BMC/Intel-BMC/linux.git/arch/parisc/mm, branch dev

mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler

2015-05-19T06:39:15+00:00

Introduce faulthandler_disabled() and use it to check for irq context and disabled pagefaults (via pagefault_disable()) in the pagefault handlers. Please note that we keep the in_atomic() checks in place - to detect whether in irq context (in which case preemption is always properly disabled). In contrast, preempt_disable() should never be used to disable pagefaults. With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt counter, and therefore the result of in_atomic() differs. We validate that condition by using might_fault() checks when calling might_sleep(). Therefore, add a comment to faulthandler_disabled(), describing why this is needed. faulthandler_disabled() and pagefault_disable() are defined in linux/uaccess.h, so let's properly add that include to all relevant files. This patch is based on a patch from Thomas Gleixner. Reviewed-and-tested-by: Thomas Gleixner Signed-off-by: David Hildenbrand Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-7-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar

parisc: expose number of page table levels on Kconfig level

2015-04-14T23:49:02+00:00

We would want to use number of page table level to define mm_struct. Let's expose it as CONFIG_PGTABLE_LEVELS. Signed-off-by: Kirill A. Shutemov Cc: "James E.J. Bottomley" Cc: Helge Deller Tested-by: Guenter Roeck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

parisc: hpux - Remove hpux gateway page

2015-02-16T21:35:06+00:00

Drop code to create HP-UX gateway page and syscall entry code. Signed-off-by: Helge Deller

vm: add VM_FAULT_SIGSEGV handling support

2015-01-29T18:51:32+00:00

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 fee7e49d4514 ("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 Tested-by: Jan Engelhardt Acked-by: Heiko Carstens # "s390 still compiles and boots" Cc: linux-arch@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

parisc: Eliminate memset after alloc_bootmem_pages

2014-07-24T20:05:08+00:00

alloc_bootmem and related function always return zeroed region of memory. Thus a memset after calls to these functions is unnecessary. The following Coccinelle semantic patch was used for making the change: @@ expression E,E1; @@ E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...) ... when != E - memset(E,0,E1); Signed-off-by: Himangi Saraogi Acked-by: Julia Lawall Signed-off-by: Helge Deller

Merge branch 'parisc-3.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux

2014-05-20T05:35:28+00:00

Pull parisc fixes from Helge Deller: "There are two patches in here: The first patch greatly improves latency and corrects the memory ordering in our light-weight atomic locking syscall. The second patch ratelimits printing of userspace segfaults in the same way as it's done on other platforms. This fixes a possible DOS on parisc since it prevents the syslog to grow too fast. For example, when the debian acl2 package was built on our debian buildd servers, this package produced lots of gigabytes in syslog in very short time and thus filled our harddisks, which then turned the server nearly completely unaccessible and unresponsive" * 'parisc-3.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Improve LWS-CAS performance parisc: ratelimit userspace segfault printing

parisc: ratelimit userspace segfault printing

2014-05-15T19:12:15+00:00

Ratelimit printing of userspace segfaults and make it runtime configurable via the /proc/sys/debug/exception-trace variable. This should resolve syslog from growing way too fast and thus prevents possible system service attacks. Signed-off-by: Helge Deller Cc: stable@vger.kernel.org # 3.13+

parisc: Replace __get_cpu_var uses for address calculation

2014-04-03T18:50:33+00:00

Convert to the use of this_cpu_ptr(). Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: linux-parisc@vger.kernel.org Signed-off-by: Christoph Lameter Signed-off-by: Helge Deller

mm, show_mem: remove SHOW_MEM_FILTER_PAGE_COUNT

2014-01-22T00:19:44+00:00

Commit 4b59e6c47309 ("mm, show_mem: suppress page counts in non-blockable contexts") introduced SHOW_MEM_FILTER_PAGE_COUNT to suppress PFN walks on large memory machines. Commit c78e93630d15 ("mm: do not walk all of system memory during show_mem") avoided a PFN walk in the generic show_mem helper which removes the requirement for SHOW_MEM_FILTER_PAGE_COUNT in that case. This patch removes PFN walkers from the arch-specific implementations that report on a per-node or per-zone granularity. ARM and unicore32 still do a PFN walk as they report memory usage on each bank which is a much finer granularity where the debugging information may still be of use. As the remaining arches doing PFN walks have relatively small amounts of memory, this patch simply removes SHOW_MEM_FILTER_PAGE_COUNT. [akpm@linux-foundation.org: fix parisc] Signed-off-by: Mel Gorman Acked-by: David Rientjes Cc: Tony Luck Cc: Russell King Cc: James Bottomley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

parisc: fix kernel memory layout in vmlinux.ld.S

2013-11-30T21:09:21+00:00

When building a 64bit kernel sometimes functions in the .init section were not able to reach the standard kernel function. Main reason for this problem is, that the linkage tables (.plt, .opd, .dlt) tend to become pretty huge and thus the distance gets too big for short calls. One option to avoid this is to use the -mlong-calls compiler option, but this increases the binary size and introduces a performance penalty. Instead, with this patch we just lay out the binary differently. Init code is stored first, followed by text, R/O and finally R/W data. This means, that init and text code is now much closer to each other, which is sufficient to reach each other by short calls. Signed-off-by: Helge Deller