linux/arch/um/sys-x86_64
Jeff Dike 3e6f2ac480 uml: kill processes instead of panicing kernel
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>
2008-02-05 09:44:28 -08:00
..
bug.c spelling fixes: arch/um/ 2007-10-20 01:23:03 +02:00
bugs.c uml: further bugs.c tidying 2008-02-05 09:44:25 -08:00
delay.c [PATCH] uml: fix unreasonably long udelay 2007-04-02 10:06:08 -07:00
fault.c uml: style fixes pass 3 2007-10-16 09:43:05 -07:00
ksyms.c [PATCH] uml: remove duplicate export 2006-10-11 11:14:20 -07:00
Makefile uml: style fixes in FP code 2007-10-16 09:43:07 -07:00
mem.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ptrace_user.c [PATCH] uml: initialize process FP registers properly 2006-02-07 16:12:32 -08:00
ptrace.c misc uml annotation and section fixes 2007-10-29 07:41:32 -07:00
setjmp.S [PATCH] uml: Use klibc setjmp/longjmp 2006-09-26 08:49:05 -07:00
signal.c uml: current.h cleanup 2008-02-05 09:44:28 -08:00
stub_segv.c uml: simplify SIGSEGV handling 2008-02-05 09:44:28 -08:00
stub.S uml: borrow const.h techniques 2008-02-05 09:44:26 -08:00
syscall_table.c i386/x86_64: move headers to include/asm-x86 2007-10-11 11:20:03 +02:00
syscalls.c uml: kill processes instead of panicing kernel 2008-02-05 09:44:28 -08:00
sysrq.c Use helpers to obtain task pid in printks (arch code) 2007-10-19 11:53:43 -07:00
tls.c uml: rename pt_regs general-purpose register file 2007-10-16 09:43:06 -07:00
um_module.c [PATCH] uml: kludgy compilation fixes for x86-64 subarch modules support 2005-05-05 16:36:33 -07:00
user-offsets.c uml: don't use glibc asm/user.h 2007-10-16 09:43:07 -07:00