diff options
| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-09-12 16:37:33 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-10-09 11:20:57 +0200 |
| commit | ce3dc447493ff4186b192b38d723ab5e8c1eb52f (patch) | |
| tree | f93f58afcd85087876a1ab9badcdaed76b5a37fe /arch/s390/kernel/head64.S | |
| parent | s390: add stack switch helper (diff) | |
| download | linux-dev-ce3dc447493ff4186b192b38d723ab5e8c1eb52f.tar.xz linux-dev-ce3dc447493ff4186b192b38d723ab5e8c1eb52f.zip | |
s390: add support for virtually mapped kernel stacks
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 <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/head64.S')
| -rw-r--r-- | arch/s390/kernel/head64.S | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S index b31dfb102700..57bba24b1c27 100644 --- a/arch/s390/kernel/head64.S +++ b/arch/s390/kernel/head64.S @@ -36,9 +36,7 @@ ENTRY(startup_continue) # larl %r14,init_task stg %r14,__LC_CURRENT - larl %r15,init_thread_union+THREAD_SIZE - stg %r15,__LC_KERNEL_STACK # set end of kernel stack - aghi %r15,-STACK_FRAME_OVERHEAD + larl %r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD # # Early setup functions that may not rely on an initialized bss section, # like moving the initrd. Returns with an initialized bss section. |