[PATCH v3 3/9] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Baoquan He <bhe@redhat.com>]

Now parse_crashkernel() is a real entry point for all kinds of
crahskernel parsing on any architecture.

And wrap the crahskernel=,high|low handling inside
CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  6 ++++++
 kernel/crash_core.c        | 36 +++++++++++++++++++++++++++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 6156355ef831..d8050a7eab01 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -79,6 +79,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
 void final_note(Elf_Word *buf);
 
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
+#endif
+#endif
+
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base,
 		unsigned long long *low_size, bool *high);
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index cca1d76e8255..dce2f5874fea 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -283,6 +283,9 @@ static int __init __parse_crashkernel(char *cmdline,
 /*
  * That function is the entry point for command line parsing and should be
  * called from the arch-specific code.
+ *
+ * If crashkernel=,high|low is supported on architecture, non-NULL values
+ * should be passed to parameters 'low_size' and 'high'.
  */
 int __init parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
@@ -296,10 +299,37 @@ int __init parse_crashkernel(char *cmdline,
 	/* crashkernel=X[@offset] */
 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
 				crash_base, NULL);
-	if (!high)
-		return ret;
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	/*
+	 * If non-NULL 'high' passed in and no normal crashkernel
+	 * setting detected, try parsing crashkernel=,high|low.
+	 */
+	if (high && ret == -ENOENT) {
+		ret = __parse_crashkernel(cmdline, 0, crash_size,
+				crash_base, suffix_tbl[SUFFIX_HIGH]);
+		if (ret || !*crash_size)
+			return -EINVAL;
 
-	return 0;
+		/*
+		 * crashkernel=Y,low can be specified or not, but invalid value
+		 * is not allowed.
+		 */
+		ret = __parse_crashkernel(cmdline, 0, low_size,
+				crash_base, suffix_tbl[SUFFIX_LOW]);
+		if (ret == -ENOENT) {
+			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
+			ret = 0;
+		} else if (ret) {
+			return ret;
+		}
+
+		*high = true;
+	}
+#endif
+	if (!*crash_size)
+		ret = -EINVAL;
+
+	return ret;
 }
 
 int __init parse_crashkernel_high(char *cmdline,
-- 
2.41.0