[PATCH v7 1/3] x86/boot: Add acpitb.c to parse acpi tables

[Chao Fan]

There is a bug that kaslr may randomly chooses some positions
which are located in movable memory regions. This will break memory
hotplug feature and make the movable memory chosen by KASLR can't be
removed. So dig SRAT table from ACPI tables to get memory information.

Imitate the ACPI code of parsing ACPI tables to dig and read ACPI
tables. Since some operations are not needed here, functions are
simplified. Functions will be used to dig only SRAT tables to get
information of memory, so that KASLR can the memory in immovable node.

And also, these functions won't influence the initialization of
ACPI after start_kernel().

Since use physical address directely, so acpi_os_map_memory()
and acpi_os_unmap_memory() are not needed.

Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/Makefile |   4 +
 arch/x86/boot/compressed/acpitb.c | 401 ++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/misc.h   |   8 +
 3 files changed, 413 insertions(+)
 create mode 100644 arch/x86/boot/compressed/acpitb.c

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 28764dacf018..394d7d93da7a 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -83,6 +83,10 @@ ifdef CONFIG_X86_64
 	vmlinux-objs-y += $(obj)/pgtable_64.o
 endif
 
+ifdef CONFIG_MEMORY_HOTREMOVE
+vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/acpitb.o
+endif
+
 $(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
new file mode 100644
index 000000000000..109c59b82cde
--- /dev/null
+++ b/arch/x86/boot/compressed/acpitb.c
@@ -0,0 +1,401 @@
+// SPDX-License-Identifier: GPL-2.0
+#define BOOT_CTYPE_H
+#include "misc.h"
+#include "error.h"
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+#include <linux/numa.h>
+#include <linux/acpi.h>
+
+extern unsigned long get_cmd_line_ptr(void);
+
+#define STATIC
+#include <linux/decompress/mm.h>
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+struct mem_vector {
+	unsigned long long start;
+	unsigned long long size;
+};
+/* Store the immovable memory regions */
+struct mem_vector immovable_mem[MAX_NUMNODES*2];
+#endif
+
+#ifdef CONFIG_EFI
+/* Search EFI table for rsdp table. */
+static bool efi_get_rsdp_addr(acpi_physical_address *rsdp_addr)
+{
+	efi_system_table_t *systab;
+	bool find_rsdp = false;
+	bool efi_64 = false;
+	void *config_tables;
+	struct efi_info *e;
+	char *sig;
+	int size;
+	int i;
+
+	e = &boot_params->efi_info;
+	sig = (char *)&e->efi_loader_signature;
+
+	if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4))
+		efi_64 = true;
+	else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4))
+		efi_64 = false;
+	else {
+		debug_putstr("Wrong EFI loader signature.\n");
+		return false;
+	}
+
+	/* Get systab from boot params. Based on efi_init(). */
+#ifdef CONFIG_X86_32
+	if (e->efi_systab_hi || e->efi_memmap_hi) {
+		debug_putstr("Table located above 4GB, disabling EFI.\n");
+		return false;
+	}
+	systab = (efi_system_table_t *)e->efi_systab;
+#else
+	systab = (efi_system_table_t *)(
+			e->efi_systab | ((__u64)e->efi_systab_hi<<32));
+#endif
+
+	if (systab == NULL)
+		return false;
+
+	/*
+	 * Get EFI tables from systab. Based on efi_config_init() and
+	 * efi_config_parse_tables(). Only dig the config_table.
+	 */
+	size = efi_64 ? sizeof(efi_config_table_64_t) :
+			sizeof(efi_config_table_32_t);
+
+	for (i = 0; i < systab->nr_tables; i++) {
+		efi_guid_t guid;
+		unsigned long table;
+
+		config_tables = (void *)(systab->tables + size * i);
+		if (efi_64) {
+			efi_config_table_64_t *tmp_table;
+
+			tmp_table = (efi_config_table_64_t *)config_tables;
+			guid = tmp_table->guid;
+			table = tmp_table->table;
+#ifndef CONFIG_64BIT
+			if (table >> 32) {
+				debug_putstr("Table located above 4G, disabling EFI.\n");
+				return false;
+			}
+#endif
+		} else {
+			efi_config_table_32_t *tmp_table;
+
+			tmp_table = (efi_config_table_32_t *)config_tables;
+			guid = tmp_table->guid;
+			table = tmp_table->table;
+		}
+
+		/*
+		 * Get rsdp from EFI tables.
+		 * If ACPI20 table found, use it and return true.
+		 * If ACPI20 table not found, but ACPI table found,
+		 * use the ACPI table and return true.
+		 * If neither ACPI table nor ACPI20 table found,
+		 * return false.
+		 */
+		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID))) {
+			*rsdp_addr = (acpi_physical_address)table;
+			find_rsdp = true;
+		} else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID))) {
+			*rsdp_addr = (acpi_physical_address)table;
+			return true;
+		}
+	}
+	return find_rsdp;
+}
+#else
+static bool efi_get_rsdp_addr(acpi_physical_address *rsdp_addr)
+{
+	return false;
+}
+#endif
+
+static u8 checksum(u8 *buffer, u32 length)
+{
+	u8 sum = 0;
+	u8 *end = buffer + length;
+
+	while (buffer < end)
+		sum = (u8)(sum + *(buffer++));
+
+	return sum;
+}
+
+/*
+ * Used to search a block of memory for the RSDP signature.
+ * Return Pointer to the RSDP if found, otherwise NULL.
+ * Based on acpi_tb_scan_memory_for_rsdp().
+ */
+static u8 *scan_mem_for_rsdp(u8 *start_address, u32 length)
+{
+	struct acpi_table_rsdp *rsdp;
+	u8 *end_address;
+	u8 *mem_rover;
+
+	end_address = start_address + length;
+
+	/* Search from given start address for the requested length */
+	for (mem_rover = start_address; mem_rover < end_address;
+	     mem_rover += ACPI_RSDP_SCAN_STEP) {
+		/*
+		 * The RSDP signature and checksum must both be correct
+		 * Note: Sometimes there exists more than one RSDP in memory;
+		 * the valid RSDP has a valid checksum, all others have an
+		 * invalid checksum.
+		 */
+		rsdp = (struct acpi_table_rsdp *)mem_rover;
+
+		/* Nope, BAD Signature */
+		if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature))
+			continue;
+
+		/* Check the standard checksum */
+		if (checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0)
+			continue;
+
+		/* Check extended checksum if table version >= 2 */
+		if ((rsdp->revision >= 2) &&
+		    (checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0))
+			continue;
+
+		/* Sig and checksum valid, we have found a real RSDP */
+		return mem_rover;
+	}
+	return NULL;
+}
+
+/*
+ * Used to search RSDP physical address.
+ * Based on acpi_find_root_pointer(). Since only use physical address
+ * in this period, so there is no need to do the memory map jobs.
+ */
+static void bios_get_rsdp_addr(acpi_physical_address *rsdp_addr)
+{
+	struct acpi_table_rsdp *rsdp;
+	u8 *table_ptr;
+	u8 *mem_rover;
+	u32 address;
+
+	/*
+	 * Get the location of the Extended BIOS Data Area (EBDA)
+	 * Since we use physical address directely, so
+	 * acpi_os_map_memory() and acpi_os_unmap_memory() are
+	 * not needed here.
+	 */
+	table_ptr = (u8 *)ACPI_EBDA_PTR_LOCATION;
+	*(u32 *)(void *)&address = *(u16 *)(void *)table_ptr;
+	address <<= 4;
+	table_ptr = (u8 *)address;
+
+	/*
+	 * Search EBDA paragraphs (EBDA is required to be a minimum of
+	 * 1K length)
+	 */
+	if (address > 0x400) {
+		mem_rover = scan_mem_for_rsdp(table_ptr, ACPI_EBDA_WINDOW_SIZE);
+
+		if (mem_rover) {
+			address += (u32)ACPI_PTR_DIFF(mem_rover, table_ptr);
+			*rsdp_addr = (acpi_physical_address)address;
+			return;
+		}
+	}
+
+	table_ptr = (u8 *)ACPI_HI_RSDP_WINDOW_BASE;
+	mem_rover = scan_mem_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
+
+	/*
+	 * Search upper memory: 16-byte boundaries in E0000h-FFFFFh
+	 * Since we use physical address directely, so
+	 * acpi_os_map_memory() and acpi_os_unmap_memory() are
+	 * not needed here.
+	 */
+	if (mem_rover) {
+		address = (u32)(ACPI_HI_RSDP_WINDOW_BASE +
+				ACPI_PTR_DIFF(mem_rover, table_ptr));
+		*rsdp_addr = (acpi_physical_address)address;
+		return;
+	}
+}
+
+#ifdef CONFIG_KEXEC
+static bool get_acpi_rsdp(acpi_physical_address *rsdp_addr)
+{
+	char *args = (char *)get_cmd_line_ptr();
+	size_t len = strlen((char *)args);
+	char *tmp_cmdline, *param, *val;
+	unsigned long long addr = 0;
+	char *endptr;
+
+	if (!strstr(args, "acpi_rsdp="))
+		return false;
+
+	tmp_cmdline = malloc(len+1);
+	if (!tmp_cmdline)
+		error("Failed to allocate space for tmp_cmdline");
+
+	memcpy(tmp_cmdline, args, len);
+	tmp_cmdline[len] = 0;
+	args = tmp_cmdline;
+
+	args = skip_spaces(args);
+
+	while (*args) {
+		args = next_arg(args, &param, &val);
+
+		if (!val && strcmp(param, "--") == 0) {
+			warn("Only '--' specified in cmdline");
+			free(tmp_cmdline);
+			return false;
+		}
+
+		if (!strcmp(param, "acpi_rsdp")) {
+			addr = simple_strtoull(val, &endptr, 0);
+
+			if (addr == 0)
+				return false;
+
+			*rsdp_addr = (acpi_physical_address)addr;
+			return true;
+		}
+	}
+	return false;
+}
+#else
+static bool get_acpi_rsdp(acpi_physical_address *rsdp_addr)
+{
+	return false;
+}
+#endif
+
+/*
+ * Used to dig rsdp table from EFI table or BIOS.
+ * If rsdp table found in EFI table, use it. Or search BIOS.
+ * Based on acpi_os_get_root_pointer().
+ */
+static acpi_physical_address get_rsdp_addr(void)
+{
+	acpi_physical_address pa = 0;
+	bool status = false;
+
+	status = get_acpi_rsdp(&pa);
+
+	if (!status || pa == 0)
+		status = efi_get_rsdp_addr(&pa);
+
+	if (!status || pa == 0)
+		bios_get_rsdp_addr(&pa);
+
+	return pa;
+}
+
+static struct acpi_table_header *get_acpi_srat_table(void)
+{
+	char *args = (char *)get_cmd_line_ptr();
+	acpi_physical_address acpi_table;
+	acpi_physical_address root_table;
+	struct acpi_table_header *header;
+	struct acpi_table_rsdp *rsdp;
+	char *signature;
+	u8 *entry;
+	u32 count;
+	u32 size;
+	int i, j;
+	u32 len;
+
+	rsdp = (struct acpi_table_rsdp *)get_rsdp_addr();
+	if (!rsdp)
+		return NULL;
+
+	/* Get rsdt or xsdt from rsdp. */
+	if (!strstr(args, "acpi=rsdt") &&
+	    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;
+	len = header->length;
+	count = (u32)((len - sizeof(struct acpi_table_header)) / size);
+	entry = ACPI_ADD_PTR(u8, header, sizeof(struct acpi_table_header));
+
+	for (i = 0; i < count; i++) {
+		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;
+			signature = header->signature;
+
+			if (!strncmp(signature, "SRAT", 4))
+				return header;
+		}
+		entry += size;
+	}
+	return NULL;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * According to ACPI table, filter the immvoable memory regions
+ * and store them in immovable_mem[].
+ */
+void get_immovable_mem(void)
+{
+	char *args = (char *)get_cmd_line_ptr();
+	struct acpi_table_header *table_header;
+	struct acpi_subtable_header *table;
+	struct acpi_srat_mem_affinity *ma;
+	unsigned long table_end;
+	int i = 0;
+
+	if (!strstr(args, "movable_node") || strstr(args, "acpi=off"))
+		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) + table->length < table_end) {
+		if (table->type == 1) {
+			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)
+				break;
+		}
+		table = (struct acpi_subtable_header *)
+			((unsigned long)table + table->length);
+	}
+	num_immovable_mem = i;
+}
+#endif
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index a1d5918765f3..bb395e5f88e3 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -116,3 +116,11 @@ static inline void console_init(void)
 void set_sev_encryption_mask(void);
 
 #endif
+
+/* acpitb.c */
+/* Store the amount of immovable memory regions */
+int num_immovable_mem;
+#ifdef CONFIG_MEMORY_HOTREMOVE
+#define ACPI_MAX_TABLES                128
+void get_immovable_mem(void);
+#endif
-- 
2.17.1