linux-kernel - [RESEND][patch V3 04/23] kprobes: Prevent probes in .noinstr.text section

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Date:   Fri, 20 Mar 2020 19:00:00 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Paul McKenney <paulmck@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Subject: [RESEND][patch V3 04/23] kprobes: Prevent probes in .noinstr.text section

Instrumentation is forbidden in the .noinstr.text section. Make kprobes
respect this.

This lacks support for .noinstr.text sections in modules, which is required
to handle VMX and SVM.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/kprobes.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1443,10 +1443,21 @@ static bool __within_kprobe_blacklist(un
 	return false;
 }
 
+/* Functions in .noinstr.text must not be probed */
+static bool within_noinstr_text(unsigned long addr)
+{
+	/* FIXME: Handle module .noinstr.text */
+	return addr >= (unsigned long)__noinstr_text_start &&
+	       addr < (unsigned long)__noinstr_text_end;
+}
+
 bool within_kprobe_blacklist(unsigned long addr)
 {
 	char symname[KSYM_NAME_LEN], *p;
 
+	if (within_noinstr_text(addr))
+		return true;
+
 	if (__within_kprobe_blacklist(addr))
 		return true;