linux-kernel - [PATCH v3 2/4] kaslr: calculate the memory region in immovable node

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Date:   Tue, 5 Dec 2017 16:51:58 +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 v3 2/4] kaslr: calculate the memory region in immovable node

If there is no immovable memory region specified, go on the old code.
There are several conditons:
1. CONFIG_MEMORY_HOTPLUG is not specified to y.
2. immovable_mem= is not specified.

Otherwise, calculate the intersecting between memmap entry and
immovable memory.

Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
---
 arch/x86/boot/compressed/kaslr.c | 59 ++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 8 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 0bbbaf5f6370..e3a3b6132da0 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -635,6 +635,39 @@ static void process_mem_region(struct mem_vector *entry,
 	}
 }
 
+static bool process_immovable_mem(struct mem_vector region,
+				  unsigned long long minimum,
+				  unsigned long long image_size)
+{
+	int i;
+
+	/*
+	 * 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, entry_end;
+
+		start = immovable_mem[i].start;
+		end = start + immovable_mem[i].size;
+
+		entry.start = clamp(region.start, start, end);
+		entry_end = clamp(region.start + region.size, start, end);
+
+		if (entry.start < entry_end) {
+			entry.size = entry_end - entry.start;
+			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
@@ -700,11 +733,16 @@ 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 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");
+				break;
+			}
+		} else if (process_immovable_mem(region, minimum, image_size))
 			break;
-		}
 	}
 	return true;
 }
@@ -731,11 +769,16 @@ 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 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");
+				break;
+			}
+		} else if (process_immovable_mem(region, minimum, image_size))
 			break;
-		}
 	}
 }
 
-- 
2.14.3