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
..
extable.c
fault_32.c	vm: add VM_FAULT_SIGSEGV handling support	2015-01-29 10:51:32 -08:00
fault_64.c	vm: add VM_FAULT_SIGSEGV handling support	2015-01-29 10:51:32 -08:00
gup.c	sparc64: Implement __get_user_pages_fast().	2014-10-24 09:59:02 -07:00
highmem.c
hugetlbpage.c	hugetlb: restrict hugepage_migration_support() to x86_64	2014-06-04 16:53:51 -07:00
hypersparc.S	[PATCH] sparc32: vm_area_struct access for old Sun SPARCs.	2013-07-10 13:56:10 -07:00
init_32.c	sparc32: fix sparse warning in devices.c	2014-04-29 01:12:26 -04:00
init_64.c	mm/debug-pagealloc: make debug-pagealloc boottime configurable	2014-12-13 12:42:48 -08:00
init_64.h	sparc64: Use kernel page tables for vmemmap.	2014-10-05 16:53:39 -07:00
io-unit.c	sparc32: fix sparse warning in io-unit.c	2014-05-18 19:01:26 -07:00
iommu.c	sparc32: fix sparse warning in iommu.c	2014-05-18 19:01:26 -07:00
leon_mm.c	sparc32: fix sparse "Should it be static?" in mm/	2014-04-29 01:12:25 -04:00
Makefile
mm_32.h	sparc32: fix sparse "Should it be static?" in mm/	2014-04-29 01:12:25 -04:00
srmmu_access.S
srmmu.c	sparc32: destroy_context() and switch_mm() needs to disable interrupts.	2014-12-18 12:47:54 -05:00
swift.S	[PATCH] sparc32: vm_area_struct access for old Sun SPARCs.	2013-07-10 13:56:10 -07:00
tlb.c	sparc: Replace __get_cpu_var uses	2014-08-26 13:45:55 -04:00
tsb.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next	2014-06-19 07:50:07 -10:00
tsunami.S	[PATCH] sparc32: vm_area_struct access for old Sun SPARCs.	2013-07-10 13:56:10 -07:00
ultra.S	sparc64: Make PAGE_OFFSET variable.	2013-11-12 15:22:34 -08:00
viking.S	[PATCH] sparc32: vm_area_struct access for old Sun SPARCs.	2013-07-10 13:56:10 -07:00