• Paul Burton's avatar
    binfmt_elf: allow arch code to examine PT_LOPROC ... PT_HIPROC headers · 774c105e
    Paul Burton authored
    MIPS is introducing new variants of its O32 ABI which differ in their
    handling of floating point, in order to enable a gradual transition
    towards a world where mips32 binaries can take advantage of new hardware
    features only available when configured for certain FP modes. In order
    to do this ELF binaries are being augmented with a new section that
    indicates, amongst other things, the FP mode requirements of the binary.
    The presence & location of such a section is indicated by a program
    header in the PT_LOPROC ... PT_HIPROC range.
    In order to allow the MIPS architecture code to examine the program
    header & section in question, pass all program headers in this range
    to an architecture-specific arch_elf_pt_proc function. This function
    may return an error if the header is deemed invalid or unsuitable for
    the system, in which case that error will be returned from
    load_elf_binary and upwards through the execve syscall.
    A means is required for the architecture code to make a decision once
    it is known that all such headers have been seen, but before it is too
    late to return from an execve syscall. For this purpose the
    arch_check_elf function is added, and called once, after all PT_LOPROC
    to PT_HIPROC headers have been passed to arch_elf_pt_proc but before
    the code which invoked execve has been lost. This enables the
    architecture code to make a decision based upon all the headers present
    in an ELF binary and its interpreter, as is required to forbid
    conflicting FP ABI requirements between an ELF & its interpreter.
    In order to allow data to be stored throughout the calls to the above
    functions, struct arch_elf_state is introduced.
    Finally a variant of the SET_PERSONALITY macro is introduced which
    accepts a pointer to the struct arch_elf_state, allowing it to act
    based upon state observed from the architecture specific program
    Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
    Cc: linux-mips@linux-mips.org
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Cc: linux-fsdevel@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Patchwork: https://patchwork.linux-mips.org/patch/7679/
    Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
binfmt_elf.c 60.5 KB