct arch_uprobe_task *autask;
+	struct uprobe_task *utask = current->utask;
 
-	autask = &current->utask->autask;
-	autask->saved_trap_nr = current->thread.trap_nr;
+	regs->ip = utask->xol_vaddr;
+	utask->autask.saved_trap_nr = current->thread.trap_nr;
 	current->thread.trap_nr = UPROBE_TRAP_NR;
-	regs->ip = current->utask->xol_vaddr;
-	pre_xol_rip_insn(auprobe, regs, autask);
 
-	autask->saved_tf = !!(regs->flags & X86_EFLAGS_TF);
+	utask->autask.saved_tf = !!(regs->flags & X86_EFLAGS_TF);
 	regs->flags |= X86_EFLAGS_TF;
 	if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))
 		set_task_blockstep(current, false);
 
+	pre_xol_rip_insn(auprobe, regs, &utask->autask);
 	return 0;
 }
 
@@ -560,22 +559,13 @@
  */
 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
-	struct uprobe_task *utask;
+	struct uprobe_task *utask = current->utask;
 	long correction;
 	int result = 0;
 
 	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
 
-	utask = current->utask;
 	current->thread.trap_nr = utask->autask.saved_trap_nr;
-	correction = (long)(utask->vaddr - utask->xol_vaddr);
-	handle_riprel_post_xol(auprobe, regs, &correction);
-	if (auprobe->fixups & UPROBE_FIX_IP)
-		regs->ip += correction;
-
-	if (auprobe->fixups & UPROBE_FIX_CALL)
-		result = adjust_ret_addr(regs->sp, correction);
-
 	/*
 	 * arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
 	 * so we can get an extra SIGTRAP if we do not clear TF. We need
@@ -586,6 +576,14 @@
 	else if (!(auprobe->fixups & UPROBE_FIX_SETF))
 		regs->flags &= ~X86_EFLAGS_TF;
 
+	correction = (long)(utask->vaddr - utask->xol_vaddr);
+	handle_riprel_post_xol(auprobe, regs, &correction);
+	if (auprobe->fixups & UPROBE_FIX_IP)
+		regs->ip += correction;
+
+	if (auprobe->fixups & UPROBE_FIX_CALL)
+		result = adjust_ret_addr(regs->sp, correction);
+
 	return result;
 }