uprobes/x86: Move UPROBE_FIX_SETF logic from arch_uprobe_post_xol() to default_post_xol_op()
UPROBE_FIX_SETF is only needed to handle "popf" correctly but it is
processed by the generic arch_uprobe_post_xol() code. This doesn't
allows us to make ->fixups private for default_xol_ops.
1 Change default_post_xol_op(UPROBE_FIX_SETF) to set ->saved_tf = T.
"popf" always reads the flags from stack, it doesn't matter if TF
was set or not before single-step. Ignoring the naming, this is
even more logical, "saved_tf" means "owned by application" and we
do not own this flag after "popf".
2. Change arch_uprobe_post_xol() to save ->saved_tf into the local
"bool send_sigtrap" before ->post_xol().
3. Change arch_uprobe_post_xol() to ignore UPROBE_FIX_SETF and just
check ->saved_tf after ->post_xol().
With this patch ->fixups and ->rip_rela_target_address are only used
by default_xol_ops hooks, we are ready to remove them from the common
part of arch_uprobe.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 2efb93f..b2bca29 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -441,6 +441,9 @@
return -ERESTART;
}
}
+ /* popf; tell the caller to not touch TF */
+ if (auprobe->fixups & UPROBE_FIX_SETF)
+ utask->autask.saved_tf = true;
return 0;
}
@@ -757,15 +760,15 @@
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
+ bool send_sigtrap = utask->autask.saved_tf;
+ int err = 0;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
current->thread.trap_nr = utask->autask.saved_trap_nr;
if (auprobe->ops->post_xol) {
- int err = auprobe->ops->post_xol(auprobe, regs);
+ err = auprobe->ops->post_xol(auprobe, regs);
if (err) {
- if (!utask->autask.saved_tf)
- regs->flags &= ~X86_EFLAGS_TF;
/*
* Restore ->ip for restart or post mortem analysis.
* ->post_xol() must not return -ERESTART unless this
@@ -773,8 +776,8 @@
*/
regs->ip = utask->vaddr;
if (err == -ERESTART)
- return 0;
- return err;
+ err = 0;
+ send_sigtrap = false;
}
}
/*
@@ -782,12 +785,13 @@
* so we can get an extra SIGTRAP if we do not clear TF. We need
* to examine the opcode to make it right.
*/
- if (utask->autask.saved_tf)
+ if (send_sigtrap)
send_sig(SIGTRAP, current, 0);
- else if (!(auprobe->fixups & UPROBE_FIX_SETF))
+
+ if (!utask->autask.saved_tf)
regs->flags &= ~X86_EFLAGS_TF;
- return 0;
+ return err;
}
/* callback routine for handling exceptions. */