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kumquat-buildroot/arch/arch.mk.arc

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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>
2019-12-18 16:55:55 +01:00
ifeq ($(BR2_arc),y)
arch/arc: always needs -matomic with atomic extensions As reported by Alexey in: https://patchwork.ozlabs.org/patch/1087480/ https://patchwork.ozlabs.org/patch/1087471/ when BR2_ARC_ATOMIC_EXT is enabled, -matomic needs to always be passed to the compiler to allow atomic instructions to be used. So instead of passing them through the command-line CFLAGS, we enforce them in the toolchain wrapper directly. Reported-by: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr> Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: Arnout Vandecappelle <arnout@mind.be> Acked-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2019-07-18 22:52:49 +02:00
# -matomic is always required when the ARC core has the atomic extensions
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>
2019-12-18 16:55:55 +01:00
ifeq ($(BR2_ARC_ATOMIC_EXT),y)
arch/arc: always needs -matomic with atomic extensions As reported by Alexey in: https://patchwork.ozlabs.org/patch/1087480/ https://patchwork.ozlabs.org/patch/1087471/ when BR2_ARC_ATOMIC_EXT is enabled, -matomic needs to always be passed to the compiler to allow atomic instructions to be used. So instead of passing them through the command-line CFLAGS, we enforce them in the toolchain wrapper directly. Reported-by: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr> Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: Arnout Vandecappelle <arnout@mind.be> Acked-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2019-07-18 22:52:49 +02:00
ARCH_TOOLCHAIN_WRAPPER_OPTS = -matomic
endif
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>
2019-12-18 16:55:55 +01:00
arch/arc: explicitly set "max-page-size" for GNU LD Back in the day we relied on a default value that used to be 8KiB and it worked perfectly fine for ARC's default 8KiB page as well as 4 KiB ones, but not for 16 KiB, see [1] for more details. So that we fixed by setting "max-page-size" if 16KiB pages are in use by commit d024d369b82d2 ("arch/arc: Accommodate 16 KiB MMU pages"). But as Yann very rightfully mentioned here [2] we should be setting this thing explicitly for all page sizes because: 1. Defaults might change unexpectedly 2. Explicitly set stuff is better understood 3. We act similarly to all settings but not only addressing some corner cases [1] https://git.buildroot.org/buildroot/commit/?id=d024d369b82d2d3d9d4d75489c19e9488202bca0 [2] https://patchwork.ozlabs.org/patch/1212544/#2330647 Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: Yann E. MORIN <yann.morin.1998@free.fr> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2019-12-24 15:10:32 +01:00
# Explicitly set LD's "max-page-size" instead of relying on some defaults
ifeq ($(BR2_ARC_PAGE_SIZE_4K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=4096
else ifeq ($(BR2_ARC_PAGE_SIZE_8K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=8192
else ifeq ($(BR2_ARC_PAGE_SIZE_16K),y)
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>
2019-12-18 16:55:55 +01:00
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=16384
endif
endif
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