Re: [PATCH v9 6/8] x86/boot: Dig out SRAT table from RSDP and find immovable memory

[Baoquan He]

On 10/17/18 at 06:20pm, Chao Fan wrote:
> Dig out SRAT table from RSDP, and then walk all memory to find
> the immovable memory regions, and fill in the immovable_mem[].
> So that we can use it to select memory for KASLR.
> 
> Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
> ---
>  arch/x86/boot/compressed/Makefile |   4 +
>  arch/x86/boot/compressed/acpitb.c | 129 ++++++++++++++++++++++++++++++
>  arch/x86/boot/compressed/misc.h   |  10 +++
>  3 files changed, 143 insertions(+)
> 
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 28764dacf018..f67674d7d2bd 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -83,6 +83,10 @@ ifdef CONFIG_X86_64
>  	vmlinux-objs-y += $(obj)/pgtable_64.o
>  endif
>  
> +#ifdef CONFIG_MEMORY_HOTREMOVE && CONFIG_RANDOMIZE_BASE
> +vmlinux-objs-$(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 37b1f4407be8..d119663c05bb 100644
> --- a/arch/x86/boot/compressed/acpitb.c
> +++ b/arch/x86/boot/compressed/acpitb.c
> @@ -11,6 +11,15 @@
>  #define STATIC
>  #include <linux/decompress/mm.h>
>  
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +struct mem_vector {
> +	unsigned long long start;
> +	unsigned long long size;
> +};

Why not moving this definition to misc.h? There has been a mem_vector in
boot/compressed/kaslr.c.

> +/* 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)
>  {
> @@ -223,3 +232,123 @@ 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;
> +	char *signature;
> +	u8 *entry;
> +	u32 count;
> +	u32 size;
> +	int i, j;
> +	u32 len;
> +
> +	rsdp = (struct acpi_table_rsdp *)get_rsdp_addr();
> +	if (!rsdp)
> +		return NULL;
> +
> +	/* Get RSDT or XSDT from RSDP. */
> +	if (!cmdline_find_option_arg("acpi", "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;
> +	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;
> +	int i = 0;
> +
> +	if (!cmdline_find_option_bool("movable_node") ||
> +	    cmdline_find_option_arg("acpi", "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)
		No warning message printed in this case?
> +				break;
> +		}
> +		table = (struct acpi_subtable_header *)
> +			((unsigned long)table + table->length);
> +	}
> +	num_immovable_mem = i;
> +}
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index 40378408d980..70c403e1444c 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -121,3 +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
> -- 
> 2.17.2
> 
> 
>