diff options
| author | Alexander Gordeev <agordeev@linux.ibm.com> | 2024-08-09 08:47:16 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2024-08-21 16:14:45 +0200 |
| commit | 32db401965f165f7c44447d0508097f070c8f576 (patch) | |
| tree | 9bcb4095ae072156c43a3ec3a60eaebbf2ba416f /arch/s390/boot | |
| parent | a3ca27c405faad584af6e8e38cdafe5be73230a1 (diff) | |
s390/mm: Pin identity mapping base to zero
SIE instruction performs faster when the virtual address of
SIE block matches the physical one. Pin the identity mapping
base to zero for the benefit of SIE and other instructions
that have similar performance impact. Still, randomize the
base when DEBUG_VM kernel configuration option is enabled.
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/boot')
| -rw-r--r-- | arch/s390/boot/startup.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index ce232552bc1c..cff34744b5a9 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -341,7 +341,8 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size) BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS)); max_mappable = max(ident_map_size, MAX_DCSS_ADDR); max_mappable = min(max_mappable, vmemmap_start); - __identity_base = round_down(vmemmap_start - max_mappable, rte_size); + if (IS_ENABLED(CONFIG_RANDOMIZE_IDENTITY_BASE)) + __identity_base = round_down(vmemmap_start - max_mappable, rte_size); return asce_limit; } |