BMC/Intel-BMC/linux.git/arch/s390/include/asm/processor.h, branch dev-4.6

s390/mm: fix asce_bits handling with dynamic pagetable levels

2016-04-21T07:50:09+00:00

There is a race with multi-threaded applications between context switch and pagetable upgrade. In switch_mm() a new user_asce is built from mm->pgd and mm->context.asce_bits, w/o holding any locks. A concurrent mmap with a pagetable upgrade on another thread in crst_table_upgrade() could already have set new asce_bits, but not yet the new mm->pgd. This would result in a corrupt user_asce in switch_mm(), and eventually in a kernel panic from a translation exception. Fix this by storing the complete asce instead of just the asce_bits, which can then be read atomically from switch_mm(), so that it either sees the old value or the new value, but no mixture. Both cases are OK. Having the old value would result in a page fault on access to the higher level memory, but the fault handler would see the new mm->pgd, if it was a valid access after the mmap on the other thread has completed. So as worst-case scenario we would have a page fault loop for the racing thread until the next time slice. Also remove dead code and simplify the upgrade/downgrade path, there are no upgrades from 2 levels, and only downgrades from 3 levels for compat tasks. There are also no concurrent upgrades, because the mmap_sem is held with down_write() in do_mmap, so the flush and table checks during upgrade can be removed. Reported-by: Michael Munday Reviewed-by: Martin Schwidefsky Signed-off-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky

s390/dumpstack: merge all four stack tracers

2016-02-23T07:56:20+00:00

We have four different stack tracers of which three had bugs. So it's time to merge them to a single stack tracer which allows to specify a call back function which will be called for each step. This patch changes behavior a bit: - the "nosched" and "in_sched_functions" check within save_stack_trace_tsk did work only for the last stack frame within a context. Now it considers the check for each stack frame like it should. - both the oprofile variant and the perf_events variant did save a return address twice if a zero back chain was detected, which indicates an interrupt frame. The new dump_trace function will call the oprofile and perf_events backends with the psw address that is contained within the corresponding pt_regs structure instead. - the original show_trace and save_context_stack functions did already use the psw address of the pt_regs structure if a zero back chain was detected. However now we ignore the psw address if it is a user space address. After all we trace the kernel stack and not the user space stack. This way we also get rid of the garbage user space address in case of warnings and / or panic call traces. So this should make life easier since now there is only one stack tracer left which we can break. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: add current_stack_pointer() helper function

2016-02-23T07:56:18+00:00

Implement current_stack_pointer() helper function and use it everywhere, instead of having several different inline assembly variants. Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky

s390: remove all usages of PSW_ADDR_AMODE

2016-01-19T11:14:02+00:00

This is a leftover from the 31 bit area. For CONFIG_64BIT the usual operation "y = x | PSW_ADDR_AMODE" is a nop. Therefore remove all usages of PSW_ADDR_AMODE and make the code a bit less confusing. Signed-off-by: Heiko Carstens Reviewed-by: David Hildenbrand

s390: rename struct _lowcore to struct lowcore

2016-01-11T11:27:15+00:00

Finally get rid of the leading underscore. I tried this already two or three years ago, however Michael Holzheu objected since this would break the crash utility (again). However Michael integrated support for the new name into the crash utility back then, so it doesn't break if the name will be changed now. So finally get rid of the ever confusing leading underscore. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/spinlock: do not yield to a CPU in udelay/mdelay

2015-11-27T08:24:18+00:00

It does not make sense to try to relinquish the time slice with diag 0x9c to a CPU in a state that does not allow to schedule the CPU. The scenario where this can happen is a CPU waiting in udelay/mdelay while holding a spin-lock. Add a CIF bit to tag a CPU in enabled wait and use it to detect that the yield of a CPU will not be successful and skip the diagnose call. Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: remove runtime instrumentation interrupts

2015-11-03T13:40:51+00:00

The external interrupts for runtime instrumentation buffer-full and runtime instrumentation halted are unused and have no current user. Remove the support and ignore the second parameter of the s390_runtime_instr system call from now on. Signed-off-by: Martin Schwidefsky

s390: don't store registers on disabled wait anymore

2015-10-27T08:33:48+00:00

The current disabled wait code stores register contents into their save areas, however it is (at least) missing the new vector registers. Given the fact that the whole exercise seems to be rather pointless simply don't save any registers anymore. In a "live" system it is always possible to inspect register contents, and in case of a dump the register contents will be stored by the dump mechanism. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: get rid of __set_psw_mask()

2015-10-27T08:33:44+00:00

With the removal of 31 bit code we can always assume that the epsw instruction is available. Therefore use the __extract_psw() function to disable and enable machine checks. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/fpu: split fpu-internal.h into fpu internals, api, and type headers

2015-10-16T07:41:12+00:00

Split the API and FPU type definitions into separate header files similar to "x86/fpu: Rename fpu-internal.h to fpu/internal.h" (78f7f1e54b). The new header files and their meaning are: asm/fpu/types.h: FPU related data types, needed for 'struct thread_struct' and 'struct task_struct'. asm/fpu/api.h: FPU related 'public' functions for other subsystems and device drivers. asm/fpu/internal.h: FPU internal functions mainly used to convert FPU register contents in signal handling. Signed-off-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky