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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>
This commit is contained in:
Oleg Nesterov 2014-04-21 20:39:56 +02:00
parent 6ded5f3848
commit 220ef8dc9a
1 changed files with 12 additions and 8 deletions
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20
arch/x86/kernel/uprobes.c
View File

@ -441,6 +441,9 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
return -ERESTART; return -ERESTART;
} }
} }
/* popf; tell the caller to not touch TF */
if (auprobe->fixups & UPROBE_FIX_SETF)
utask->autask.saved_tf = true;
return 0; return 0;
} }
@ -757,15 +760,15 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t)
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{ {
struct uprobe_task *utask = current->utask; 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); WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
current->thread.trap_nr = utask->autask.saved_trap_nr; current->thread.trap_nr = utask->autask.saved_trap_nr;
if (auprobe->ops->post_xol) { if (auprobe->ops->post_xol) {
int err = auprobe->ops->post_xol(auprobe, regs); err = auprobe->ops->post_xol(auprobe, regs);
if (err) { if (err) {
if (!utask->autask.saved_tf)
regs->flags &= ~X86_EFLAGS_TF;
/* /*
* Restore ->ip for restart or post mortem analysis. * Restore ->ip for restart or post mortem analysis.
* ->post_xol() must not return -ERESTART unless this * ->post_xol() must not return -ERESTART unless this
@ -773,8 +776,8 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
*/ */
regs->ip = utask->vaddr; regs->ip = utask->vaddr;
if (err == -ERESTART) if (err == -ERESTART)
return 0; err = 0;
return err; send_sigtrap = false;
} }
} }
/* /*
@ -782,12 +785,13 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
* so we can get an extra SIGTRAP if we do not clear TF. We need * so we can get an extra SIGTRAP if we do not clear TF. We need
* to examine the opcode to make it right. * to examine the opcode to make it right.
*/ */
if (utask->autask.saved_tf) if (send_sigtrap)
send_sig(SIGTRAP, current, 0); send_sig(SIGTRAP, current, 0);
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
if (!utask->autask.saved_tf)
regs->flags &= ~X86_EFLAGS_TF; regs->flags &= ~X86_EFLAGS_TF;
return 0; return err;
} }
/* callback routine for handling exceptions. */ /* callback routine for handling exceptions. */