linux-kernel - Re: [PATCH v4 2/4] kaslr: calculate the memory region in immovable node

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Date:   Tue, 12 Dec 2017 20:18:11 +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>
Subject: Re: [PATCH v4 2/4] kaslr: calculate the memory region in immovable
 node

On Tue, Dec 12, 2017 at 08:07:03PM +0800, Chao Fan wrote:
>kaslr: calculate the memory region in immovable node
>
>If there is no immovable memory region specified, use region directely.
>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.
>
>Rename process_mem_region to slots_count to match
>slots_fetch_random, and rename new function sa process_mem_region.
>
>Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
>---
> arch/x86/boot/compressed/kaslr.c | 65 +++++++++++++++++++++++++++++++++-------
> 1 file changed, 54 insertions(+), 11 deletions(-)
>
>diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
>index 40f299d8cd34..fe49d6e79c50 100644
>--- a/arch/x86/boot/compressed/kaslr.c
>+++ b/arch/x86/boot/compressed/kaslr.c
>@@ -579,9 +579,9 @@ static unsigned long slots_fetch_random(void)
> 	return 0;
> }
> 
>-static void process_mem_region(struct mem_vector *entry,
>-			       unsigned long minimum,
>-			       unsigned long image_size)
>+static void slots_count(struct mem_vector *entry,
>+			unsigned long minimum,
>+			unsigned long image_size)
> {
> 	struct mem_vector region, overlap;
> 	struct slot_area slot_area;
>@@ -658,6 +658,53 @@ static void process_mem_region(struct mem_vector *entry,
> 	}
> }
> 
>+static bool process_mem_region(struct mem_vector region,
>+			       unsigned long long minimum,
>+			       unsigned long long image_size)
>+{

Hi Kees and Baoquan,

I follow Kees's suggestion, put num_immovable_region into #ifdef
CONFIG_MEMORY_HOTPLUG, since there won't be num_immovable_region if
not in #ifdef ..., so I changh the order of these two situations
of Baoquan's version.

Thanks,
Chao Fan

>+#ifdef CONFIG_MEMORY_HOTPLUG
>+	/*
>+	 * If immovable_mem= specified, walk all immovable regions, and
>+	 * filter the intersection to slots_count.
>+	 */
>+	if (num_immovable_region > 0) {
>+		for (int i = 0; i < num_immovable_region; i++) {
>+			struct mem_vector entry;
>+			unsigned long long start, end, entry_end, region_end;
>+
>+			start = immovable_mem[i].start;
>+			end = start + immovable_mem[i].size;
>+			region_end = region.start + region.size;
>+
>+			entry.start = clamp(region.start, start, end);
>+			entry_end = clamp(region_end, start, end);
>+
>+			if (entry.start < entry_end) {
>+				entry.size = entry_end - entry.start;
>+				slots_count(&entry, minimum, image_size);
>+			}
>+
>+			if (slot_area_index == MAX_SLOT_AREA) {
>+				debug_putstr("Aborted memmap scan (slot_areas full)!\n");
>+				return 1;
>+			}
>+		}
>+		return 0;
>+	}
>+#endif
>+
>+	/*
>+	 * If no immovable_mem stored, or CONFIG_MEMORY_HOTPLUG not specified,
>+	 * use region directly
>+	 */
>+	slots_count(&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
>@@ -723,11 +770,9 @@ 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 (process_mem_region(region, minimum, image_size))
> 			break;
>-		}
> 	}
> 	return true;
> }
>@@ -754,11 +799,9 @@ 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 (process_mem_region(region, minimum, image_size))
> 			break;
>-		}
> 	}
> }
> 
>-- 
>2.14.3
>