[PATCH v9 2/5] arm64: kdump: reserve crashkenel above 4G for crash dump kernel
From: Chen Zhou <hidden>
Date: 2020-06-28 08:30:47
Also in:
kexec, linux-arm-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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. Suggested by James, just introduced crashkernel=X,low to arm64. As memtioned above, if crashkernel=X,low is specified simultaneously, reserve spcified size low memory for crash kdump kernel devices firstly and then reserve memory above 4G, which is much simpler. Signed-off-by: Chen Zhou <redacted> Tested-by: John Donnelly <redacted> Tested-by: Prabhakar Kushwaha <redacted> --- 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 93b3844cf442..4dc51a2ac012 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 1e93cfc7c47a..ce7ced85f5fb 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c@@ -81,6 +81,7 @@ 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);
@@ -88,12 +89,38 @@ 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);
--
2.20.1