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Date:   Fri, 30 Nov 2018 09:54:33 -0500
From:   Masayoshi Mizuma <msys.mizuma@gmail.com>
To:     Chao Fan <fanc.fnst@cn.fujitsu.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org, bp@alien8.de,
        tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
        keescook@chromium.org, bhe@redhat.com, indou.takao@jp.fujitsu.com,
        caoj.fnst@cn.fujitsu.com
Subject: Re: [PATCH v12 4/5] x86/boot: Parse SRAT table from RSDP and store
 immovable memory
Message-ID: <20181130145432.j2iwbglwrtj5xdus@gabell>
References: <20181129081631.11139-1-fanc.fnst@cn.fujitsu.com>
 <20181129081631.11139-5-fanc.fnst@cn.fujitsu.com>
 <20181129175520.xcmj3bv4yhdr7kk3@gabell>
 <20181130012454.GB1527@localhost.localdomain>
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On Fri, Nov 30, 2018 at 09:24:54AM +0800, Chao Fan wrote:
> On Thu, Nov 29, 2018 at 12:55:21PM -0500, Masayoshi Mizuma wrote:
> >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@cn.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?
> 
> I will change it to 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
> 
> Yes, it's from  ACPI code, include/acpi/actbl*h.
> Boris said there should be a check for the num_entries,
> I didn't get a good idea, so I use the max number to check it.
> So do you have some advice?

Ah, got it. How about adding the check for len to prevent the wrap?
Like as:

	len = header->length;
	if (len <= sizeof(struct acpi_table_header))
		return NULL;
 	num_entries = (u32)((len - sizeof(struct acpi_table_header)) / size);

Thanks,
Masa