linux-kernel - [patch V4 part 4 07/24] x86/traps: Split int3 handler up

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:   Tue, 05 May 2020 15:49:33 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 4 07/24] x86/traps: Split int3 handler up

For code simplicity split up the int3 handler into a kernel and user part
which makes the code flow simpler to understand.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/traps.c |   67 +++++++++++++++++++++++++++---------------------
 1 file changed, 39 insertions(+), 28 deletions(-)

--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -564,6 +564,35 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_pr
 	cond_local_irq_disable(regs);
 }
 
+static bool do_int3(struct pt_regs *regs)
+{
+	int res;
+
+#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
+	if (kgdb_ll_trap(DIE_INT3, "int3", regs, 0, X86_TRAP_BP,
+			 SIGTRAP) == NOTIFY_STOP)
+		return true;
+#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
+
+#ifdef CONFIG_KPROBES
+	if (kprobe_int3_handler(regs))
+		return true;
+#endif
+	res = notify_die(DIE_INT3, "int3", regs, 0, X86_TRAP_BP, SIGTRAP);
+
+	return res == NOTIFY_STOP;
+}
+
+static void do_int3_user(struct pt_regs *regs)
+{
+	if (do_int3(regs))
+		return;
+
+	cond_local_irq_enable(regs);
+	do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, 0, 0, NULL);
+	cond_local_irq_disable(regs);
+}
+
 DEFINE_IDTENTRY_RAW(exc_int3)
 {
 	/*
@@ -581,37 +610,19 @@ DEFINE_IDTENTRY_RAW(exc_int3)
 	 * because the INT3 could have been hit in any context including
 	 * NMI.
 	 */
-	if (user_mode(regs))
+	if (user_mode(regs)) {
 		idtentry_enter(regs);
-	else
-		nmi_enter();
-
-	instr_begin();
-#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
-	if (kgdb_ll_trap(DIE_INT3, "int3", regs, 0, X86_TRAP_BP,
-				SIGTRAP) == NOTIFY_STOP)
-		goto exit;
-#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
-
-#ifdef CONFIG_KPROBES
-	if (kprobe_int3_handler(regs))
-		goto exit;
-#endif
-
-	if (notify_die(DIE_INT3, "int3", regs, 0, X86_TRAP_BP,
-			SIGTRAP) == NOTIFY_STOP)
-		goto exit;
-
-	cond_local_irq_enable(regs);
-	do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, 0, 0, NULL);
-	cond_local_irq_disable(regs);
-
-exit:
-	instr_end();
-	if (user_mode(regs))
+		instr_begin();
+		do_int3_user(regs);
+		instr_end();
 		idtentry_exit(regs);
-	else
+	} else {
+		nmi_enter();
+		instr_begin();
+		do_int3(regs);
+		instr_end();
 		nmi_exit();
+	}
 }
 
 #ifdef CONFIG_X86_64