linux-kernel - [PATCH v18 04/17] x86/setup: Add helper parse_crashkernel_in

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Date:   Wed, 22 Dec 2021 21:08:07 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        <kexec@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        "Will Deacon" <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, Jonathan Corbet <corbet@....net>,
        <linux-doc@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>,
        "John Donnelly" <John.p.donnelly@...cle.com>
Subject: [PATCH v18 04/17] x86/setup: Add helper parse_crashkernel_in_order()

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@...wei.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@...set"
+ * @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