Messages in this thread | | | Date | Mon, 17 Dec 2018 18:43:24 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH v14 5/5] x86/boot/KASLR: Limit KASLR to extracting kernel in immovable memory |
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* Chao Fan <fanc.fnst@cn.fujitsu.com> wrote:
> KASLR randomly chooses some positions which may locate in movable > memory regions. It will break memory hotplug feature and make the > movable memory chosen by KASLR practically immovable. > > The solution is to limit KASLR to choose memory regions in immovable > node according to SRAT tables. > When CONFIG_EARLY_PARSE_RSDP is enabled, walk through SRAT to get the > information of immovable memory so that KASLR knows where should be > chosen for randomization. > > Rename process_mem_region() as __process_mem_region() and name new > function as process_mem_region(). > > Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com> > --- > arch/x86/boot/compressed/kaslr.c | 75 +++++++++++++++++++++++++++----- > 1 file changed, 64 insertions(+), 11 deletions(-)
Ok, I like this basic approach of automatically detecing memory areas we should not KASLR into - it's far better than earlier iterations.
> +++ 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_EARLY_SRAT_PARSE > +/* The immovable memory regions */ > +extern struct mem_vector immovable_mem[MAX_NUMNODES*2]; > +#endif
What logic is the maximum size of this array based on?
Thanks,
Ingo
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