page size change on MIPS

page size change on MIPS

[keshav yadav]

Hi All,

I observe one different behavior when we have page size set to 4KB or
16KB in kernel busybox receive argc[0] argument correct, but
when page size set to 64KB I am getting argv[0] as empty. So what may
be issue. I am using codesourcercy toolchain.

Kind regards




---------- Forwarded message ----------
From: naveen yadav <yad.naveen@gmail.com>
Date: Fri, Feb 4, 2011 at 9:46 AM
Subject: Re: page size change on MIPS
To: Ralf Baechle <ralf@linux-mips.org>
Cc: kernelnewbies@nl.linux.org, Himanshu Aggarwal
<lkml.himanshu@gmail.com>, David Daney <ddaney@caviumnetworks.com>,
linux-mips@linux-mips.org


Hi, I am adding readelf info also .

mips-linux-gnu-readelf -S squashfs-root/bin/busybox
There are 35 section headers, starting at offset 0x174290:

Section Headers:
 [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
 [ 0]                   NULL            00000000 000000 000000 00      0   0  0
 [ 1] .note.ABI-tag     NOTE            004000d4 0000d4 000020 00   A  0   0  4
 [ 2] .reginfo          MIPS_REGINFO    004000f4 0000f4 000018 18   A  0   0  4
 [ 3] .rel.dyn          REL             0040010c 00010c 000010 08   A  0   0  4
 [ 4] .init             PROGBITS        0040011c 00011c 00005c 00  AX  0   0  4
 [ 5] .text             PROGBITS        00400180 000180 11d2b0 00  AX  0   0 16
 [ 6] __libc_freeres_fn PROGBITS        0051d430 11d430 001368 00  AX  0   0  4
 [ 7] __libc_thread_fre PROGBITS        0051e798 11e798 000148 00  AX  0   0  4
 [ 8] .fini             PROGBITS        0051e8e0 11e8e0 000034 00  AX  0   0  4
 [ 9] .rodata           PROGBITS        0051e920 11e920 02d560 00   A  0   0 16
 [10] __libc_subfreeres PROGBITS        0054be80 14be80 000058 00   A  0   0  4
 [11] __libc_atexit     PROGBITS        0054bed8 14bed8 000004 00   A  0   0  4
 [12] __libc_thread_sub PROGBITS        0054bedc 14bedc 000008 00   A  0   0  4
 [13] .gcc_except_table PROGBITS        0054bee4 14bee4 0001fb 00   A  0   0  1
 [14] .eh_frame         PROGBITS        0055c0e0 14c0e0 002464 00  WA  0   0  4
 [15] .tdata            PROGBITS        0055e544 14e544 000018 00 WAT  0   0  4
 [16] .tbss             NOBITS          0055e55c 14e55c 000034 00 WAT  0   0  4
 [17] .ctors            PROGBITS        0055e55c 14e55c 000008 00  WA  0   0  4
 [18] .dtors            PROGBITS        0055e564 14e564 00000c 00  WA  0   0  4
 [19] .jcr              PROGBITS        0055e570 14e570 000004 00  WA  0   0  4
 [20] .data.rel.ro      PROGBITS        0055e574 14e574 000030 00  WA  0   0  4
 [21] .data             PROGBITS        0055e5b0 14e5b0 000b30 00  WA  0   0 16
 [22] .got              PROGBITS        0055f0e0 14f0e0 000148 04 WAp  0   0 16
 [23] .sdata            PROGBITS        0055f228 14f228 000004 00 WAp  0   0  4
 [24] .sbss             NOBITS          0055f230 14f22c 000184 00 WAp  0   0  8
 [25] .bss              NOBITS          0055f3c0 14f22c 00516c 00  WA  0   0 16
 [26] __libc_freeres_pt NOBITS          0056452c 14f22c 000040 00  WA  0   0  4
 [27] .pdr              PROGBITS        00000000 14f22c 016880 00      0   0  4
 [28] .comment          PROGBITS        00000000 165aac 0027e0 00      0   0  1
 [29] .debug_frame      MIPS_DWARF      00000000 16828c 00be88 00      0   0  4
 [30] .gnu.attributes   LOOS+ffffff5    00000000 174114 000010 00      0   0  1
 [31] .mdebug.abi32     PROGBITS        000030c0 174124 000000 00      0   0  1
 [32] .shstrtab         STRTAB          00000000 174124 00016c 00      0   0  1
 [33] .symtab           SYMTAB          00000000 174808 015320 10
34 2843  4
 [34] .strtab           STRTAB          00000000 189b28 012f65 00      0   0  1
Key to Flags:
 W (write), A (alloc), X (execute), M (merge), S (strings)
 I (info), L (link order), G (group), x (unknown)
 O (extra OS processing required) o (OS specific), p (processor specific)


On Fri, Feb 4, 2011 at 8:54 AM, naveen yadav <yad.naveen@gmail.com> wrote:
> thanaks a lot for your suggestion ..
>
>
> I debug this issue further, and here is my observations:
>
> 1. If I replace init with simple static link executable binary, this
> can be executed.
> 2. In case of busy-box, I debug the reason why init fails to excute.
>
> When I execute init command from busybox the control goes in main()
> function of busybox(appletlib.c) with argv value
> as the command you are suppose to execute, which in our case is init.
>
> But when i check argv is coming null when page size is 64KB and it
> comes init when page size is 16KB.
>
> This behaviour is very strange and i am still debugging this issue.
>
>
> I have check in Glibc, the max_page size it support is 64 KB in
> codesourcercy toolchain 4.4.1
>
> How can I check alignment issue as mention by Mr. Ralf Baechle.
>
>
>
> Kind regards
>
>
>
>
> On Mon, Jan 31, 2011 at 6:38 PM, Ralf Baechle <ralf@linux-mips.org> wrote:
>> On Sun, Jan 30, 2011 at 08:32:43PM +0530, Himanshu Aggarwal wrote:
>>
>>> Why should the application or the toolchains depend on pagesize? I am
>>> not very clear on this. Can someone explain it?
>>
>> To allow loading directly with mmap the executable file's layout must
>> be such that it's it's segments are on offsets that are a multiple of
>> the page size so in turn the linker must know that alignment.
>>
>>  Ralf
>>
>

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

page size change on MIPS

[keshav yadav]

Hi All,

I observe one different behavior when we have page size set to 4KB or
16KB in kernel busybox receive argc[0] argument correct, but
when page size set to 64KB I am getting argv[0] as empty. So what may
be issue. I am using codesourcercy toolchain.

Kind regards




---------- Forwarded message ----------
From: naveen yadav <yad.naveen@gmail.com>
Date: Fri, Feb 4, 2011 at 9:46 AM
Subject: Re: page size change on MIPS
To: Ralf Baechle <ralf@linux-mips.org>
Cc: kernelnewbies@nl.linux.org, Himanshu Aggarwal
<lkml.himanshu@gmail.com>, David Daney <ddaney@caviumnetworks.com>,
linux-mips@linux-mips.org


Hi, I am adding readelf info also .

mips-linux-gnu-readelf -S squashfs-root/bin/busybox
There are 35 section headers, starting at offset 0x174290:

Section Headers:
 [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
 [ 0]                   NULL            00000000 000000 000000 00      0   0  0
 [ 1] .note.ABI-tag     NOTE            004000d4 0000d4 000020 00   A  0   0  4
 [ 2] .reginfo          MIPS_REGINFO    004000f4 0000f4 000018 18   A  0   0  4
 [ 3] .rel.dyn          REL             0040010c 00010c 000010 08   A  0   0  4
 [ 4] .init             PROGBITS        0040011c 00011c 00005c 00  AX  0   0  4
 [ 5] .text             PROGBITS        00400180 000180 11d2b0 00  AX  0   0 16
 [ 6] __libc_freeres_fn PROGBITS        0051d430 11d430 001368 00  AX  0   0  4
 [ 7] __libc_thread_fre PROGBITS        0051e798 11e798 000148 00  AX  0   0  4
 [ 8] .fini             PROGBITS        0051e8e0 11e8e0 000034 00  AX  0   0  4
 [ 9] .rodata           PROGBITS        0051e920 11e920 02d560 00   A  0   0 16
 [10] __libc_subfreeres PROGBITS        0054be80 14be80 000058 00   A  0   0  4
 [11] __libc_atexit     PROGBITS        0054bed8 14bed8 000004 00   A  0   0  4
 [12] __libc_thread_sub PROGBITS        0054bedc 14bedc 000008 00   A  0   0  4
 [13] .gcc_except_table PROGBITS        0054bee4 14bee4 0001fb 00   A  0   0  1
 [14] .eh_frame         PROGBITS        0055c0e0 14c0e0 002464 00  WA  0   0  4
 [15] .tdata            PROGBITS        0055e544 14e544 000018 00 WAT  0   0  4
 [16] .tbss             NOBITS          0055e55c 14e55c 000034 00 WAT  0   0  4
 [17] .ctors            PROGBITS        0055e55c 14e55c 000008 00  WA  0   0  4
 [18] .dtors            PROGBITS        0055e564 14e564 00000c 00  WA  0   0  4
 [19] .jcr              PROGBITS        0055e570 14e570 000004 00  WA  0   0  4
 [20] .data.rel.ro      PROGBITS        0055e574 14e574 000030 00  WA  0   0  4
 [21] .data             PROGBITS        0055e5b0 14e5b0 000b30 00  WA  0   0 16
 [22] .got              PROGBITS        0055f0e0 14f0e0 000148 04 WAp  0   0 16
 [23] .sdata            PROGBITS        0055f228 14f228 000004 00 WAp  0   0  4
 [24] .sbss             NOBITS          0055f230 14f22c 000184 00 WAp  0   0  8
 [25] .bss              NOBITS          0055f3c0 14f22c 00516c 00  WA  0   0 16
 [26] __libc_freeres_pt NOBITS          0056452c 14f22c 000040 00  WA  0   0  4
 [27] .pdr              PROGBITS        00000000 14f22c 016880 00      0   0  4
 [28] .comment          PROGBITS        00000000 165aac 0027e0 00      0   0  1
 [29] .debug_frame      MIPS_DWARF      00000000 16828c 00be88 00      0   0  4
 [30] .gnu.attributes   LOOS+ffffff5    00000000 174114 000010 00      0   0  1
 [31] .mdebug.abi32     PROGBITS        000030c0 174124 000000 00      0   0  1
 [32] .shstrtab         STRTAB          00000000 174124 00016c 00      0   0  1
 [33] .symtab           SYMTAB          00000000 174808 015320 10
34 2843  4
 [34] .strtab           STRTAB          00000000 189b28 012f65 00      0   0  1
Key to Flags:
 W (write), A (alloc), X (execute), M (merge), S (strings)
 I (info), L (link order), G (group), x (unknown)
 O (extra OS processing required) o (OS specific), p (processor specific)


On Fri, Feb 4, 2011 at 8:54 AM, naveen yadav <yad.naveen@gmail.com> wrote:
> thanaks a lot for your suggestion ..
>
>
> I debug this issue further, and here is my observations:
>
> 1. If I replace init with simple static link executable binary, this
> can be executed.
> 2. In case of busy-box, I debug the reason why init fails to excute.
>
> When I execute init command from busybox the control goes in main()
> function of busybox(appletlib.c) with argv value
> as the command you are suppose to execute, which in our case is init.
>
> But when i check argv is coming null when page size is 64KB and it
> comes init when page size is 16KB.
>
> This behaviour is very strange and i am still debugging this issue.
>
>
> I have check in Glibc, the max_page size it support is 64 KB in
> codesourcercy toolchain 4.4.1
>
> How can I check alignment issue as mention by Mr. Ralf Baechle.
>
>
>
> Kind regards
>
>
>
>
> On Mon, Jan 31, 2011 at 6:38 PM, Ralf Baechle <ralf@linux-mips.org> wrote:
>> On Sun, Jan 30, 2011 at 08:32:43PM +0530, Himanshu Aggarwal wrote:
>>
>>> Why should the application or the toolchains depend on pagesize? I am
>>> not very clear on this. Can someone explain it?
>>
>> To allow loading directly with mmap the executable file's layout must
>> be such that it's it's segments are on offsets that are a multiple of
>> the page size so in turn the linker must know that alignment.
>>
>>  Ralf
>>
>

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: page size change on MIPS

[Ian Lance Taylor]

keshav yadav <keshav.yadav2005@gmail.com> writes:

> I observe one different behavior when we have page size set to 4KB or
> 16KB in kernel busybox receive argc[0] argument correct, but
> when page size set to 64KB I am getting argv[0] as empty. So what may
> be issue. I am using codesourcercy toolchain.

I have no idea what the problem but I know that it is extremely unlikely
to have anything to do with gcc.

Ian

Re: page size change on MIPS

[David Daney]

On 02/04/2011 08:26 AM, Ian Lance Taylor wrote:
> keshav yadav<keshav.yadav2005@gmail.com>  writes:
>
>> I observe one different behavior when we have page size set to 4KB or
>> 16KB in kernel busybox receive argc[0] argument correct, but
>> when page size set to 64KB I am getting argv[0] as empty. So what may
>> be issue. I am using codesourcercy toolchain.
>
> I have no idea what the problem but I know that it is extremely unlikely
> to have anything to do with gcc.
>

I agree.

We routinely run programs compiled with a wide variety of stock GCC 
versions, under all three MIPS/Linux ABIs (o32, n32, n64) on kernels 
with 4K, 8K, 16K, 32K and 64K page sizes with no problems.

If you suspect a defect in your toolchain, you could try building a 
'stock' toolchain with recent Binutils and GCC versions.

David Daney

Re: page size change on MIPS

[naveen yadav]

Thanks a lot for your input.

This is o/p for my busybox.I am booting with INITRAMFS. and kernel
version is 2.6.30.9.
I also try latest codesourcery mips toolchain and result is same. I
could not get any hint to debug this issue.


#mips-linux-gnu-readelf -l busybox

Elf file type is EXEC (Executable file)
Entry point 0x400180
There are 5 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  REGINFO        0x0000f4 0x004000f4 0x004000f4 0x00018 0x00018 R   0x4
  LOAD           0x000000 0x00400000 0x00400000 0x1a8c6f 0x1a8c6f R E 0x10000
  LOAD           0x1a9000 0x005b9000 0x005b9000 0x03170 0x084ac RW  0x10000
  NOTE           0x0000d4 0x004000d4 0x004000d4 0x00020 0x00020 R   0x4
  TLS            0x1ab464 0x005bb464 0x005bb464 0x00018 0x0004c R   0x4

 Section to Segment mapping:
  Segment Sections...
   00     .reginfo
   01     .note.ABI-tag .reginfo .rel.dyn .init .text
__libc_freeres_fn __libc_thread_freeres_fn .fini .rodata
__libc_subfreeres __libc_atexit __libc_thread_subfreeres
.gcc_except_table
   02     .eh_frame .tdata .ctors .dtors .jcr .data.rel.ro .data .got
.sdata .sbss .bss __libc_freeres_ptrs
   03     .note.ABI-tag
   04     .tdata .tbss


On Fri, Feb 4, 2011 at 11:09 PM, David Daney <ddaney@caviumnetworks.com> wrote:
> On 02/04/2011 08:26 AM, Ian Lance Taylor wrote:
>>
>> keshav yadav<keshav.yadav2005@gmail.com>  writes:
>>
>>> I observe one different behavior when we have page size set to 4KB or
>>> 16KB in kernel busybox receive argc[0] argument correct, but
>>> when page size set to 64KB I am getting argv[0] as empty. So what may
>>> be issue. I am using codesourcercy toolchain.
>>
>> I have no idea what the problem but I know that it is extremely unlikely
>> to have anything to do with gcc.
>>
>
> I agree.
>
> We routinely run programs compiled with a wide variety of stock GCC
> versions, under all three MIPS/Linux ABIs (o32, n32, n64) on kernels with
> 4K, 8K, 16K, 32K and 64K page sizes with no problems.
>
> If you suspect a defect in your toolchain, you could try building a 'stock'
> toolchain with recent Binutils and GCC versions.
>
> David Daney
>

Re: page size change on MIPS

[David Daney]

On 02/07/2011 07:22 AM, naveen yadav wrote:
> Thanks a lot for your input.
>
> This is o/p for my busybox.I am booting with INITRAMFS. and kernel
> version is 2.6.30.9.
> I also try latest codesourcery mips toolchain and result is same. I
> could not get any hint to debug this issue.
>

The Debian mips/mipsel root filesystems will work with 64K pages.

Install Debian, then use a chroot environment to debug your root 
filesystem.  You should even be able to do that from within qemu.




>
> #mips-linux-gnu-readelf -l busybox
>
> Elf file type is EXEC (Executable file)
> Entry point 0x400180
> There are 5 program headers, starting at offset 52
>
> Program Headers:
>    Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
>    REGINFO        0x0000f4 0x004000f4 0x004000f4 0x00018 0x00018 R   0x4
>    LOAD           0x000000 0x00400000 0x00400000 0x1a8c6f 0x1a8c6f R E 0x10000
>    LOAD           0x1a9000 0x005b9000 0x005b9000 0x03170 0x084ac RW  0x10000
>    NOTE           0x0000d4 0x004000d4 0x004000d4 0x00020 0x00020 R   0x4
>    TLS            0x1ab464 0x005bb464 0x005bb464 0x00018 0x0004c R   0x4
>

Why are you statically linking glibc?  That is usually never a good idea.

Other than that it looks reasonably sane.


>   Section to Segment mapping:
>    Segment Sections...
>     00     .reginfo
>     01     .note.ABI-tag .reginfo .rel.dyn .init .text
> __libc_freeres_fn __libc_thread_freeres_fn .fini .rodata
> __libc_subfreeres __libc_atexit __libc_thread_subfreeres
> .gcc_except_table
>     02     .eh_frame .tdata .ctors .dtors .jcr .data.rel.ro .data .got
> .sdata .sbss .bss __libc_freeres_ptrs
>     03     .note.ABI-tag
>     04     .tdata .tbss
>
>
> On Fri, Feb 4, 2011 at 11:09 PM, David Daney<ddaney@caviumnetworks.com>  wrote:
>> On 02/04/2011 08:26 AM, Ian Lance Taylor wrote:
>>>
>>> keshav yadav<keshav.yadav2005@gmail.com>    writes:
>>>
>>>> I observe one different behavior when we have page size set to 4KB or
>>>> 16KB in kernel busybox receive argc[0] argument correct, but
>>>> when page size set to 64KB I am getting argv[0] as empty. So what may
>>>> be issue. I am using codesourcercy toolchain.
>>>
>>> I have no idea what the problem but I know that it is extremely unlikely
>>> to have anything to do with gcc.
>>>
>>
>> I agree.
>>
>> We routinely run programs compiled with a wide variety of stock GCC
>> versions, under all three MIPS/Linux ABIs (o32, n32, n64) on kernels with
>> 4K, 8K, 16K, 32K and 64K page sizes with no problems.
>>
>> If you suspect a defect in your toolchain, you could try building a 'stock'
>> toolchain with recent Binutils and GCC versions.
>>
>> David Daney
>>
>

Re: page size change on MIPS

[naveen yadav]

Hi All,

I debug this issue further, I check in kernel  File name is
binfmt_elf.c and function name is  create_elf_tables()

I put a debug print here to check what kernel is reading from user space.

		if (__put_user((elf_addr_t)p, argv++))
			return -EFAULT;
		len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
		printk("\n Lenght of arg=%ld,%s \n",len,(void __user *)p);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}


when Page size is 16KB  o/p is

Lenght of arg=6,/init

when Page size is 64KB  o/p is

Lenght of arg=1,

so I got null when it read from ELF


On Tue, Feb 8, 2011 at 5:13 AM, David Daney <ddaney@caviumnetworks.com> wrote:
> On 02/07/2011 07:22 AM, naveen yadav wrote:
>>
>> Thanks a lot for your input.
>>
>> This is o/p for my busybox.I am booting with INITRAMFS. and kernel
>> version is 2.6.30.9.
>> I also try latest codesourcery mips toolchain and result is same. I
>> could not get any hint to debug this issue.
>>
>
> The Debian mips/mipsel root filesystems will work with 64K pages.
>
> Install Debian, then use a chroot environment to debug your root filesystem.
>  You should even be able to do that from within qemu.
>
>
>
>
>>
>> #mips-linux-gnu-readelf -l busybox
>>
>> Elf file type is EXEC (Executable file)
>> Entry point 0x400180
>> There are 5 program headers, starting at offset 52
>>
>> Program Headers:
>>   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
>>   REGINFO        0x0000f4 0x004000f4 0x004000f4 0x00018 0x00018 R   0x4
>>   LOAD           0x000000 0x00400000 0x00400000 0x1a8c6f 0x1a8c6f R E
>> 0x10000
>>   LOAD           0x1a9000 0x005b9000 0x005b9000 0x03170 0x084ac RW
>>  0x10000
>>   NOTE           0x0000d4 0x004000d4 0x004000d4 0x00020 0x00020 R   0x4
>>   TLS            0x1ab464 0x005bb464 0x005bb464 0x00018 0x0004c R   0x4
>>
>
> Why are you statically linking glibc?  That is usually never a good idea.
>
> Other than that it looks reasonably sane.
>
>
>>  Section to Segment mapping:
>>   Segment Sections...
>>    00     .reginfo
>>    01     .note.ABI-tag .reginfo .rel.dyn .init .text
>> __libc_freeres_fn __libc_thread_freeres_fn .fini .rodata
>> __libc_subfreeres __libc_atexit __libc_thread_subfreeres
>> .gcc_except_table
>>    02     .eh_frame .tdata .ctors .dtors .jcr .data.rel.ro .data .got
>> .sdata .sbss .bss __libc_freeres_ptrs
>>    03     .note.ABI-tag
>>    04     .tdata .tbss
>>
>>
>> On Fri, Feb 4, 2011 at 11:09 PM, David Daney<ddaney@caviumnetworks.com>
>>  wrote:
>>>
>>> On 02/04/2011 08:26 AM, Ian Lance Taylor wrote:
>>>>
>>>> keshav yadav<keshav.yadav2005@gmail.com>    writes:
>>>>
>>>>> I observe one different behavior when we have page size set to 4KB or
>>>>> 16KB in kernel busybox receive argc[0] argument correct, but
>>>>> when page size set to 64KB I am getting argv[0] as empty. So what may
>>>>> be issue. I am using codesourcercy toolchain.
>>>>
>>>> I have no idea what the problem but I know that it is extremely unlikely
>>>> to have anything to do with gcc.
>>>>
>>>
>>> I agree.
>>>
>>> We routinely run programs compiled with a wide variety of stock GCC
>>> versions, under all three MIPS/Linux ABIs (o32, n32, n64) on kernels with
>>> 4K, 8K, 16K, 32K and 64K page sizes with no problems.
>>>
>>> If you suspect a defect in your toolchain, you could try building a
>>> 'stock'
>>> toolchain with recent Binutils and GCC versions.
>>>
>>> David Daney
>>>
>>
>
>