linux-kernel - [Patch v3 3/7] x86, kaslr: Add two functions which will be used later

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Date:	Sun,  8 Mar 2015 13:38:51 +0800
From:	Baoquan He <bhe@...hat.com>
To:	keescook@...omium.org, yinghai@...nel.org, hpa@...or.com,
	mingo@...hat.com, bp@...e.de, matt.fleming@...el.com,
	vgoyal@...hat.com, tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org, Baoquan He <bhe@...hat.com>
Subject: [Patch v3 3/7] x86, kaslr: Add two functions which will be used later

Add two functions mem_min_overlap() and store_slot_info() which will be
used later.

Given a memory region mem_min_overlap will iterate all avoid region to
find the first one which overlap with it.

store_slot_info() calculates the slot info of passed in region and
store it into slot_areas[].

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 arch/x86/boot/compressed/aslr.c | 51 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index c452a60..afb1641 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -230,6 +230,40 @@ static bool mem_avoid_overlap(struct mem_vector *img)
 	return false;
 }
 
+static unsigned long
+mem_min_overlap(struct mem_vector *img, struct mem_vector *out)
+{
+	int i;
+	struct setup_data *ptr;
+	unsigned long min = img->start + img->size;
+
+	for (i = 0; i < MEM_AVOID_MAX; i++) {
+		if (mem_overlaps(img, &mem_avoid[i]) &&
+			(mem_avoid[i].start < min)) {
+			*out = mem_avoid[i];
+			min = mem_avoid[i].start;
+		}
+	}
+
+	/* Check all entries in the setup_data linked list. */
+	ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
+	while (ptr) {
+		struct mem_vector avoid;
+
+		avoid.start = (unsigned long)ptr;
+		avoid.size = sizeof(*ptr) + ptr->len;
+
+		if (mem_overlaps(img, &avoid) && (avoid.start < min)) {
+			*out = avoid;
+			min = avoid.start;
+		}
+
+		ptr = (struct setup_data *)(unsigned long)ptr->next;
+	}
+
+	return min;
+}
+
 static unsigned long slots[CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
 			   CONFIG_PHYSICAL_ALIGN];
 
@@ -246,6 +280,23 @@ static unsigned long slot_max;
 
 static unsigned long slot_area_index;
 
+static void store_slot_info(struct mem_vector *region, unsigned long image_size)
+{
+	struct slot_area slot_area;
+
+	slot_area.addr = region->start;
+	if (image_size <= CONFIG_PHYSICAL_ALIGN)
+		slot_area.num = region->size / CONFIG_PHYSICAL_ALIGN;
+	else
+		slot_area.num = (region->size - image_size) /
+				CONFIG_PHYSICAL_ALIGN + 1;
+
+	if (slot_area.num > 0) {
+		slot_areas[slot_area_index++] = slot_area;
+		slot_max += slot_area.num;
+	}
+}
+
 static void slots_append(unsigned long addr)
 {
 	/* Overflowing the slots list should be impossible. */
-- 
1.9.3

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