[PATCH v12 4/5] x86/boot: Parse SRAT table from RSDP and store immovable memory

[Chao Fan <fanc.fnst@cn.fujitsu.com>]

To fix the conflict between KASLR and memory-hotremove, SRAT table
should be parsed by RSDP pointer, then find the immovable
memory regions and store them in an array called immovable_mem[].
The array called immovable_mem[] will extern to KASLR, then
KASLR will avoid to extract kernel to these regions.

Add 'CONFIG_EARLY_PARSE_RSDP' which depends on RANDOMIZE_BASE &&
MEMORY_HOTREMOVE, cause only when both KASLR and memory-hotremove
are enabled, RSDP needs to be parsed in compressed period.

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
---
 arch/x86/Kconfig                  |  10 +++
 arch/x86/boot/compressed/Makefile |   2 +
 arch/x86/boot/compressed/acpitb.c | 125 ++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/kaslr.c  |   4 -
 arch/x86/boot/compressed/misc.h   |  20 +++++
 5 files changed, 157 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a29d49ef4d56..bc775968557b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2146,6 +2146,16 @@ config X86_NEED_RELOCS
 	def_bool y
 	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
 
+config CONFIG_EARLY_PARSE_RSDP
+	bool "Parse RSDP pointer on compressed period for KASLR"
+	def_bool n
+	depends on RANDOMIZE_BASE && MEMORY_HOTREMOVE
+	help
+	  This option parses RSDP pointer in compressed period. Works
+	  for KASLR to get memory information by SRAT table and choose
+	  immovable memory to extract kernel.
+	  Say Y if you want to use both KASLR and memory-hotremove.
+
 config PHYSICAL_ALIGN
 	hex "Alignment value to which kernel should be aligned"
 	default "0x200000"
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 466f66c8a7f8..4cbfb58bf083 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -84,6 +84,8 @@ ifdef CONFIG_X86_64
 	vmlinux-objs-y += $(obj)/pgtable_64.o
 endif
 
+vmlinux-objs-$(CONFIG_EARLY_PARSE_RSDP) += $(obj)/acpitb.o
+
 $(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone
 
 vmlinux-objs-$(CONFIG_EFI_STUB) += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \
diff --git a/arch/x86/boot/compressed/acpitb.c b/arch/x86/boot/compressed/acpitb.c
index 82d27c4b8978..023b33d0cd3b 100644
--- a/arch/x86/boot/compressed/acpitb.c
+++ b/arch/x86/boot/compressed/acpitb.c
@@ -195,3 +195,128 @@ static acpi_physical_address bios_get_rsdp_addr(void)
 		return (acpi_physical_address)address;
 	}
 }
+
+/* Used to determine RSDP table, based on acpi_os_get_root_pointer(). */
+static acpi_physical_address get_rsdp_addr(void)
+{
+	acpi_physical_address pa = 0;
+
+	pa = get_acpi_rsdp();
+
+	if (!pa)
+		pa = efi_get_rsdp_addr();
+
+	if (!pa)
+		pa = bios_get_rsdp_addr();
+
+	return pa;
+}
+
+/* Compute SRAT table from RSDP. */
+static struct acpi_table_header *get_acpi_srat_table(void)
+{
+	acpi_physical_address acpi_table;
+	acpi_physical_address root_table;
+	struct acpi_table_header *header;
+	struct acpi_table_rsdp *rsdp;
+	int num_entries;
+	char arg[10];
+	u8 *entry;
+	u32 size;
+	u32 len;
+
+	rsdp = (struct acpi_table_rsdp *)get_rsdp_addr();
+	if (!rsdp)
+		return NULL;
+
+	/* Get RSDT or XSDT from RSDP. */
+	if (!(cmdline_find_option("acpi", arg, sizeof(arg)) == 4 &&
+	    !strncmp(arg, "rsdt", 4)) &&
+	    rsdp->xsdt_physical_address &&
+	    rsdp->revision > 1) {
+		root_table = rsdp->xsdt_physical_address;
+		size = ACPI_XSDT_ENTRY_SIZE;
+	} else {
+		root_table = rsdp->rsdt_physical_address;
+		size = ACPI_RSDT_ENTRY_SIZE;
+	}
+
+	/* Get ACPI root table from RSDT or XSDT.*/
+	header = (struct acpi_table_header *)root_table;
+	if (!header)
+		return NULL;
+
+	len = header->length;
+	num_entries = (u32)((len - sizeof(struct acpi_table_header)) / size);
+	if (num_entries > MAX_ACPI_SIG)
+		return NULL;
+
+	entry = ACPI_ADD_PTR(u8, header, sizeof(struct acpi_table_header));
+
+	while (num_entries--) {
+		u64 address64;
+
+		if (size == ACPI_RSDT_ENTRY_SIZE)
+			acpi_table = ((acpi_physical_address)
+				      (*ACPI_CAST_PTR(u32, entry)));
+		else {
+			*(u64 *)(void *)&address64 = *(u64 *)(void *)entry;
+			acpi_table = (acpi_physical_address) address64;
+		}
+
+		if (acpi_table) {
+			header = (struct acpi_table_header *)acpi_table;
+
+			if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
+				return header;
+		}
+		entry += size;
+	}
+	return NULL;
+}
+
+/*
+ * According to ACPI table, filter the immovable memory regions
+ * and store them in immovable_mem[].
+ */
+void get_immovable_mem(void)
+{
+	struct acpi_table_header *table_header;
+	struct acpi_subtable_header *table;
+	struct acpi_srat_mem_affinity *ma;
+	unsigned long table_end;
+	char arg[10];
+	int i = 0;
+
+	if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
+	    !strncmp(arg, "off", 3))
+		return;
+
+	table_header = get_acpi_srat_table();
+	if (!table_header)
+		return;
+
+	table_end = (unsigned long)table_header + table_header->length;
+	table = (struct acpi_subtable_header *)
+		((unsigned long)table_header + sizeof(struct acpi_table_srat));
+
+	while (((unsigned long)table) +
+		       sizeof(struct acpi_subtable_header) < table_end) {
+		if (table->type == ACPI_SRAT_TYPE_MEMORY_AFFINITY) {
+			ma = (struct acpi_srat_mem_affinity *)table;
+			if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE)) {
+				immovable_mem[i].start = ma->base_address;
+				immovable_mem[i].size = ma->length;
+				i++;
+			}
+
+			if (i >= MAX_NUMNODES*2) {
+				debug_putstr("Too many immovable memory regions, aborting.\n");
+				return;
+			}
+		}
+		table = (struct acpi_subtable_header *)
+			((unsigned long)table + table->length);
+	}
+	num_immovable_mem = i;
+}
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 9ed9709d9947..b251572e77af 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -87,10 +87,6 @@ static unsigned long get_boot_seed(void)
 #define KASLR_COMPRESSED_BOOT
 #include "../../lib/kaslr.c"
 
-struct mem_vector {
-	unsigned long long start;
-	unsigned long long size;
-};
 
 /* Only supporting at most 4 unusable memmap regions with kaslr */
 #define MAX_MEMMAP_REGIONS	4
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 809c31effa4b..d94e2a419c13 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -77,6 +77,11 @@ void choose_random_location(unsigned long input,
 			    unsigned long *output,
 			    unsigned long output_size,
 			    unsigned long *virt_addr);
+struct mem_vector {
+	unsigned long long start;
+	unsigned long long size;
+};
+
 /* cpuflags.c */
 bool has_cpuflag(int flag);
 #else
@@ -118,5 +123,20 @@ void set_sev_encryption_mask(void);
 #endif
 
 /* acpitb.c */
+#ifdef CONFIG_RANDOMIZE_BASE
+/* Store the amount of immovable memory regions */
+int num_immovable_mem;
+#endif
+
+#ifdef CONFIG_EARLY_PARSE_RSDP
+void get_immovable_mem(void);
+/* There are 72 kinds of ACPI_SIG in head file of ACPI. */
+#define MAX_ACPI_SIG	72
+#else
+static void get_immovable_mem(void)
+{
+}
+#endif
+
 #define BOOT_STRING
 extern int kstrtoull(const char *s, unsigned int base, unsigned long long *res);
-- 
2.19.1