lwn.git/arch/s390/kernel/early.c, branch v5.7-rc6

s390: remove last diag 0x44 caller

2019-12-11T18:53:24+00:00

diag 0x44 is a voluntary undirected yield of a virtual CPU. This has caused a lot of performance issues in the past. There is only one caller left, and that one is only executed if diag 0x9c (directed yield) is not present. Given that all hypervisors implement diag 0x9c anyway, remove the last diag 0x44 to avoid that more callers will be added. Worst case that could happen now, if diag 0x9c is not present, is that a virtual CPU would loop a bit instead of giving its time slice up. diag 0x44 statistics in debugfs are kept and will always be zero, so that user space can tell that there are no calls. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/early: move access registers setup in C code

2019-11-20T11:58:13+00:00

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

s390/early: move control registers setup in C code

2019-11-20T11:58:12+00:00

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

s390: avoid double handling of "noexec" option

2019-10-31T16:20:52+00:00

"noexec" option is already parsed during startup and its value is exposed via noexec_disabled variable. Simply reuse that value during machine facilities detection. Suggested-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: clean .bss before running uncompressed kernel

2019-08-21T10:58:52+00:00

Clean uncompressed kernel .bss section in the startup code before the uncompressed kernel is executed. At this point of time initrd and certificates have been already rescued. Uncompressed kernel .bss size is known from vmlinux_info. It is also taken into consideration during uncompressed kernel positioning by kaslr (so it is safe to clean it). With that uncompressed kernel is starting with .bss section zeroed and no .bss section usage restrictions apply. Which makes chkbss checks for uncompressed kernel objects obsolete and they can be removed. early_nobss.c is also not needed anymore. Parts of it which are still relevant are moved to early.c. Kasan initialization code is now called directly from head64 (early.c is instrumented and should not be executed before kasan shadow memory is set up). Reviewed-by: Philipp Rudo Signed-off-by: Vasily Gorbik

s390: fix setting of mio addressing control

2019-07-11T18:40:02+00:00

Move enablement of mio addressing control from detect_machine_facilities to pci_base_init. detect_machine_facilities runs so early that the static branches have not been toggled yet, thus mio addressing control was always off. In pci_base_init we have to use the SMP aware ctl_set_bit though. Fixes: 833b441ec0f6 ("s390: enable processes for mio instructions") Signed-off-by: Sebastian Ott Signed-off-by: Vasily Gorbik

s390: simplify disabled_wait

2019-05-02T11:54:11+00:00

The disabled_wait() function uses its argument as the PSW address when it stops the CPU with a wait PSW that is disabled for interrupts. The different callers sometimes use a specific number like 0xdeadbeef to indicate a specific failure, the early boot code uses 0 and some other calls sites use __builtin_return_address(0). At the time a dump is created the current PSW and the registers of a CPU are written to lowcore to make them avaiable to the dump analysis tool. For a CPU stopped with disabled_wait the PSW and the registers do not really make sense together, the PSW address does not point to the function the registers belong to. Simplify disabled_wait() by using _THIS_IP_ for the PSW address and drop the argument to the function. Signed-off-by: Martin Schwidefsky

s390/kernel: introduce .dma sections

2019-04-29T08:47:10+00:00

With a relocatable kernel that could reside at any place in memory, code and data that has to stay below 2 GB needs special handling. This patch introduces .dma sections for such text, data and ex_table. The sections will be part of the decompressor kernel, so they will not be relocated and stay below 2 GB. Their location is passed over to the decompressed / relocated kernel via the .boot.preserved.data section. The duald and aste for control register setup also need to stay below 2 GB, so move the setup code from arch/s390/kernel/head64.S to arch/s390/boot/head.S. The duct and linkage_stack could reside above 2 GB, but their content has to be preserved for the decompresed kernel, so they are also moved into the .dma section. The start and end address of the .dma sections is added to vmcoreinfo, for crash support, to help debugging in case the kernel crashed there. Signed-off-by: Gerald Schaefer Reviewed-by: Philipp Rudo Signed-off-by: Martin Schwidefsky

s390: enable processes for mio instructions

2019-04-29T08:47:01+00:00

Allow for userspace to use PCI MIO instructions. Signed-off-by: Sebastian Ott Signed-off-by: Martin Schwidefsky

s390: move ipl block to .boot.preserved.data section

2019-04-10T15:47:11+00:00

.boot.preserved.data is a better fit for ipl block than .boot.data which is discarded after init. Reusing .boot.preserved.data allows to simplify code a little bit and avoid copying data from .boot.data to persistent variables. Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky