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Subject[PATCH v7 2/4] arm64: kdump: reserve crashkenel above 4G for crash dump kernel
Date
Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
arch/arm64/kernel/setup.c | 8 +++++++-
arch/arm64/mm/init.c | 31 +++++++++++++++++++++++++++++--
2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 56f6645..04d1c87 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -238,7 +238,13 @@ static void __init request_standard_resources(void)
kernel_data.end <= res->end)
request_resource(res, &kernel_data);
#ifdef CONFIG_KEXEC_CORE
- /* Userspace will find "Crash kernel" region in /proc/iomem. */
+ /*
+ * Userspace will find "Crash kernel" region in /proc/iomem.
+ * Note: the low region is renamed as Crash kernel (low).
+ */
+ 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 b65dffd..0d7afd5 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -80,6 +80,7 @@ static void __init reserve_crashkernel(void)
{
unsigned long long crash_base, crash_size;
int ret;
+ phys_addr_t crash_max = arm64_dma32_phys_limit;

ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
&crash_size, &crash_base);
@@ -87,12 +88,38 @@ static void __init reserve_crashkernel(void)
if (ret || !crash_size)
return;

+ ret = reserve_crashkernel_low();
+ if (!ret && crashk_low_res.end) {
+ /*
+ * If crashkernel=X,low specified, there may be two regions,
+ * we need to make some changes as follows:
+ *
+ * 1. rename the low region as "Crash kernel (low)"
+ * In order to distinct from the high region and make no effect
+ * to the use of existing kexec-tools, rename the low region as
+ * "Crash kernel (low)".
+ *
+ * 2. change the upper bound for crash memory
+ * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
+ *
+ * 3. mark the low region as "nomap"
+ * The low region is intended to be used for crash dump kernel
+ * devices, just mark the low region as "nomap" simply.
+ */
+ const char *rename = "Crash kernel (low)";
+
+ crashk_low_res.name = rename;
+ crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
+ memblock_mark_nomap(crashk_low_res.start,
+ resource_size(&crashk_low_res));
+ }
+
crash_size = PAGE_ALIGN(crash_size);

if (crash_base == 0) {
/* Current arm64 boot protocol requires 2MB alignment */
- crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
- crash_size, SZ_2M);
+ crash_base = memblock_find_in_range(0, crash_max, crash_size,
+ SZ_2M);
if (crash_base == 0) {
pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
crash_size);
--
2.7.4
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