BMC/Intel-BMC/linux.git/arch/s390/kernel/process.c, branch dev-4.6

s390: remove all usages of PSW_ADDR_INSN

2016-01-19T11:14:03+00:00

Yet another leftover from the 31 bit era. The usual operation "y = x & PSW_ADDR_INSN" with the PSW_ADDR_INSN mask is a nop for CONFIG_64BIT. Therefore remove all usages and hope the code is a bit less confusing. Signed-off-by: Heiko Carstens Reviewed-by: David Hildenbrand

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: avoid cache aliasing under z/VM and KVM

2015-11-16T11:04:18+00:00

commit 1f6b83e5e4d3 ("s390: avoid z13 cache aliasing") checks for the machine type to optimize address space randomization and zero page allocation to avoid cache aliases. This check might fail under a hypervisor with migration support. z/VMs "Single System Image and Live Guest Relocation" facility will "fake" the machine type of the oldest system in the group. For example in a group of zEC12 and Z13 the guest appears to run on a zEC12 (architecture fencing within the relocation domain) Remove the machine type detection and always use cache aliasing rules that are known to work for all machines. These are the z13 aliasing rules. Suggested-by: Christian Borntraeger 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/fpu: add static FPU save area for init_task

2015-10-14T12:32:08+00:00

Previously, the init task did not have an allocated FPU save area and saving an FPU state was not possible. Now if the vector extension is always enabled, provide a static FPU save area to save FPU states of vector instructions that can be executed quite early. Signed-off-by: Hendrik Brueckner Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/fpu: always enable the vector facility if it is available

2015-10-14T12:32:08+00:00

If the kernel detects that the s390 hardware supports the vector facility, it is enabled by default at an early stage. To force it off, use the novx kernel parameter. Note that there is a small time window, where the vector facility is enabled before it is forced to be off. With enabling the vector facility by default, the FPU save and restore functions can be improved. They do not longer require to manage expensive control register updates to enable or disable the vector enablement control for particular processes. Signed-off-by: Hendrik Brueckner Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/kernel: remove save_fpu_regs() parameter and use __LC_CURRENT instead

2015-08-03T08:04:37+00:00

All calls to save_fpu_regs() specify the fpu structure of the current task pointer as parameter. The task pointer of the current task can also be retrieved from the CPU lowcore directly. Remove the parameter definition, load the __LC_CURRENT task pointer from the CPU lowcore, and rebase the FPU structure onto the task structure. Apply the same approach for the load_fpu_regs() function. Reviewed-by: Heiko Carstens Signed-off-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky

s390/kernel: lazy restore fpu registers

2015-07-22T07:58:01+00:00

Improve the save and restore behavior of FPU register contents to use the vector extension within the kernel. The kernel does not use floating-point or vector registers and, therefore, saving and restoring the FPU register contents are performed for handling signals or switching processes only. To prepare for using vector instructions and vector registers within the kernel, enhance the save behavior and implement a lazy restore at return to user space from a system call or interrupt. To implement the lazy restore, the save_fpu_regs() sets a CPU information flag, CIF_FPU, to indicate that the FPU registers must be restored. Saving and setting CIF_FPU is performed in an atomic fashion to be interrupt-safe. When the kernel wants to use the vector extension or wants to change the FPU register state for a task during signal handling, the save_fpu_regs() must be called first. The CIF_FPU flag is also set at process switch. At return to user space, the FPU state is restored. In particular, the FPU state includes the floating-point or vector register contents, as well as, vector-enablement and floating-point control. The FPU state restore and clearing CIF_FPU is also performed in an atomic fashion. For KVM, the restore of the FPU register state is performed when restoring the general-purpose guest registers before the SIE instructions is started. Because the path towards the SIE instruction is interruptible, the CIF_FPU flag must be checked again right before going into SIE. If set, the guest registers must be reloaded again by re-entering the outer SIE loop. This is the same behavior as if the SIE critical section is interrupted. Signed-off-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky

s390/kernel: dynamically allocate FP register save area

2015-07-22T07:58:00+00:00

Make the floating-point save area dynamically allocated and uses a flag to distinguish whether a task uses floating-point or vector registers. Signed-off-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky

s390/kernel: introduce fpu-internal.h with fpu helper functions

2015-07-22T07:58:00+00:00

Introduce a new structure to manage FP and VX registers. Refactor the save and restore of floating point and vector registers with a set of helper functions in fpu-internal.h. Signed-off-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky