uprobes/x86: Cleanup the single-stepping code

No functional changes.

Now that default arch_uprobe_enable/disable_step() helpers do nothing,
x86 has no reason to reimplement them. Change arch_uprobe_*_xol() hooks
to do the necessary work and remove the x86-specific hooks.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

1 files changed, 19 insertions, 35 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index aafa5557b396..c71025b67462 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -478,6 +478,11 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
         regs->ip = current->utask->xol_vaddr;
         pre_xol_rip_insn(auprobe, regs, autask);
 
+        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);
+
         return 0;
 }
 
@@ -603,6 +608,16 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
         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
+         * to examine the opcode to make it right.
+         */
+        if (utask->autask.saved_tf)
+                send_sig(SIGTRAP, current, 0);
+        else if (!(auprobe->fixups & UPROBE_FIX_SETF))
+                regs->flags &= ~X86_EFLAGS_TF;
+
         return result;
 }
 
@@ -647,6 +662,10 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
         current->thread.trap_nr = utask->autask.saved_trap_nr;
         handle_riprel_post_xol(auprobe, regs, NULL);
         instruction_pointer_set(regs, utask->vaddr);
+
+        /* clear TF if it was set by us in arch_uprobe_pre_xol() */
+        if (!utask->autask.saved_tf)
+                regs->flags &= ~X86_EFLAGS_TF;
 }
 
 /*
@@ -676,38 +695,3 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
                 send_sig(SIGTRAP, current, 0);
         return ret;
 }
-
-void arch_uprobe_enable_step(struct arch_uprobe *auprobe)
-{
-        struct task_struct *task = current;
-        struct arch_uprobe_task *autask = &task->utask->autask;
-        struct pt_regs *regs = task_pt_regs(task);
-
-        autask->saved_tf = !!(regs->flags & X86_EFLAGS_TF);
-
-        regs->flags |= X86_EFLAGS_TF;
-        if (test_tsk_thread_flag(task, TIF_BLOCKSTEP))
-                set_task_blockstep(task, false);
-}
-
-void arch_uprobe_disable_step(struct arch_uprobe *auprobe)
-{
-        struct task_struct *task = current;
-        struct arch_uprobe_task *autask = &task->utask->autask;
-        bool trapped = (task->utask->state == UTASK_SSTEP_TRAPPED);
-        struct pt_regs *regs = task_pt_regs(task);
-        /*
-         * The state of TIF_BLOCKSTEP was not saved so we can get an extra
-         * SIGTRAP if we do not clear TF. We need to examine the opcode to
-         * make it right.
-         */
-        if (unlikely(trapped)) {
-                if (!autask->saved_tf)
-                        regs->flags &= ~X86_EFLAGS_TF;
-        } else {
-                if (autask->saved_tf)
-                        send_sig(SIGTRAP, task, 0);
-                else if (!(auprobe->fixups & UPROBE_FIX_SETF))
-                        regs->flags &= ~X86_EFLAGS_TF;
-        }
-}