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    Subject[PATCH v13 5/6] x86/boot: Parse SRAT from RSDP and store immovable memory
    Date
    SRAT should be parsed by RSDP to fix the conflict between KASLR
    and memory-hotremove, then find the immovable memory regions and store
    them in an array called immovable_mem[]. With immovable_mem[], KASLR
    can avoid to extract kernel to specific regions.

    Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
    ---
    arch/x86/boot/compressed/Makefile | 2 +
    arch/x86/boot/compressed/acpi.c | 128 ++++++++++++++++++++++++++++++
    arch/x86/boot/compressed/kaslr.c | 4 -
    arch/x86/boot/compressed/misc.h | 15 ++++
    4 files changed, 145 insertions(+), 4 deletions(-)

    diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
    index 466f66c8a7f8..bcc6560fb2ec 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)/acpi.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/acpi.c b/arch/x86/boot/compressed/acpi.c
    index c546a463b8ba..6fa0a1ff5ba0 100644
    --- a/arch/x86/boot/compressed/acpi.c
    +++ b/arch/x86/boot/compressed/acpi.c
    @@ -13,6 +13,9 @@

    #include "../string.h"

    +/* Store the immovable memory regions. */
    +struct mem_vector immovable_mem[MAX_NUMNODES*2];
    +
    static acpi_physical_address get_acpi_rsdp(void)
    {
    #ifdef CONFIG_KEXEC
    @@ -192,3 +195,128 @@ static acpi_physical_address bios_get_rsdp_addr(void)
    return (acpi_physical_address)address;
    }
    }
    +
    +/* Determine RSDP, 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 address 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;
    + u32 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;
    + if (len < sizeof(struct acpi_table_header) + size)
    + return NULL;
    +
    + num_entries = (u32)((len - sizeof(struct acpi_table_header)) / size);
    + 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 72fcfbfec3c6..c6b4c8c3c2fc 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
    @@ -118,7 +123,17 @@ void set_sev_encryption_mask(void);
    #endif

    /* acpi.c */
    +#ifdef CONFIG_RANDOMIZE_BASE
    +/* Amount of immovable memory regions */
    +int num_immovable_mem;
    +#endif
    +
    #ifdef CONFIG_EARLY_PARSE_RSDP
    +void get_immovable_mem(void);
    /* Max length of 64-bit hex address string is 18, prefix "0x" + 16 hex digit. */
    #define MAX_ADDRESS_LENGTH 18
    +#else
    +static void get_immovable_mem(void)
    +{
    +}
    #endif
    --
    2.19.2


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