NetCube-Systems-Austria/kumquat-buildroot
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
4e5b4b26bf
kumquat-buildroot/arch/arch.mk.arc

9 lines
179 B
Plaintext
Raw Normal View History

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: set ld's common-page-size explicitly On some CPU architecures it's possible to use MMU pages of different sizes, for example on ARC or ARM. And while for user-space applications the page size is supposed to be transparent, there's still some use of that extra information. In particular it's possible to align data structures or code/data sections on page boundary, etc. For these tricks to become possible tools which pack data (think of the linker, like GNU "ld") need to be informed of the page size to be considered. Obviously, there're some sane defaults which are being used most of the time, so we even think about that peculiarity, but when non-default value needs to be used, GNU "ld" accepts 2 properties related to page size: -z common-page-size=XXX -z max-page-size=YYY And while in thery those might be different (but always "common" <= "max"), and that might make sense if we build for some unknown platfrom, in case of Buildroot when we build entire target's filesystem and so know exactly the configuration we're targeting to, we may safely assume "common-page-size"="max-page-size". See a lengthy discussion in this thread [1]. Fixes: http://autobuild.buildroot.net/results/c8b2f331c98453670cd982558144c4fd84674a3d/ (uclibc) http://autobuild.buildroot.net/results/3a22f7aac38145b26c549254b819f87329e7a77e/ (glibc) And while at it, recover use of "XX-page-size" for ARC, as with [2] moving page size selection in the generic code we've got unexpected override for ARC (note "=", but not "+="): --------------------->8-------------------- ARCH_TOOLCHAIN_WRAPPER_OPTS = -matomic --------------------->8-------------------- [1] https://lists.buildroot.org/pipermail/buildroot/2022-July/646176.html [2] https://git.buildroot.net/buildroot/commit/?id=dcb74db89e74e512e36b32cea6f574a1a1ca84c4 Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2022-08-15 19:17:44 +02:00
ARCH_TOOLCHAIN_WRAPPER_OPTS += -matomic
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
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
endif
Reference in New Issue Copy Permalink