[PATCH v18 04/17] x86/setup: Add helper parse_crashkernel_in_order()

[Zhen Lei]

Currently, there are two possible combinations of configurations.
(1) crashkernel=X[@offset]
(2) crashkernel=X,high, with or without crashkernel=X,low

(1) has the highest priority, if it is configured correctly, (2) will be
ignored. Similarly, in combination (2), crashkernel=X,low is valid only
when crashkernel=X,high is valid.

Putting the operations of parsing all "crashkernel=" configurations in one
function helps to sort out the strong dependency.

So add helper parse_crashkernel_in_order(). The "__maybe_unused" will be
removed in the next patch.

Signed-off-by: Zhen Lei <thunder.leizhen at huawei.com>
---
 arch/x86/kernel/setup.c | 51 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d9080bfa131a654..f997074d36f2484 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -439,6 +439,57 @@ static int __init reserve_crashkernel_low(void)
 }
 #endif
 
+#define CRASHKERNEL_MEM_NONE		0x0	/* crashkernel= is not exist or invalid */
+#define CRASHKERNEL_MEM_CLASSIC		0x1	/* crashkernel=X[@offset] is valid */
+#define CRASHKERNEL_MEM_HIGH		0x2	/* crashkernel=X,high is valid */
+#define CRASHKERNEL_MEM_LOW		0x4	/* crashkernel=X,low is valid */
+
+/**
+ * parse_crashkernel_in_order - Parse all "crashkernel=" configurations in
+ *				priority order until a valid combination is found.
+ * @cmdline:	The bootup command line.
+ * @system_ram: Total system memory size.
+ * @crash_size: Save the memory size specified by "crashkernel=X[@offset]" or
+ *		"crashkernel=X,high".
+ * @crash_base: Save the base address specified by "crashkernel=X at offset"
+ * @low_size:	Save the memory size specified by "crashkernel=X,low"
+ *
+ * Returns the status flag of the parsing result of "crashkernel=", such as
+ * CRASHKERNEL_MEM_NONE, CRASHKERNEL_MEM_HIGH.
+ */
+__maybe_unused
+static int __init parse_crashkernel_in_order(char *cmdline,
+					     unsigned long long system_ram,
+					     unsigned long long *crash_size,
+					     unsigned long long *crash_base,
+					     unsigned long long *low_size)
+{
+	int ret, flag = CRASHKERNEL_MEM_NONE;
+
+	BUG_ON(!crash_size || !crash_base || !low_size);
+
+	/* crashkernel=X[@offset] */
+	ret = parse_crashkernel(cmdline, system_ram, crash_size, crash_base);
+	if (!ret && crash_size > 0)
+		return CRASHKERNEL_MEM_CLASSIC;
+
+#ifdef CONFIG_X86_64
+	/* crashkernel=X,high */
+	ret = parse_crashkernel_high(cmdline, system_ram, crash_size, crash_base);
+	if (ret || crash_size <= 0)
+		return CRASHKERNEL_MEM_NONE;
+
+	flag = CRASHKERNEL_MEM_HIGH;
+
+	/* crashkernel=Y,low */
+	ret = parse_crashkernel_low(cmdline, system_ram, low_size, crash_base);
+	if (!ret)
+		flag |= CRASHKERNEL_MEM_LOW;
+#endif
+
+	return flag;
+}
+
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_size, crash_base, total_mem;
-- 
2.25.1