Re: 3 gold testcases...

[Ian Lance Taylor <iant at google dot com>]

David Miller <davem@davemloft.net> writes:

> I've analyzed each one, and they really aren't sparc target
> bugs per-se, but rather testcases that need some tweaks of
> some sort:

Cool.

Yes, the linker script tests are definitely touchy.


> 1) justsyms puts a string at 0x10000 hoping that will be
>    out of the way and not in some mapped region of the
>    executable image so that it will generate a segfault.
>
>    This happens to be where the .text gets mapped so the
>    segfault doesn't happen and the testcase fails.

Ouch, bad luck.  Really, though, the address can be anywhere.  What if
we change it to 0x100?


> 2) script_test_2 fails because of the assertion:
>
>    assert(reinterpret_cast<uintptr_t>(start_test_area_1 + 48 + 7 + 4)
> 	 == reinterpret_cast<uintptr_t>(start_data));
>
>    It assumes that the string will only consume 7 bytes, but on
>    Sparc strings are emitted by the compiler with an ".align 8"
>    directive, and thus the size consumed by the string is rounded
>    up to 8 bytes.

Would it work if we make both strings 8 characters long and adjust
accordingly?


> 3) script_test_3 fails because the PT_LOAD segments created overlap
>    within a page, and the kernel thus refuses to load the binary.

I'm not sure I understand this one.  It's normally OK for PT_LOAD
segments to overlap within a page in the file.  The segments here do
not overlap in virtual address space, unless your pages are very
large.

>
>    Actually, if I run the program as:
>
> 	bash$ /lib/ld-linux.so.2 ./script_test_3
>
>    it works, so I suppose the PT_LOAD mapping rules of the dynamic
>    linker are more relaxed than that of the kernel.
>
>   Section Headers:
>     [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
>     [ 0]                   NULL            00000000 000000 000000 00      0   0  0
>     [ 1] .interp           PROGBITS        10000000 010000 000013 00   A  0   0  1
>  ...
>     [14] .text             PROGBITS        100004e0 0104e0 000b48 00  AX  0   0 32
>     [15] .text             PROGBITS        10001028 011028 0002a8 00  AX  0   0  4
>
>    Program Headers:
>      Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
>      INTERP         0x010000 0x10000000 0x10000000 0x004c8 0x004c8 R   0x8
>          [Requesting program interpreter: /lib/ld-linux.so.2]
>      LOAD           0x000000 0x0fff0000 0x0fff0000 0x11398 0x11398 R E 0x2000
>      LOAD           0x011400 0x10101400 0x10101400 0x001e0 0x001e0 RWE 0x2000
>      LOAD           0x011600 0x10201600 0x10201600 0x00000 0x00088 RW  0x2000
>      DYNAMIC        0x011400 0x10101400 0x10101400 0x000d0 0x000d0 R   0x4