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SubjectRe: [PATCH v5 4/4] x86/boot/KASLR: Limit kaslr to choosing the immovable memory
On 08/27/18 at 01:56pm, Baoquan He wrote:
> On 08/07/18 at 02:50pm, Chao Fan wrote:
> > If 'CONFIG_MEMORY_HOTREMOVE' specified and the account of immovable
> If CONFIG_MEMORY_HOTREMOVE is enabled,
> > memory regions is not zero. Calculate the intersection between memory
> > regions from e820/efi memory table and immovable memory regions.
> > Or go on the old code.
> >
> > Rename process_mem_region to slots_count to match slots_fetch_random,
> > and name new function as process_mem_region.
> >
> > Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
> > ---
> > arch/x86/boot/compressed/kaslr.c | 66 ++++++++++++++++++++++++++------
> > 1 file changed, 55 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> > index 720878f967a3..9c6e24a23a2d 100644
> > --- a/arch/x86/boot/compressed/kaslr.c
> > +++ b/arch/x86/boot/compressed/kaslr.c
> > @@ -635,9 +635,9 @@ 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;
> > @@ -714,6 +714,56 @@ 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)
> > +{
>
> Is it possible to take num_immovable_mem definition out from #ifdef
> CONFIG_MEMORY_HOTREMOVE block and check it here like below? This way,
> one level of indentation can be reduced in the for loop, and code is
> more readable.
>
>
> static bool process_mem_region(struct mem_vector *region,
> unsigned long long minimum,
> unsigned long long image_size)
> {
>
> /*
> * If no immovable memory found, or MEMORY_HOTREMOVE disabled,
> * walk all the regions, so use region directely.
> */
> if (num_immovable_mem > 0) {
Sorry, I meant if (!num_immovable_mem) {


> slots_count(region, minimum, image_size);
>
> if (slot_area_index == MAX_SLOT_AREA) {
> debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");
> return 1;
> }
> return 0;
> }
>
> #ifdef CONFIG_MEMORY_HOTREMOVE
> for (i = 0; i < num_immovable_mem; i++) {
> ...
> }
> #endif
> }
>
> > +#ifdef CONFIG_MEMORY_HOTREMOVE
> > + /*
> > + * If immovable memory found, filter the intersection between
> > + * immovable memory and region to slots_count.
> > + * Otherwise, go on old code.
> > + */
> > + if (num_immovable_mem > 0) {
> > + int i;
> > +
> > + for (i = 0; i < num_immovable_mem; 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 + image_size < entry_end) {
> > + entry.size = entry_end - entry.start;
> > + slots_count(&entry, minimum, image_size);
> > +
> > + if (slot_area_index == MAX_SLOT_AREA) {
> > + debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");
> > + return 1;
> > + }
> > + }
> > + }
> > + return 0;
> > + }
> > +#endif
> > + /*
> > + * If no immovable memory found, or MEMORY_HOTREMOVE disabled,
> > + * walk all the regions, so use region directely.
> > + */
> > + slots_count(region, minimum, image_size);
> > +
> > + if (slot_area_index == MAX_SLOT_AREA) {
> > + debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");
> > + return 1;
> > + }
> > + return 0;
> > +}
> > +
> > #ifdef CONFIG_EFI
> > /*
> > * Returns true if mirror region found (and must have been processed
> > @@ -779,11 +829,8 @@ 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;
> > }
> > @@ -810,11 +857,8 @@ 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;
> > - }
> > }
> > }
> >
> > --
> > 2.17.1
> >
> >
> >

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