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* s390/mm: define Real Memory Copy size and mask macrosAlexander Gordeev2023-08-161-0/+3
| | | | | | | | | | Make Real Memory Copy area size and mask explicit. This does not bring any functional change and only needed for clarity. Acked-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
* s390/mm: allocate Real Memory Copy Area in decompressorAlexander Gordeev2023-01-131-1/+1
| | | | | | | | | | Move Real Memory Copy Area allocation to the decompressor. As result, memcpy_real() and memcpy_real_iter() movers become usable since the very moment the kernel starts. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
* s390/mm: uninline copy_oldmem_kernel() functionAlexander Gordeev2022-09-141-0/+3
| | | | | | | | | | Uninline copy_oldmem_kernel() function and make it consistent with a very similar memcpy_real() implementation, by moving to code to crash_dump.c, where it actually belongs. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
* s390/mm: rework memcpy_real() to avoid DAT-off modeAlexander Gordeev2022-09-141-0/+14
Function memcpy_real() is an univeral data mover that does not require DAT mode to be able reading from a physical address. Its advantage is an ability to read from any address, even those for which no kernel virtual mapping exists. Although memcpy_real() is interrupt-safe, there are no handlers that make use of this function. The compiler instrumentation have to be disabled and separate no-DAT stack used to allow execution of the function once DAT mode is disabled. Rework memcpy_real() to overcome these shortcomings. As result, data copying (which is primarily reading out a crashed system memory by a user process) is executed on a regular stack with enabled interrupts. Also, use of memcpy_real_buf swap buffer becomes unnecessary and the swapping is eliminated. The above is achieved by using a fixed virtual address range that spans a single page and remaps that page repeatedly when memcpy_real() is called for a particular physical address. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>