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>
52 lines
927 B
C
52 lines
927 B
C
/*
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* Copyright (C) 2004 PathScale, Inc
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* Copyright (C) 2004 - 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 <errno.h>
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#include <string.h>
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#include <sys/ptrace.h>
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#include "sysdep/ptrace.h"
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int save_registers(int pid, struct uml_pt_regs *regs)
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{
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int err;
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err = ptrace(PTRACE_GETREGS, pid, 0, regs->gp);
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if (err < 0)
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return -errno;
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return 0;
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}
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int restore_registers(int pid, struct uml_pt_regs *regs)
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{
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int err;
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err = ptrace(PTRACE_SETREGS, pid, 0, regs->gp);
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if (err < 0)
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return -errno;
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return 0;
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}
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/* This is set once at boot time and not changed thereafter */
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static unsigned long exec_regs[MAX_REG_NR];
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int init_registers(int pid)
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{
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int err;
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err = ptrace(PTRACE_GETREGS, pid, 0, exec_regs);
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if (err < 0)
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return -errno;
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arch_init_registers(pid);
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return 0;
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}
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void get_safe_registers(unsigned long *regs)
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{
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memcpy(regs, exec_regs, sizeof(exec_regs));
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}
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