[PATCH v4 3/3] riscv: kdump: Fix crash memory reserve exceed system memory bug

[Jinjie Ruan]

Similar with x86_32, on Riscv32 Qemu "virt" machine with 1GB memory, the
crash kernel "crashkernel=4G" is ok as below:
	crashkernel reserved: 0x00000000bf400000 - 0x00000001bf400000 (4096 MB)

The cause is that the crash_size is parsed and printed with "unsigned long
long" data type which is 8 bytes but allocated used with "phys_addr_t"
which is 4 bytes in memblock_phys_alloc_range().

Fix it by checking if the crash_size is greater than system RAM size and
warn out as parse_crashkernel_mem() do it if so.

After this patch, it fails and there is no above confusing reserve
success info.

Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 arch/riscv/mm/init.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index bfa2dea95354..5d66a4937fcd 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1381,6 +1381,11 @@ static void __init arch_reserve_crashkernel(void)
 	if (ret)
 		return;
 
+	if (crash_size >= memblock_phys_mem_size()) {
+		pr_warn("Crashkernel: invalid size.");
+		return;
+	}
+
 	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
 				    low_size, high);
 }
-- 
2.34.1