BMC/Intel-BMC/linux.git/arch/m68k/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

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

m68k/mm: Eliminate memset after alloc_bootmem_pages

2014-11-10T08:56:44+00:00

alloc_bootmem and related functions always return a 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: Geert Uytterhoeven

m68k: Reformat arch/m68k/mm/hwtest.c

2014-10-03T08:50:56+00:00

No functional changes Signed-off-by: Geert Uytterhoeven

m68k: Disable/restore interrupts in hwreg_present()/hwreg_write()

2014-10-03T08:50:56+00:00

hwreg_present() and hwreg_write() temporarily change the VBR register to another vector table. This table contains a valid bus error handler only, all other entries point to arbitrary addresses. If an interrupt comes in while the temporary table is active, the processor will start executing at such an arbitrary address, and the kernel will crash. While most callers run early, before interrupts are enabled, or explicitly disable interrupts, Finn Thain pointed out that macsonic has one callsite that doesn't, causing intermittent boot crashes. There's another unsafe callsite in hilkbd. Fix this for good by disabling and restoring interrupts inside hwreg_present() and hwreg_write(). Explicitly disabling interrupts can be removed from the callsites later. Reported-by: Finn Thain Signed-off-by: Geert Uytterhoeven Cc: stable@vger.kernel.org

m68k: Increase initial mapping to 8 or 16 MiB if possible

2014-05-28T08:11:54+00:00

If the size of the first memory chunk is at least 8 or 16 MiB increase the initial mapping to 8 resp. 16 MiB instead of 4 MiB. This makes it possible to 1. Map more memory in the first node without running out of space for the page tables, 2. Boot kernels that don't fit in 4 MiB (e.g. multi_defconfig). Signed-off-by: Andreas Schwab - Add support for 8 MiB, - Store initial mapping size in head.S for later reuse, - Add comment about large kernels. Signed-off-by: Geert Uytterhoeven

m68k/mm: kmap spelling/grammar fixes

2013-12-30T20:01:11+00:00

Signed-off-by: Geert Uytterhoeven

m68k: Convert arch/m68k/mm/fault.c to pr_*()

2013-12-30T20:01:10+00:00

Signed-off-by: Geert Uytterhoeven

m68k/mm: Check for mm != NULL in do_page_fault() debug code

2013-12-30T20:01:09+00:00

When DEBUG is enabled, do_page_fault() may dereference a NULL pointer, causing recursive bus errors. Signed-off-by: Geert Uytterhoeven

m68k/UAPI: Move generic definitions to

2013-11-26T10:09:16+00:00

Move generic definitions used by bootstraps to uapi/asm/bootinfo.h: - Machine types, - CPU, FPU, and MMU types, - struct mem_info. Keep a copy of struct mem_info for in-kernel use, and rename it to struct m68k_mem_info, as the exported one will be modified later. Signed-off-by: Geert Uytterhoeven