Date: Tue, 4 Dec 2018 00:15:47 +0000 (UTC) From: Brooks Davis <brooks@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r341449 - head/sys/kern Message-ID: <201812040015.wB40Flla015023@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: brooks Date: Tue Dec 4 00:15:47 2018 New Revision: 341449 URL: https://svnweb.freebsd.org/changeset/base/341449 Log: Remove a needlessly clever hack to start init with sys_exec(). Construct a struct image_args with the help of new exec_args_*() helper functions and call kern_execve(). The previous code mapped a page in userspace, copied arguments out to it one at a time, and then constructed a struct execve_args all so that sys_execve() can call exec_copyin_args() to copy the data back in to a struct image_args. Opencode the part of pre_execve()/post_execve() that releases a reference to the initial vmspace. We don't need to stop threads like they do. Reviewed by: kib, jhb (prior version) Obtained from: CheriBSD Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D15469 Modified: head/sys/kern/init_main.c Modified: head/sys/kern/init_main.c ============================================================================== --- head/sys/kern/init_main.c Mon Dec 3 23:42:04 2018 (r341448) +++ head/sys/kern/init_main.c Tue Dec 4 00:15:47 2018 (r341449) @@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$"); #include <sys/exec.h> #include <sys/file.h> #include <sys/filedesc.h> +#include <sys/imgact.h> #include <sys/jail.h> #include <sys/ktr.h> #include <sys/lock.h> @@ -716,15 +717,15 @@ SYSCTL_INT(_kern, OID_AUTO, init_shutdown_timeout, static void start_init(void *dummy) { - vm_offset_t addr; - struct execve_args args; + struct image_args args; int options, error; size_t pathlen; + char flags[8], *flagp; char *var, *path; char *free_init_path, *tmp_init_path; - char *ucp, **uap, *arg0, *arg1; struct thread *td; struct proc *p; + struct vmspace *oldvmspace; TSENTER(); /* Here so we don't overlap with mi_startup. */ @@ -736,16 +737,6 @@ start_init(void *dummy) /* Wipe GELI passphrase from the environment. */ kern_unsetenv("kern.geom.eli.passphrase"); - /* - * Need just enough stack to hold the faked-up "execve()" arguments. - */ - addr = p->p_sysent->sv_usrstack - PAGE_SIZE; - if (vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr, PAGE_SIZE, 0, - VMFS_NO_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0) != 0) - panic("init: couldn't allocate argument space"); - p->p_vmspace->vm_maxsaddr = (caddr_t)addr; - p->p_vmspace->vm_ssize = 1; - if ((var = kern_getenv("init_path")) != NULL) { strlcpy(init_path, var, sizeof(init_path)); freeenv(var); @@ -757,63 +748,65 @@ start_init(void *dummy) if (bootverbose) printf("start_init: trying %s\n", path); - /* - * Move out the boot flag argument. - */ + memset(&args, 0, sizeof(args)); + error = exec_alloc_args(&args); + if (error != 0) + panic("%s: Can't allocate space for init arguments %d", + __func__, error); + + error = exec_args_add_fname(&args, path, UIO_SYSSPACE); + if (error != 0) + panic("%s: Can't add fname %d", __func__, error); + + error = exec_args_add_arg(&args, path, UIO_SYSSPACE); + if (error != 0) + panic("%s: Can't add argv[0] %d", __func__, error); + options = 0; - ucp = (char *)p->p_sysent->sv_usrstack; - (void)subyte(--ucp, 0); /* trailing zero */ + flagp = &flags[0]; + *flagp++ = '-'; if (boothowto & RB_SINGLE) { - (void)subyte(--ucp, 's'); - options = 1; + *flagp++ = 's'; + options++; } #ifdef notyet if (boothowto & RB_FASTBOOT) { - (void)subyte(--ucp, 'f'); - options = 1; + *flagp++ = 'f'; + options++; } #endif - #ifdef BOOTCDROM - (void)subyte(--ucp, 'C'); - options = 1; + *flagp++ = 'C'; + options++; #endif - if (options == 0) - (void)subyte(--ucp, '-'); - (void)subyte(--ucp, '-'); /* leading hyphen */ - arg1 = ucp; + *flagp++ = '-'; + *flagp++ = 0; + KASSERT(flagp <= &flags[0] + sizeof(flags), ("Overran flags")); + error = exec_args_add_arg(&args, flags, UIO_SYSSPACE); + if (error != 0) + panic("%s: Can't add argv[0] %d", __func__, error); /* - * Move out the file name (also arg 0). - */ - ucp -= pathlen; - copyout(path, ucp, pathlen); - arg0 = ucp; - - /* - * Move out the arg pointers. - */ - uap = (char **)rounddown2((intptr_t)ucp, sizeof(intptr_t)); - (void)suword((caddr_t)--uap, (long)0); /* terminator */ - (void)suword((caddr_t)--uap, (long)(intptr_t)arg1); - (void)suword((caddr_t)--uap, (long)(intptr_t)arg0); - - /* - * Point at the arguments. - */ - args.fname = arg0; - args.argv = uap; - args.envv = NULL; - - /* * Now try to exec the program. If can't for any reason * other than it doesn't exist, complain. * * Otherwise, return via fork_trampoline() all the way * to user mode as init! */ - if ((error = sys_execve(td, &args)) == EJUSTRETURN) { + KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, + ("nested execve")); + oldvmspace = td->td_proc->p_vmspace; + error = kern_execve(td, &args, NULL); + KASSERT(error != 0, + ("kern_execve returned success, not EJUSTRETURN")); + if (error == EJUSTRETURN) { + if ((td->td_pflags & TDP_EXECVMSPC) != 0) { + KASSERT(p->p_vmspace != oldvmspace, + ("oldvmspace still used")); + vmspace_free(oldvmspace); + td->td_pflags &= ~TDP_EXECVMSPC; + } free(free_init_path, M_TEMP); TSEXIT(); return;
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201812040015.wB40Flla015023>