Re: [tip:x86/boot] ACPI/NUMA: Add warning message if the padding size for KASLR is not enough

[Masayoshi Mizuma]

On Wed, Oct 03, 2018 at 02:48:14PM +0200, Borislav Petkov wrote:
> On Wed, Oct 03, 2018 at 02:34:02PM +0200, Peter Zijlstra wrote:
> > 
> > Subject: ACPI/NUMA: Fix KASLR build error
> > 
> > There is no point in trying to compile KASLR specific code when there is
> > no KASLR.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > ---
> 
> Yeah, Peter and I were just talking on IRC and he gave me a much better
> idea how to fix this, see below. I'll run this through the *config builder and
> commit it if no complaints.

Hi Boris and Peter,

Thank you for the fix. It is great!

- Masa

> 
> ---
> From: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
> Date: Wed, 3 Oct 2018 14:41:27 +0200
> Subject: [PATCH] ACPI/NUMA: Fix KASLR build error
> 
> There is no point in trying to compile KASLR specific code when there is
> no KASLR.
> 
>  [ bp: Move the whole crap into kaslr.c and make
>    rand_mem_physical_padding static. ]
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Cc: <m.mizuma@xxxxxxxxxxxxxx>
> Cc: <bhe@xxxxxxxxxx>
> Cc: <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: <tglx@xxxxxxxxxxxxx>
> Cc: <mingo@xxxxxxxxxx>
> Cc: <hpa@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/20181003123402.GA15494@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> ---
>  arch/x86/include/asm/kaslr.h |  2 ++
>  arch/x86/include/asm/setup.h |  2 --
>  arch/x86/mm/kaslr.c          | 18 +++++++++++++++++-
>  drivers/acpi/numa.c          | 15 +++------------
>  4 files changed, 22 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kaslr.h b/arch/x86/include/asm/kaslr.h
> index db7ba2feb947..95ef3fc01d12 100644
> --- a/arch/x86/include/asm/kaslr.h
> +++ b/arch/x86/include/asm/kaslr.h
> @@ -6,8 +6,10 @@ unsigned long kaslr_get_random_long(const char *purpose);
>  
>  #ifdef CONFIG_RANDOMIZE_MEMORY
>  void kernel_randomize_memory(void);
> +void kaslr_check_padding(void);
>  #else
>  static inline void kernel_randomize_memory(void) { }
> +static inline void kaslr_check_padding(void) { }
>  #endif /* CONFIG_RANDOMIZE_MEMORY */
>  
>  #endif
> diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
> index 65a5bf8f6aba..ae13bc974416 100644
> --- a/arch/x86/include/asm/setup.h
> +++ b/arch/x86/include/asm/setup.h
> @@ -80,8 +80,6 @@ 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/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
> index 00cf4cae38f5..d58b7da0d55c 100644
> --- a/arch/x86/mm/kaslr.c
> +++ b/arch/x86/mm/kaslr.c
> @@ -40,7 +40,7 @@
>   */
>  static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE;
>  
> -int __initdata rand_mem_physical_padding = CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
> +static int __initdata rand_mem_physical_padding = CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
>  /*
>   * Memory regions randomized by KASLR (except modules that use a separate logic
>   * earlier during boot). The list is ordered based on virtual addresses. This
> @@ -70,6 +70,22 @@ static inline bool kaslr_memory_enabled(void)
>  	return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
>  }
>  
> +/*
> + * Check the padding size for KASLR is enough.
> + */
> +void kaslr_check_padding(void)
> +{
> +	u64 max_possible_phys, max_actual_phys, threshold;
> +
> +	max_actual_phys = roundup(PFN_PHYS(max_pfn), 1ULL << 40);
> +	max_possible_phys = roundup(PFN_PHYS(max_possible_pfn), 1ULL << 40);
> +	threshold = max_actual_phys + ((u64)rand_mem_physical_padding << 40);
> +
> +	if (max_possible_phys > threshold)
> +		pr_warn("Set 'rand_mem_physical_padding=%llu' to avoid memory hotadd failure.\n",
> +			(max_possible_phys - max_actual_phys) >> 40);
> +}
> +
>  static int __init rand_mem_physical_padding_setup(char *str)
>  {
>  	int max_padding = (1 << (MAX_PHYSMEM_BITS - TB_SHIFT)) - 1;
> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> index 3d69834c692f..4408e37600ef 100644
> --- a/drivers/acpi/numa.c
> +++ b/drivers/acpi/numa.c
> @@ -32,7 +32,7 @@
>  #include <linux/numa.h>
>  #include <linux/nodemask.h>
>  #include <linux/topology.h>
> -#include <asm/setup.h>
> +#include <asm/kaslr.h>
>  
>  static nodemask_t nodes_found_map = NODE_MASK_NONE;
>  
> @@ -436,7 +436,6 @@ acpi_table_parse_srat(enum acpi_srat_type id,
>  int __init acpi_numa_init(void)
>  {
>  	int cnt = 0;
> -	u64 max_possible_phys, max_actual_phys, threshold;
>  
>  	if (acpi_disabled)
>  		return -EINVAL;
> @@ -466,17 +465,9 @@ int __init acpi_numa_init(void)
>  		cnt = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
>  					    acpi_parse_memory_affinity, 0);
>  
> -		/* check the padding size for KASLR is enough. */
> -		if (parsed_numa_memblks && kaslr_enabled()) {
> -			max_actual_phys = roundup(PFN_PHYS(max_pfn), 1ULL << 40);
> -			max_possible_phys = roundup(PFN_PHYS(max_possible_pfn), 1ULL << 40);
> -			threshold = max_actual_phys + ((u64)rand_mem_physical_padding << 40);
> +		if (parsed_numa_memblks)
> +			kaslr_check_padding();
>  
> -			if (max_possible_phys > threshold) {
> -				pr_warn("Set 'rand_mem_physical_padding=%llu' to avoid memory hotadd failure.\n",
> -				  (max_possible_phys - max_actual_phys) >> 40);
> -			}
> -		}
>  	}
>  
>  	/* SLIT: System Locality Information Table */
> -- 
> 2.19.0.271.gfe8321ec057f
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> Good mailing practices for 400: avoid top-posting and trim the reply.