linux-kernel - [PATCH v2 1/2] x86/boot/KASLR: Adapt process_e820

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Message-Id: <1499155442-17467-2-git-send-email-bhe@redhat.com>
Date:   Tue,  4 Jul 2017 16:04:01 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, hpa@...or.com, tglx@...utronix.de,
        mingo@...nel.org, keescook@...omium.org, thgarnie@...gle.com,
        caoj.fnst@...fujitsu.com, izumi.taku@...fujitsu.com,
        Baoquan He <bhe@...hat.com>
Subject: [PATCH v2 1/2] x86/boot/KASLR: Adapt process_e820_entry for any type of memory entry

Now function process_e820_entry is only used to process e820 memory
entries. Adapt it for any type of memory entry, not just for e820.
Later we will use it to process efi mirror regions.

So rename the old process_e820_entry to process_mem_region, and
extract and wrap the e820 specific processing code into process_e820_entry.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 arch/x86/boot/compressed/kaslr.c | 60 ++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 91f27ab970ef..85c360eec4a6 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -479,35 +479,31 @@ static unsigned long slots_fetch_random(void)
 	return 0;
 }
 
-static void process_e820_entry(struct boot_e820_entry *entry,
+static void process_mem_region(struct mem_vector *entry,
 			       unsigned long minimum,
 			       unsigned long image_size)
 {
 	struct mem_vector region, overlap;
 	struct slot_area slot_area;
 	unsigned long start_orig, end;
-	struct boot_e820_entry cur_entry;
-
-	/* Skip non-RAM entries. */
-	if (entry->type != E820_TYPE_RAM)
-		return;
+	struct mem_vector cur_entry;
 
 	/* On 32-bit, ignore entries entirely above our maximum. */
-	if (IS_ENABLED(CONFIG_X86_32) && entry->addr >= KERNEL_IMAGE_SIZE)
+	if (IS_ENABLED(CONFIG_X86_32) && entry->start >= KERNEL_IMAGE_SIZE)
 		return;
 
 	/* Ignore entries entirely below our minimum. */
-	if (entry->addr + entry->size < minimum)
+	if (entry->start + entry->size < minimum)
 		return;
 
 	/* Ignore entries above memory limit */
-	end = min(entry->size + entry->addr, mem_limit);
-	if (entry->addr >= end)
+	end = min(entry->size + entry->start, mem_limit);
+	if (entry->start >= end)
 		return;
-	cur_entry.addr = entry->addr;
-	cur_entry.size = end - entry->addr;
+	cur_entry.start = entry->start;
+	cur_entry.size = end - entry->start;
 
-	region.start = cur_entry.addr;
+	region.start = cur_entry.start;
 	region.size = cur_entry.size;
 
 	/* Give up if slot area array is full. */
@@ -522,7 +518,7 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 		region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
 
 		/* Did we raise the address above this e820 region? */
-		if (region.start > cur_entry.addr + cur_entry.size)
+		if (region.start > cur_entry.start + cur_entry.size)
 			return;
 
 		/* Reduce size by any delta from the original address. */
@@ -562,12 +558,31 @@ static void process_e820_entry(struct boot_e820_entry *entry,
 	}
 }
 
-static unsigned long find_random_phys_addr(unsigned long minimum,
-					   unsigned long image_size)
+static void process_e820_entry(unsigned long minimum, unsigned long image_size)
 {
 	int i;
-	unsigned long addr;
+	struct mem_vector region;
+	struct boot_e820_entry *entry;
+
+	/* Verify potential e820 positions, appending to slots list. */
+	for (i = 0; i < boot_params->e820_entries; i++) {
+		entry = &boot_params->e820_table[i];
+		/* Skip non-RAM entries. */
+		if (entry->type != E820_TYPE_RAM)
+			continue;
+		region.start = entry->addr;
+		region.size = entry->size;
+		process_mem_region(&region, minimum, image_size);
+		if (slot_area_index == MAX_SLOT_AREA) {
+			debug_putstr("Aborted e820 scan (slot_areas full)!\n");
+			break;
+		}
+	}
+}
 
+static unsigned long find_random_phys_addr(unsigned long minimum,
+					   unsigned long image_size)
+{
 	/* Check if we had too many memmaps. */
 	if (memmap_too_large) {
 		debug_putstr("Aborted e820 scan (more than 4 memmap= args)!\n");
@@ -577,16 +592,7 @@ static unsigned long find_random_phys_addr(unsigned long minimum,
 	/* Make sure minimum is aligned. */
 	minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
 
-	/* Verify potential e820 positions, appending to slots list. */
-	for (i = 0; i < boot_params->e820_entries; i++) {
-		process_e820_entry(&boot_params->e820_table[i], minimum,
-				   image_size);
-		if (slot_area_index == MAX_SLOT_AREA) {
-			debug_putstr("Aborted e820 scan (slot_areas full)!\n");
-			break;
-		}
-	}
-
+	process_e820_entry(minimum, image_size);
 	return slots_fetch_random();
 }
 
-- 
2.5.5