[PATCH v2 5/9] uprobes/x86: move the UPROBE_FIX_{RIP,IP,CALL} code at the end of pre/post hooks

From: Oleg Nesterov
Date: Fri Apr 04 2014 - 14:53:40 EST


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@xxxxxxxxxx>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Reviewed-by: Jim Keniston <jkenisto@xxxxxxxxxx>
Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/uprobes.c | 30 ++++++++++++++----------------
1 files changed, 14 insertions(+), 16 deletions(-)

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_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
*/
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 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t)
*/
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 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
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;
}

--
1.5.5.1

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