ARC processors are known for its configurability and one of those
configurable things is MMU page size which might be set to any
power of two from 4 KiB to 16 MiB, though in the Linux kernel we
only support 4, 8 and 16 KiB due to practical considerations.
And the most used setting is 8 KiB thus GNU LD assumes maximum
page size is 8 KiB by default and while this works for smaller
pages (it's OK to align segments by larger value it will be still
peoperly aligned) this breaks execution of user-space apps on HW
with larger pages because Elf sections might very well span across
allocated pages and thus make executable broken.
Simplest example:
------------------------------------>8-----------------------------------
$ arc-linux-gcc test.c
$ arc-linux-readelf --segments a.out
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
...
LOAD 0x000000 0x00010000 0x00010000 0x003e8 0x003e8 R E 0x2000 <-- See
LOAD 0x001f24 0x00013f24 0x00013f24 0x000f0 0x0010c RW 0x2000
------------------------------------>8-----------------------------------
Fortunately we may override default page size settings with "max-page-size"
linker option this way:
------------------------------------>8-----------------------------------
$ arc-linux-gcc test.c -Wl,-z,max-page-size=16384
$ arc-linux-readelf --segments a.out
Elf file type is EXEC (Executable file)
Entry point 0x102c4
There are 8 program headers, starting at offset 52
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
...
LOAD 0x000000 0x00010000 0x00010000 0x003e8 0x003e8 R E 0x4000 <-- See
LOAD 0x001f24 0x00015f24 0x00015f24 0x000f0 0x0010c RW 0x4000
------------------------------------>8-----------------------------------
Which we implement with that change.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
[yann.morin.1998@free.fr: fix comment: s/8196/8192/]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
d024d369b8