Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory

Chao Fan
2019-02-11T01:46:05Z

On Tue, Feb 05, 2019 at 10:05:16AM -0500, Masayoshi Mizuma wrote:
[...]

Hi Masa,

Sorry for delay, since last days were Chinese holiday.

>diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
>index c5a949335..7dd61b943 100644
>--- a/arch/x86/boot/compressed/acpi.c
>+++ b/arch/x86/boot/compressed/acpi.c
>@@ -288,6 +288,7 @@ int count_immovable_mem_regions(void)
> struct acpi_subtable_header *sub_table;
> struct acpi_table_header *table_header;
> char arg[MAX_ACPI_ARG_LENGTH];
>+ unsigned long long possible_addr, max_possible_addr = 0;

This line is so long that it should be added in first line.

> int num = 0;
>
> if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
>@@ -308,10 +309,19 @@ int count_immovable_mem_regions(void)
> struct acpi_srat_mem_affinity *ma;
>
> ma = (struct acpi_srat_mem_affinity *)sub_table;
>- if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && ma->length) {
>- immovable_mem[num].start = ma->base_address;
>- immovable_mem[num].size = ma->length;
>- num++;
>+ if (ma->length) {
>+ if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) {
>+ possible_addr =
>+ ma->base_address + ma->length;
>+ if (possible_addr > max_possible_addr)
>+ max_possible_addr =
>+ possible_addr;
>+ } else {
>+ immovable_mem[num].start =
>+ ma->base_address;
>+ immovable_mem[num].size = ma->length;
>+ num++;
>+ }
> }

It looks better in another mail where you add a new function.

Thanks,
Chao Fan

>
> if (num >= MAX_NUMNODES*2) {
>@@ -320,6 +330,7 @@ int count_immovable_mem_regions(void)
> }
> }
> table += sub_table->length;
>+ boot_params->possible_mem_addr = max_possible_addr;
> }
> return num;
> }
>diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
>index 60733f137..5b64b606e 100644
>--- a/arch/x86/include/uapi/asm/bootparam.h
>+++ b/arch/x86/include/uapi/asm/bootparam.h
>@@ -156,7 +156,7 @@ struct boot_params {
> __u64 tboot_addr; /* 0x058 */
> struct ist_info ist_info; /* 0x060 */
> __u64 acpi_rsdp_addr; /* 0x070 */
>- __u8 _pad3[8]; /* 0x078 */
>+ __u64 possible_mem_addr; /* 0x078 */
> __u8 hd0_info[16]; /* obsolete! */ /* 0x080 */
> __u8 hd1_info[16]; /* obsolete! */ /* 0x090 */
> struct sys_desc_table sys_desc_table; /* obsolete! */ /* 0x0a0 */
>diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
>index 3f452ffed..71fc28570 100644
>--- a/arch/x86/mm/kaslr.c
>+++ b/arch/x86/mm/kaslr.c
>@@ -70,6 +70,30 @@ static inline bool kaslr_memory_enabled(void)
> return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
> }
>
>+static unsigned int __init kaslr_padding(void)
>+{
>+ unsigned int rand_mem_physical_padding =
>+ CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
>+#ifdef CONFIG_MEMORY_HOTPLUG
>+ unsigned long long max_possible_phys, max_actual_phys, threshold;
>+
>+ if (!boot_params.possible_mem_addr)
>+ goto out;
>+
>+ max_actual_phys = roundup(PFN_PHYS(max_pfn), 1ULL << TB_SHIFT);
>+ max_possible_phys = roundup(boot_params.possible_mem_addr,
>+ 1ULL << TB_SHIFT);
>+ threshold = max_actual_phys +
>+ ((unsigned long long)rand_mem_physical_padding << TB_SHIFT);
>+
>+ if (max_possible_phys > threshold)
>+ rand_mem_physical_padding =
>+ (max_possible_phys - max_actual_phys) >> TB_SHIFT;
>+out:
>+#endif
>+ return rand_mem_physical_padding;
>+}
>+
> /* Initialize base and padding for each memory region randomized with KASLR */
> void __init kernel_randomize_memory(void)
> {
>@@ -103,7 +127,7 @@ void __init kernel_randomize_memory(void)
> */
> BUG_ON(kaslr_regions[0].base != &page_offset_base);
> memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
>- CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
>+ kaslr_padding();
>
> /* Adapt phyiscal memory region size based on available memory */
> if (memory_tb < kaslr_regions[0].size_tb)
>--
>2.20.1
>
>Thanks,
>Masa
>
>