[PATCH v2 3/3] arm64: kdump: Remove some redundant checks in map_mem()

From: Zhen Lei
Date: Tue Jun 21 2022 - 08:45:11 EST


arm64_memblock_init()
if (!IS_ENABLED(CONFIG_ZONE_DMA/DMA32))
reserve_crashkernel()
//initialize crashk_res when
//"crashkernel=" is correctly specified
paging_init()
map_mem()

As shown in the above pseudo code, the crashk_res.end can only be
initialized to non-zero when both "!IS_ENABLED(CONFIG_ZONE_DMA/DMA32)"
and crash_mem_map are true. So some checks in map_mem() can be adjusted
or optimized.

Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 25 +++++++++++--------------
1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 626ec32873c6c36..6028a5757e4eae2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -529,12 +529,12 @@ static void __init map_mem(pgd_t *pgdp)

#ifdef CONFIG_KEXEC_CORE
if (crash_mem_map) {
- if (IS_ENABLED(CONFIG_ZONE_DMA) ||
- IS_ENABLED(CONFIG_ZONE_DMA32))
- flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
- else if (crashk_res.end)
+ if (crashk_res.end)
memblock_mark_nomap(crashk_res.start,
resource_size(&crashk_res));
+ else if (IS_ENABLED(CONFIG_ZONE_DMA) ||
+ IS_ENABLED(CONFIG_ZONE_DMA32))
+ flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
}
#endif

@@ -571,16 +571,13 @@ static void __init map_mem(pgd_t *pgdp)
* through /sys/kernel/kexec_crash_size interface.
*/
#ifdef CONFIG_KEXEC_CORE
- if (crash_mem_map &&
- !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) {
- if (crashk_res.end) {
- __map_memblock(pgdp, crashk_res.start,
- crashk_res.end + 1,
- PAGE_KERNEL,
- NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
- memblock_clear_nomap(crashk_res.start,
- resource_size(&crashk_res));
- }
+ if (crashk_res.end) {
+ __map_memblock(pgdp, crashk_res.start,
+ crashk_res.end + 1,
+ PAGE_KERNEL,
+ NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
+ memblock_clear_nomap(crashk_res.start,
+ resource_size(&crashk_res));
}
#endif
}
--
2.25.1