To architecture maintainers: please, review the current situation in git.kernel.org/pub/scm/linux/kernel/git/viro/signal #execve2 and consider sending the corresponding patches for missing architectures. What's getting done is unification of sys_execve()/kernel_execve() into arch-independent code. x86, alpha, arm, s390, um and ppc are already converted in #execve2. The plan is: * provide a new primitive - ret_from_kernel_execve(); it takes two pointers to struct pt_regs, one being the normal location of pt_regs for a userland process, another - new pt_regs just filled by do_execve(). It should copy the latter to the former and bugger off to userland. Called from generic kernel_execve() implementation (see fs/exec.c in #execve2). It almost always has to be done in assembler - normally it does equivalent of something along the lines of memmove(normal, new, sizeof(struct pt_regs)) sp = normal, or whatever is needed to get a valid stack frame (e.g. on s390 there's ->back_chain that needs to be set to NULL) set other registers ret_from_sys_call expects to be set (e.g. i386 syscall entry has current_thread_info() value cached in %ebp and since it's a callee-saved register there, ret_from_sys_call expects to find that value still in %ebp, so we need to set it); basically, check what has to be set in ret_from_fork - it tends to jump to the same place. goto ret_from_sys_call, or whatever the equivalent is called on particular architecture. * define __ARCH_WANT_KERNEL_EXECVE in unistd.h, remove your old kernel_execve() * pull whatever work you'd been doing *after* do_execve() call in your sys_execve() (most of the architectures don't do anything after that anyway) into start_thread(); that's the point of no return for execve(2) and if we get there, we'll either succeed or get killed with SIGKILL. The same goes for compat variant of execve(), with s/start_thread/compat_start_thread/. * define __ARCH_WANT_SYS_EXECVE in unistd.h, kill your sys_execve() and compat counterpart (if any). * if there's a better way to calculate task_pt_regs(current), you can provide it in your ptrace.h - macro should be called current_pt_regs(); it's optional. Status: x86, arm, um, s390 - converted, tested, seem to work. alpha and ppc - need testing. The rest - hadn't touched yet. unicore32 and blackfin should be trivial to convert (they are doing kernel_execve() in that manner already). Other may be more or less tricky - depends on how gnarly their return from syscall path happens to be. I'll do what I can and test what I can (some on emulators, some on real hardware), but for quite a few architectures I've no way to test. Nor am I fond of sniffing dozens of variants of assembler glue, to put it mildly. Patches and/or help with testing setups would be very welcome. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
