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Subject[PATCH v16 6/7] x86/boot: Parse SRAT address from RSDP and store immovable memory
Date
SRAT should be parsed by RSDP to fix the conflict between KASLR and
memory-hotremove, then filter the immovable memory regions and
accoring to the memory information, KASLR can avoid to extract kernel
to movable memory regions.

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
---
arch/x86/boot/compressed/acpi.c | 122 +++++++++++++++++++++++++++++++
arch/x86/boot/compressed/kaslr.c | 4 -
arch/x86/boot/compressed/misc.h | 11 +++
3 files changed, 133 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index c207791332c7..11dec68501c5 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -4,9 +4,23 @@
#include "error.h"
#include "../string.h"

+#include <linux/numa.h>
#include <linux/efi.h>
#include <asm/efi.h>

+/*
+ * Longest parameter of 'acpi=' is 'copy_dsdt', plus an extra '\0'
+ * for termination.
+ */
+#define MAX_ACPI_ARG_LENGTH 10
+
+/*
+ * Information of immovable memory regions.
+ * Max amount of memory regions is MAX_NUMNODES*2, so need such array
+ * to place immovable memory regions if all of the memory is immovable.
+ */
+struct mem_vector immovable_mem[MAX_NUMNODES*2];
+
#ifdef CONFIG_ACPI

/*
@@ -217,3 +231,111 @@ acpi_physical_address get_rsdp_addr(void)
return pa;
}
#endif /* CONFIG_ACPI */
+
+#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)
+/* Compute SRAT address from RSDP. */
+static unsigned long get_acpi_srat_table(void)
+{
+ unsigned long root_table, acpi_table;
+ struct acpi_table_header *header;
+ struct acpi_table_rsdp *rsdp;
+ u32 num_entries, size, len;
+ char arg[10];
+ u8 *entry;
+
+ rsdp = (struct acpi_table_rsdp *)(long)boot_params->acpi_rsdp_addr;
+ if (!rsdp)
+ return 0;
+
+ /* Get ACPI root table 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;
+ }
+
+ if (!root_table)
+ return 0;
+
+ header = (struct acpi_table_header *)root_table;
+ len = header->length;
+ if (len < sizeof(struct acpi_table_header) + size)
+ return 0;
+
+ num_entries = (len - sizeof(struct acpi_table_header)) / size;
+ entry = (u8 *)(root_table + sizeof(struct acpi_table_header));
+
+ while (num_entries--) {
+ if (size == ACPI_RSDT_ENTRY_SIZE)
+ acpi_table = *(u32 *)entry;
+ else
+ acpi_table = *(u64 *)entry;
+
+ if (acpi_table) {
+ header = (struct acpi_table_header *)acpi_table;
+
+ if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
+ return acpi_table;
+ }
+ entry += size;
+ }
+ return 0;
+}
+
+/**
+ * count_immovable_mem_regions - early parse SRAT, filter immovable
+ * memory regions
+ *
+ * Return amount of immovable memory regions on success, 0 on
+ * - Too many immovable memory regions
+ * - ACPI off or no SRAT found
+ * - No immovable memory region found
+ */
+int count_immovable_mem_regions(void)
+{
+ unsigned long table_addr, table_end, table;
+ struct acpi_subtable_header *sub_table;
+ struct acpi_table_header *table_header;
+ char arg[MAX_ACPI_ARG_LENGTH];
+ int num = 0;
+
+ if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
+ !strncmp(arg, "off", 3))
+ return 0;
+
+ table_addr = get_acpi_srat_table();
+ if (!table_addr)
+ return 0;
+
+ table_header = (struct acpi_table_header *)table_addr;
+ table_end = table_addr + table_header->length;
+ table = table_addr + sizeof(struct acpi_table_srat);
+
+ while (table + sizeof(struct acpi_subtable_header) < table_end) {
+ sub_table = (struct acpi_subtable_header *)table;
+ if (sub_table->type == ACPI_SRAT_TYPE_MEMORY_AFFINITY) {
+ struct acpi_srat_mem_affinity *ma;
+
+ ma = (struct acpi_srat_mem_affinity *)sub_table;
+ if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) &&
+ ma->length) {
+ immovable_mem[num].start = ma->base_address;
+ immovable_mem[num].size = ma->length;
+ num++;
+ }
+
+ if (num >= MAX_NUMNODES*2) {
+ debug_putstr("Too many immovable memory regions, aborting.\n");
+ return 0;
+ }
+ }
+ table += sub_table->length;
+ }
+ return num;
+}
+#endif /* CONFIG_RANDOMIZE_BASE && CONFIG_MEMORY_HOTREMOVE */
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 e1dd15769cf3..6fc51cebec7e 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -80,6 +80,11 @@ 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
@@ -126,3 +131,9 @@ acpi_physical_address get_rsdp_addr(void);
#else
static inline acpi_physical_address get_rsdp_addr(void) { return 0; }
#endif
+
+#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)
+int count_immovable_mem_regions(void);
+#else
+static inline int count_immovable_mem_regions(void) { return 0; }
+#endif
--
2.20.1


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