When crashkernel is reserved above 4G in memory, kernel should
reserve some amount of low memory for swiotlb and some DMA buffers.
Meanwhile, support crashkernel=X,[high,low] in arm64. When use
crashkernel=X parameter, try low memory first and fall back to high
memory unless "crashkernel=X,high" is specified.
Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
---
arch/arm64/include/asm/kexec.h | 3 +++
arch/arm64/kernel/setup.c | 3 +++
arch/arm64/mm/init.c | 34 ++++++++++++++++++++++++++++------
3 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 67e4cb7..32949bf 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -28,6 +28,9 @@
#define KEXEC_ARCH KEXEC_ARCH_AARCH64
+/* 2M alignment for crash kernel regions */
+#define CRASH_ALIGN SZ_2M
+
#ifndef __ASSEMBLY__
/**
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 413d566..82cd9a0 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -243,6 +243,9 @@ static void __init request_standard_resources(void)
request_resource(res, &kernel_data);
#ifdef CONFIG_KEXEC_CORE
/* Userspace will find "Crash kernel" region in /proc/iomem. */
+ if (crashk_low_res.end && crashk_low_res.start >= res->start &&
+ crashk_low_res.end <= res->end)
+ request_resource(res, &crashk_low_res);
if (crashk_res.end && crashk_res.start >= res->start &&
crashk_res.end <= res->end)
request_resource(res, &crashk_res);
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index d2adffb..3fcd739 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -74,20 +74,37 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
static void __init reserve_crashkernel(void)
{
unsigned long long crash_base, crash_size;
+ bool high = false;
int ret;
ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
&crash_size, &crash_base);
/* no crashkernel= or invalid value specified */
- if (ret || !crash_size)
- return;
+ if (ret || !crash_size) {
+ /* crashkernel=X,high */
+ ret = parse_crashkernel_high(boot_command_line,
+ memblock_phys_mem_size(),
+ &crash_size, &crash_base);
+ if (ret || !crash_size)
+ return;
+ high = true;
+ }
crash_size = PAGE_ALIGN(crash_size);
if (crash_base == 0) {
- /* Current arm64 boot protocol requires 2MB alignment */
- crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
- crash_size, SZ_2M);
+ /*
+ * Try low memory first and fall back to high memory
+ * unless "crashkernel=size[KMG],high" is specified.
+ */
+ if (!high)
+ crash_base = memblock_find_in_range(0,
+ ARCH_LOW_ADDRESS_LIMIT,
+ crash_size, CRASH_ALIGN);
+ if (!crash_base)
+ crash_base = memblock_find_in_range(0,
+ memblock_end_of_DRAM(),
+ crash_size, CRASH_ALIGN);
if (crash_base == 0) {
pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
crash_size);
@@ -105,13 +122,18 @@ static void __init reserve_crashkernel(void)
return;
}
- if (!IS_ALIGNED(crash_base, SZ_2M)) {
+ if (!IS_ALIGNED(crash_base, CRASH_ALIGN)) {
pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
return;
}
}
memblock_reserve(crash_base, crash_size);
+ if (crash_base >= SZ_4G && reserve_crashkernel_low()) {
+ memblock_free(crash_base, crash_size);
+ return;
+ }
+
pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
crash_base, crash_base + crash_size, crash_size >> 20);
--
2.7.4
