Re: [PATCH v8 1/3] x86/boot: Add acpitb.c to parse acpi tables

Chao Fan
2018-10-16T01:50:51Z

On Mon, Oct 15, 2018 at 04:26:09PM -0400, Masayoshi Mizuma wrote:
>Hi Chao,
>
>Let me add some suggestions.

Thanks for your review and suggestion.
I will change them in next version.

Thanks,
Chao Fan

>
>On Wed, Oct 10, 2018 at 04:41:17PM +0800, Chao Fan wrote:
>> There is a bug that kaslr may randomly chooses some positions
>> which are located in movable memory regions. This will break memory
>> hotplug feature and make the movable memory chosen by KASLR can't be
>> removed. So dig SRAT table from ACPI tables to get memory information.
>>
>> Imitate the ACPI code of parsing ACPI tables to dig and read ACPI
>> tables. Since some operations are not needed here, functions are
>> simplified. Functions will be used to dig only SRAT tables to get
>> information of memory, so that KASLR can the memory in immovable node.
>>
>> And also, these functions won't influence the initialization of
>> ACPI after start_kernel().
>>
>> Since use physical address directely, so acpi_os_map_memory()
>> and acpi_os_unmap_memory() are not needed.
>>
>> Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
>> ---
>> arch/x86/boot/compressed/Makefile | 2 +
>> arch/x86/boot/compressed/acpitb.c | 405 ++++++++++++++++++++++++++++++
>> arch/x86/boot/compressed/misc.h | 8 +
>> 3 files changed, 415 insertions(+)
>> create mode 100644 arch/x86/boot/compressed/acpitb.c
>>
>...cut...
>> +static struct acpi_table_header *get_acpi_srat_table(void)
>> +{
>> + char *args = (char *)get_cmd_line_ptr();
>> + 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 (!strstr(args, "acpi=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 (!strncmp(signature, "SRAT", 4))
>
> if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
>
>> + return header;
>> + }
>> + entry += size;
>> + }
>> + return NULL;
>> +}
>> +
>> +#ifdef CONFIG_MEMORY_HOTREMOVE
>> +/*
>> + * According to ACPI table, filter the immvoable memory regions
>> + * and store them in immovable_mem[].
>> + */
>> +void get_immovable_mem(void)
>> +{
>> + char *args = (char *)get_cmd_line_ptr();
>> + 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 (!strstr(args, "movable_node") || strstr(args, "acpi=off"))
>> + 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) + table->length < table_end) {
>
> while (((unsigned long)table) +
> sizeof(struct acpi_subtable_header) < table_end) {
>
>> + if (table->type == 1) {
>
> 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)
>> + break;
>> + }
>> + table = (struct acpi_subtable_header *)
>> + ((unsigned long)table + table->length);
>> + }
>> + num_immovable_mem = i;
>> +}
>
>Thanks,
>Masa
>
>