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From:   Martin Fernandez <martin.fernandez@eclypsium.com>
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        Martin Fernandez <martin.fernandez@eclypsium.com>
Subject: [PATCH v9 4/9] x86/e820: Refactor __e820__range_update
Date:   Mon,  4 Jul 2022 10:58:28 -0300
Message-Id: <20220704135833.1496303-5-martin.fernandez@eclypsium.com>
In-Reply-To: <20220704135833.1496303-1-martin.fernandez@eclypsium.com>
References: <20220704135833.1496303-1-martin.fernandez@eclypsium.com>
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Precedence: bulk

Refactor __e820__range_update with the introduction of
e820_type_updater_data, indented to be used as the void pointer in the
e820_entry_updater callbacks, and the implementation of the callbacks
to perform the update of the type in a range of a e820_table.

Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com>
---
 arch/x86/kernel/e820.c | 119 +++++++++++++++++++++--------------------
 1 file changed, 62 insertions(+), 57 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index e0fa3ab755a5..36a22c0a2199 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -586,80 +586,85 @@ __e820__handle_range_update(struct e820_table *table,
 	return updated_size;
 }
 
-static u64 __init
-__e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type)
-{
-	u64 end;
-	unsigned int i;
-	u64 real_updated_size = 0;
-
-	BUG_ON(old_type == new_type);
-
-	if (size > (ULLONG_MAX - start))
-		size = ULLONG_MAX - start;
+/*
+ * Type helper for the e820_entry_updater callbacks.
+ */
+struct e820_type_updater_data {
+	enum e820_type old_type;
+	enum e820_type new_type;
+};
 
-	end = start + size;
-	printk(KERN_DEBUG "e820: update [mem %#010Lx-%#010Lx] ", start, end - 1);
-	e820_print_type(old_type);
-	pr_cont(" ==> ");
-	e820_print_type(new_type);
-	pr_cont("\n");
+static bool __init type_updater__should_update(const struct e820_entry *entry,
+					       const void *data)
+{
+	const struct e820_type_updater_data *type_updater_data = data;
 
-	for (i = 0; i < table->nr_entries; i++) {
-		struct e820_entry *entry = &table->entries[i];
-		u64 final_start, final_end;
-		u64 entry_end;
+	return entry->type == type_updater_data->old_type;
+}
 
-		if (entry->type != old_type)
-			continue;
+static void __init type_updater__update(struct e820_entry *entry,
+					const void *data)
+{
+	const struct e820_type_updater_data *type_updater_data = data;
 
-		entry_end = entry->addr + entry->size;
+	entry->type = type_updater_data->new_type;
+}
 
-		/* Completely covered by new range? */
-		if (entry->addr >= start && entry_end <= end) {
-			entry->type = new_type;
-			real_updated_size += entry->size;
-			continue;
-		}
+static void __init type_updater__new(struct e820_table *table, u64 new_start,
+				     u64 new_size,
+				     const struct e820_entry *original,
+				     const void *data)
+{
+	const struct e820_type_updater_data *type_updater_data = data;
 
-		/* New range is completely covered? */
-		if (entry->addr < start && entry_end > end) {
-			__e820__range_add(table, start, size, new_type);
-			__e820__range_add(table, end, entry_end - end, entry->type);
-			entry->size = start - entry->addr;
-			real_updated_size += size;
-			continue;
-		}
+	__e820__range_add(table, new_start, new_size,
+			  type_updater_data->new_type);
+}
 
-		/* Partially covered: */
-		final_start = max(start, entry->addr);
-		final_end = min(end, entry_end);
-		if (final_start >= final_end)
-			continue;
+static u64 __init __e820__range_update(struct e820_table *table, u64 start,
+				       u64 size, enum e820_type old_type,
+				       enum e820_type new_type)
+{
+	struct e820_entry_updater updater = {
+		.should_update = type_updater__should_update,
+		.update = type_updater__update,
+		.new = type_updater__new
+	};
 
-		__e820__range_add(table, final_start, final_end - final_start, new_type);
+	struct e820_type_updater_data data = {
+		.old_type = old_type,
+		.new_type = new_type
+	};
 
-		real_updated_size += final_end - final_start;
+	BUG_ON(old_type == new_type);
 
-		/*
-		 * Left range could be head or tail, so need to update
-		 * its size first:
-		 */
-		entry->size -= final_end - final_start;
-		if (entry->addr < final_start)
-			continue;
+	printk(KERN_DEBUG "e820: update [mem %#018Lx-%#018Lx] ", start,
+	       start + size - 1);
+	e820_print_type(old_type);
+	pr_cont(" ==> ");
+	e820_print_type(new_type);
+	pr_cont("\n");
 
-		entry->addr = final_end;
-	}
-	return real_updated_size;
+	return __e820__handle_range_update(table, start, size, &updater, &data);
 }
 
-u64 __init e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type)
+/*
+ * Update type of addresses in [@start, @start + @size) from @old_type
+ * to @new_type in e820_table.
+ */
+u64 __init e820__range_update(u64 start, u64 size, enum e820_type old_type,
+			      enum e820_type new_type)
 {
 	return __e820__range_update(e820_table, start, size, old_type, new_type);
 }
 
-static u64 __init e820__range_update_kexec(u64 start, u64 size, enum e820_type old_type, enum e820_type  new_type)
+/*
+ * Update type of addresses in [@start, @start + @size) from @old_type
+ * to @new_type in e820_table_kexec.
+ */
+static u64 __init e820__range_update_kexec(u64 start, u64 size,
+					   enum e820_type old_type,
+					   enum e820_type new_type)
 {
 	return __e820__range_update(e820_table_kexec, start, size, old_type, new_type);
 }
-- 
2.30.2