s390/kasan: use noexec and large pages

To lower memory footprint and speed up kasan initialisation detect
EDAT availability and use large pages if possible. As we know how
much memory is needed for initialisation, another simplistic large
page allocator is introduced to avoid memory fragmentation.

Since facilities list is retrieved anyhow, detect noexec support and
adjust pages attributes. Handle noexec kernel option to avoid inconsistent
kasan shadow memory pages flags.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 48 insertions, 1 deletions

diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 7f8e546400a1..9dab596be98e 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -13,6 +13,7 @@ int __bootdata(early_ipl_block_valid);
 
 unsigned long __bootdata(memory_end);
 int __bootdata(memory_end_set);
+int __bootdata(noexec_disabled);
 
 static inline int __diag308(unsigned long subcode, void *addr)
 {
@@ -145,8 +146,10 @@ void setup_boot_command_line(void)
 static char command_line_buf[COMMAND_LINE_SIZE] __section(.data);
 static void parse_mem_opt(void)
 {
-	char *args;
 	char *param, *val;
+	bool enabled;
+	char *args;
+	int rc;
 
 	args = strcpy(command_line_buf, early_command_line);
 	while (*args) {
@@ -156,6 +159,12 @@ static void parse_mem_opt(void)
 			memory_end = memparse(val, NULL);
 			memory_end_set = 1;
 		}
+
+		if (!strcmp(param, "noexec")) {
+			rc = kstrtobool(val, &enabled);
+			if (!rc && !enabled)
+				noexec_disabled = 1;
+		}
 	}
 }
 
diff --git a/arch/s390/boot/string.c b/arch/s390/boot/string.c
index 09ca9130e73a..25aca07898ba 100644
--- a/arch/s390/boot/string.c
+++ b/arch/s390/boot/string.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/ctype.h>
 #include <linux/kernel.h>
+#include <linux/errno.h>
 #include "../lib/string.c"
 
 int strncmp(const char *cs, const char *ct, size_t count)
@@ -98,3 +99,40 @@ long simple_strtol(const char *cp, char **endp, unsigned int base)
 
 	return simple_strtoull(cp, endp, base);
 }
+
+int kstrtobool(const char *s, bool *res)
+{
+	if (!s)
+		return -EINVAL;
+
+	switch (s[0]) {
+	case 'y':
+	case 'Y':
+	case '1':
+		*res = true;
+		return 0;
+	case 'n':
+	case 'N':
+	case '0':
+		*res = false;
+		return 0;
+	case 'o':
+	case 'O':
+		switch (s[1]) {
+		case 'n':
+		case 'N':
+			*res = true;
+			return 0;
+		case 'f':
+		case 'F':
+			*res = false;
+			return 0;
+		default:
+			break;
+		}
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}