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s390: Optimize __pa/__va when RANDOMIZE_IDENTITY_BASE is off

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Use a zero identity base when CONFIG_RANDOMIZE_IDENTITY_BASE is off,
slightly optimizing __pa/__va calculations.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2024-12-11 12:29:40 +01:00 committed by Alexander Gordeev
parent 9af310ef10
commit d7bebcb4a8
3 changed files with 8 additions and 3 deletions
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5
arch/s390/boot/startup.c
View File

@ -372,8 +372,9 @@ 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);
if (IS_ENABLED(CONFIG_RANDOMIZE_IDENTITY_BASE))
__identity_base = round_down(vmemmap_start - max_mappable, rte_size);
#ifdef CONFIG_RANDOMIZE_IDENTITY_BASE
__identity_base = round_down(vmemmap_start - max_mappable, rte_size);
#endif
boot_debug("identity map: 0x%016lx-0x%016lx\n", __identity_base,
__identity_base + ident_map_size);

4
arch/s390/include/asm/page.h
View File

@ -184,7 +184,11 @@ extern struct vm_layout vm_layout;
#define __kaslr_offset vm_layout.kaslr_offset
#define __kaslr_offset_phys vm_layout.kaslr_offset_phys
#ifdef CONFIG_RANDOMIZE_IDENTITY_BASE
#define __identity_base vm_layout.identity_base
#else
#define __identity_base 0UL
#endif
#define ident_map_size vm_layout.identity_size
static inline unsigned long kaslr_offset(void)

2
arch/s390/kernel/setup.c
View File

@ -740,7 +740,7 @@ static void __init reserve_lowcore(void)
void *lowcore_end = lowcore_start + sizeof(struct lowcore);
void *start, *end;
if ((void *)__identity_base < lowcore_end) {
if (absolute_pointer(__identity_base) < lowcore_end) {
start = max(lowcore_start, (void *)__identity_base);
end = min(lowcore_end, (void *)(__identity_base + ident_map_size));
memblock_reserve(__pa(start), __pa(end));