[PATCH v4 1/3] x86/kexec: Fix crash memory reserve exceed system memory bug

[Jinjie Ruan]

On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=4G" is ok
as below:
	crashkernel reserved: 0x0000000020000000 - 0x0000000120000000 (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 as Baoquan suggested.

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

Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
Suggested-by: Baoquan He <bhe at redhat.com>
---
v4:
- Update the warn info to align with parse_crashkernel_mem().
- Update the commit message.
v3:
- Handle the check in arch_reserve_crashkernel() Baoquan suggested.
- Split x86_32 and arm32.
- Add Suggested-by.
- Drop the wrong fix tag.
v2:
- Also fix for x86_32.
- Update the fix method.
- Peel off the other two patches.
- Update the commit message.
---
 arch/x86/kernel/setup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 5d34cad9b7b1..77b937dbd98c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -482,6 +482,11 @@ static void __init arch_reserve_crashkernel(void)
 	if (ret)
 		return;
 
+	if (crash_size >= memblock_phys_mem_size()) {
+		pr_warn("Crashkernel: invalid size.");
+		return;
+	}
+
 	if (xen_pv_domain()) {
 		pr_info("Ignoring crashkernel for a Xen PV domain\n");
 		return;
-- 
2.34.1