On Fri, 29 Jan 2016, Daniel Wagner wrote: > Depending on the configuration either the 32 or 64 bit version of > elf_check_arch() is defined. parse_crash_elf32_headers() does > some basic verification of the ELF header via elf_check_arch(). > parse_crash_elf64_headers() does it via vmcore_elf64_check_arch() > which expands to the same elf_check_check(). > > In file included from include/linux/elf.h:4:0, > from fs/proc/vmcore.c:13: > fs/proc/vmcore.c: In function 'parse_crash_elf64_headers': > >> arch/mips/include/asm/elf.h:228:23: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types] > struct elfhdr *__h = (hdr); \ > ^ > include/linux/crash_dump.h:41:37: note: in expansion of macro 'elf_check_arch' > #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x)) > ^ > fs/proc/vmcore.c:1015:4: note: in expansion of macro 'vmcore_elf64_check_arch' > !vmcore_elf64_check_arch(&ehdr) || > ^ > > Since the MIPS ELF header for 32 bit and 64 bit differ we need > to check accordingly. I fail to see how it can work as it stands given that `elf_check_arch' is called from the same source file both on a pointer to `Elf32_Ehdr' and one to `Elf64_Ehdr'. However the MIPS implementations of `elf_check_arch' only use an auxiliary variable to avoid multiple evaluation of a macro argument and therefore instead I recommend the use of the usual approach taken in such a situation within a statement expression, that is to declare the variable with `typeof' rather than an explicit type. As an upside this will minimise code disruption as well. For consistency I suggest making the same change to the `elf_check_arch' definitions in arch/mips/kernel/binfmt_elf*.c as well. Maciej
