diff options
Diffstat (limited to 'arch/um/os-Linux/skas/process.c')
| -rw-r--r-- | arch/um/os-Linux/skas/process.c | 644 |
1 files changed, 644 insertions, 0 deletions
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c new file mode 100644 index 000000000..7a9777570 --- /dev/null +++ b/arch/um/os-Linux/skas/process.c @@ -0,0 +1,644 @@ +/* + * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + */ + +#include <stdlib.h> +#include <unistd.h> +#include <sched.h> +#include <errno.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/wait.h> +#include <asm/unistd.h> +#include <as-layout.h> +#include <init.h> +#include <kern_util.h> +#include <mem.h> +#include <os.h> +#include <ptrace_user.h> +#include <registers.h> +#include <skas.h> +#include <sysdep/stub.h> + +int is_skas_winch(int pid, int fd, void *data) +{ + return pid == getpgrp(); +} + +static int ptrace_dump_regs(int pid) +{ + unsigned long regs[MAX_REG_NR]; + int i; + + if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) + return -errno; + + printk(UM_KERN_ERR "Stub registers -\n"); + for (i = 0; i < ARRAY_SIZE(regs); i++) + printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]); + + return 0; +} + +/* + * Signals that are OK to receive in the stub - we'll just continue it. + * SIGWINCH will happen when UML is inside a detached screen. + */ +#define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH)) + +/* Signals that the stub will finish with - anything else is an error */ +#define STUB_DONE_MASK (1 << SIGTRAP) + +void wait_stub_done(int pid) +{ + int n, status, err; + + while (1) { + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); + if ((n < 0) || !WIFSTOPPED(status)) + goto bad_wait; + + if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0) + break; + + err = ptrace(PTRACE_CONT, pid, 0, 0); + if (err) { + printk(UM_KERN_ERR "wait_stub_done : continue failed, " + "errno = %d\n", errno); + fatal_sigsegv(); + } + } + + if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0) + return; + +bad_wait: + err = ptrace_dump_regs(pid); + if (err) + printk(UM_KERN_ERR "Failed to get registers from stub, " + "errno = %d\n", -err); + printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, " + "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno, + status); + fatal_sigsegv(); +} + +extern unsigned long current_stub_stack(void); + +static void get_skas_faultinfo(int pid, struct faultinfo *fi) +{ + int err; + unsigned long fpregs[FP_SIZE]; + + err = get_fp_registers(pid, fpregs); + if (err < 0) { + printk(UM_KERN_ERR "save_fp_registers returned %d\n", + err); + fatal_sigsegv(); + } + err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV); + if (err) { + printk(UM_KERN_ERR "Failed to continue stub, pid = %d, " + "errno = %d\n", pid, errno); + fatal_sigsegv(); + } + wait_stub_done(pid); + + /* + * faultinfo is prepared by the stub-segv-handler at start of + * the stub stack page. We just have to copy it. + */ + memcpy(fi, (void *)current_stub_stack(), sizeof(*fi)); + + err = put_fp_registers(pid, fpregs); + if (err < 0) { + printk(UM_KERN_ERR "put_fp_registers returned %d\n", + err); + fatal_sigsegv(); + } +} + +static void handle_segv(int pid, struct uml_pt_regs * regs) +{ + get_skas_faultinfo(pid, ®s->faultinfo); + segv(regs->faultinfo, 0, 1, NULL); +} + +/* + * To use the same value of using_sysemu as the caller, ask it that value + * (in local_using_sysemu + */ +static void handle_trap(int pid, struct uml_pt_regs *regs, + int local_using_sysemu) +{ + int err, status; + + if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END)) + fatal_sigsegv(); + + /* Mark this as a syscall */ + UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp); + + if (!local_using_sysemu) + { + err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, + __NR_getpid); + if (err < 0) { + printk(UM_KERN_ERR "handle_trap - nullifying syscall " + "failed, errno = %d\n", errno); + fatal_sigsegv(); + } + + err = ptrace(PTRACE_SYSCALL, pid, 0, 0); + if (err < 0) { + printk(UM_KERN_ERR "handle_trap - continuing to end of " + "syscall failed, errno = %d\n", errno); + fatal_sigsegv(); + } + + CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); + if ((err < 0) || !WIFSTOPPED(status) || + (WSTOPSIG(status) != SIGTRAP + 0x80)) { + err = ptrace_dump_regs(pid); + if (err) + printk(UM_KERN_ERR "Failed to get registers " + "from process, errno = %d\n", -err); + printk(UM_KERN_ERR "handle_trap - failed to wait at " + "end of syscall, errno = %d, status = %d\n", + errno, status); + fatal_sigsegv(); + } + } + + handle_syscall(regs); +} + +extern int __syscall_stub_start; + +static int userspace_tramp(void *stack) +{ + void *addr; + int err, fd; + unsigned long long offset; + + ptrace(PTRACE_TRACEME, 0, 0, 0); + + signal(SIGTERM, SIG_DFL); + signal(SIGWINCH, SIG_IGN); + err = set_interval(); + if (err) { + printk(UM_KERN_ERR "userspace_tramp - setting timer failed, " + "errno = %d\n", err); + exit(1); + } + + /* + * This has a pte, but it can't be mapped in with the usual + * tlb_flush mechanism because this is part of that mechanism + */ + fd = phys_mapping(to_phys(&__syscall_stub_start), &offset); + addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE, + PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset); + if (addr == MAP_FAILED) { + printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, " + "errno = %d\n", STUB_CODE, errno); + exit(1); + } + + if (stack != NULL) { + fd = phys_mapping(to_phys(stack), &offset); + addr = mmap((void *) STUB_DATA, + UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_SHARED, fd, offset); + if (addr == MAP_FAILED) { + printk(UM_KERN_ERR "mapping segfault stack " + "at 0x%lx failed, errno = %d\n", + STUB_DATA, errno); + exit(1); + } + } + if (stack != NULL) { + struct sigaction sa; + + unsigned long v = STUB_CODE + + (unsigned long) stub_segv_handler - + (unsigned long) &__syscall_stub_start; + + set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE); + sigemptyset(&sa.sa_mask); + sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO; + sa.sa_sigaction = (void *) v; + sa.sa_restorer = NULL; + if (sigaction(SIGSEGV, &sa, NULL) < 0) { + printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV " + "handler failed - errno = %d\n", errno); + exit(1); + } + } + + kill(os_getpid(), SIGSTOP); + return 0; +} + +/* Each element set once, and only accessed by a single processor anyway */ +#undef NR_CPUS +#define NR_CPUS 1 +int userspace_pid[NR_CPUS]; + +int start_userspace(unsigned long stub_stack) +{ + void *stack; + unsigned long sp; + int pid, status, n, flags, err; + + stack = mmap(NULL, UM_KERN_PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (stack == MAP_FAILED) { + err = -errno; + printk(UM_KERN_ERR "start_userspace : mmap failed, " + "errno = %d\n", errno); + return err; + } + + sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *); + + flags = CLONE_FILES | SIGCHLD; + + pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack); + if (pid < 0) { + err = -errno; + printk(UM_KERN_ERR "start_userspace : clone failed, " + "errno = %d\n", errno); + return err; + } + + do { + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); + if (n < 0) { + err = -errno; + printk(UM_KERN_ERR "start_userspace : wait failed, " + "errno = %d\n", errno); + goto out_kill; + } + } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM)); + + if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) { + err = -EINVAL; + printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got " + "status = %d\n", status); + goto out_kill; + } + + if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, + (void *) PTRACE_O_TRACESYSGOOD) < 0) { + err = -errno; + printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS " + "failed, errno = %d\n", errno); + goto out_kill; + } + + if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) { + err = -errno; + printk(UM_KERN_ERR "start_userspace : munmap failed, " + "errno = %d\n", errno); + goto out_kill; + } + + return pid; + + out_kill: + os_kill_ptraced_process(pid, 1); + return err; +} + +void userspace(struct uml_pt_regs *regs) +{ + struct itimerval timer; + unsigned long long nsecs, now; + int err, status, op, pid = userspace_pid[0]; + /* To prevent races if using_sysemu changes under us.*/ + int local_using_sysemu; + siginfo_t si; + + /* Handle any immediate reschedules or signals */ + interrupt_end(); + + if (getitimer(ITIMER_VIRTUAL, &timer)) + printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno); + nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC + + timer.it_value.tv_usec * UM_NSEC_PER_USEC; + nsecs += os_nsecs(); + + while (1) { + /* + * This can legitimately fail if the process loads a + * bogus value into a segment register. It will + * segfault and PTRACE_GETREGS will read that value + * out of the process. However, PTRACE_SETREGS will + * fail. In this case, there is nothing to do but + * just kill the process. + */ + if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp)) + fatal_sigsegv(); + + if (put_fp_registers(pid, regs->fp)) + fatal_sigsegv(); + + /* Now we set local_using_sysemu to be used for one loop */ + local_using_sysemu = get_using_sysemu(); + + op = SELECT_PTRACE_OPERATION(local_using_sysemu, + singlestepping(NULL)); + + if (ptrace(op, pid, 0, 0)) { + printk(UM_KERN_ERR "userspace - ptrace continue " + "failed, op = %d, errno = %d\n", op, errno); + fatal_sigsegv(); + } + + CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); + if (err < 0) { + printk(UM_KERN_ERR "userspace - wait failed, " + "errno = %d\n", errno); + fatal_sigsegv(); + } + + regs->is_user = 1; + if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) { + printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, " + "errno = %d\n", errno); + fatal_sigsegv(); + } + + if (get_fp_registers(pid, regs->fp)) { + printk(UM_KERN_ERR "userspace - get_fp_registers failed, " + "errno = %d\n", errno); + fatal_sigsegv(); + } + + UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */ + + if (WIFSTOPPED(status)) { + int sig = WSTOPSIG(status); + + ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si); + + switch (sig) { + case SIGSEGV: + if (PTRACE_FULL_FAULTINFO) { + get_skas_faultinfo(pid, + ®s->faultinfo); + (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si, + regs); + } + else handle_segv(pid, regs); + break; + case SIGTRAP + 0x80: + handle_trap(pid, regs, local_using_sysemu); + break; + case SIGTRAP: + relay_signal(SIGTRAP, (struct siginfo *)&si, regs); + break; + case SIGVTALRM: + now = os_nsecs(); + if (now < nsecs) + break; + block_signals(); + (*sig_info[sig])(sig, (struct siginfo *)&si, regs); + unblock_signals(); + nsecs = timer.it_value.tv_sec * + UM_NSEC_PER_SEC + + timer.it_value.tv_usec * + UM_NSEC_PER_USEC; + nsecs += os_nsecs(); + break; + case SIGIO: + case SIGILL: + case SIGBUS: + case SIGFPE: + case SIGWINCH: + block_signals(); + (*sig_info[sig])(sig, (struct siginfo *)&si, regs); + unblock_signals(); + break; + default: + printk(UM_KERN_ERR "userspace - child stopped " + "with signal %d\n", sig); + fatal_sigsegv(); + } + pid = userspace_pid[0]; + interrupt_end(); + + /* Avoid -ERESTARTSYS handling in host */ + if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET) + PT_SYSCALL_NR(regs->gp) = -1; + } + } +} + +static unsigned long thread_regs[MAX_REG_NR]; +static unsigned long thread_fp_regs[FP_SIZE]; + +static int __init init_thread_regs(void) +{ + get_safe_registers(thread_regs, thread_fp_regs); + /* Set parent's instruction pointer to start of clone-stub */ + thread_regs[REGS_IP_INDEX] = STUB_CODE + + (unsigned long) stub_clone_handler - + (unsigned long) &__syscall_stub_start; + thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE - + sizeof(void *); +#ifdef __SIGNAL_FRAMESIZE + thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE; +#endif + return 0; +} + +__initcall(init_thread_regs); + +int copy_context_skas0(unsigned long new_stack, int pid) +{ + struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ }; + int err; + unsigned long current_stack = current_stub_stack(); + struct stub_data *data = (struct stub_data *) current_stack; + struct stub_data *child_data = (struct stub_data *) new_stack; + unsigned long long new_offset; + int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset); + + /* + * prepare offset and fd of child's stack as argument for parent's + * and child's mmap2 calls + */ + *data = ((struct stub_data) { .offset = MMAP_OFFSET(new_offset), + .fd = new_fd, + .timer = ((struct itimerval) + { .it_value = tv, + .it_interval = tv }) }); + + err = ptrace_setregs(pid, thread_regs); + if (err < 0) { + err = -errno; + printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS " + "failed, pid = %d, errno = %d\n", pid, -err); + return err; + } + + err = put_fp_registers(pid, thread_fp_regs); + if (err < 0) { + printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers " + "failed, pid = %d, err = %d\n", pid, err); + return err; + } + + /* set a well known return code for detection of child write failure */ + child_data->err = 12345678; + + /* + * Wait, until parent has finished its work: read child's pid from + * parent's stack, and check, if bad result. + */ + err = ptrace(PTRACE_CONT, pid, 0, 0); + if (err) { + err = -errno; + printk(UM_KERN_ERR "Failed to continue new process, pid = %d, " + "errno = %d\n", pid, errno); + return err; + } + + wait_stub_done(pid); + + pid = data->err; + if (pid < 0) { + printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports " + "error %d\n", -pid); + return pid; + } + + /* + * Wait, until child has finished too: read child's result from + * child's stack and check it. + */ + wait_stub_done(pid); + if (child_data->err != STUB_DATA) { + printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports " + "error %ld\n", child_data->err); + err = child_data->err; + goto out_kill; + } + + if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, + (void *)PTRACE_O_TRACESYSGOOD) < 0) { + err = -errno; + printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS " + "failed, errno = %d\n", errno); + goto out_kill; + } + + return pid; + + out_kill: + os_kill_ptraced_process(pid, 1); + return err; +} + +void new_thread(void *stack, jmp_buf *buf, void (*handler)(void)) +{ + (*buf)[0].JB_IP = (unsigned long) handler; + (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE - + sizeof(void *); +} + +#define INIT_JMP_NEW_THREAD 0 +#define INIT_JMP_CALLBACK 1 +#define INIT_JMP_HALT 2 +#define INIT_JMP_REBOOT 3 + +void switch_threads(jmp_buf *me, jmp_buf *you) +{ + if (UML_SETJMP(me) == 0) + UML_LONGJMP(you, 1); +} + +static jmp_buf initial_jmpbuf; + +/* XXX Make these percpu */ +static void (*cb_proc)(void *arg); +static void *cb_arg; +static jmp_buf *cb_back; + +int start_idle_thread(void *stack, jmp_buf *switch_buf) +{ + int n; + + set_handler(SIGWINCH); + + /* + * Can't use UML_SETJMP or UML_LONGJMP here because they save + * and restore signals, with the possible side-effect of + * trying to handle any signals which came when they were + * blocked, which can't be done on this stack. + * Signals must be blocked when jumping back here and restored + * after returning to the jumper. + */ + n = setjmp(initial_jmpbuf); + switch (n) { + case INIT_JMP_NEW_THREAD: + (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup; + (*switch_buf)[0].JB_SP = (unsigned long) stack + + UM_THREAD_SIZE - sizeof(void *); + break; + case INIT_JMP_CALLBACK: + (*cb_proc)(cb_arg); + longjmp(*cb_back, 1); + break; + case INIT_JMP_HALT: + kmalloc_ok = 0; + return 0; + case INIT_JMP_REBOOT: + kmalloc_ok = 0; + return 1; + default: + printk(UM_KERN_ERR "Bad sigsetjmp return in " + "start_idle_thread - %d\n", n); + fatal_sigsegv(); + } + longjmp(*switch_buf, 1); +} + +void initial_thread_cb_skas(void (*proc)(void *), void *arg) +{ + jmp_buf here; + + cb_proc = proc; + cb_arg = arg; + cb_back = &here; + + block_signals(); + if (UML_SETJMP(&here) == 0) + UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK); + unblock_signals(); + + cb_proc = NULL; + cb_arg = NULL; + cb_back = NULL; +} + +void halt_skas(void) +{ + block_signals(); + UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT); +} + +void reboot_skas(void) +{ + block_signals(); + UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT); +} + +void __switch_mm(struct mm_id *mm_idp) +{ + userspace_pid[0] = mm_idp->u.pid; +} |