kernel.git/arch/s390/kernel/idle.c, branch linux-5.18.y

s390/time,idle: get rid of unsigned long long

2021-03-08T09:46:27Z

Get rid of unsigned long long, and use unsigned long instead everywhere. The usage of unsigned long long is a leftover from 31 bit kernel support. Signed-off-by: Heiko Carstens

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/idle: allow arch_cpu_idle() to be kprobed

2020-12-16T13:55:50Z

Remove NOKPROBE_SYMBOL() for arch_cpu_idle(). This might have made sense when enabled_wait() (aka arch_cpu_idle()) was called from udelay. But now there shouldn't be a reason why s390 should be the only architecture which doesn't allow arch_cpu_idle() to be probed. Signed-off-by: Heiko Carstens

s390/idle: remove raw_local_irq_save()/restore() from arch_cpu_idle()

2020-12-16T13:55:49Z

arch_cpu_idle() gets called with interrupts disabled, and psw_idle() returns with interrupts disabled. No reason to use raw_local_irq_save() / restore(). Signed-off-by: Heiko Carstens

s390/idle: merge enabled_wait() and arch_cpu_idle()

2020-12-16T13:55:49Z

The only caller of enabled_wait() besides arch_cpu_idle() was udelay(). Since that call doesn't exist anymore, merge enabled_wait() and arch_cpu_idle(). Signed-off-by: Heiko Carstens

sched/idle: Fix arch_cpu_idle() vs tracing

2020-11-24T15:47:35Z

We call arch_cpu_idle() with RCU disabled, but then use local_irq_{en,dis}able(), which invokes tracing, which relies on RCU. Switch all arch_cpu_idle() implementations to use raw_local_irq_{en,dis}able() and carefully manage the lockdep,rcu,tracing state like we do in entry. (XXX: we really should change arch_cpu_idle() to not return with interrupts enabled) Reported-by: Sven Schnelle Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mark Rutland Tested-by: Mark Rutland Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org

s390/idle: fix suspicious RCU usage

2020-09-14T08:08:07Z

After commit eb1f00237aca ("lockdep,trace: Expose tracepoints") the lock tracepoints are visible to lockdep and RCU-lockdep is finding a bunch more RCU violations that were previously hidden. Switch the idle->seqcount over to using raw_write_*() to avoid the lockdep annotation and thus the lock tracepoints. Reported-by: Guenter Roeck Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

cpuidle: Move trace_cpu_idle() into generic code

2020-08-26T10:41:54Z

Remove trace_cpu_idle() from the arch_cpu_idle() implementations and put it in the generic code, right before disabling RCU. Gets rid of more trace_*_rcuidle() users. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Thomas Gleixner Acked-by: Rafael J. Wysocki Tested-by: Marco Elver Link: https://lkml.kernel.org/r/20200821085348.428433395@infradead.org

s390: add trace events for idle enter/exit

2020-07-10T13:08:27Z

Helpful for debugging. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens

s390: remove critical section cleanup from entry.S

2020-05-28T10:21:54Z

The current code is rather complex and caused a lot of subtle and hard to debug bugs in the past. Simplify the code by calling the system_call handler with interrupts disabled, save machine state, and re-enable them later. This requires significant changes to the machine check handling code as well. When the machine check interrupt arrived while being in kernel mode the new code will signal pending machine checks with a SIGP external call. When userspace was interrupted, the handler will switch to the kernel stack and directly execute s390_handle_mcck(). Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik