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Date: Tue, 12 Dec 2017 20:07:02 +0800
From: Chao Fan <fanc.fnst@...fujitsu.com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>,
<tglx@...utronix.de>, <mingo@...hat.com>, <bhe@...hat.com>,
<keescook@...omium.org>, <yasu.isimatu@...il.com>
CC: <indou.takao@...fujitsu.com>, <caoj.fnst@...fujitsu.com>,
<douly.fnst@...fujitsu.com>, Chao Fan <fanc.fnst@...fujitsu.com>
Subject: [PATCH v4 1/4] kaslr: add immovable_mem=nn[KMG]@ss[KMG] to specify extracting memory
In current code, kaslr may choose the memory region in movable
nodes to extract kernel, which will make the nodes can't be hot-removed.
To solve it, we can specify the memory region in immovable node.
Create immovable_mem to store the regions in immovable_mem, where should
be chosen by kaslr.
Also change the "handle_mem_memmap" to "handle_mem_filter", since
it will not only handle memmap parameter now.
Since "immovable_mem=" only works with "movable_node", so "immovable_mem="
doesn't work alone. If specify "movable_node" without "immovable_mem=",
disable KASLR.
Multiple regions can be specified, comma delimited.
Considering the usage of memory, only support for 4 regions.
4 regions contains 2 nodes at least, enough for kernel to extract.
Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
---
arch/x86/boot/compressed/kaslr.c | 112 +++++++++++++++++++++++++++++++++++++--
1 file changed, 109 insertions(+), 3 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 8199a6187251..40f299d8cd34 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -108,6 +108,19 @@ enum mem_avoid_index {
static struct mem_vector mem_avoid[MEM_AVOID_MAX];
+#ifdef CONFIG_MEMORY_HOTPLUG
+/* Only supporting at most 4 immovable memory regions with kaslr */
+#define MAX_IMMOVABLE_MEM 4
+
+static bool lack_immovable_mem;
+
+/* Store the memory regions in immovable node */
+static struct mem_vector immovable_mem[MAX_IMMOVABLE_MEM];
+
+/* The immovable regions user specify, not more than 4 */
+static int num_immovable_region;
+#endif
+
static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two)
{
/* Item one is entirely before item two. */
@@ -206,17 +219,99 @@ static void mem_avoid_memmap(char *str)
memmap_too_large = true;
}
-static int handle_mem_memmap(void)
+#ifdef CONFIG_MEMORY_HOTPLUG
+static int parse_immovable_mem(char *p,
+ unsigned long long *start,
+ unsigned long long *size)
+{
+ char *oldp;
+
+ if (!p)
+ return -EINVAL;
+
+ oldp = p;
+ *size = memparse(p, &p);
+ if (p == oldp)
+ return -EINVAL;
+
+ switch (*p) {
+ case '@':
+ *start = memparse(p + 1, &p);
+ return 0;
+ default:
+ /*
+ * If w/o offset, only size specified, immovable_mem=nn[KMG]
+ * has the same behaviour as immovable_mem=nn[KMG]@0. It means
+ * the region starts from 0.
+ */
+ *start = 0;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static void parse_immovable_mem_regions(char *str)
+{
+ static int i;
+
+ while (str && (i < MAX_IMMOVABLE_MEM)) {
+ int rc;
+ unsigned long long start, size;
+ char *k = strchr(str, ',');
+
+ if (k)
+ *k++ = 0;
+
+ rc = parse_immovable_mem(str, &start, &size);
+ if (rc < 0)
+ break;
+ str = k;
+
+ immovable_mem[i].start = start;
+ immovable_mem[i].size = size;
+ i++;
+ }
+ num_immovable_region = i;
+}
+#else
+static inline void parse_immovable_mem_regions(char *str)
+{
+}
+#endif
+
+static int handle_mem_filter(void)
{
char *args = (char *)get_cmd_line_ptr();
size_t len = strlen((char *)args);
+ bool exist_movable_node = false;
char *tmp_cmdline;
char *param, *val;
u64 mem_size;
- if (!strstr(args, "memmap=") && !strstr(args, "mem="))
+ if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
+ !strstr(args, "movable_node"))
return 0;
+#ifdef CONFIG_MEMORY_HOTPLUG
+ if (strstr(args, "movable_node")) {
+ /*
+ * Confirm "movable_node" specified, otherwise
+ * "immovable_mem=" doesn't work.
+ */
+ exist_movable_node = true;
+
+ /*
+ * If only specify "movable_node" without "immovable_mem=",
+ * disable KASLR.
+ */
+ if (!strstr(args, "immovable_mem=")) {
+ lack_immovable_mem = true;
+ return 0;
+ }
+ }
+#endif
+
tmp_cmdline = malloc(len + 1);
if (!tmp_cmdline)
error("Failed to allocate space for tmp_cmdline");
@@ -239,6 +334,9 @@ static int handle_mem_memmap(void)
if (!strcmp(param, "memmap")) {
mem_avoid_memmap(val);
+ } else if (!strcmp(param, "immovable_mem=") &&
+ exist_movable_node) {
+ parse_immovable_mem_regions(val);
} else if (!strcmp(param, "mem")) {
char *p = val;
@@ -378,7 +476,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
/* We don't need to set a mapping for setup_data. */
/* Mark the memmap regions we need to avoid */
- handle_mem_memmap();
+ handle_mem_filter();
#ifdef CONFIG_X86_VERBOSE_BOOTUP
/* Make sure video RAM can be used. */
@@ -673,6 +771,14 @@ static unsigned long find_random_phys_addr(unsigned long minimum,
return 0;
}
+#ifdef CONFIG_MEMORY_HOTPLUG
+ /* Check if specify "movable_node" without "immovable_mem=". */
+ if (lack_immovable_mem) {
+ debug_putstr("Fail KASLR when movable_node specified without immovable_mem=.\n");
+ return 0;
+ }
+#endif
+
/* Make sure minimum is aligned. */
minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
--
2.14.3
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