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    Subject[PATCH v15 5/6] 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 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.

    Since 'RANDOMIZE_BASE' && 'MEMORY_HOTREMOVE' is needed, introduce
    'CONFIG_EARLY_SRAT_PARSE' to make ifdeffery clear.

    Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
    ---
    arch/x86/Kconfig | 12 +++
    arch/x86/boot/compressed/Makefile | 2 +
    arch/x86/boot/compressed/acpi.c | 138 ++++++++++++++++++++++++++++++
    arch/x86/boot/compressed/kaslr.c | 4 -
    arch/x86/boot/compressed/misc.h | 19 ++++
    5 files changed, 171 insertions(+), 4 deletions(-)

    diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
    index ba7e3464ee92..c1457609f2e3 100644
    --- a/arch/x86/Kconfig
    +++ b/arch/x86/Kconfig
    @@ -2149,6 +2149,18 @@ config X86_NEED_RELOCS
    def_bool y
    depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)

    +config EARLY_SRAT_PARSE
    + bool "EARLY SRAT parsing"
    + def_bool y
    + depends on RANDOMIZE_BASE && MEMORY_HOTREMOVE
    + help
    + This option enables early SRAT parsing in compressed boot stage
    + so that memory hot-remove ranges do not overlap with KASLR
    + chosen ranges. Kernel won't be extracted in hot-removable
    + memory, so that make sure memory-hotremove works well with
    + KASLR enabled.
    + 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..23491d74939d 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_SRAT_PARSE) += $(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 e9dd84f459ed..f7a9e9cbd254 100644
    --- a/arch/x86/boot/compressed/acpi.c
    +++ b/arch/x86/boot/compressed/acpi.c
    @@ -5,6 +5,7 @@
    #include "../string.h"

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

    @@ -14,6 +15,19 @@
    */
    #define MAX_HEX_ADDRESS_STRING_LEN 19

    +/*
    + * Longest parameter of 'acpi=' in cmldine is 'copy_dsdt', so max length
    + * is 10, which contains '\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];
    +
    static acpi_physical_address get_acpi_rsdp(void)
    {
    #ifdef CONFIG_KEXEC
    @@ -197,3 +211,127 @@ static acpi_physical_address bios_get_rsdp_addr(void)
    }
    return 0;
    }
    +
    +/* Determine RSDP, based on acpi_os_get_root_pointer(). */
    +static acpi_physical_address get_rsdp_addr(void)
    +{
    + acpi_physical_address pa;
    +
    + 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 *)(long)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.*/
    + if (!root_table)
    + return NULL;
    + header = (struct acpi_table_header *)(long)root_table;
    +
    + 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_CAST_PTR(u32, entry);
    + else {
    + address64 = *(u64 *)entry;
    + acpi_table = address64;
    + }
    +
    + if (acpi_table) {
    + header = (struct acpi_table_header *)(long)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;
    + char arg[MAX_ACPI_ARG_LENGTH];
    + unsigned long table_end;
    + 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 a1d5918765f3..b49748366a5b 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 +121,17 @@ static inline void console_init(void)
    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_SRAT_PARSE
    +void get_immovable_mem(void);
    +#else
    +static void get_immovable_mem(void)
    +{
    +}
    +#endif
    --
    2.20.1


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