RE: [PATCH] makedumpfile: Enable --mem-usage for s390x

[Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>]

>> I think the Michael's first idea below is better since it implements
>> is_real_addr() only for --mem-usage as a common function for all
>> architectures, it's explicit design.
>>
>> >@@ -854,7 +854,7 @@ int get_kcore_dump_loads(void)
>> >
>> > 	for (i = 0; i < num_pt_loads; ++i) {
>> > 		struct pt_load_segment *p = &pt_loads[i];
>> >-		if (is_vmalloc_addr(p->virt_start))
>> >+		if (!is_real_addr(p->virt_start))
>> > 			continue;
>> > 		loads++;
>> > 	}
>>
>> However, this code will not work since the argument of is_real_addr()
>> must be physical address. Even unluckily, /proc/kcore's PT_LOAD looks
>> useless for VtoP converting because PhysAddr is always 0:
>>
>> Program Headers:
>>   Type           Offset             VirtAddr           PhysAddr
>>                  FileSiz            MemSiz              Flags  Align
>>   NOTE           0x00000000000002a8 0x0000000000000000 0x0000000000000000
>>                  0x0000000000000a84 0x0000000000000000         0
>>   LOAD           0x00007fffff601000 0xffffffffff600000 0x0000000000000000
>>                  0x0000000000001000 0x0000000000001000  RWE    1000
>>   LOAD           0x00007fff81001000 0xffffffff81000000 0x0000000000000000
>>                  0x0000000000a1b000 0x0000000000a1b000  RWE    1000
>>   LOAD           0x0000490000001000 0xffffc90000000000 0x0000000000000000
>>                  0x00001fffffffffff 0x00001fffffffffff  RWE    1000
>>   LOAD           0x00007fffa0001000 0xffffffffa0000000 0x0000000000000000
>>                  0x000000005f000000 0x000000005f000000  RWE    1000
>>   ...
>>
>>
>> So the way using /proc/iomem seems inappropriate, we have to consider other
>> approaches (but I still don't have any good ideas...)
>
>Hello Atsushi,
>
>Hmmm ok, sure. For x86 using /proc/iomem does not work because there is no 1:1
>mapping for the kernel address space. The kernel/real memory is mapped somewhere
>at the end, right?

Exactly.

>For s390 we have a 1:1 mapping for the kernel physical memory that starts with
>zero. Therefore IMHO we could use /proc/iomem. For example, on my s390x system
>with 1GB memory and 256MB crashkernel:
>
>$ cat /proc/iomem
>00000000-2fffffff : System RAM
>  00000000-007ddd4b : Kernel code
>  007ddd4c-00bfcc5f : Kernel data
>  00e18000-01c28b1f : Kernel bss
>30000000-3fffffff : Crash kernel
>
>$ objdump -h /proc/kcore
>...
>  Type           Offset             VirtAddr           PhysAddr
>                 FileSiz            MemSiz              Flags  Align
>  NOTE           0x0000000000000158 0x0000000000000000 0x0000000000000000
>                 0x00000000000027fc 0x0000000000000000         0
>  LOAD           0x000003e080003000 0x000003e080000000 0x0000000000000000
>                 0x0000001f00000000 0x0000001f00000000  RWE    1000
>  LOAD           0x000003ff80003000 0x000003ff80000000 0x0000000000000000
>                 0x0000000080000000 0x0000000080000000  RWE    1000
>  LOAD           0x0000000000003000 0x0000000000000000 0x0000000000000000
>                 0x0000000030000000 0x0000000030000000  RWE    1000
>  LOAD           0x000003d100003000 0x000003d100000000 0x0000000000000000
>                 0x0000000000c00000 0x0000000000c00000  RWE    1000
>
>So in that case every /proc/kcore load that is below 0x30000000 must
>be real memory.
>
>Michael

I understand why your patch works on s390x, so how about this way ?

 1. Define "is_phys_addr()" for --mem-usage.
 2. Implement is_phys_addr() using is_iomem_phys_addr() for s390x
    while x86_64 uses is_vmalloc_addr_x86_64().
 3. Use is_phys_addr() instead of is_vmalloc_addr() in get_kcore_dump_loads().


Thanks,
Atsushi Kumagai

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