linux/arch/m68k
Linus Torvalds 33692f2759 vm: add VM_FAULT_SIGSEGV handling support
The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d45 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Jan Engelhardt <jengelh@inai.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-01-29 10:51:32 -08:00
..
68000 m68k: fix crufty 68000 and 68360 intro comments 2014-09-29 09:18:35 +10:00
68360 m68k: fix crufty 68000 and 68360 intro comments 2014-09-29 09:18:35 +10:00
amiga m68k/amiga: Convert printk(foo to pr_foo() 2014-05-28 10:11:54 +02:00
apollo m68k/apollo: Convert printk to pr_foo() 2014-05-28 10:11:55 +02:00
atari atari_scsi: Convert to platform device 2014-11-20 09:11:14 +01:00
bvme6000 m68k/UAPI: Use proper types (endianness/size) in <asm/bootinfo*.h> 2013-11-26 11:09:21 +01:00
coldfire m68k/coldfire: remove second asm/mcfclk.h inclusion in m54xx.c 2014-09-29 09:18:36 +10:00
configs tgt: defconfig cleanup 2014-07-17 22:07:44 +02:00
emu Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
fpsp040 Fix common misspellings 2011-03-31 11:26:23 -03:00
hp300 m68k/hp300: Convert printk to pr_foo() 2014-05-28 10:11:55 +02:00
ifpsp060 Fix common misspellings 2011-03-31 11:26:23 -03:00
include m68k: Wire up execveat 2015-01-11 11:14:14 +01:00
kernel m68k: Wire up execveat 2015-01-11 11:14:14 +01:00
lib m68k/uaccess: Fix asm constraints for userspace access 2013-06-24 19:44:19 +02:00
mac mac_scsi: Convert to platform device 2014-11-20 09:11:13 +01:00
math-emu m68k/math-emu: unsigned issue, 'unsigned long' will never be less than zero 2013-06-24 19:44:19 +02:00
mm vm: add VM_FAULT_SIGSEGV handling support 2015-01-29 10:51:32 -08:00
mvme16x m68k/mvme16x: Adopt common boot console 2014-05-28 10:11:53 +02:00
mvme147 m68k/UAPI: Use proper types (endianness/size) in <asm/bootinfo*.h> 2013-11-26 11:09:21 +01:00
q40 m68k: Mark functions only called from setup_arch() __init 2013-11-26 11:08:54 +01:00
sun3 sun3_scsi: Convert to platform device 2014-11-20 09:11:15 +01:00
sun3x m68k: Remove superfluous inclusions of <asm/bootinfo.h> 2013-11-26 11:09:22 +01:00
tools/amiga
install.sh
Kconfig kexec: remove CONFIG_KEXEC dependency on crypto 2014-08-29 16:28:16 -07:00
Kconfig.bus m68k/atari: ROM port ISA adapter support 2013-04-16 21:08:11 +02:00
Kconfig.cpu Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2013-05-10 07:22:35 -07:00
Kconfig.debug m68k: Multi-platform EARLY_PRINTK 2014-05-28 10:10:04 +02:00
Kconfig.devices Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k 2014-10-08 05:40:17 -04:00
Kconfig.machine m68k: remove 16 unused boards in Kconfig.machine 2013-08-26 16:51:14 +10:00
Makefile m68k: move non-mmu 68360 platform code 2014-09-29 09:18:35 +10:00