[PATCH v11 4/5] x86/boot: Dig out SRAT table from RSDP and find immovable memory

Chao Fan
2018-11-12T09:46:44Z

To avoid KASLR extracting kernel on movable memory, slove the
conflict between KASLR and movable_node feature, dig the SRAT tables
from RSDP pointer. Walk the SRAT tables and store the immovable
memory regions in immovable_mem[].

There are three methods to get RSDP pointer: KEXEC condition,
EFI confition, BIOS condition.
If KEXEC add 'acpi_rsdp' to cmdline, use it.
Otherwise, parse EFI table for RSDP.
Then, search memory for RSDP.

Imitate from ACPI code, based on acpi_os_get_root_pointer().
Process: RSDP->RSDT/XSDT->ACPI root table->SRAT.

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
---
arch/x86/boot/compressed/Makefile | 4 +
arch/x86/boot/compressed/acpitb.c | 139 ++++++++++++++++++++++++++++++
arch/x86/boot/compressed/kaslr.c | 4 -
arch/x86/boot/compressed/misc.h | 15 ++++
4 files changed, 158 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 466f66c8a7f8..b51f7629b8ef 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -84,6 +84,10 @@ ifdef CONFIG_X86_64
vmlinux-objs-y += $(obj)/pgtable_64.o
endif

+#if (defined CONFIG_MEMORY_HOTREMOVE) && (defined CONFIG_RANDOMIZE_BASE)
+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
index 5cfb4efa5a19..161f21a7fb3b 100644
--- a/arch/x86/boot/compressed/acpitb.c
+++ b/arch/x86/boot/compressed/acpitb.c
@@ -14,6 +14,11 @@
#define BOOT_STRING
#include "../string.h"

+#ifdef CONFIG_MEMORY_HOTREMOVE
+/* Store the immovable memory regions */
+struct mem_vector immovable_mem[MAX_NUMNODES*2];
+#endif
+
/* Search EFI table for RSDP table. */
static void efi_get_rsdp_addr(acpi_physical_address *rsdp_addr)
{
@@ -226,3 +231,137 @@ static void get_acpi_rsdp(acpi_physical_address *rsdp_addr)
}
#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;
+
+ get_acpi_rsdp(&pa);
+
+ if (!pa)
+ efi_get_rsdp_addr(&pa);
+
+ if (!pa)
+ bios_get_rsdp_addr(&pa);
+
+ return pa;
+}
+
+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;
+ bool acpi_use_rsdt = false;
+ char *signature;
+ char arg[10];
+ u8 *entry;
+ u32 count;
+ u32 size;
+ int i, j;
+ int ret;
+ u32 len;
+
+ rsdp = (struct acpi_table_rsdp *)get_rsdp_addr();
+ if (!rsdp)
+ return NULL;
+
+ ret = cmdline_find_option("acpi", arg, sizeof(arg));
+ if (ret == 4 && !strncmp(arg, "rsdt", 4))
+ acpi_use_rsdt = true;
+
+ /* Get RSDT or XSDT from RSDP. */
+ if (!acpi_use_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 (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
+ return header;
+ }
+ entry += size;
+ }
+ return NULL;
+}
+
+/*
+ * According to ACPI table, filter the immvoable 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;
+ int ret;
+
+ ret = cmdline_find_option("acpi", arg, sizeof(arg));
+ if (ret == 3 && !strncmp(arg, "off", 3))
+ return;
+
+ if (!cmdline_find_option_bool("movable_node"))
+ 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, aborted.\n");
+ break;
+ }
+ }
+ 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 a1d5918765f3..4a3645fda0ed 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
@@ -116,3 +121,13 @@ static inline void console_init(void)
void set_sev_encryption_mask(void);

#endif
+
+/* acpitb.c */
+#ifdef CONFIG_RANDOMIZE_BASE
+int num_immovable_mem;
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/* Store the amount of immovable memory regions */
+#define ACPI_MAX_TABLES 128
+void get_immovable_mem(void);
+#endif
+#endif
--
2.19.1