From 774c105ed8d791b709b40082d107f5bb40254374 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Thu, 11 Sep 2014 08:30:16 +0100 Subject: binfmt_elf: allow arch code to examine PT_LOPROC ... PT_HIPROC headers 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 headers. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/7679/ Signed-off-by: Ralf Baechle --- fs/Kconfig.binfmt | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/Kconfig.binfmt') diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt index 370b24cee4d8..c055d56ec63d 100644 --- a/fs/Kconfig.binfmt +++ b/fs/Kconfig.binfmt @@ -30,6 +30,9 @@ config COMPAT_BINFMT_ELF config ARCH_BINFMT_ELF_RANDOMIZE_PIE bool +config ARCH_BINFMT_ELF_STATE + bool + config BINFMT_ELF_FDPIC bool "Kernel support for FDPIC ELF binaries" default y -- cgit v1.2.3-59-g8ed1b