kernel.git/arch/s390/kernel/setup.c, branch linux-5.13.y

s390/sclp_vt220: fix console name to match device

2021-07-20T14:00:17Z

[ Upstream commit b7d91d230a119fdcc334d10c9889ce9c5e15118b ] Console name reported in /proc/consoles: ttyS1 -W- (EC p ) 4:65 does not match the char device name: crw--w---- 1 root root 4, 65 May 17 12:18 /dev/ttysclp0 so debian-installer inside a QEMU s390x instance gets confused and fails to start with the following error: steal-ctty: No such file or directory Signed-off-by: Valentin Vidic Link: https://lore.kernel.org/r/20210427194010.9330-1-vvidic@valentin-vidic.from.hr Signed-off-by: Christian Borntraeger Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390: preempt: Fix preempt_count initialization

2021-07-14T15:07:51Z

commit 6a942f5780545ebd11aca8b3ac4b163397962322 upstream. S390's init_idle_preempt_count(p, cpu) doesn't actually let us initialize the preempt_count of the requested CPU's idle task: it unconditionally writes to the current CPU's. This clearly conflicts with idle_threads_init(), which intends to initialize *all* the idle tasks, including their preempt_count (or their CPU's, if the arch uses a per-CPU preempt_count). Unfortunately, it seems the way s390 does things doesn't let us initialize every possible CPU's preempt_count early on, as the pages where this resides are only allocated when a CPU is brought up and are freed when it is brought down. Let the arch-specific code set a CPU's preempt_count when its lowcore is allocated, and turn init_idle_preempt_count() into an empty stub. Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") Reported-by: Guenter Roeck Signed-off-by: Valentin Schneider Tested-by: Guenter Roeck Reviewed-by: Heiko Carstens Link: https://lore.kernel.org/r/20210707163338.1623014-1-valentin.schneider@arm.com Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390: fix detection of vector enhancements facility 1 vs. vector packed decimal facility

2021-05-04T17:10:56Z

The PoP documents: 134: The vector packed decimal facility is installed in the z/Architecture architectural mode. When bit 134 is one, bit 129 is also one. 135: The vector enhancements facility 1 is installed in the z/Architecture architectural mode. When bit 135 is one, bit 129 is also one. Looks like we confuse the vector enhancements facility 1 ("EXT") with the Vector packed decimal facility ("BCD"). Let's fix the facility checks. Detected while working on QEMU/tcg z14 support and only unlocking the vector enhancements facility 1, but not the vector packed decimal facility. Fixes: 2583b848cad0 ("s390: report new vector facilities") Cc: Vasily Gorbik Signed-off-by: David Hildenbrand Reviewed-by: Christian Borntraeger Reviewed-by: Cornelia Huck Reviewed-by: Janosch Frank Link: https://lore.kernel.org/r/20210503121244.25232-1-david@redhat.com Signed-off-by: Heiko Carstens

s390/setup: use memblock_free_late() to free old stack

2021-04-07T12:37:28Z

Use memblock_free_late() to free the old machine check stack to the buddy allocator instead of leaking it. Fixes: b61b1595124a ("s390: add stack for machine check handler") Cc: Vasily Gorbik Acked-by: Sven Schnelle Signed-off-by: Heiko Carstens

s390: add stack for machine check handler

2021-02-13T16:17:53Z

The previous code used the normal kernel stack for machine checks. This is problematic when a machine check interrupts a system call or interrupt handler right at the beginning where registers are set up. Assume system_call is interrupted at the first instruction and a machine check is triggered. The machine check handler is called, checks the PSW to see whether it is coming from user space, notices that it is already in kernel mode but %r15 still contains the user space stack. This would lead to a kernel crash. There are basically two ways of fixing that: Either using the 'critical cleanup' approach which compares the address in the PSW to see whether it is already at a point where the stack has been set up, or use an extra stack for the machine check handler. For simplicity, we will go with the second approach and allocate an extra stack. This adds some memory overhead for large systems, but usually large system have plenty of memory so this isn't really a concern. But it keeps the mchk stack setup simple and less error prone. Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S") Signed-off-by: Sven Schnelle Cc: # v5.8+ Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: use WRITE_ONCE when re-allocating async stack

2021-02-13T16:17:53Z

The code does: S390_lowcore.async_stack = new + STACK_INIT_OFFSET; But the compiler is free to first assign one value and add the other value later. If a IRQ would be coming in between these two operations, it would run with an invalid stack. Prevent this by using WRITE_ONCE. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390: convert to generic entry

2021-01-19T11:29:26Z

This patch converts s390 to use the generic entry infrastructure from kernel/entry/*. There are a few special things on s390: - PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't know about our PIF flags in exit_to_user_mode_loop(). - The old code had several ways to restart syscalls: a) PIF_SYSCALL_RESTART, which was only set during execve to force a restart after upgrading a process (usually qemu-kvm) to pgste page table extensions. b) PIF_SYSCALL, which is set by do_signal() to indicate that the current syscall should be restarted. This is changed so that do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use PIF_SYSCALL doesn't work with the generic code, and changing it to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART more unique. - On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by executing a svc instruction on the process stack which causes a fault. While handling that fault the fault code sets PIF_SYSCALL to hand over processing to the syscall code on exit to usermode. The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets a return value for a syscall. The s390x ptrace ABI uses r2 both for the syscall number and return value, so ptrace cannot set the syscall number + return value at the same time. The flag makes handling that a bit easier. do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET is set. CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY. CR1/7/13 will be checked both on kernel entry and exit to contain the correct asces. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390/delay: remove udelay_simple()

2020-12-16T13:55:49Z

udelay_simple() callers can make use of the now simplified udelay() implementation. No need to keep it. Signed-off-by: Heiko Carstens

s390/mm: add support to allocate gigantic hugepages using CMA

2020-12-10T20:11:01Z

Commit cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma") added support for allocating gigantic hugepages using CMA, by specifying the hugetlb_cma= kernel parameter, which will disable any boot-time allocation of gigantic hugepages. This patch enables that option also for s390. Signed-off-by: Gerald Schaefer Signed-off-by: Heiko Carstens

s390: unify identity mapping limits handling

2020-11-20T18:19:10Z

Currently we have to consider too many different values which in the end only affect identity mapping size. These are: 1. max_physmem_end - end of physical memory online or standby. Always <= end of the last online memory block (get_mem_detect_end()). 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the kernel is able to support. 3. "mem=" kernel command line option which limits physical memory usage. 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as crash kernel. 5. "hsa" size which is a memory limit when the kernel is executed during zfcp/nvme dump. Through out kernel startup and run we juggle all those values at once but that does not bring any amusement, only confusion and complexity. Unify all those values to a single one we should really care, that is our identity mapping size. Signed-off-by: Vasily Gorbik Reviewed-by: Alexander Gordeev Acked-by: Heiko Carstens Signed-off-by: Heiko Carstens