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

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Date:   Mon, 11 Feb 2019 09:46:05 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>
CC:     Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        "Baoquan He" <bhe@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-efi@...r.kernel.org>,
        <linux-acpi@...r.kernel.org>, <mingo@...hat.com>,
        <keescook@...omium.org>, <rjw@...ysocki.net>, <lenb@...nel.org>,
        <ard.biesheuvel@...aro.org>, <indou.takao@...fujitsu.com>,
        <caoj.fnst@...fujitsu.com>
Subject: Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr
 in immovable memory

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
>
>