On Fri, Nov 16, 2018 at 02:50:39PM +0100, Borislav Petkov wrote: > Subject: Re: [PATCH v11 5/5] x86/boot/KASLR: Walk srat tables to filter > immovable memory > >s/srat/SRAT/g > >On Mon, Nov 12, 2018 at 05:46:45PM +0800, Chao Fan wrote: >> KASLR may randomly chooses some positions which are located in movable > > choose > >> memory regions. This will break memory hotplug feature and make the >> movable memory chosen by KASLR can't be removed. > > by KASLR practically immovable.
Thanks, > >:) > >> The solution is limite KASLR to choose memory regions in immovable > >limite? > >"to limit" > >> node according to SRAT tables. >> >> If CONFIG_MEMORY_HOTREMOVE enabled, walk through the SRAT memory > > *is* enabled, > >> tables and store those immovable memory regions so that KASLR can get >> where to choose for randomization. >> >> If the amount of immovable memory regions is not zero, which >> means the immovable memory regions existing. Calculate the intersection >> between memory regions from e820/efi memory table and immovable memory >> regions. > >This is explaining *what* the patch does and generally doesn't need to >be in the commit messge as people can read it in the patch itself. OK, > >> Signed-off-by: Chao Fan <fanc.f...@cn.fujitsu.com> >> --- >> arch/x86/boot/compressed/kaslr.c | 77 +++++++++++++++++++++++++++----- >> 1 file changed, 66 insertions(+), 11 deletions(-) >> >> diff --git a/arch/x86/boot/compressed/kaslr.c >> b/arch/x86/boot/compressed/kaslr.c >> index b251572e77af..174d2114045e 100644 >> --- a/arch/x86/boot/compressed/kaslr.c >> +++ b/arch/x86/boot/compressed/kaslr.c >> @@ -97,6 +97,11 @@ static bool memmap_too_large; >> /* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ >> static unsigned long long mem_limit = ULLONG_MAX; >> >> +#ifdef CONFIG_MEMORY_HOTREMOVE >> +/* Store the immovable memory regions */ >> +extern struct mem_vector immovable_mem[MAX_NUMNODES*2]; >> +#endif > >For this and the other occurrences of ifdef CONFIG_MEMORY_HOTREMOVE, >define empty stubs for those functions in a header and remove the >ifdeffery at the call sites. OK, > >> + >> >> enum mem_avoid_index { >> MEM_AVOID_ZO_RANGE = 0, >> @@ -413,6 +418,11 @@ static void mem_avoid_init(unsigned long input, >> unsigned long input_size, >> /* Mark the memmap regions we need to avoid */ >> handle_mem_options(); >> >> +#ifdef CONFIG_MEMORY_HOTREMOVE >> + /* Mark the immovable regions we need to choose */ >> + get_immovable_mem(); >> +#endif >> + >> #ifdef CONFIG_X86_VERBOSE_BOOTUP >> /* Make sure video RAM can be used. */ >> add_identity_map(0, PMD_SIZE); >> @@ -568,9 +578,9 @@ 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, > >That's a strange rename. > I will change it. Thanks, Chao Fan >__process_mem_region() makes more sense to me. > >> + unsigned long minimum, >> + unsigned long image_size) >> { >> struct mem_vector region, overlap; >> unsigned long start_orig, end; >> @@ -646,6 +656,57 @@ 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) >> +{ >> + int i; >> + /* >> + * If no immovable memory found, or MEMORY_HOTREMOVE disabled, >> + * walk all the regions, so use region directely. > >"directly" > >> + */ >> + if (num_immovable_mem == 0) { > > if (!... > >> + 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; >> + } >> + > >-- >Regards/Gruss, > Boris. > >Good mailing practices for 400: avoid top-posting and trim the reply. > >