When a program check, interrupt or machine check is triggered, the PSW address is compared to a certain range of the sie64a() function to figure out whether SIE was interrupted and a cleanup of SIE is needed. This doesn't work with kprobes: If kprobes probes an instruction, it copies the instruction to the kprobes instruction page and overwrites the original instruction with an undefind instruction (Opcode 00). When this instruction is hit later, kprobes single-steps the instruction on the kprobes_instruction page. However, if this instruction is a relative branch instruction it will now point to a different location in memory due to being moved to the kprobes instruction page. If the new branch target points into sie64a() the kernel assumes it interrupted SIE when processing the breakpoint and will crash trying to access the SIE control block. Instead of comparing the address, introduce a new CIF_SIE flag which indicates whether SIE was interrupted. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Suggested-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The first invocation of kernel_fpu_begin() after switching from user to kernel context will save all vector registers, even if only parts of the vector registers are used within the kernel fpu context. Given that save and restore of all vector registers is quite expensive change the current approach in several ways: - Instead of saving and restoring all user registers limit this to those registers which are actually used within an kernel fpu context. - On context switch save all remaining user fpu registers, so they can be restored when the task is rescheduled. - Saving user registers within kernel_fpu_begin() is done without disabling and enabling interrupts - which also slightly reduces runtime. In worst case (e.g. interrupt context uses the same registers) this may lead to the situation that registers are saved several times, however the assumption is that this will not happen frequently, so that the new method is faster in nearly all cases. - save_user_fpu_regs() can still be called from all contexts and saves all (or all remaining) user registers to a tasks ufpu user fpu save area. Overall this reduces the time required to save and restore the user fpu context for nearly all cases. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
KVM was the only user which modified the regs pointer in struct fpu. Remove the pointer and convert the rest of the core fpu code to directly access the save area embedded within struct fpu. Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Make the kernel fpu context preemptible. Add another fpu structure to the thread_struct, and use it to save and restore the kernel fpu context if its task uses fpu registers when it is preempted. Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Rename save_fpu_regs(), load_fpu_regs(), and struct thread_struct's fpu member to save_user_fpu_regs(), load_user_fpu_regs(), and ufpu. This way the function and variable names reflect for which context they are supposed to be used. This large and trivial conversion is a prerequisite for making the kernel fpu usage preemptible. Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The FPU state, as represented by the CIF_FPU flag reflects the FPU state of a task, not the CPU it is running on. Therefore convert the flag to a regular TIF flag. This removes the magic in switch_to() where a save_fpu_regs() call for the currently (previous) running task sets the per-cpu CIF_FPU flag, which is required to restore FPU register contents of the next task, when it returns to user space. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Move, rename, and merge the fpu and vx header files. This way fpu header files have a consistent naming scheme (fpu*.h). Also get rid of the fpu subdirectory and move header files to asm directory, so that all fpu and vx header files can be found at the same location. Merge internal.h header file into other header files, since the internal helpers are used at many locations. so those helper functions are really not internal. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Pull s390 updates from Alexander Gordeev: - Add machine variable capacity information to /proc/sysinfo. - Limit the waste of page tables and always align vmalloc area size and base address on segment boundary. - Fix a memory leak when an attempt to register interruption sub class (ISC) for the adjunct-processor (AP) guest failed. - Reset response code AP_RESPONSE_INVALID_GISA to understandable by guest AP_RESPONSE_INVALID_ADDRESS in response to a failed interruption sub class (ISC) registration attempt. - Improve reaction to adjunct-processor (AP) AP_RESPONSE_OTHERWISE_CHANGED response code when enabling interrupts on behalf of a guest. - Fix incorrect sysfs 'status' attribute of adjunct-processor (AP) queue device bound to the vfio_ap device driver when the mediated device is attached to a guest, but the queue device is not passed through. - Rework struct ap_card to hold the whole adjunct-processor (AP) card hardware information. As result, all the ugly bit checks are replaced by simple evaluations of the required bit fields. - Improve handling of some weird scenarios between service element (SE) host and SE guest with adjunct-processor (AP) pass-through support. - Change local_ctl_set_bit() and local_ctl_clear_bit() so they return the previous value of the to be changed control register. This is useful if a bit is only changed temporarily and the previous content needs to be restored. - The kernel starts with machine checks disabled and is expected to enable it once trap_init() is called. However the implementation allows machine checks early. Consistently enable it in trap_init() only. - local_mcck_disable() and local_mcck_enable() assume that machine checks are always enabled. Instead implement and use local_mcck_save() and local_mcck_restore() to disable machine checks and restore the previous state. - Modification of floating point control (FPC) register of a traced process using ptrace interface may lead to corruption of the FPC register of the tracing process. Fix this. - kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control (FPC) register in vCPU, but may lead to corruption of the FPC register of the host process. Fix this. - Use READ_ONCE() to read a vCPU floating point register value from the memory mapped area. This avoids that, depending on code generation, a different value is tested for validity than the one that is used. - Get rid of test_fp_ctl(), since it is quite subtle to use it correctly. Instead copy a new floating point control register value into its save area and test the validity of the new value when loading it. - Remove superfluous save_fpu_regs() call. - Remove s390 support for ARCH_WANTS_DYNAMIC_TASK_STRUCT. All machines provide the vector facility since many years and the need to make the task structure size dependent on the vector facility does not exist. - Remove the "novx" kernel command line option, as the vector code runs without any problems since many years. - Add the vector facility to the z13 architecture level set (ALS). All hypervisors support the vector facility since many years. This allows compile time optimizations of the kernel. - Get rid of MACHINE_HAS_VX and replace it with cpu_has_vx(). As result, the compiled code will have less runtime checks and less code. - Convert pgste_get_lock() and pgste_set_unlock() ASM inlines to C. - Convert the struct subchannel spinlock from pointer to member. * tag 's390-6.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (24 commits) Revert "s390: update defconfigs" s390/cio: make sch->lock spinlock pointer a member s390: update defconfigs s390/mm: convert pgste locking functions to C s390/fpu: get rid of MACHINE_HAS_VX s390/als: add vector facility to z13 architecture level set s390/fpu: remove "novx" option s390/fpu: remove ARCH_WANTS_DYNAMIC_TASK_STRUCT support KVM: s390: remove superfluous save_fpu_regs() call s390/fpu: get rid of test_fp_ctl() KVM: s390: use READ_ONCE() to read fpc register value KVM: s390: fix setting of fpc register s390/ptrace: handle setting of fpc register correctly s390/nmi: implement and use local_mcck_save() / local_mcck_restore() s390/nmi: consistently enable machine checks in trap_init() s390/ctlreg: return old register contents when changing bits s390/ap: handle outband SE bind state change s390/ap: store TAPQ hwinfo in struct ap_card s390/vfio-ap: fix sysfs status attribute for AP queue devices s390/vfio-ap: improve reaction to response code 07 from PQAP(AQIC) command ...
s390 selects ARCH_WANTS_DYNAMIC_TASK_STRUCT in order to make the size of the task structure dependent on the availability of the vector facility. This doesn't make sense anymore because since many years all machines provide the vector facility. Therefore simplify the code a bit and remove s390 support for ARCH_WANTS_DYNAMIC_TASK_STRUCT. Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Instead of using local_mcck_disable() / local_mcck_enable() implement and use local_mcck_save() / local_mcck_restore() to disable machine checks, and restoring the previous state. The problem with using local_mcck_disable() / local_mcck_enable() is that there is an assumption that machine checks are always enabled. While this is currently the case the code still looks quite odd, readers need to double check if the code is correct. In order to increase readability save and then restore the old machine check mask bit, instead of assuming that it must have been enabled. Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>