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authorGravatar Alexey Brodkin <Alexey.Brodkin@synopsys.com>2019-12-18 18:55:55 +0300
committerGravatar Yann E. MORIN <yann.morin.1998@free.fr>2019-12-22 21:56:21 +0100
commitd024d369b82d2d3d9d4d75489c19e9488202bca0 (patch)
tree22090ea043841ff26b6cbb07fdcfc92b8d5271fe /arch
parentd7a771816d938f9d8d04b24fd07d2f3f52e73f99 (diff)
downloadbuildroot-d024d369b82d2d3d9d4d75489c19e9488202bca0.tar.gz
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arch/arc: Accommodate 16 KiB MMU pages
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/arch.mk.arc12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/arch.mk.arc b/arch/arch.mk.arc
index 5fcffb7f4b..9c04a85a8d 100644
--- a/arch/arch.mk.arc
+++ b/arch/arch.mk.arc
@@ -1,4 +1,14 @@
+ifeq ($(BR2_arc),y)
+
# -matomic is always required when the ARC core has the atomic extensions
-ifeq ($(BR2_arc)$(BR2_ARC_ATOMIC_EXT),yy)
+ifeq ($(BR2_ARC_ATOMIC_EXT),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS = -matomic
endif
+
+# By default MAXPAGESIZE for ARC is 8192 so for larger MMU pages
+# it needs to be overridden.
+ifeq ($(BR2_ARC_PAGE_SIZE_16K),y)
+ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=16384
+endif
+
+endif