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

Masayoshi Mizuma
2018-11-12T21:51:59Z

On Mon, Nov 12, 2018 at 05:46:44PM +0800, Chao Fan wrote:
> 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

'#' in Makefile means comment out...

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
> 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

This #ifdef isn't needed.

Could you please check the other #ifdef statement as well?

Thanks,
Masa

> +
> /* 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
>
>
>