kernel/git/stable/linux.git/arch/mips, branch linux-4.11.y

MIPS: Fix IRQ tracing & lockdep when rescheduling

2017-07-05T12:41:38+00:00

commit d8550860d910c6b7b70f830f59003b33daaa52c9 upstream. When the scheduler sets TIF_NEED_RESCHED & we call into the scheduler from arch/mips/kernel/entry.S we disable interrupts. This is true regardless of whether we reach work_resched from syscall_exit_work, resume_userspace or by looping after calling schedule(). Although we disable interrupts in these paths we don't call trace_hardirqs_off() before calling into C code which may acquire locks, and we therefore leave lockdep with an inconsistent view of whether interrupts are disabled or not when CONFIG_PROVE_LOCKING & CONFIG_DEBUG_LOCKDEP are both enabled. Without tracing this interrupt state lockdep will print warnings such as the following once a task returns from a syscall via syscall_exit_partial with TIF_NEED_RESCHED set: [ 49.927678] ------------[ cut here ]------------ [ 49.934445] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3687 check_flags.part.41+0x1dc/0x1e8 [ 49.946031] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 49.946355] CPU: 0 PID: 1 Comm: init Not tainted 4.10.0-00439-gc9fd5d362289-dirty #197 [ 49.963505] Stack : 0000000000000000 ffffffff81bb5d6a 0000000000000006 ffffffff801ce9c4 [ 49.974431] 0000000000000000 0000000000000000 0000000000000000 000000000000004a [ 49.985300] ffffffff80b7e487 ffffffff80a24498 a8000000ff160000 ffffffff80ede8b8 [ 49.996194] 0000000000000001 0000000000000000 0000000000000000 0000000077c8030c [ 50.007063] 000000007fd8a510 ffffffff801cd45c 0000000000000000 a8000000ff127c88 [ 50.017945] 0000000000000000 ffffffff801cf928 0000000000000001 ffffffff80a24498 [ 50.028827] 0000000000000000 0000000000000001 0000000000000000 0000000000000000 [ 50.039688] 0000000000000000 a8000000ff127bd0 0000000000000000 ffffffff805509bc [ 50.050575] 00000000140084e0 0000000000000000 0000000000000000 0000000000040a00 [ 50.061448] 0000000000000000 ffffffff8010e1b0 0000000000000000 ffffffff805509bc [ 50.072327] ... [ 50.076087] Call Trace: [ 50.079869] [] show_stack+0x80/0xa8 [ 50.086577] [] dump_stack+0x10c/0x190 [ 50.093498] [] __warn+0xf0/0x108 [ 50.099889] [] warn_slowpath_fmt+0x3c/0x48 [ 50.107241] [] check_flags.part.41+0x1dc/0x1e8 [ 50.114961] [] lock_is_held_type+0x8c/0xb0 [ 50.122291] [] __schedule+0x8c0/0x10f8 [ 50.129221] [] schedule+0x30/0x98 [ 50.135659] [] work_resched+0x8/0x34 [ 50.142397] ---[ end trace 0cb4f6ef5b99fe21 ]--- [ 50.148405] possible reason: unannotated irqs-off. [ 50.154600] irq event stamp: 400463 [ 50.159566] hardirqs last enabled at (400463): [] _raw_spin_unlock_irqrestore+0x40/0xa8 [ 50.171981] hardirqs last disabled at (400462): [] _raw_spin_lock_irqsave+0x30/0xb0 [ 50.183897] softirqs last enabled at (400450): [] __do_softirq+0x4ac/0x6a8 [ 50.195015] softirqs last disabled at (400425): [] irq_exit+0x110/0x128 Fix this by using the TRACE_IRQS_OFF macro to call trace_hardirqs_off() when CONFIG_TRACE_IRQFLAGS is enabled. This is done before invoking schedule() following the work_resched label because: 1) Interrupts are disabled regardless of the path we take to reach work_resched() & schedule(). 2) Performing the tracing here avoids the need to do it in paths which disable interrupts but don't call out to C code before hitting a path which uses the RESTORE_SOME macro that will call trace_hardirqs_on() or trace_hardirqs_off() as appropriate. We call trace_hardirqs_on() using the TRACE_IRQS_ON macro before calling syscall_trace_leave() for similar reasons, ensuring that lockdep has a consistent view of state after we re-enable interrupts. Signed-off-by: Paul Burton Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15385/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

MIPS: pm-cps: Drop manual cache-line alignment of ready_count

2017-07-05T12:41:38+00:00

commit 161c51ccb7a6faf45ffe09aa5cf1ad85ccdad503 upstream. We allocate memory for a ready_count variable per-CPU, which is accessed via a cached non-coherent TLB mapping to perform synchronisation between threads within the core using LL/SC instructions. In order to ensure that the variable is contained within its own data cache line we allocate 2 lines worth of memory & align the resulting pointer to a line boundary. This is however unnecessary, since kmalloc is guaranteed to return memory which is at least cache-line aligned (see ARCH_DMA_MINALIGN). Stop the redundant manual alignment. Besides cleaning up the code & avoiding needless work, this has the side effect of avoiding an arithmetic error found by Bryan on 64 bit systems due to the 32 bit size of the former dlinesz. This led the ready_count variable to have its upper 32b cleared erroneously for MIPS64 kernels, causing problems when ready_count was later used on MIPS64 via cpuidle. Signed-off-by: Paul Burton Fixes: 3179d37ee1ed ("MIPS: pm-cps: add PM state entry code for CPS systems") Reported-by: Bryan O'Donoghue Reviewed-by: Bryan O'Donoghue Tested-by: Bryan O'Donoghue Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15383/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

MIPS: Avoid accidental raw backtrace

2017-07-05T12:41:38+00:00

commit 854236363370995a609a10b03e35fd3dc5e9e4a1 upstream. Since commit 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with usermode") show_backtrace() invokes the raw backtracer when cp0_status & ST0_KSU indicates user mode to fix issues on EVA kernels where user and kernel address spaces overlap. However this is used by show_stack() which creates its own pt_regs on the stack and leaves cp0_status uninitialised in most of the code paths. This results in the non deterministic use of the raw back tracer depending on the previous stack content. show_stack() deals exclusively with kernel mode stacks anyway, so explicitly initialise regs.cp0_status to KSU_KERNEL (i.e. 0) to ensure we get a useful backtrace. Fixes: 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with usermode") Signed-off-by: James Hogan Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16656/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

MIPS: head: Reorder instructions missing a delay slot

2017-07-05T12:41:38+00:00

commit 25d8b92e0af75d72ce8b99e63e5a449cc0888efa upstream. In this sequence the 'move' is assumed in the delay slot of the 'beq', but head.S is in reorder mode and the former gets pushed one 'nop' farther by the assembler. The corrected behavior made booting with an UHI supplied dtb erratic. Fixes: 15f37e158892 ("MIPS: store the appended dtb address in a variable") Signed-off-by: Karl Beldan Reviewed-by: James Hogan Cc: Jonas Gorski Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/16614/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

KVM: MIPS: Fix maybe-uninitialized build failure

2017-06-29T11:02:46+00:00

commit e27a9eca5d4a392b96ce5d5238c8d637bcb0a52c upstream. This commit fixes a "maybe-uninitialized" build failure in arch/mips/kvm/tlb.c when KVM, DYNAMIC_DEBUG and JUMP_LABEL are all enabled. The failure is: In file included from ./include/linux/printk.h:329:0, from ./include/linux/kernel.h:13, from ./include/asm-generic/bug.h:15, from ./arch/mips/include/asm/bug.h:41, from ./include/linux/bug.h:4, from ./include/linux/thread_info.h:11, from ./include/asm-generic/current.h:4, from ./arch/mips/include/generated/asm/current.h:1, from ./include/linux/sched.h:11, from arch/mips/kvm/tlb.c:13: arch/mips/kvm/tlb.c: In function ‘kvm_mips_host_tlb_inv’: ./include/linux/dynamic_debug.h:126:3: error: ‘idx_kernel’ may be used uninitialized in this function [-Werror=maybe-uninitialized] __dynamic_pr_debug(&descriptor, pr_fmt(fmt), \ ^~~~~~~~~~~~~~~~~~ arch/mips/kvm/tlb.c:169:16: note: ‘idx_kernel’ was declared here int idx_user, idx_kernel; ^~~~~~~~~~ There is a similar error relating to "idx_user". Both errors were observed with GCC 6. As far as I can tell, it is impossible for either idx_user or idx_kernel to be uninitialized when they are later read in the calls to kvm_debug, but to satisfy the compiler, add zero initializers to both variables. Signed-off-by: James Cowgill Fixes: 57e3869cfaae ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID") Acked-by: James Hogan Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman

mm: larger stack guard gap, between vmas

2017-06-24T05:06:22+00:00

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds [wt: backport to 4.11: adjust context] Signed-off-by: Willy Tarreau Signed-off-by: Greg Kroah-Hartman

MIPS: .its targets depend on vmlinux

2017-06-24T05:06:21+00:00

commit bcd7c45e0d5a82be9a64b90050f0e09d41a50758 upstream. The .its targets require information about the kernel binary, such as its entry point, which is extracted from the vmlinux ELF. We therefore require that the ELF is built before the .its files are generated. Declare this requirement in the Makefile such that make will ensure this is always the case, otherwise in corner cases we can hit issues as the .its is generated with an incorrect (either invalid or stale) entry point. Signed-off-by: Paul Burton Fixes: cf2a5e0bb4c6 ("MIPS: Support generating Flattened Image Trees (.itb)") Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16179/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

MIPS: Fix bnezc/jialc return address calculation

2017-06-24T05:06:21+00:00

commit 1a73d9310e093fc3adffba4d0a67b9fab2ee3f63 upstream. The code handling the pop76 opcode (ie. bnezc & jialc instructions) in __compute_return_epc_for_insn() needs to set the value of $31 in the jialc case, which is encoded with rs = 0. However its check to differentiate bnezc (rs != 0) from jialc (rs = 0) was unfortunately backwards, meaning that if we emulate a bnezc instruction we clobber $31 & if we emulate a jialc instruction it actually behaves like a jic instruction. Fix this by inverting the check of rs to match the way the instructions are actually encoded. Signed-off-by: Paul Burton Fixes: 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC instructions") Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16178/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

kthread: fix boot hang (regression) on MIPS/OpenRISC

2017-06-14T13:07:51+00:00

commit b0f5a8f32e8bbdaae1abb8abe2d3cbafaba57e08 upstream. This fixes a regression in commit 4d6501dce079 where I didn't notice that MIPS and OpenRISC were reinitialising p->{set,clear}_child_tid to NULL after our initialisation in copy_process(). We can simply get rid of the arch-specific initialisation here since it is now always done in copy_process() before hitting copy_thread{,_tls}(). Review notes: - As far as I can tell, copy_process() is the only user of copy_thread_tls(), which is the only caller of copy_thread() for architectures that don't implement copy_thread_tls(). - After this patch, there is no arch-specific code touching p->set_child_tid or p->clear_child_tid whatsoever. - It may look like MIPS/OpenRISC wanted to always have these fields be NULL, but that's not true, as copy_process() would unconditionally set them again _after_ calling copy_thread_tls() before commit 4d6501dce079. Fixes: 4d6501dce079c1eb6bf0b1d8f528a5e81770109e ("kthread: Fix use-after-free if kthread fork fails") Reported-by: Guenter Roeck Tested-by: Guenter Roeck # MIPS only Acked-by: Stafford Horne Acked-by: Oleg Nesterov Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: openrisc@lists.librecores.org Cc: Jamie Iles Cc: Thomas Gleixner Signed-off-by: Vegard Nossum Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

MIPS: Loongson-3: Select MIPS_L1_CACHE_SHIFT_6

2017-05-25T13:46:27+00:00

commit 17c99d9421695a0e0de18bf1e7091d859e20ec1d upstream. Some newer Loongson-3 have 64 bytes cache lines, so select MIPS_L1_CACHE_SHIFT_6. Signed-off-by: Huacai Chen Cc: John Crispin Cc: Steven J . Hill Cc: Fuxin Zhang Cc: Zhangjin Wu Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15755/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman