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>
117 lines
2.9 KiB
C
117 lines
2.9 KiB
C
/*
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* Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Copyright 2003 PathScale, Inc.
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*
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* Licensed under the GPL
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*/
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#include "linux/linkage.h"
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#include "linux/personality.h"
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#include "linux/utsname.h"
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#include "asm/prctl.h" /* XXX This should get the constants from libc */
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#include "asm/uaccess.h"
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#include "os.h"
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asmlinkage long sys_uname64(struct new_utsname __user * name)
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{
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int err;
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down_read(&uts_sem);
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err = copy_to_user(name, utsname(), sizeof (*name));
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up_read(&uts_sem);
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if (personality(current->personality) == PER_LINUX32)
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err |= copy_to_user(&name->machine, "i686", 5);
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return err ? -EFAULT : 0;
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}
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long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
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{
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unsigned long *ptr = addr, tmp;
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long ret;
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int pid = task->mm->context.id.u.pid;
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/*
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* With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
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* be safe), we need to call arch_prctl on the host because
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* setting %fs may result in something else happening (like a
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* GDT or thread.fs being set instead). So, we let the host
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* fiddle the registers and thread struct and restore the
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* registers afterwards.
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*
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* So, the saved registers are stored to the process (this
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* needed because a stub may have been the last thing to run),
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* arch_prctl is run on the host, then the registers are read
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* back.
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*/
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switch (code) {
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case ARCH_SET_FS:
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case ARCH_SET_GS:
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ret = restore_registers(pid, ¤t->thread.regs.regs);
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if (ret)
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return ret;
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break;
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case ARCH_GET_FS:
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case ARCH_GET_GS:
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/*
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* With these two, we read to a local pointer and
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* put_user it to the userspace pointer that we were
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* given. If addr isn't valid (because it hasn't been
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* faulted in or is just bogus), we want put_user to
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* fault it in (or return -EFAULT) instead of having
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* the host return -EFAULT.
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*/
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ptr = &tmp;
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}
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ret = os_arch_prctl(pid, code, ptr);
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if (ret)
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return ret;
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switch (code) {
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case ARCH_SET_FS:
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current->thread.arch.fs = (unsigned long) ptr;
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ret = save_registers(pid, ¤t->thread.regs.regs);
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break;
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case ARCH_SET_GS:
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ret = save_registers(pid, ¤t->thread.regs.regs);
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break;
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case ARCH_GET_FS:
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ret = put_user(tmp, addr);
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break;
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case ARCH_GET_GS:
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ret = put_user(tmp, addr);
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break;
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}
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return ret;
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}
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long sys_arch_prctl(int code, unsigned long addr)
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{
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return arch_prctl(current, code, (unsigned long __user *) addr);
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}
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long sys_clone(unsigned long clone_flags, unsigned long newsp,
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void __user *parent_tid, void __user *child_tid)
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{
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long ret;
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if (!newsp)
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newsp = UPT_SP(¤t->thread.regs.regs);
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current->thread.forking = 1;
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ret = do_fork(clone_flags, newsp, ¤t->thread.regs, 0, parent_tid,
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child_tid);
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current->thread.forking = 0;
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return ret;
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}
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void arch_switch_to(struct task_struct *to)
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{
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if ((to->thread.arch.fs == 0) || (to->mm == NULL))
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return;
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arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
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}
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