linux-kernel - [PATCH v2 2/4] kaslr: select the memory region in immovable node to process

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Message-ID: <20171101113203.27741-3-fanc.fnst@cn.fujitsu.com>
Date:   Wed, 1 Nov 2017 19:32:01 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bhe@...hat.com>,
        <keescook@...omium.org>, <yasu.isimatu@...il.com>
CC:     <indou.takao@...fujitsu.com>, <caoj.fnst@...fujitsu.com>,
        <douly.fnst@...fujitsu.com>, Chao Fan <fanc.fnst@...fujitsu.com>
Subject: [PATCH v2 2/4] kaslr: select the memory region in immovable node to process

Compare the region of memmap entry and immovable_mem, then choose the
intersection to process_mem_region.

Since the interrelationship between e820 or efi entries and memory
region in immovable_mem is different:
One memory region in one node may contain several entries of e820 or
efi sometimes, and one entry of e820 or efi may contain the memory in
different nodes sometimes.
It may split one node or one entry to several regions.

Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
---
 arch/x86/boot/compressed/kaslr.c | 60 ++++++++++++++++++++++++++++++++++------
 1 file changed, 52 insertions(+), 8 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 0a591c0023f1..fcd640fdeaed 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -634,6 +634,54 @@ static void process_mem_region(struct mem_vector *entry,
 	}
 }
 
+static bool select_immovable_node(struct mem_vector region,
+				  unsigned long long minimum,
+				  unsigned long long image_size)
+{
+	int i;
+
+	/* If no immovable_mem stored, use region directly */
+	if (num_immovable_region == 0) {
+		process_mem_region(&region, minimum, image_size);
+
+		if (slot_area_index == MAX_SLOT_AREA) {
+			debug_putstr("Aborted memmap scan (slot_areas full)!\n");
+			return 1;
+		}
+	} else {
+		/*
+		 * Walk all immovable regions, and filter the intersection
+		 * to process_mem_region.
+		 */
+		for (i = 0; i < num_immovable_region; i++) {
+			struct mem_vector entry;
+			unsigned long long start, end, select_end, region_end;
+
+			region_end = region.start + region.size - 1;
+			start = immovable_mem[i].start;
+			end = start + immovable_mem[i].size - 1;
+
+			if (region_end < start || region.start > end)
+				continue;
+
+			/* May split one region to several entries. */
+			entry.start = start > region.start ?
+				      start : region.start;
+			select_end = end > region_end ? region_end : end;
+
+			entry.size = select_end - entry.start + 1;
+
+			process_mem_region(&entry, minimum, image_size);
+
+			if (slot_area_index == MAX_SLOT_AREA) {
+				debug_putstr("Aborted memmap scan (slot_areas full)!\n");
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+
 #ifdef CONFIG_EFI
 /*
  * Returns true if mirror region found (and must have been processed
@@ -699,11 +747,9 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
 
 		region.start = md->phys_addr;
 		region.size = md->num_pages << EFI_PAGE_SHIFT;
-		process_mem_region(&region, minimum, image_size);
-		if (slot_area_index == MAX_SLOT_AREA) {
-			debug_putstr("Aborted EFI scan (slot_areas full)!\n");
+
+		if (select_immovable_node(region, minimum, image_size))
 			break;
-		}
 	}
 	return true;
 }
@@ -730,11 +776,9 @@ static void process_e820_entries(unsigned long minimum,
 			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");
+
+		if (select_immovable_node(region, minimum, image_size))
 			break;
-		}
 	}
 }
 
-- 
2.13.6