linux-dev/arch/s390/kernel/asm-offsets.c, branch linus/master

s390/stack: add union to reflect kvm stack slot usages

2022-06-01T10:03:17Z

Add a union which describes how the empty stack slots are being used by kvm and perf. This should help to avoid another bug like the one which was fixed with commit c9bfb460c3e4 ("s390/perf: obtain sie_block from the right address"). Reviewed-by: Nico Boehr Tested-by: Nico Boehr Signed-off-by: Heiko Carstens

s390/stack: merge empty stack frame slots

2022-06-01T10:03:17Z

Merge empty1 and empty2 arrays within the stack frame to one single array. This is possible since with commit 42b01a553a56 ("s390: always use the packed stack layout") the alternative stack frame layout is gone. Reviewed-by: Nico Boehr Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390: generate register offsets into pt_regs automatically

2022-05-25T09:46:02Z

Use asm offsets method to generate register offsets into pt_regs, instead of open-coding at several places. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390: raise minimum supported machine generation to z10

2022-03-10T14:58:17Z

Machine generations up to z9 (released in May 2006) have been officially out of service for several years now (z9 end of service - January 31, 2019). No distributions build kernels supporting those old machine generations anymore, except Debian, which seems to pick the oldest supported generation. The team supporting Debian on s390 has been notified about the change. Raising minimum supported machine generation to z10 helps to reduce maintenance cost and effectively remove code, which is not getting enough testing coverage due to lack of older hardware and distributions support. Besides that this unblocks some optimization opportunities and allows to use wider instruction set in asm files for future features implementation. Due to this change spectre mitigation and usercopy implementations could be drastically simplified and many newer instructions could be converted from ".insn" encoding to instruction names. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/asm-offsets: remove unused defines

2022-03-07T23:33:01Z

Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/dump: fix old lowcore virtual vs physical address confusion

2022-02-09T21:56:03Z

Virtual addresses of vmcore_info and os_info members are wrongly passed to copy_oldmem_kernel(), while the function expects physical address of the source. Instead, __pa() macro should have been applied. Yet, use of __pa() macro could be somehow confusing, since copy_oldmem_kernel() may treat the source as an offset, not as a direct physical address (that depens from the oldmem availability and location). Fix the virtual vs physical address confusion and make the way the old lowcore is read consistent across all sources. Reviewed-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Vasily Gorbik

s390: support command lines longer than 896 bytes

2021-10-26T13:21:31Z

Currently s390 supports a fixed maximum command line length of 896 bytes. This isn't enough as some installers are trying to pass all configuration data via kernel command line, and even with zfcp alone it is easy to generate really long command lines. Therefore extend the command line to 4 kbytes. In the parm area where the command line is stored there is no indication of the maximum allowed length, so a new field which contains the maximum length is added. The parm area has always been initialized to zero, so with old kernels this field would read zero. This is important because tools like zipl could read this field. If it contains a number larger than zero zipl knows the maximum length that can be stored in the parm area, otherwise it must assume that it is booting a legacy kernel and only 896 bytes are available. The removing of trailing whitespace in head.S is also removed because code to do this is already present in setup_boot_command_line(). Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: add support for BEAR enhancement facility

2021-10-26T13:21:29Z

The Breaking-Event-Address-Register (BEAR) stores the address of the last breaking event instruction. Breaking events are usually instructions that change the program flow - for example branches, and instructions that modify the address in the PSW like lpswe. This is useful for debugging wild branches, because one could easily figure out where the wild branch was originating from. What is problematic is that lpswe is considered a breaking event, and therefore overwrites BEAR on kernel exit. The BEAR enhancement facility adds new instructions that allow to save/restore BEAR and also an lpswey instruction that doesn't cause a breaking event. So we can save BEAR on kernel entry and restore it on exit to user space. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: rename last_break to pgm_last_break

2021-10-26T13:21:28Z

With the upcoming BEAR enhancements last_break isn't really unique, so rename it to pgm_last_break. This way it should be more obvious that this is the last_break value that is written by the hardware when a program check occurs. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: make STACK_FRAME_OVERHEAD available via asm-offsets.h

2021-10-19T13:39:53Z

Make STACK_FRAME_OVERHEAD available via asm-offsets.h. This allows to add s390 specific asm code to e.g. ftrace samples, without requiring to add random header files, which might cause all sort of problems on other architectures. asm-offsets.h can be assumed to be non-problematic. Acked-by: Ilya Leoshkevich Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Acked-by: Steven Rostedt (VMware) Link: https://lore.kernel.org/r/20211012133802.2460757-3-hca@linux.ibm.com Signed-off-by: Vasily Gorbik