[PATCH v4 2/2] x86/boot/KASLR: skip the specified crashkernel region

[Pingfan Liu]

crashkernel=x@y or or =range1:size1[,range2:size2,...]@offset option may
fail to reserve the required memory region if KASLR puts kernel into the
region. To avoid this uncertainty, asking KASLR to skip the required
region.

Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Nicolas Pitre <nico@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
CC: Hari Bathini <hbathini@xxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 arch/x86/boot/compressed/kaslr.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 2e53c05..765a593 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -107,6 +107,7 @@ 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_CRASHKERNEL,
 	MEM_AVOID_MAX,
 };
 
@@ -131,6 +132,11 @@ char *skip_spaces(const char *str)
 }
 #include "../../../../lib/ctype.c"
 #include "../../../../lib/cmdline.c"
+#ifdef CONFIG_CRASH_CORE
+#define printk
+#define _BOOT_KASLR
+#include "../../../../lib/parse_crashkernel.c"
+#endif
 
 static int
 parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
@@ -292,6 +298,39 @@ static void handle_mem_options(void)
 	return;
 }
 
+static u64 mem_ram_size(void)
+{
+	struct boot_e820_entry *entry;
+	u64 total_sz = 0;
+	int i;
+
+	for (i = 0; i < boot_params->e820_entries; i++) {
+		entry = &boot_params->e820_table[i];
+		/* Skip non-RAM entries. */
+		if (entry->type != E820_TYPE_RAM)
+			continue;
+		total_sz += entry->size;
+	}
+	return total_sz;
+}
+
+/*
+ * For crashkernel=size@offset or =range1:size1[,range2:size2,...]@offset
+ * options, recording mem_avoid for them.
+ */
+static void handle_crashkernel_options(void)
+{
+	unsigned long long crash_size, crash_base = 0;
+	char *cmdline = (char *)get_cmd_line_ptr();
+	u64 total_sz = mem_ram_size();
+
+	parse_crashkernel(cmdline, total_sz, &crash_size, &crash_base);
+	if (crash_base) {
+		mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base;
+		mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size;
+	}
+}
+
 /*
  * In theory, KASLR can put the kernel anywhere in the range of [16M, 64T).
  * The mem_avoid array is used to store the ranges that need to be avoided
@@ -414,6 +453,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 
 	/* Mark the memmap regions we need to avoid */
 	handle_mem_options();
+	handle_crashkernel_options();
 
 	/* Enumerate the immovable memory regions */
 	num_immovable_mem = count_immovable_mem_regions();
-- 
2.7.4