On Tue, 18 May 2021 at 03:20, Rasmus Villemoes rasmus.villemoes@prevas.dk wrote:
The layout and contents of struct global_data depends on a lot of CONFIG_* preprocessor macros, not all of which are entirely converted to Kconfig - not to mention weird games played here and there. This can result in one translation unit using one definition of struct global_data while the actual layout is another.
That can be very hard to debug. But we already have a mechanism that can help catch such bugs at build time, namely the asm-offsets machinery which is necessary anyway to provide assembly code with the necessary constants. So make sure that every C translation unit that include global_data.h actually sees the same size of struct global_data as that which was seen by the asm-offsets.c TU.
It is likely that this patch will break the build of some boards. For example, without the patch from Matt Merhar (https://lists.denx.de/pipermail/u-boot/2021-May/450135.html) or some other fix, this breaks P2041RDB_defconfig:
CC arch/powerpc/lib/traps.o AS arch/powerpc/cpu/mpc85xx/start.o In file included from include/asm-generic/global_data.h:26, from ./arch/powerpc/include/asm/global_data.h:109, from include/init.h:21, from arch/powerpc/lib/traps.c:7: include/linux/build_bug.h:99:41: error: static assertion failed: "sizeof(struct global_data) == GD_SIZE" 99 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg) | ^~~~~~~~~~~~~~ include/linux/build_bug.h:98:34: note: in expansion of macro ‘__static_assert’ 98 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) | ^~~~~~~~~~~~~~~ include/asm-generic/global_data.h:470:1: note: in expansion of macro ‘static_assert’ 470 | static_assert(sizeof(struct global_data) == GD_SIZE); | ^~~~~~~~~~~~~ make[1]: *** [scripts/Makefile.build:266: arch/powerpc/lib/traps.o] Error 1 make: *** [Makefile:1753: arch/powerpc/lib] Error 2 make: *** Waiting for unfinished jobs....
Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk
include/asm-generic/global_data.h | 5 +++++ 1 file changed, 5 insertions(+)
Reviewed-by: Simon Glass sjg@chromium.org