[Bug ld/19162] Huge binary after linking sections with "a" and "wa" flags

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=19162

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WONTFIX

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Ilya Verbin from comment #0)
> The testcase:
> 
> $ cat t1.s
> .section ".AAA", "a"
> .long 0x12345678
> $ cat t2.s
> .section ".AAA", "wa"
> .long 0x12345678
> $ as t1.s -o t1.o
> $ as t2.s -o t2.o
> $ ld -shared t1.o t2.o
> $ ls -lh a.out
> 2.1M a.out
> 
> Some strange 2MB offset is inserted into another section:
> 
> [Nr] Name              Type             Address           Offset
>      Size              EntSize          Flags  Link  Info  Align
> [ 0]                   NULL             0000000000000000  00000000
>      0000000000000000  0000000000000000           0     0     0
> [ 1] .hash             HASH             00000000000000b0  000000b0
>      0000000000000028  0000000000000004   A       2     0     8
> [ 2] .dynsym           DYNSYM           00000000000000d8  000000d8
>      0000000000000078  0000000000000018   A       3     2     8
> [ 3] .dynstr           STRTAB           0000000000000150  00000150
>      0000000000000019  0000000000000000   A       0     0     1
> [ 4] .AAA              PROGBITS         0000000000000169  00000169
>      0000000000000008  0000000000000000  WA       0     0     1
> [ 5] .eh_frame         PROGBITS         0000000000000178  00000178
>      0000000000000000  0000000000000000   A       0     0     8
> [ 6] .dynamic          DYNAMIC          0000000000200178  00200178  <-- ???
>      00000000000000b0  0000000000000010  WA       3     0     8
> 
> It seems that something goes wrong during section-to-segment mapping,
> because when both .AAA have "wa" flags, we got small binary with 2 LOAD
> segments:
>   Type           Offset             VirtAddr           PhysAddr
>                  FileSiz            MemSiz              Flags  Align
>   LOAD           0x0000000000000000 0x0000000000000000 0x0000000000000000
>                  0x00000000000001a8 0x00000000000001a8  R      200000
>   LOAD           0x00000000000001a8 0x00000000002001a8 0x00000000002001a8
>                  0x00000000000000b8 0x00000000000000b8  RW     200000
> 
> But when one .AAA has "a" flag, and another .AAA has "wa" flag, we got huge
> binary with only one big LOAD segment:
>   Type           Offset             VirtAddr           PhysAddr
>                  FileSiz            MemSiz              Flags  Align
>   LOAD           0x0000000000000000 0x0000000000000000 0x0000000000000000
>                  0x0000000000200228 0x0000000000200228  RW     200000

Since ld defaults to 2MB maximum page size, it is normal:

address@hidden pr19162]$ make clean
rm -f *.o *.so *.a
address@hidden pr19162]$ make
gcc  -fPIC -O2 -c -o t1.o t1.s
gcc  -fPIC -O2 -c -o t2.o t2.s
./ld -shared  -o x.so t1.o t2.o
ls -lh x.so
-rwxrwxr-x 1 hjl hjl 2.1M Oct 22 08:22 x.so
address@hidden pr19162]$ make clean
rm -f *.o *.so *.a
address@hidden pr19162]$ make LDFLAGS="-z max-page-size=0x1000"
gcc  -fPIC -O2 -c -o t1.o t1.s
gcc  -fPIC -O2 -c -o t2.o t2.s
./ld -shared -z max-page-size=0x1000 -o x.so t1.o t2.o
ls -lh x.so
-rwxrwxr-x 1 hjl hjl 5.6K Oct 22 08:22 x.so
address@hidden pr19162]$

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