On Fri, Sep 28, 2018 at 10:48:57AM +0800, Baoquan He wrote:
> On 09/27/18 at 04:31pm, Masayoshi Mizuma wrote:
> > From: Masayoshi Mizuma <m.miz...@jp.fujitsu.com>
> >
> > Add warning message if the padding size for KASLR,
> > rand_mem_physical_padding, is not enough. The message also
> > says the suitable padding size.
> >
> > Signed-off-by: Masayoshi Mizuma <m.miz...@jp.fujitsu.com>
> > ---
> > arch/x86/include/asm/setup.h | 2 ++
> > drivers/acpi/numa.c | 14 ++++++++++++++
> > 2 files changed, 16 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
> > index ae13bc9..65a5bf8 100644
> > --- a/arch/x86/include/asm/setup.h
> > +++ b/arch/x86/include/asm/setup.h
> > @@ -80,6 +80,8 @@ static inline unsigned long kaslr_offset(void)
> > return (unsigned long)&_text - __START_KERNEL;
> > }
> >
> > +extern int rand_mem_physical_padding;
> > +
> > /*
> > * Do NOT EVER look at the BIOS memory size location.
> > * It does not work on many machines.
> > diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> > index 8516760..9c3cc3c 100644
> > --- a/drivers/acpi/numa.c
> > +++ b/drivers/acpi/numa.c
> > @@ -32,6 +32,7 @@
> > #include <linux/numa.h>
> > #include <linux/nodemask.h>
> > #include <linux/topology.h>
> > +#include <asm/setup.h>
> >
> > static nodemask_t nodes_found_map = NODE_MASK_NONE;
> >
> > @@ -435,6 +436,8 @@ acpi_table_parse_srat(enum acpi_srat_type id,
> > int __init acpi_numa_init(void)
> > {
> > int cnt = 0;
> > + u32 max_phys_addr_tb;
> > + u64 max_phys_addr;
> >
> > if (acpi_disabled)
> > return -EINVAL;
> > @@ -463,6 +466,17 @@ int __init acpi_numa_init(void)
> >
> > cnt = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
> > acpi_parse_memory_affinity, 0);
> > +
> > + if (parsed_numa_memblks && kaslr_enabled()) {
> > + max_phys_addr = PFN_PHYS(max_possible_pfn);
> > + max_phys_addr_tb = (roundup(max_phys_addr, 1ULL << 40))
> > >> 40;
> > +
> > + if (max_phys_addr_tb > rand_mem_physical_padding)
>
> Here I assume max_phys_addr_tb is the end of the possible RAM in system.
Yes, correct.
> rand_mem_physical_padding is the preserved space for later memory
> extending. Don't we add the actual RAM size to the
> rand_mem_physical_padding, then compare with max_phys_addr_tb?
This is very good point! You are right, the padding should be
adjusted to exceed the possible RAM size, like as follows.
ADDRESS
0
:
1TB <= actual RAM size
:
2TB <= possible RAM size
2TB and more <= actual + padding size (kaslr_regions[0].size_tb)
I'll fix it, thanks!
- Masa
>
> Please correct me if I am wrong.
>
> Thanks
> Baoquan
>
> > + pr_warn("Set 'rand_mem_physical_padding=%d' "
> > + "as the kernel parameter. "
> > + "Otherwise, memory hotadd may be
> > failed.\n",
> > + max_phys_addr_tb);
> > + }
> > }
> >
> > /* SLIT: System Locality Information Table */
> > --
> > 2.18.0
> >
