[PATCH v6 5/5] kaslr: add kaslr_mem=nn[KMG]!ss[KMG] to avoid memory regions

[Chao Fan]

In current code, kaslr choose the only suitable memory region for 1G
huge page, so the no suitable region for 1G huge page. So add this
feature to store these regions.

Of coure, we can use memmap= to do this job. But memmap will be handled
in the later code, but kaslr_mem= only works in this period.

It can help users to avoid more memory regions, not only the 1G huge
huge page issue.

Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/kaslr.c | 56 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index fc531fa1f10c..c71189cf8d56 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -95,6 +95,18 @@ static bool memmap_too_large;
 /* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
 unsigned long long mem_limit = ULLONG_MAX;
 
+/*
+ * Only supporting at most 4 unusable memory regions for
+ * "kaslr_mem=nn[KMG]!ss[KMG]"
+ */
+#define MAX_KASLR_MEM_AVOID	4
+
+static bool kaslr_mem_avoid_too_large;
+
+enum kaslr_mem_type {
+	CMD_MEM_USABLE = 1,
+	CMD_MEM_AVOID,
+};
 
 enum mem_avoid_index {
 	MEM_AVOID_ZO_RANGE = 0,
@@ -103,6 +115,8 @@ enum mem_avoid_index {
 	MEM_AVOID_BOOTPARAMS,
 	MEM_AVOID_MEMMAP_BEGIN,
 	MEM_AVOID_MEMMAP_END = MEM_AVOID_MEMMAP_BEGIN + MAX_MEMMAP_REGIONS - 1,
+	MEM_AVOID_KASLR_MEM_BEGIN,
+	MEM_AVOID_KASLR_MEM_END = MEM_AVOID_KASLR_MEM_BEGIN + MAX_KASLR_MEM_AVOID - 1,
 	MEM_AVOID_MAX,
 };
 
@@ -217,7 +231,8 @@ static void mem_avoid_memmap(char *str)
 
 static int parse_kaslr_mem(char *p,
 			   unsigned long long *start,
-			   unsigned long long *size)
+			   unsigned long long *size,
+			   int *cmd_type)
 {
 	char *oldp;
 
@@ -230,8 +245,13 @@ static int parse_kaslr_mem(char *p,
 		return -EINVAL;
 
 	switch (*p) {
+	case '!' :
+		*start = memparse(p + 1, &p);
+		*cmd_type = CMD_MEM_AVOID;
+		return 0;
 	case '@':
 		*start = memparse(p + 1, &p);
+		*cmd_type = CMD_MEM_USABLE;
 		return 0;
 	default:
 		/*
@@ -240,6 +260,7 @@ static int parse_kaslr_mem(char *p,
 		 * the region starts from 0.
 		 */
 		*start = 0;
+		*cmd_type = CMD_MEM_USABLE;
 		return 0;
 	}
 
@@ -248,26 +269,44 @@ static int parse_kaslr_mem(char *p,
 
 static void parse_kaslr_mem_regions(char *str)
 {
-	static int i;
+	static int i = 0, j = 0;
+	int cmd_type = 0;
 
 	while (str && (i < MAX_KASLR_MEM_USABLE)) {
 		int rc;
 		unsigned long long start, size;
 		char *k = strchr(str, ',');
 
+		if (i >= MAX_KASLR_MEM_USABLE && j >= MAX_KASLR_MEM_AVOID)
+			break;
+
 		if (k)
 			*k++ = 0;
 
-		rc = parse_kaslr_mem(str, &start, &size);
+		rc = parse_kaslr_mem(str, &start, &size, &cmd_type);
 		if (rc < 0)
 			break;
 		str = k;
 
-		mem_usable[i].start = start;
-		mem_usable[i].size = size;
-		i++;
+		if (cmd_type == CMD_MEM_USABLE) {
+			if (i >= MAX_KASLR_MEM_USABLE)
+				continue;
+			mem_usable[i].start = start;
+			mem_usable[i].size = size;
+			i++;
+		} else if (cmd_type == CMD_MEM_AVOID) {
+			if (j >= MAX_KASLR_MEM_AVOID)
+				continue;
+			mem_avoid[MEM_AVOID_KASLR_MEM_BEGIN + j].start = start;
+			mem_avoid[MEM_AVOID_KASLR_MEM_BEGIN + j].size = size;
+			j++;
+		}
 	}
 	num_usable_region = i;
+
+	/* More than 4 kaslr_mem avoid, fail kaslr */
+	if ((j >= MAX_KASLR_MEM_AVOID) && str)
+		kaslr_mem_avoid_too_large = true;
 }
 
 static int handle_mem_filter(void)
@@ -799,6 +838,11 @@ static unsigned long find_random_phys_addr(unsigned long minimum,
 		return 0;
 	}
 
+	/* Check if we had too many kaslr_mem avoid. */
+	if (kaslr_mem_avoid_too_large) {
+		debug_putstr("Aborted memory entries scan (more than 4 kaslr_mem avoid args)!\n");
+		return 0;
+	}
 	/* Make sure minimum is aligned. */
 	minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
 
-- 
2.14.3