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
..
alchemy	Please consider pulling the clk framework changes toward 3.19. It is	2014-12-20 16:42:36 -08:00
ar7
ath25
ath79
bcm47xx
bcm63xx
bcm3384
boot
cavium-octeon	USB patches for 3.19-rc1	2014-12-14 14:57:16 -08:00
cobalt
configs	PM: Eliminate CONFIG_PM_RUNTIME	2014-12-19 22:55:06 +01:00
dec
emma
fw
include	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2014-12-12 16:11:12 -08:00
jazz
jz4740
kernel	MIPS: Use phys_addr_t instead of phys_t	2014-12-12 15:36:13 -08:00
kvm
lantiq	Driver core patches for 3.19-rc1	2014-12-14 16:10:09 -08:00
lasat
lib
loongson
loongson1
math-emu
mm	vm: add VM_FAULT_SIGSEGV handling support	2015-01-29 10:51:32 -08:00
mti-malta
mti-sead3	Driver core patches for 3.19-rc1	2014-12-14 16:10:09 -08:00
net	module: remove mod arg from module_free, rename module_memfree().	2015-01-20 11:38:33 +10:30
netlogic
oprofile
paravirt
pci	Driver core patches for 3.19-rc1	2014-12-14 16:10:09 -08:00
pmcs-msp71xx
pnx833x
power
ralink	Driver core patches for 3.19-rc1	2014-12-14 16:10:09 -08:00
rb532
sgi-ip22
sgi-ip27
sgi-ip32
sibyte
sni
txx9	Driver core patches for 3.19-rc1	2014-12-14 16:10:09 -08:00
vr41xx
Kbuild
Kbuild.platforms
Kconfig
Kconfig.debug
Makefile