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

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Date:   Thu, 19 Oct 2017 18:02:41 +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>
CC:     <indou.takao@...fujitsu.com>, <caoj.fnst@...fujitsu.com>,
        <douly.fnst@...fujitsu.com>, Chao Fan <fanc.fnst@...fujitsu.com>
Subject: [PATCH 2/4] kaslr: select the memory region in immovable node to process

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. So select the intersection as a region to
process_mem_region. 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 | 72 ++++++++++++++++++++++++++++++++--------
 1 file changed, 58 insertions(+), 14 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 3c1f5204693b..22330cbe8515 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -563,6 +563,7 @@ static void process_mem_region(struct mem_vector *entry,
 	end = min(entry->size + entry->start, mem_limit);
 	if (entry->start >= end)
 		return;
+
 	cur_entry.start = entry->start;
 	cur_entry.size = end - entry->start;
 
@@ -621,6 +622,52 @@ static void process_mem_region(struct mem_vector *entry,
 	}
 }
 
+static bool select_immovable_node(unsigned long long start,
+				  unsigned long long size,
+				  unsigned long long minimum,
+				  unsigned long long image_size)
+{
+	struct mem_vector region;
+	int i;
+
+	if (num_immovable_region == 0) {
+		region.start = start;
+		region.size = size;
+		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 {
+		for (i = 0; i < num_immovable_region; i++) {
+			unsigned long long end, select_end;
+			unsigned long long region_start, region_end;
+
+			end = start + size - 1;
+			region_start = immovable_mem[i].start;
+			region_end = region_start + immovable_mem[i].size - 1;
+
+			if (end < region_start || start > region_end)
+				continue;
+
+			region.start = start > region_start ?
+				       start : region_start;
+			select_end = end > region_end ? region_end : end;
+
+			region.size = select_end - region.start + 1;
+
+			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;
+			}
+		}
+	}
+	return 0;
+}
+
 #ifdef CONFIG_EFI
 /*
  * Returns true if mirror region found (and must have been processed
@@ -631,7 +678,6 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
 {
 	struct efi_info *e = &boot_params->efi_info;
 	bool efi_mirror_found = false;
-	struct mem_vector region;
 	efi_memory_desc_t *md;
 	unsigned long pmap;
 	char *signature;
@@ -664,6 +710,8 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
 	}
 
 	for (i = 0; i < nr_desc; i++) {
+		unsigned long long start, size;
+
 		md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i);
 
 		/*
@@ -684,13 +732,11 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
 		    !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
 			continue;
 
-		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");
+		start = md->phys_addr;
+		size = md->num_pages << EFI_PAGE_SHIFT;
+
+		if (select_immovable_node(start, size, minimum, image_size))
 			break;
-		}
 	}
 	return true;
 }
@@ -706,22 +752,20 @@ static void process_e820_entries(unsigned long minimum,
 				 unsigned long image_size)
 {
 	int i;
-	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++) {
+		unsigned long long start, size;
 		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");
+		start = entry->addr;
+		size = entry->size;
+
+		if (select_immovable_node(start, size, minimum, image_size))
 			break;
-		}
 	}
 }
 
-- 
2.13.6