linux-kernel - [PATCH 3/4] uprobes/x86: Cleanup the single-stepping code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 28 Oct 2012 18:39:31 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Anton Arapov <anton@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Rabin Vincent <rabin@....in>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] 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@...hat.com>
---
 arch/x86/kernel/uprobes.c |   54 +++++++++++++++-----------------------------
 1 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index aafa555..c71025b 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;
-	}
-}
-- 
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/