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/include | |
| parent | ff340d2472ec7618443913928af9fb85a7009270 (diff) | |
| download | linux-ce3dc447493ff4186b192b38d723ab5e8c1eb52f.tar.bz2 | |
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/include')
| -rw-r--r-- | arch/s390/include/asm/lowcore.h | 4 | ||||
| -rw-r--r-- | arch/s390/include/asm/processor.h | 8 | ||||
| -rw-r--r-- | arch/s390/include/asm/thread_info.h | 3 |
3 files changed, 10 insertions, 5 deletions
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h index 406d940173ab..cc0947e08b6f 100644 --- a/arch/s390/include/asm/lowcore.h +++ b/arch/s390/include/asm/lowcore.h @@ -102,9 +102,9 @@ struct lowcore { __u64 current_task; /* 0x0338 */ __u64 kernel_stack; /* 0x0340 */ - /* Interrupt, panic and restart stack. */ + /* Interrupt, DAT-off and restartstack. */ __u64 async_stack; /* 0x0348 */ - __u64 panic_stack; /* 0x0350 */ + __u64 nodat_stack; /* 0x0350 */ __u64 restart_stack; /* 0x0358 */ /* Restart function and parameter. */ diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index 43494a014d5b..3c1e723a143a 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -163,6 +163,14 @@ struct thread_struct { typedef struct thread_struct thread_struct; /* + * General size of a stack + */ +#define STACK_ORDER 2 +#define STACK_SIZE (PAGE_SIZE << STACK_ORDER) +#define STACK_INIT_OFFSET \ + (STACK_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs)) + +/* * Stack layout of a C stack frame. */ #ifndef __PACK_STACK diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h index 3c883c368eb0..3fa2fea0ba23 100644 --- a/arch/s390/include/asm/thread_info.h +++ b/arch/s390/include/asm/thread_info.h @@ -14,10 +14,7 @@ * Size of kernel stack for each process */ #define THREAD_SIZE_ORDER 2 -#define ASYNC_ORDER 2 - #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER) -#define ASYNC_SIZE (PAGE_SIZE << ASYNC_ORDER) #ifndef __ASSEMBLY__ #include <asm/lowcore.h> |