Hi Masahiro, > The latest binutils stopped aligning section data in relocatable ELF. > It saves small number of bytes that were previously inserted between > sections. However, modpost crashes due to unaligned access: > https://sourceware.org/bugzilla/show_bug.cgi?id=32435 > https://sourceware.org/bugzilla/show_bug.cgi?id=32493 > > Similar to kernel space, unaligned data access in userspace can be > problematic on some architectures. > > Simple example on ARM: > > $ CC=arm-linux-gnueabihf-gcc > $ echo 'int foo(int *p) { return *p + *(p + 1); }' | ${CC} -O2 -x c - -c -o foo.o > $ echo 'int foo(int *p); int main(void) { char str[16] = "helloworld"; return foo((int *)(str + 1)); }' | ${CC} -x c - -c -o main.o > $ ${CC} -static -o unalign-test main.o foo.o > $ qemu-armhf unalign-test > qemu: uncaught target signal 7 (Bus error) - core dumped > Bus error (core dumped) > > In this case, the 'ldrd' instruction causes a bus error due to an > unaligned access. If the -O2 flag is omitted, this issue does not occur. > > To avoid potential unaligned access, use the get_unaligned() approach > as seen in the kernel space. I have just applied this series against Linus' tree and I can confirm that it fixes the unalignment access anymore on sparc64. There is no more "Bus error" and the build succeeds. Tested-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx> Thanks, Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
