BMC/Intel-BMC/linux.git/arch/s390/kernel/head64.S, branch dev-5.2

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: remove dead code

2019-02-07T10:56:57+00:00

Remove some dead code from head64.S, which was left over since commit da292bbe1f62 ("[S390] eliminate ipl_device from lowcore") removed ipl_device from lowcore. Reviewed-by: Heiko Carstens Signed-off-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky

s390: add support for virtually mapped kernel stacks

2018-10-09T09:20:57+00:00

With virtually mapped kernel stacks the kernel stack overflow detection is now fault based, every stack has a guard page in the vmalloc space. The panic_stack is renamed to nodat_stack and is used for all function that need to run without DAT, e.g. memcpy_real or do_start_kdump. The main effect is a reduction in the kernel image size as with vmap stacks the old style overflow checking that adds two instructions per function is not needed anymore. Result from bloat-o-meter: add/remove: 20/1 grow/shrink: 13/26854 up/down: 2198/-216240 (-214042) In regard to performance the micro-benchmark for fork has a hit of a few microseconds, allocating 4 pages in vmalloc space is more expensive compare to an order-2 page allocation. But with real workload I could not find a noticeable difference. Acked-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: clean up stacks setup

2018-09-20T11:20:29+00:00

Replace hard coded stack frame overhead values with STACK_FRAME_OVERHEAD definition. Avoid unnecessary arithmetic instructions. Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390: correct _stext offset

2018-07-02T09:24:59+00:00

Avoid unnecessary rewrite of psw and merge _stext into startup_continue. This allows to move _stext definition to vmlinux.lds.S, where _etext is also defined and set _stext to the actual beginning of .text at 0x100000. This fixes the problem with setting the last .text page as not-executable due to vmem_map_init relying on page alinged _stext and _etext. Fixes: bd79d6632958 ("s390/decompressor: trim the kernel image up to 1M") Reported-by: Nils Hoppmann Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390: get rid of the first mb of uncompressed image

2018-07-02T09:24:58+00:00

Instead of generating uncompressed kernel image starting at 0, filling first mb with zeros (with ".org 0x100000") and then trimming it off from vmlinux.bin before compression, simply generate a kernel image starting from 0x100000. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390: remove unused _ehead symbol

2018-07-02T09:24:58+00:00

Since startup code now reserves memory ranges [0, PARMAREA_END] and [_stext, ] _ehead symbol is not used and could be cleaned up. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/boot: make head.S and als.c be part of the decompressor only

2018-06-25T08:14:38+00:00

Since uncompressed kernel image does not have to be bootable anymore, move head.S, head_kdump.S and als.c to boot/ folder and compile them in just in the decompressor. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/decompressor: trim the kernel image up to 1M

2018-06-25T08:14:38+00:00

Move head64.S main kernel entry point "startup_continue" to 0x100000 and trim everything which is below 1M during build. So, that the decompressor would unpack the main kernel image, move it to 0x100000 and jump to startup_continue. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/early: move functions which may not access bss section to extra file

2018-05-09T08:55:01+00:00

Move functions which may not access bss section to extra file. This makes it easier to verify that all early functions which may not rely on an initialized bss section are not accessing it. Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky