Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1640839 > unrolled thread

[PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option Baoquan He <bhe@redhat.com> - 2017-05-13 07:50 +0200
    Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and  mem option Dou Liyang <douly.fnst@cn.fujitsu.com> - 2017-05-16 03:00 +0200
      Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap  and mem option Baoquan He <bhe@redhat.com> - 2017-05-16 03:20 +0200
        Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and  mem option Dou Liyang <douly.fnst@cn.fujitsu.com> - 2017-05-16 03:50 +0200
          Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap  and mem option Baoquan He <bhe@redhat.com> - 2017-05-16 04:40 +0200
    [tip:x86/boot] x86/KASLR: Handle the memory limit specified by the  'memmap=' and 'mem=' boot options tip-bot for Baoquan He <tipbot@zytor.com> - 2017-05-24 12:30 +0200

#1640839 — [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

Option mem= will limit the max address a system can use and any memory
region above the limit will be removed.

Furthermore, memmap=nn[KMG] which has no offset specified has the same
behaviour as mem=.

KASLR needs to consider this when choosing the random position for
decompressing the kernel. Do it now.

Signed-off-by: Baoquan He <bhe@redhat.com>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
---
 arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 106e13b..e0eba12 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -88,6 +88,10 @@ struct mem_vector {
 static bool memmap_too_large;
 
 
+/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
+unsigned long long mem_limit = ULLONG_MAX;
+
+
 enum mem_avoid_index {
 	MEM_AVOID_ZO_RANGE = 0,
 	MEM_AVOID_INITRD,
@@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
 		return -EINVAL;
 
 	switch (*p) {
-	case '@':
-		/* Skip this region, usable */
-		*start = 0;
-		*size = 0;
-		return 0;
 	case '#':
 	case '$':
 	case '!':
 		*start = memparse(p + 1, &p);
 		return 0;
+	case '@':
+		/* memmap=nn@ss specifies usable region, should be skipped */
+		*size = 0;
+		/* Fall through */
+	default:
+		/*
+		 * If w/o offset, only size specified, memmap=nn[KMG] has the
+		 * same behaviour as mem=nn[KMG]. It limits the max address
+		 * system can use. Region above the limit should be avoided.
+		 */
+		*start = 0;
+		return 0;
 	}
 
 	return -EINVAL;
@@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
 		if (rc < 0)
 			break;
 		str = k;
-		/* A usable region that should not be skipped */
-		if (size == 0)
+
+		if (start == 0) {
+			/* Store the specified memory limit if size > 0 */
+			if (size > 0)
+				mem_limit = size;
+
 			continue;
+		}
 
 		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
 		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
@@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
 		memmap_too_large = true;
 }
 
-
-/*
- * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove
- * this note later.
- */
 static int handle_mem_memmap(void)
 {
 	char *args = (char *)get_cmd_line_ptr();
 	size_t len = strlen((char *)args);
 	char *tmp_cmdline;
 	char *param, *val;
+	u64 mem_size;
 
-	if (!strstr(args, "memmap="))
+	if (!strstr(args, "memmap=") && !strstr(args, "mem="))
 		return 0;
 
 	tmp_cmdline = malloc(len + 1);
@@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
 			return -1;
 		}
 
-		if (!strcmp(param, "memmap"))
+		if (!strcmp(param, "memmap")) {
 			mem_avoid_memmap(val);
+		} else if (!strcmp(param, "mem")) {
+			char *p = val;
+
+			if (!strcmp(p, "nopentium"))
+				continue;
+			mem_size = memparse(p, &p);
+			if (mem_size == 0) {
+				free(tmp_cmdline);
+				return -EINVAL;
+			}
+			mem_limit = mem_size;
+		}
 	}
 
 	free(tmp_cmdline);
@@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 {
 	struct mem_vector region, overlap;
 	struct slot_area slot_area;
-	unsigned long start_orig;
+	unsigned long start_orig, end;
+	struct boot_e820_entry cur_entry;
 
 	/* Skip non-RAM entries. */
 	if (entry->type != E820_TYPE_RAM)
@@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 	if (entry->addr + entry->size < minimum)
 		return;
 
-	region.start = entry->addr;
-	region.size = entry->size;
+	/* Ignore entries above memory limit */
+	end = min(entry->size + entry->addr, mem_limit);
+	if (entry->addr >= end)
+		return;
+	cur_entry.addr = entry->addr;
+	cur_entry.size = end - entry->addr;
+
+	region.start = cur_entry.addr;
+	region.size = cur_entry.size;
 
 	/* Give up if slot area array is full. */
 	while (slot_area_index < MAX_SLOT_AREA) {
@@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
 
 		/* Did we raise the address above this e820 region? */
-		if (region.start > entry->addr + entry->size)
+		if (region.start > cur_entry.addr + cur_entry.size)
 			return;
 
 		/* Reduce size by any delta from the original address. */
-- 
2.5.5

[toc] | [next] | [standalone]

#1642149 — Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

Hi Baoquan,

At 05/13/2017 01:46 PM, Baoquan He wrote:
> Option mem= will limit the max address a system can use and any memory
> region above the limit will be removed.
>
> Furthermore, memmap=nn[KMG] which has no offset specified has the same
> behaviour as mem=.
>
> KASLR needs to consider this when choosing the random position for
> decompressing the kernel. Do it now.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
> ---
>  arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
>  1 file changed, 50 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 106e13b..e0eba12 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -88,6 +88,10 @@ struct mem_vector {
>  static bool memmap_too_large;
>
>
> +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
> +unsigned long long mem_limit = ULLONG_MAX;
> +
> +
>  enum mem_avoid_index {
>  	MEM_AVOID_ZO_RANGE = 0,
>  	MEM_AVOID_INITRD,
> @@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
>  		return -EINVAL;
>
>  	switch (*p) {
> -	case '@':
> -		/* Skip this region, usable */
> -		*start = 0;
> -		*size = 0;
> -		return 0;
>  	case '#':
>  	case '$':
>  	case '!':
>  		*start = memparse(p + 1, &p);
>  		return 0;
> +	case '@':
> +		/* memmap=nn@ss specifies usable region, should be skipped */
> +		*size = 0;
> +		/* Fall through */
> +	default:
> +		/*
> +		 * If w/o offset, only size specified, memmap=nn[KMG] has the
> +		 * same behaviour as mem=nn[KMG]. It limits the max address
> +		 * system can use. Region above the limit should be avoided.
> +		 */
> +		*start = 0;
> +		return 0;
>  	}
>
>  	return -EINVAL;
> @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
>  		if (rc < 0)
>  			break;
>  		str = k;
> -		/* A usable region that should not be skipped */
> -		if (size == 0)
> +
> +		if (start == 0) {
> +			/* Store the specified memory limit if size > 0 */
> +			if (size > 0)
> +				mem_limit = size;

Baoquan,

I am not sure about setting the value of mem_limit to mem_size directly.

If the command line has both the "memmap" and "mem", such as
  ... mem=2G memmap=4G ...

...in that code, the mem_limit may be 4G not 2G.

In my opinion, How about following:

mem_limit = mem_limit > mem_size ? mem_size : mem_limit;

> +
>  			continue;
> +		}
>
>  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
>  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
> @@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
>  		memmap_too_large = true;
>  }
>
> -
> -/*
> - * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove
> - * this note later.
> - */
>  static int handle_mem_memmap(void)
>  {
>  	char *args = (char *)get_cmd_line_ptr();
>  	size_t len = strlen((char *)args);
>  	char *tmp_cmdline;
>  	char *param, *val;
> +	u64 mem_size;
>
> -	if (!strstr(args, "memmap="))
> +	if (!strstr(args, "memmap=") && !strstr(args, "mem="))
>  		return 0;
>
>  	tmp_cmdline = malloc(len + 1);
> @@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
>  			return -1;
>  		}
>
> -		if (!strcmp(param, "memmap"))
> +		if (!strcmp(param, "memmap")) {
>  			mem_avoid_memmap(val);
> +		} else if (!strcmp(param, "mem")) {
> +			char *p = val;
> +
> +			if (!strcmp(p, "nopentium"))
> +				continue;
> +			mem_size = memparse(p, &p);
> +			if (mem_size == 0) {
> +				free(tmp_cmdline);
> +				return -EINVAL;
> +			}
> +			mem_limit = mem_size;

The same as above.

Thanks,
	Liyang.

> +		}
>  	}
>
>  	free(tmp_cmdline);
> @@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>  {
>  	struct mem_vector region, overlap;
>  	struct slot_area slot_area;
> -	unsigned long start_orig;
> +	unsigned long start_orig, end;
> +	struct boot_e820_entry cur_entry;
>
>  	/* Skip non-RAM entries. */
>  	if (entry->type != E820_TYPE_RAM)
> @@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>  	if (entry->addr + entry->size < minimum)
>  		return;
>
> -	region.start = entry->addr;
> -	region.size = entry->size;
> +	/* Ignore entries above memory limit */
> +	end = min(entry->size + entry->addr, mem_limit);
> +	if (entry->addr >= end)
> +		return;
> +	cur_entry.addr = entry->addr;
> +	cur_entry.size = end - entry->addr;
> +
> +	region.start = cur_entry.addr;
> +	region.size = cur_entry.size;
>
>  	/* Give up if slot area array is full. */
>  	while (slot_area_index < MAX_SLOT_AREA) {
> @@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>  		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
>
>  		/* Did we raise the address above this e820 region? */
> -		if (region.start > entry->addr + entry->size)
> +		if (region.start > cur_entry.addr + cur_entry.size)
>  			return;
>
>  		/* Reduce size by any delta from the original address. */
>

[toc] | [prev] | [next] | [standalone]

#1642160 — Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

On 05/16/17 at 08:56am, Dou Liyang wrote:
> Hi Baoquan,
> 
> At 05/13/2017 01:46 PM, Baoquan He wrote:
> > Option mem= will limit the max address a system can use and any memory
> > region above the limit will be removed.
> > 
> > Furthermore, memmap=nn[KMG] which has no offset specified has the same
> > behaviour as mem=.
> > 
> > KASLR needs to consider this when choosing the random position for
> > decompressing the kernel. Do it now.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
> > ---
> >  arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
> >  1 file changed, 50 insertions(+), 18 deletions(-)
> > 
> > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> > index 106e13b..e0eba12 100644
> > --- a/arch/x86/boot/compressed/kaslr.c
> > +++ b/arch/x86/boot/compressed/kaslr.c
> > @@ -88,6 +88,10 @@ struct mem_vector {
> >  static bool memmap_too_large;
> > 
> > 
> > +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
> > +unsigned long long mem_limit = ULLONG_MAX;
> > +
> > +
> >  enum mem_avoid_index {
> >  	MEM_AVOID_ZO_RANGE = 0,
> >  	MEM_AVOID_INITRD,
> > @@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
> >  		return -EINVAL;
> > 
> >  	switch (*p) {
> > -	case '@':
> > -		/* Skip this region, usable */
> > -		*start = 0;
> > -		*size = 0;
> > -		return 0;
> >  	case '#':
> >  	case '$':
> >  	case '!':
> >  		*start = memparse(p + 1, &p);
> >  		return 0;
> > +	case '@':
> > +		/* memmap=nn@ss specifies usable region, should be skipped */
> > +		*size = 0;
> > +		/* Fall through */
> > +	default:
> > +		/*
> > +		 * If w/o offset, only size specified, memmap=nn[KMG] has the
> > +		 * same behaviour as mem=nn[KMG]. It limits the max address
> > +		 * system can use. Region above the limit should be avoided.
> > +		 */
> > +		*start = 0;
> > +		return 0;
> >  	}
> > 
> >  	return -EINVAL;
> > @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
> >  		if (rc < 0)
> >  			break;
> >  		str = k;
> > -		/* A usable region that should not be skipped */
> > -		if (size == 0)
> > +
> > +		if (start == 0) {
> > +			/* Store the specified memory limit if size > 0 */
> > +			if (size > 0)
> > +				mem_limit = size;
> 
> Baoquan,
> 
> I am not sure about setting the value of mem_limit to mem_size directly.
> 
> If the command line has both the "memmap" and "mem", such as
>  ... mem=2G memmap=4G ...
> 
> ...in that code, the mem_limit may be 4G not 2G.

No, could you tell why you want to add both "memmap=nnKMG" and "mem=" at
the same time? As you sid, what if I add "mem=4G mem=2G mem=1G"?

> 
> In my opinion, How about following:
> 
> mem_limit = mem_limit > mem_size ? mem_size : mem_limit;
> 
> > +
> >  			continue;
> > +		}
> > 
> >  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
> >  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
> > @@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
> >  		memmap_too_large = true;
> >  }
> > 
> > -
> > -/*
> > - * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove
> > - * this note later.
> > - */
> >  static int handle_mem_memmap(void)
> >  {
> >  	char *args = (char *)get_cmd_line_ptr();
> >  	size_t len = strlen((char *)args);
> >  	char *tmp_cmdline;
> >  	char *param, *val;
> > +	u64 mem_size;
> > 
> > -	if (!strstr(args, "memmap="))
> > +	if (!strstr(args, "memmap=") && !strstr(args, "mem="))
> >  		return 0;
> > 
> >  	tmp_cmdline = malloc(len + 1);
> > @@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
> >  			return -1;
> >  		}
> > 
> > -		if (!strcmp(param, "memmap"))
> > +		if (!strcmp(param, "memmap")) {
> >  			mem_avoid_memmap(val);
> > +		} else if (!strcmp(param, "mem")) {
> > +			char *p = val;
> > +
> > +			if (!strcmp(p, "nopentium"))
> > +				continue;
> > +			mem_size = memparse(p, &p);
> > +			if (mem_size == 0) {
> > +				free(tmp_cmdline);
> > +				return -EINVAL;
> > +			}
> > +			mem_limit = mem_size;
> 
> The same as above.
> 
> Thanks,
> 	Liyang.
> 
> > +		}
> >  	}
> > 
> >  	free(tmp_cmdline);
> > @@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
> >  {
> >  	struct mem_vector region, overlap;
> >  	struct slot_area slot_area;
> > -	unsigned long start_orig;
> > +	unsigned long start_orig, end;
> > +	struct boot_e820_entry cur_entry;
> > 
> >  	/* Skip non-RAM entries. */
> >  	if (entry->type != E820_TYPE_RAM)
> > @@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry,
> >  	if (entry->addr + entry->size < minimum)
> >  		return;
> > 
> > -	region.start = entry->addr;
> > -	region.size = entry->size;
> > +	/* Ignore entries above memory limit */
> > +	end = min(entry->size + entry->addr, mem_limit);
> > +	if (entry->addr >= end)
> > +		return;
> > +	cur_entry.addr = entry->addr;
> > +	cur_entry.size = end - entry->addr;
> > +
> > +	region.start = cur_entry.addr;
> > +	region.size = cur_entry.size;
> > 
> >  	/* Give up if slot area array is full. */
> >  	while (slot_area_index < MAX_SLOT_AREA) {
> > @@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
> >  		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
> > 
> >  		/* Did we raise the address above this e820 region? */
> > -		if (region.start > entry->addr + entry->size)
> > +		if (region.start > cur_entry.addr + cur_entry.size)
> >  			return;
> > 
> >  		/* Reduce size by any delta from the original address. */
> > 
> 
> 

[toc] | [prev] | [next] | [standalone]

#1642174 — Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

At 05/16/2017 09:12 AM, Baoquan He wrote:
> On 05/16/17 at 08:56am, Dou Liyang wrote:
>> Hi Baoquan,
>>
>> At 05/13/2017 01:46 PM, Baoquan He wrote:
>>> Option mem= will limit the max address a system can use and any memory
>>> region above the limit will be removed.
>>>
>>> Furthermore, memmap=nn[KMG] which has no offset specified has the same
>>> behaviour as mem=.
>>>
>>> KASLR needs to consider this when choosing the random position for
>>> decompressing the kernel. Do it now.
>>>
>>> Signed-off-by: Baoquan He <bhe@redhat.com>
>>> Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
>>> ---
>>>  arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
>>>  1 file changed, 50 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
>>> index 106e13b..e0eba12 100644
>>> --- a/arch/x86/boot/compressed/kaslr.c
>>> +++ b/arch/x86/boot/compressed/kaslr.c
>>> @@ -88,6 +88,10 @@ struct mem_vector {
>>>  static bool memmap_too_large;
>>>
>>>
>>> +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
>>> +unsigned long long mem_limit = ULLONG_MAX;
>>> +
>>> +
>>>  enum mem_avoid_index {
>>>  	MEM_AVOID_ZO_RANGE = 0,
>>>  	MEM_AVOID_INITRD,
>>> @@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
>>>  		return -EINVAL;
>>>
>>>  	switch (*p) {
>>> -	case '@':
>>> -		/* Skip this region, usable */
>>> -		*start = 0;
>>> -		*size = 0;
>>> -		return 0;
>>>  	case '#':
>>>  	case '$':
>>>  	case '!':
>>>  		*start = memparse(p + 1, &p);
>>>  		return 0;
>>> +	case '@':
>>> +		/* memmap=nn@ss specifies usable region, should be skipped */
>>> +		*size = 0;
>>> +		/* Fall through */
>>> +	default:
>>> +		/*
>>> +		 * If w/o offset, only size specified, memmap=nn[KMG] has the
>>> +		 * same behaviour as mem=nn[KMG]. It limits the max address
>>> +		 * system can use. Region above the limit should be avoided.
>>> +		 */
>>> +		*start = 0;
>>> +		return 0;
>>>  	}
>>>
>>>  	return -EINVAL;
>>> @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
>>>  		if (rc < 0)
>>>  			break;
>>>  		str = k;
>>> -		/* A usable region that should not be skipped */
>>> -		if (size == 0)
>>> +
>>> +		if (start == 0) {
>>> +			/* Store the specified memory limit if size > 0 */
>>> +			if (size > 0)
>>> +				mem_limit = size;
>>
>> Baoquan,
>>
>> I am not sure about setting the value of mem_limit to mem_size directly.
>>
>> If the command line has both the "memmap" and "mem", such as
>>  ... mem=2G memmap=4G ...
>>
>> ...in that code, the mem_limit may be 4G not 2G.
>
> No, could you tell why you want to add both "memmap=nnKMG" and "mem=" at
> the same time? As you sid, what if I add "mem=4G mem=2G mem=1G"?

Just for testing :)

Ok, thanks, I see. We should be responsible for our command line. don't
need to consider with these situations in kernel.

Thanks,
Liyang.
>
>>
>> In my opinion, How about following:
>>
>> mem_limit = mem_limit > mem_size ? mem_size : mem_limit;
>>
>>> +
>>>  			continue;
>>> +		}
>>>
>>>  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
>>>  		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
>>> @@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
>>>  		memmap_too_large = true;
>>>  }
>>>
>>> -
>>> -/*
>>> - * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove
>>> - * this note later.
>>> - */
>>>  static int handle_mem_memmap(void)
>>>  {
>>>  	char *args = (char *)get_cmd_line_ptr();
>>>  	size_t len = strlen((char *)args);
>>>  	char *tmp_cmdline;
>>>  	char *param, *val;
>>> +	u64 mem_size;
>>>
>>> -	if (!strstr(args, "memmap="))
>>> +	if (!strstr(args, "memmap=") && !strstr(args, "mem="))
>>>  		return 0;
>>>
>>>  	tmp_cmdline = malloc(len + 1);
>>> @@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
>>>  			return -1;
>>>  		}
>>>
>>> -		if (!strcmp(param, "memmap"))
>>> +		if (!strcmp(param, "memmap")) {
>>>  			mem_avoid_memmap(val);
>>> +		} else if (!strcmp(param, "mem")) {
>>> +			char *p = val;
>>> +
>>> +			if (!strcmp(p, "nopentium"))
>>> +				continue;
>>> +			mem_size = memparse(p, &p);
>>> +			if (mem_size == 0) {
>>> +				free(tmp_cmdline);
>>> +				return -EINVAL;
>>> +			}
>>> +			mem_limit = mem_size;
>>
>> The same as above.
>>
>> Thanks,
>> 	Liyang.
>>
>>> +		}
>>>  	}
>>>
>>>  	free(tmp_cmdline);
>>> @@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>>>  {
>>>  	struct mem_vector region, overlap;
>>>  	struct slot_area slot_area;
>>> -	unsigned long start_orig;
>>> +	unsigned long start_orig, end;
>>> +	struct boot_e820_entry cur_entry;
>>>
>>>  	/* Skip non-RAM entries. */
>>>  	if (entry->type != E820_TYPE_RAM)
>>> @@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>>>  	if (entry->addr + entry->size < minimum)
>>>  		return;
>>>
>>> -	region.start = entry->addr;
>>> -	region.size = entry->size;
>>> +	/* Ignore entries above memory limit */
>>> +	end = min(entry->size + entry->addr, mem_limit);
>>> +	if (entry->addr >= end)
>>> +		return;
>>> +	cur_entry.addr = entry->addr;
>>> +	cur_entry.size = end - entry->addr;
>>> +
>>> +	region.start = cur_entry.addr;
>>> +	region.size = cur_entry.size;
>>>
>>>  	/* Give up if slot area array is full. */
>>>  	while (slot_area_index < MAX_SLOT_AREA) {
>>> @@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
>>>  		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
>>>
>>>  		/* Did we raise the address above this e820 region? */
>>> -		if (region.start > entry->addr + entry->size)
>>> +		if (region.start > cur_entry.addr + cur_entry.size)
>>>  			return;
>>>
>>>  		/* Reduce size by any delta from the original address. */
>>>
>>
>>
>
>
>

[toc] | [prev] | [next] | [standalone]

#1642190 — Re: [PATCH v5 2/3] KASLR: Handle memory limit specified by memmap and mem option

On 05/16/17 at 09:43am, Dou Liyang wrote:
> 
> 
> At 05/16/2017 09:12 AM, Baoquan He wrote:
> > On 05/16/17 at 08:56am, Dou Liyang wrote:
> > > Hi Baoquan,
> > > 
> > > At 05/13/2017 01:46 PM, Baoquan He wrote:
> > > > Option mem= will limit the max address a system can use and any memory
> > > > region above the limit will be removed.
> > > > 
> > > > Furthermore, memmap=nn[KMG] which has no offset specified has the same
> > > > behaviour as mem=.
> > > > 
> > > > KASLR needs to consider this when choosing the random position for
> > > > decompressing the kernel. Do it now.
> > > > 
> > > > Signed-off-by: Baoquan He <bhe@redhat.com>
> > > > Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
> > > > ---
> > > >  arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
> > > >  1 file changed, 50 insertions(+), 18 deletions(-)
> > > > 
> > > >  	return -EINVAL;
> > > > @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
> > > >  		if (rc < 0)
> > > >  			break;
> > > >  		str = k;
> > > > -		/* A usable region that should not be skipped */
> > > > -		if (size == 0)
> > > > +
> > > > +		if (start == 0) {
> > > > +			/* Store the specified memory limit if size > 0 */
> > > > +			if (size > 0)
> > > > +				mem_limit = size;
> > > 
> > > Baoquan,
> > > 
> > > I am not sure about setting the value of mem_limit to mem_size directly.
> > > 
> > > If the command line has both the "memmap" and "mem", such as
> > >  ... mem=2G memmap=4G ...
> > > 
> > > ...in that code, the mem_limit may be 4G not 2G.
> > 
> > No, could you tell why you want to add both "memmap=nnKMG" and "mem=" at
> > the same time? As you sid, what if I add "mem=4G mem=2G mem=1G"?
> 
> Just for testing :)
> 
> Ok, thanks, I see. We should be responsible for our command line. don't
> need to consider with these situations in kernel.

Thanks for testing and looking into this patchset, Liyang. I understand
your worry, this patch is trying to have the same behaviour as in
arch/x86/kernel/e820.c. Seems the liability of specifying them right lays
on users' shoulder.

Thanks
Baoquan

[toc] | [prev] | [next] | [standalone]

#1649438 — [tip:x86/boot] x86/KASLR: Handle the memory limit specified by the 'memmap=' and 'mem=' boot options

Commit-ID:  4cdba14f84c9102c4434384731cd61018b970d59
Gitweb:     http://git.kernel.org/tip/4cdba14f84c9102c4434384731cd61018b970d59
Author:     Baoquan He <bhe@redhat.com>
AuthorDate: Sat, 13 May 2017 13:46:29 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 May 2017 09:50:27 +0200

x86/KASLR: Handle the memory limit specified by the 'memmap=' and 'mem=' boot options

The 'mem=' boot option limits the max address a system can use - any memory
region above the limit will be removed.

Furthermore, the 'memmap=nn[KMG]' variant (with no offset specified) has the same
behaviour as 'mem='.

KASLR needs to consider this when choosing the random position for
decompressing the kernel. Do it.

Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Cc: douly.fnst@cn.fujitsu.com
Cc: dyoung@redhat.com
Link: http://lkml.kernel.org/r/1494654390-23861-3-git-send-email-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 106e13b..e0eba12 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -88,6 +88,10 @@ struct mem_vector {
 static bool memmap_too_large;
 
 
+/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
+unsigned long long mem_limit = ULLONG_MAX;
+
+
 enum mem_avoid_index {
 	MEM_AVOID_ZO_RANGE = 0,
 	MEM_AVOID_INITRD,
@@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
 		return -EINVAL;
 
 	switch (*p) {
-	case '@':
-		/* Skip this region, usable */
-		*start = 0;
-		*size = 0;
-		return 0;
 	case '#':
 	case '$':
 	case '!':
 		*start = memparse(p + 1, &p);
 		return 0;
+	case '@':
+		/* memmap=nn@ss specifies usable region, should be skipped */
+		*size = 0;
+		/* Fall through */
+	default:
+		/*
+		 * If w/o offset, only size specified, memmap=nn[KMG] has the
+		 * same behaviour as mem=nn[KMG]. It limits the max address
+		 * system can use. Region above the limit should be avoided.
+		 */
+		*start = 0;
+		return 0;
 	}
 
 	return -EINVAL;
@@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
 		if (rc < 0)
 			break;
 		str = k;
-		/* A usable region that should not be skipped */
-		if (size == 0)
+
+		if (start == 0) {
+			/* Store the specified memory limit if size > 0 */
+			if (size > 0)
+				mem_limit = size;
+
 			continue;
+		}
 
 		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
 		mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
@@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
 		memmap_too_large = true;
 }
 
-
-/*
- * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove
- * this note later.
- */
 static int handle_mem_memmap(void)
 {
 	char *args = (char *)get_cmd_line_ptr();
 	size_t len = strlen((char *)args);
 	char *tmp_cmdline;
 	char *param, *val;
+	u64 mem_size;
 
-	if (!strstr(args, "memmap="))
+	if (!strstr(args, "memmap=") && !strstr(args, "mem="))
 		return 0;
 
 	tmp_cmdline = malloc(len + 1);
@@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
 			return -1;
 		}
 
-		if (!strcmp(param, "memmap"))
+		if (!strcmp(param, "memmap")) {
 			mem_avoid_memmap(val);
+		} else if (!strcmp(param, "mem")) {
+			char *p = val;
+
+			if (!strcmp(p, "nopentium"))
+				continue;
+			mem_size = memparse(p, &p);
+			if (mem_size == 0) {
+				free(tmp_cmdline);
+				return -EINVAL;
+			}
+			mem_limit = mem_size;
+		}
 	}
 
 	free(tmp_cmdline);
@@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 {
 	struct mem_vector region, overlap;
 	struct slot_area slot_area;
-	unsigned long start_orig;
+	unsigned long start_orig, end;
+	struct boot_e820_entry cur_entry;
 
 	/* Skip non-RAM entries. */
 	if (entry->type != E820_TYPE_RAM)
@@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 	if (entry->addr + entry->size < minimum)
 		return;
 
-	region.start = entry->addr;
-	region.size = entry->size;
+	/* Ignore entries above memory limit */
+	end = min(entry->size + entry->addr, mem_limit);
+	if (entry->addr >= end)
+		return;
+	cur_entry.addr = entry->addr;
+	cur_entry.size = end - entry->addr;
+
+	region.start = cur_entry.addr;
+	region.size = cur_entry.size;
 
 	/* Give up if slot area array is full. */
 	while (slot_area_index < MAX_SLOT_AREA) {
@@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
 
 		/* Did we raise the address above this e820 region? */
-		if (region.start > entry->addr + entry->size)
+		if (region.start > cur_entry.addr + cur_entry.size)
 			return;
 
 		/* Reduce size by any delta from the original address. */

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web