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Date: Thu, 29 Nov 2018 12:55:21 -0500
From: Masayoshi Mizuma <msys.mizuma@...il.com>
To: Chao Fan <fanc.fnst@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, bp@...en8.de,
tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
keescook@...omium.org, bhe@...hat.com, indou.takao@...fujitsu.com,
caoj.fnst@...fujitsu.com
Subject: Re: [PATCH v12 4/5] x86/boot: Parse SRAT table from RSDP and store
immovable memory
On Thu, Nov 29, 2018 at 04:16:30PM +0800, Chao Fan wrote:
> To fix the conflict between KASLR and memory-hotremove, SRAT table
> should be parsed by RSDP pointer, then find the immovable
> memory regions and store them in an array called immovable_mem[].
> The array called immovable_mem[] will extern to KASLR, then
> KASLR will avoid to extract kernel to these regions.
>
> Add 'CONFIG_EARLY_PARSE_RSDP' which depends on RANDOMIZE_BASE &&
> MEMORY_HOTREMOVE, cause only when both KASLR and memory-hotremove
> are enabled, RSDP needs to be parsed in compressed period.
>
> Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
> ---
> arch/x86/Kconfig | 10 +++
> arch/x86/boot/compressed/Makefile | 2 +
> arch/x86/boot/compressed/acpitb.c | 125 ++++++++++++++++++++++++++++++
> arch/x86/boot/compressed/kaslr.c | 4 -
> arch/x86/boot/compressed/misc.h | 20 +++++
> 5 files changed, 157 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a29d49ef4d56..bc775968557b 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2146,6 +2146,16 @@ config X86_NEED_RELOCS
> def_bool y
> depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
>
> +config CONFIG_EARLY_PARSE_RSDP
config EARLY_PARSE_RSDP
> + bool "Parse RSDP pointer on compressed period for KASLR"
> + def_bool n
Should be def_bool y?
It is better to enable EARLY_PARSE_RSDP by default if
RANDOMIZE_BASE and MEMORY_HOTREMOVE are enabled.
> + depends on RANDOMIZE_BASE && MEMORY_HOTREMOVE
> + help
> + This option parses RSDP pointer in compressed period. Works
> + for KASLR to get memory information by SRAT table and choose
> + immovable memory to extract kernel.
> + 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..4cbfb58bf083 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)/acpitb.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/acpitb.c b/arch/x86/boot/compressed/acpitb.c
> index 82d27c4b8978..023b33d0cd3b 100644
> --- a/arch/x86/boot/compressed/acpitb.c
> +++ b/arch/x86/boot/compressed/acpitb.c
> @@ -195,3 +195,128 @@ static acpi_physical_address bios_get_rsdp_addr(void)
> return (acpi_physical_address)address;
> }
> }
> +
> +/* Used to determine RSDP table, 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 table 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;
> + int 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;
> + num_entries = (u32)((len - sizeof(struct acpi_table_header)) / size);
> + if (num_entries > MAX_ACPI_SIG)
> + return NULL;
I think this check isn't needed...
> +
> + 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 809c31effa4b..d94e2a419c13 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
> @@ -118,5 +123,20 @@ void set_sev_encryption_mask(void);
> #endif
>
> /* acpitb.c */
> +#ifdef CONFIG_RANDOMIZE_BASE
> +/* Store the amount of immovable memory regions */
> +int num_immovable_mem;
> +#endif
> +
> +#ifdef CONFIG_EARLY_PARSE_RSDP
> +void get_immovable_mem(void);
> +/* There are 72 kinds of ACPI_SIG in head file of ACPI. */
> +#define MAX_ACPI_SIG 72
The 72 isn't the specification of ACPI, right? So the number
of SIG may increase and decrease in the future.
This macro and the check I commented above isn't needed...
Thanks,
Masa
> +#else
> +static void get_immovable_mem(void)
> +{
> +}
> +#endif
> +
> #define BOOT_STRING
> extern int kstrtoull(const char *s, unsigned int base, unsigned long long *res);
> --
> 2.19.1
>
>
>
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