[CRIU] [RFC] Check page size at run time

[Christopher Covington]

On 10/05/2015 06:22 AM, Pavel Emelyanov wrote:
> On 10/03/2015 03:47 PM, Christopher Covington wrote:
>> CRIU can be built to support different PAGE_SIZE values. Move the
>> page size check from build time to run time.
>>
>> Signed-off-by: Christopher Covington <cov at codeaurora.org>
>> ---
>>  crtools.c       |  2 --
>>  include/image.h |  5 -----
>>  kerndat.c       | 13 +++++++++++++
>>  3 files changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/crtools.c b/crtools.c
>> index ea8b889..52d148b 100644
>> --- a/crtools.c
>> +++ b/crtools.c
>> @@ -255,8 +255,6 @@ int main(int argc, char *argv[], char *envp[])
>>  		{ },
>>  	};
>>  
>> -	BUILD_BUG_ON(PAGE_SIZE != PAGE_IMAGE_SIZE);
>> -
>>  	cr_pb_init();
>>  	if (restrict_uid(getuid(), getgid()))
>>  		return 1;
>> diff --git a/include/image.h b/include/image.h
>> index 305febf..a1e5544 100644
>> --- a/include/image.h
>> +++ b/include/image.h
>> @@ -11,11 +11,6 @@
>>  #include "bfd.h"
>>  #include "bug.h"
>>  
>> -#ifdef _ARCH_PPC64
>> -#define PAGE_IMAGE_SIZE	65536
>> -#else
>> -#define PAGE_IMAGE_SIZE	4096
>> -#endif /* _ARCH_PPC64 */
>>  #define PAGE_RSS	1
>>  #define PAGE_ANON	2
>>  
>> diff --git a/kerndat.c b/kerndat.c
>> index e57c6fd..4e10e63 100644
>> --- a/kerndat.c
>> +++ b/kerndat.c
>> @@ -296,6 +296,17 @@ static int get_task_size(void)
>>  	return 0;
>>  }
>>  
>> +static int check_page_size(void)
>> +{
>> +	if (PAGE_SIZE != page_size()) {
>> +		pr_err("Page size mismatch.\n");
>> +		pr_err("Built for: %ld running with: %ld.\n", (unsigned long)PAGE_SIZE,
>> +		       page_size());
>> +		return -1;
>> +	}
>> +	return 0;
>> +}
>> +
>>  int kerndat_fdinfo_has_lock()
>>  {
>>  	int fd, pfd = -1, exit_code = -1, len;
>> @@ -348,6 +359,8 @@ int kerndat_init(void)
> 
> The kerndat_init() is only called on dump, restore calls kerndat_init_rst(). Do
> we want to check page-size on restore as well?

Yes.

Also, these checks are whether the CRIU binary was built to support the page
size of the current system. Ideally we'll eventually have a single CRIU binary
that can support all page sizes.

Something that I'm not yet checking is whether the page size of the dumped
process matches that of the current system. I think I need to add a field to
the image files for this. If you have any suggestions about where specifically
to put it (I was thinking maybe near the AArch64 CPU fields), please let me know

Thanks,
Christopher Covington

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