linux/arch/arc, branch v3.12

ARC: Incorrect mm reference used in vmalloc fault handler

2013-11-02T17:27:04Z

A vmalloc fault needs to sync up PGD/PTE entry from init_mm to current task's "active_mm". ARC vmalloc fault handler however was using mm. A vmalloc fault for non user task context (actually pre-userland, from init thread's open for /dev/console) caused the handler to deref NULL mm (for mm->pgd) The reasons it worked so far is amazing: 1. By default (!SMP), vmalloc fault handler uses a cached value of PGD. In SMP that MMU register is repurposed hence need for mm pointer deref. 2. In pre-3.12 SMP kernel, the problem triggering vmalloc didn't exist in pre-userland code path - it was introduced with commit 20bafb3d23d108bc "n_tty: Move buffers into n_tty_data" Signed-off-by: Vineet Gupta Cc: Gilad Ben-Yossef Cc: Noam Camus Cc: stable@vger.kernel.org #3.10 and 3.11 Cc: Peter Hurley Signed-off-by: Linus Torvalds

ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc"

2013-10-12T06:30:36Z

ARCompact TRAP_S insn used for breakpoints, commits before exception is taken (updating architectural PC). So ptregs->ret contains next-PC and not the breakpoint PC itself. This is different from other restartable exceptions such as TLB Miss where ptregs->ret has exact faulting PC. gdb needs to know exact-PC hence ARC ptrace GETREGSET provides for @stop_pc which returns ptregs->ret vs. EFA depending on the situation. However, writing stop_pc (SETREGSET request), which updates ptregs->ret doesn't makes sense stop_pc doesn't always correspond to that reg as described above. This was not an issue so far since user_regs->ret / user_regs->stop_pc had same value and both writing to ptregs->ret was OK, needless, but NOT broken, hence not observed. With gdb "jump", they diverge, and user_regs->ret updating ptregs is overwritten immediately with stop_pc, which this patch fixes. Reported-by: Anton Kolesov Signed-off-by: Vineet Gupta

ARC: Fix signal frame management for SA_SIGINFO

2013-10-03T04:13:56Z

Previously, when a signal was registered with SA_SIGINFO, parameters 2 and 3 of the signal handler were written to registers r1 and r2 before the register set was saved. This led to corruption of these two registers after returning from the signal handler (the wrong values were restored). With this patch, registers are now saved before any parameters are passed, thus maintaining the processor state from before signal entry. Signed-off-by: Christian Ruppert Signed-off-by: Vineet Gupta

ARC: Use clockevents_config_and_register over clockevents_register_device

2013-09-27T10:58:48Z

clockevents_config_and_register is more clever and correct than doing it by hand; so use it. [vgupta: fixed build failure due to missing ; in patch] Signed-off-by: Uwe Kleine-König Signed-off-by: Vineet Gupta

ARC: Workaround spinlock livelock in SMP SystemC simulation

2013-09-27T10:58:48Z

Some ARC SMP systems lack native atomic R-M-W (LLOCK/SCOND) insns and can only use atomic EX insn (reg with mem) to build higher level R-M-W primitives. This includes a SystemC based SMP simulation model. So rwlocks need to use a protecting spinlock for atomic cmp-n-exchange operation to update reader(s)/writer count. The spinlock operation itself looks as follows: mov reg, 1 ; 1=locked, 0=unlocked retry: EX reg, [lock] ; load existing, store 1, atomically BREQ reg, 1, rety ; if already locked, retry In single-threaded simulation, SystemC alternates between the 2 cores with "N" insn each based scheduling. Additionally for insn with global side effect, such as EX writing to shared mem, a core switch is enforced too. Given that, 2 cores doing a repeated EX on same location, Linux often got into a livelock e.g. when both cores were fiddling with tasklist lock (gdbserver / hackbench) for read/write respectively as the sequence diagram below shows: core1 core2 -------- -------- 1. spin lock [EX r=0, w=1] - LOCKED 2. rwlock(Read) - LOCKED 3. spin unlock [ST 0] - UNLOCKED spin lock [EX r=0,w=1] - LOCKED -- resched core 1---- 5. spin lock [EX r=1] - ALREADY-LOCKED -- resched core 2---- 6. rwlock(Write) - READER-LOCKED 7. spin unlock [ST 0] 8. rwlock failed, retry again 9. spin lock [EX r=0, w=1] -- resched core 1---- 10 spinlock locked in #9, retry #5 11. spin lock [EX gets 1] -- resched core 2---- ... ... The fix was to unlock using the EX insn too (step 7), to trigger another SystemC scheduling pass which would let core1 proceed, eliding the livelock. Signed-off-by: Vineet Gupta

ARC: Fix 32-bit wrap around in access_ok()

2013-09-27T10:58:47Z

Anton reported | LTP tests syscalls/process_vm_readv01 and process_vm_writev01 fail | similarly in one testcase test_iov_invalid -> lvec->iov_base. | Testcase expects errno EFAULT and return code -1, | but it gets return code 1 and ERRNO is 0 what means success. Essentially test case was passing a pointer of -1 which access_ok() was not catching. It was doing [@addr + @sz <= TASK_SIZE] which would pass for @addr == -1 Fixed that by rewriting as [@addr <= TASK_SIZE - @sz] Reported-by: Anton Kolesov Signed-off-by: Vineet Gupta

ARC: Handle zero-overhead-loop in unaligned access handler

2013-09-27T10:58:23Z

If a load or store is the last instruction in a zero-overhead-loop, and it's misaligned, the loop would execute only once. This fixes that problem. Signed-off-by: Mischa Jonker Signed-off-by: Vineet Gupta

Remove GENERIC_HARDIRQ config option

2013-09-13T13:09:52Z

After the last architecture switched to generic hard irqs the config options HAVE_GENERIC_HARDIRQS & GENERIC_HARDIRQS and the related code for !CONFIG_GENERIC_HARDIRQS can be removed. Signed-off-by: Martin Schwidefsky

Merge branch 'akpm' (patches from Andrew Morton)

2013-09-12T22:44:27Z

Merge more patches from Andrew Morton: "The rest of MM. Plus one misc cleanup" * emailed patches from Andrew Morton : (35 commits) mm/Kconfig: add MMU dependency for MIGRATION. kernel: replace strict_strto*() with kstrto*() mm, thp: count thp_fault_fallback anytime thp fault fails thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page() thp: do_huge_pmd_anonymous_page() cleanup thp: move maybe_pmd_mkwrite() out of mk_huge_pmd() mm: cleanup add_to_page_cache_locked() thp: account anon transparent huge pages into NR_ANON_PAGES truncate: drop 'oldsize' truncate_pagecache() parameter mm: make lru_add_drain_all() selective memcg: document cgroup dirty/writeback memory statistics memcg: add per cgroup writeback pages accounting memcg: check for proper lock held in mem_cgroup_update_page_stat memcg: remove MEMCG_NR_FILE_MAPPED memcg: reduce function dereference memcg: avoid overflow caused by PAGE_ALIGN memcg: rename RESOURCE_MAX to RES_COUNTER_MAX memcg: correct RESOURCE_MAX to ULLONG_MAX mm: memcg: do not trap chargers with full callstack on OOM mm: memcg: rework and document OOM waiting and wakeup ...

arch: mm: pass userspace fault flag to generic fault handler

2013-09-12T22:38:01Z

Unlike global OOM handling, memory cgroup code will invoke the OOM killer in any OOM situation because it has no way of telling faults occuring in kernel context - which could be handled more gracefully - from user-triggered faults. Pass a flag that identifies faults originating in user space from the architecture-specific fault handlers to generic code so that memcg OOM handling can be improved. Signed-off-by: Johannes Weiner Reviewed-by: Michal Hocko Cc: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: azurIt Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds