kernel.git/arch/s390, branch linux-4.14.y

s390/vx: fix save/restore of fpu kernel context

2024-01-08T10:25:02Z

[ Upstream commit e6b2dab41888332bf83f592131e7ea07756770a4 ] The KERNEL_FPR mask only contains a flag for the first eight vector registers. However floating point registers overlay parts of the first sixteen vector registers. This could lead to vector register corruption if a kernel fpu context uses any of the vector registers 8 to 15 and is interrupted or calls a KERNEL_FPR context. If that context uses also vector registers 8 to 15, their contents will be corrupted on return. Luckily this is currently not a real bug, since the kernel has only one KERNEL_FPR user with s390_adjust_jiffies() and it is only using floating point registers 0 to 2. Fix this by using the correct bits for KERNEL_FPR. Fixes: 7f79695cc1b6 ("s390/fpu: improve kernel_fpu_[begin|end]") Signed-off-by: Heiko Carstens Reviewed-by: Hendrik Brueckner Signed-off-by: Alexander Gordeev Signed-off-by: Sasha Levin

KVM: s390/mm: Properly reset no-dat

2023-12-13T15:46:17Z

commit 27072b8e18a73ffeffb1c140939023915a35134b upstream. When the CMMA state needs to be reset, the no-dat bit also needs to be reset. Failure to do so could cause issues in the guest, since the guest expects the bit to be cleared after a reset. Cc: Reviewed-by: Nico Boehr Message-ID: <20231109123624.37314-1-imbrenda@linux.ibm.com> Signed-off-by: Claudio Imbrenda Signed-off-by: Greg Kroah-Hartman

s390/pci: fix iommu bitmap allocation

2023-10-25T09:13:33Z

commit c1ae1c59c8c6e0b66a718308c623e0cb394dab6b upstream. Since the fixed commits both zdev->iommu_bitmap and zdev->lazy_bitmap are allocated as vzalloc(zdev->iommu_pages / 8). The problem is that zdev->iommu_bitmap is a pointer to unsigned long but the above only yields an allocation that is a multiple of sizeof(unsigned long) which is 8 on s390x if the number of IOMMU pages is a multiple of 64. This in turn is the case only if the effective IOMMU aperture is a multiple of 64 * 4K = 256K. This is usually the case and so didn't cause visible issues since both the virt_to_phys(high_memory) reduced limit and hardware limits use nice numbers. Under KVM, and in particular with QEMU limiting the IOMMU aperture to the vfio DMA limit (default 65535), it is possible for the reported aperture not to be a multiple of 256K however. In this case we end up with an iommu_bitmap whose allocation is not a multiple of 8 causing bitmap operations to access it out of bounds. Sadly we can't just fix this in the obvious way and use bitmap_zalloc() because for large RAM systems (tested on 8 TiB) the zdev->iommu_bitmap grows too large for kmalloc(). So add our own bitmap_vzalloc() wrapper. This might be a candidate for common code, but this area of code will be replaced by the upcoming conversion to use the common code DMA API on s390 so just add a local routine. Fixes: 224593215525 ("s390/pci: use virtual memory for iommu bitmap") Fixes: 13954fd6913a ("s390/pci_dma: improve lazy flush for unmap") Cc: stable@vger.kernel.org Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

treewide: Remove uninitialized_var() usage

2023-08-11T09:33:32Z

commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

s390/ptrace: fix PTRACE_GET_LAST_BREAK error handling

2023-04-26T09:18:56Z

[ Upstream commit f9bbf25e7b2b74b52b2f269216a92657774f239c ] Return -EFAULT if put_user() for the PTRACE_GET_LAST_BREAK request fails, instead of silently ignoring it. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/uaccess: add missing earlyclobber annotations to __clear_user()

2023-04-05T09:14:21Z

commit 89aba4c26fae4e459f755a18912845c348ee48f3 upstream. Add missing earlyclobber annotation to size, to, and tmp2 operands of the __clear_user() inline assembly since they are modified or written to before the last usage of all input operands. This can lead to incorrect register allocation for the inline assembly. Fixes: 6c2a9e6df604 ("[S390] Use alternative user-copy operations for new hardware.") Reported-by: Mark Rutland Link: https://lore.kernel.org/all/20230321122514.1743889-3-mark.rutland@arm.com/ Cc: stable@vger.kernel.org Reviewed-by: Gerald Schaefer Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/setup: init jump labels before command line parsing

2023-03-11T15:26:55Z

commit 95e61b1b5d6394b53d147c0fcbe2ae70fbe09446 upstream. Command line parameters might set static keys. This is true for s390 at least since commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options"). To avoid the following WARN: static_key_enable_cpuslocked(): static key 'init_on_alloc+0x0/0x40' used before call to jump_label_init() call jump_label_init() just before parse_early_param(). jump_label_init() is safe to call multiple times (x86 does that), doesn't do any memory allocations and hence should be safe to call that early. Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options") Cc: # 5.3: d6df52e9996d: s390/maccess: add no DAT mode to kernel_write Cc: # 5.3 Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/maccess: add no DAT mode to kernel_write

2023-03-11T15:26:55Z

commit d6df52e9996dcc2062c3d9c9123288468bb95b52 upstream. To be able to patch kernel code before paging is initialized do plain memcpy if DAT is off. This is required to enable early jump label initialization. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/kprobes: fix current_kprobe never cleared after kprobes reenter

2023-03-11T15:26:44Z

commit cd57953936f2213dfaccce10d20f396956222c7d upstream. Recent test_kprobe_missed kprobes kunit test uncovers the following problem. Once kprobe is triggered from another kprobe (kprobe reenter), all future kprobes on this cpu are considered as kprobe reenter, thus pre_handler and post_handler are not being called and kprobes are counted as "missed". Commit b9599798f953 ("[S390] kprobes: activation and deactivation") introduced a simpler scheme for kprobes (de)activation and status tracking by using push_kprobe/pop_kprobe, which supposed to work for both initial kprobe entry as well as kprobe reentry and helps to avoid handling those two cases differently. The problem is that a sequence of calls in case of kprobes reenter: push_kprobe() <- NULL (current_kprobe) push_kprobe() <- kprobe1 (current_kprobe) pop_kprobe() -> kprobe1 (current_kprobe) pop_kprobe() -> kprobe1 (current_kprobe) leaves "kprobe1" as "current_kprobe" on this cpu, instead of setting it to NULL. In fact push_kprobe/pop_kprobe can only store a single state (there is just one prev_kprobe in kprobe_ctlblk). Which is a hack but sufficient, there is no need to have another prev_kprobe just to store NULL. To make a simple and backportable fix simply reset "prev_kprobe" when kprobe is poped from this "stack". No need to worry about "kprobe_status" in this case, because its value is only checked when current_kprobe != NULL. Cc: stable@vger.kernel.org Fixes: b9599798f953 ("[S390] kprobes: activation and deactivation") Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/kprobes: fix irq mask clobbering on kprobe reenter from post_handler

2023-03-11T15:26:44Z

commit 42e19e6f04984088b6f9f0507c4c89a8152d9730 upstream. Recent test_kprobe_missed kprobes kunit test uncovers the following error (reported when CONFIG_DEBUG_ATOMIC_SLEEP is enabled): BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 662, name: kunit_try_catch preempt_count: 0, expected: 0 RCU nest depth: 0, expected: 0 no locks held by kunit_try_catch/662. irq event stamp: 280 hardirqs last enabled at (279): [<00000003e60a3d42>] __do_pgm_check+0x17a/0x1c0 hardirqs last disabled at (280): [<00000003e3bd774a>] kprobe_exceptions_notify+0x27a/0x318 softirqs last enabled at (0): [<00000003e3c5c890>] copy_process+0x14a8/0x4c80 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 46 PID: 662 Comm: kunit_try_catch Tainted: G N 6.2.0-173644-g44c18d77f0c0 #2 Hardware name: IBM 3931 A01 704 (LPAR) Call Trace: [<00000003e60a3a00>] dump_stack_lvl+0x120/0x198 [<00000003e3d02e82>] __might_resched+0x60a/0x668 [<00000003e60b9908>] __mutex_lock+0xc0/0x14e0 [<00000003e60bad5a>] mutex_lock_nested+0x32/0x40 [<00000003e3f7b460>] unregister_kprobe+0x30/0xd8 [<00000003e51b2602>] test_kprobe_missed+0xf2/0x268 [<00000003e51b5406>] kunit_try_run_case+0x10e/0x290 [<00000003e51b7dfa>] kunit_generic_run_threadfn_adapter+0x62/0xb8 [<00000003e3ce30f8>] kthread+0x2d0/0x398 [<00000003e3b96afa>] __ret_from_fork+0x8a/0xe8 [<00000003e60ccada>] ret_from_fork+0xa/0x40 The reason for this error report is that kprobes handling code failed to restore irqs. The problem is that when kprobe is triggered from another kprobe post_handler current sequence of enable_singlestep / disable_singlestep is the following: enable_singlestep <- original kprobe (saves kprobe_saved_imask) enable_singlestep <- kprobe triggered from post_handler (clobbers kprobe_saved_imask) disable_singlestep <- kprobe triggered from post_handler (restores kprobe_saved_imask) disable_singlestep <- original kprobe (restores wrong clobbered kprobe_saved_imask) There is just one kprobe_ctlblk per cpu and both calls saves and loads irq mask to kprobe_saved_imask. To fix the problem simply move resume_execution (which calls disable_singlestep) before calling post_handler. This also fixes the problem that post_handler is called with pt_regs which were not yet adjusted after single-stepping. Cc: stable@vger.kernel.org Fixes: 4ba069b802c2 ("[S390] add kprobes support.") Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman