3e6f2ac480
UML was panicing in the case of failures of libc calls which shouldn't happen. This is an overreaction since a failure from libc doesn't normally mean that kernel data structures are in an unknown state. Instead, the current process should just be killed if there is no way to recover. The case that prompted this was a failure of PTRACE_SETREGS restoring the same state that was read by PTRACE_GETREGS. It appears that when a process tries to load a bogus value into a segment register, it segfaults (as expected) and the value is actually loaded and is seen by PTRACE_GETREGS (not expected). This case is fixed by forcing a fatal SIGSEGV on the process so that it immediately dies. fatal_sigsegv was added for this purpose. It was declared as noreturn, so in order to pursuade gcc that it actually does not return, I added a call to os_dump_core (and declared it noreturn) so that I get a core file if somehow the process survives. All other calls in arch/um/os-Linux/skas/process.c got the same treatment, with failures causing the process to die instead of a kernel panic, with some exceptions. userspace_tramp exits with status 1 if anything goes wrong there. That will cause start_userspace to return an error. copy_context_skas0 and map_stub_pages also now return errors instead of panicing. Callers of thes functions were changed to check for errors and do something appropriate. Usually that's to return an error to their callers. check_skas3_ptrace_faultinfo just exits since that's too early to do anything else. save_registers, restore_registers, and init_registers now return status instead of panicing on failure, with their callers doing something appropriate. There were also duplicate declarations of save_registers and restore_registers in os.h - these are gone. I noticed and fixed up some whitespace damage. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
81 lines
1.5 KiB
C
81 lines
1.5 KiB
C
/*
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include "linux/init.h"
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#include "linux/sched.h"
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#include "as-layout.h"
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#include "kern.h"
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#include "os.h"
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#include "skas.h"
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int new_mm(unsigned long stack)
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{
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int fd, err;
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fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
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if (fd < 0)
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return fd;
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if (skas_needs_stub) {
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err = map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
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if (err) {
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os_close_file(fd);
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return err;
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}
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}
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return fd;
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}
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extern void start_kernel(void);
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static int __init start_kernel_proc(void *unused)
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{
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int pid;
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block_signals();
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pid = os_getpid();
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cpu_tasks[0].pid = pid;
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cpu_tasks[0].task = current;
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#ifdef CONFIG_SMP
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cpu_online_map = cpumask_of_cpu(0);
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#endif
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start_kernel();
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return 0;
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}
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extern int userspace_pid[];
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extern char cpu0_irqstack[];
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int __init start_uml(void)
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{
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stack_protections((unsigned long) &cpu0_irqstack);
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set_sigstack(cpu0_irqstack, THREAD_SIZE);
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if (proc_mm) {
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userspace_pid[0] = start_userspace(0);
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if (userspace_pid[0] < 0) {
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printf("start_uml - start_userspace returned %d\n",
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userspace_pid[0]);
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exit(1);
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}
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}
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init_new_thread_signals();
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init_task.thread.request.u.thread.proc = start_kernel_proc;
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init_task.thread.request.u.thread.arg = NULL;
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return start_idle_thread(task_stack_page(&init_task),
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&init_task.thread.switch_buf);
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}
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unsigned long current_stub_stack(void)
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{
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if (current->mm == NULL)
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return 0;
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return current->mm->context.id.stack;
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}
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