From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Sun, 12 May 2019 13:17:08 +0000 (+0100)
Subject: xen/ubsan: Support for -fsanitise=builtin
X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~1981
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=0ff8c6cf906060e3612e2243aca7c3cb5e9c3b42;p=xen.git

xen/ubsan: Support for -fsanitise=builtin

This fixes the UBSAN build for GCC 8 and later.  The sanitiser checks for
passing 0 to the ctz()/clz() builtins.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/common/ubsan/ubsan.c b/xen/common/ubsan/ubsan.c
index 50a4e14fac..0fddacabda 100644
--- a/xen/common/ubsan/ubsan.c
+++ b/xen/common/ubsan/ubsan.c
@@ -518,3 +518,26 @@ void __ubsan_handle_pointer_overflow(struct pointer_overflow_data *data,
 
 	ubsan_epilogue(&flags);
 }
+
+void __ubsan_handle_invalid_builtin(struct invalid_builtin_data *data)
+{
+	unsigned long flags;
+	const char *fn = NULL;
+
+	if (suppress_report(&data->location))
+		return;
+
+	ubsan_prologue(&data->location, &flags);
+
+	switch (data->kind) {
+	case kind_ctz: fn = "ctz"; break;
+	case kind_clz: fn = "clz"; break;
+	}
+
+	if (fn)
+		pr_err("passing zero to %s(), which is not a valid argument\n", fn);
+	else
+		pr_err("Unknown kind %u\n", data->kind);
+
+	ubsan_epilogue(&flags);
+}
diff --git a/xen/common/ubsan/ubsan.h b/xen/common/ubsan/ubsan.h
index 2710cd423e..a3159040fe 100644
--- a/xen/common/ubsan/ubsan.h
+++ b/xen/common/ubsan/ubsan.h
@@ -84,6 +84,15 @@ struct pointer_overflow_data {
 	struct source_location location;
 };
 
+struct invalid_builtin_data {
+	struct source_location location;
+	unsigned char kind;
+};
+enum {
+	kind_ctz,
+	kind_clz,
+};
+
 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 typedef __int128 s_max;
 typedef unsigned __int128 u_max;