Subject: Re: [PATCH 01/25] powerpc: initial pkey plumbing

From: Balbir Singh <[email-masked]>
Date: Thu, 14 Sep 2017 13:32:05 +1000

On Fri,  8 Sep 2017 15:44:49 -0700
Ram Pai <[email-masked]> wrote:

> Basic  plumbing  to   initialize  the   pkey  system.
> Nothing is enabled yet. A later patch will enable it
> ones all the infrastructure is in place.
> 
> Signed-off-by: Ram Pai <[email-masked]>
> ---
>  arch/powerpc/Kconfig                   |   16 +++++++++++
>  arch/powerpc/include/asm/mmu_context.h |    5 +++
>  arch/powerpc/include/asm/pkeys.h       |   45 ++++++++++++++++++++++++++++++++
>  arch/powerpc/kernel/setup_64.c         |    4 +++
>  arch/powerpc/mm/Makefile               |    1 +
>  arch/powerpc/mm/hash_utils_64.c        |    1 +
>  arch/powerpc/mm/pkeys.c                |   33 +++++++++++++++++++++++
>  7 files changed, 105 insertions(+), 0 deletions(-)
>  create mode 100644 arch/powerpc/include/asm/pkeys.h
>  create mode 100644 arch/powerpc/mm/pkeys.c
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 9fc3c0b..a4cd210 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -864,6 +864,22 @@ config SECCOMP
>  
>  	  If unsure, say Y. Only embedded should say N here.
>  
> +config PPC64_MEMORY_PROTECTION_KEYS
> +	prompt "PowerPC Memory Protection Keys"
> +	def_bool y
> +	# Note: only available in 64-bit mode
> +	depends on PPC64

This is not sufficient right, you need PPC_BOOK3S_64
for compile time at-least?

> +	select ARCH_USES_HIGH_VMA_FLAGS
> +	select ARCH_HAS_PKEYS
> +	---help---
> +	  Memory Protection Keys provides a mechanism for enforcing
> +	  page-based protections, but without requiring modification of the
> +	  page tables when an application changes protection domains.
> +
> +	  For details, see Documentation/vm/protection-keys.txt
> +
> +	  If unsure, say y.
> +
>  endmenu
>  
>  config ISA_DMA_API
> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> index 3095925..7badf29 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -141,5 +141,10 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
>  	/* by default, allow everything */
>  	return true;
>  }
> +
> +#ifndef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +#define pkey_initialize()
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
>  #endif /* __KERNEL__ */
>  #endif /* __ASM_POWERPC_MMU_CONTEXT_H */
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> new file mode 100644
> index 0000000..c02305a
> --- /dev/null
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -0,0 +1,45 @@
> +#ifndef _ASM_PPC64_PKEYS_H
> +#define _ASM_PPC64_PKEYS_H
> +
> +extern bool pkey_inited;
> +extern bool pkey_execute_disable_support;
> +#define ARCH_VM_PKEY_FLAGS 0
> +
> +static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
> +{
> +	return (pkey == 0);
> +}
> +
> +static inline int mm_pkey_alloc(struct mm_struct *mm)
> +{
> +	return -1;
> +}
> +
> +static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
> +{
> +	return -EINVAL;
> +}
> +
> +/*
> + * Try to dedicate one of the protection keys to be used as an
> + * execute-only protection key.
> + */
> +static inline int execute_only_pkey(struct mm_struct *mm)
> +{
> +	return 0;
> +}
> +
> +static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
> +		int prot, int pkey)
> +{
> +	return 0;
> +}
> +
> +static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
> +		unsigned long init_val)
> +{
> +	return 0;
> +}
> +
> +extern void pkey_initialize(void);
> +#endif /*_ASM_PPC64_PKEYS_H */
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index b89c6aa..3b67014 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -37,6 +37,7 @@
>  #include <linux/memblock.h>
>  #include <linux/memory.h>
>  #include <linux/nmi.h>
> +#include <linux/pkeys.h>
>  
>  #include <asm/io.h>
>  #include <asm/kdump.h>
> @@ -316,6 +317,9 @@ void __init early_setup(unsigned long dt_ptr)
>  	/* Initialize the hash table or TLB handling */
>  	early_init_mmu();
>  
> +	/* initialize the key subsystem */
> +	pkey_initialize();
> +
>  	/*
>  	 * At this point, we can let interrupts switch to virtual mode
>  	 * (the MMU has been setup), so adjust the MSR in the PACA to
> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
> index fb844d2..927620a 100644
> --- a/arch/powerpc/mm/Makefile
> +++ b/arch/powerpc/mm/Makefile
> @@ -43,3 +43,4 @@ obj-$(CONFIG_PPC_COPRO_BASE)	+= copro_fault.o
>  obj-$(CONFIG_SPAPR_TCE_IOMMU)	+= mmu_context_iommu.o
>  obj-$(CONFIG_PPC_PTDUMP)	+= dump_linuxpagetables.o
>  obj-$(CONFIG_PPC_HTDUMP)	+= dump_hashpagetable.o
> +obj-$(CONFIG_PPC64_MEMORY_PROTECTION_KEYS)	+= pkeys.o
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 0dff57b..67f62b5 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -35,6 +35,7 @@
>  #include <linux/memblock.h>
>  #include <linux/context_tracking.h>
>  #include <linux/libfdt.h>
> +#include <linux/pkeys.h>
>  
>  #include <asm/debugfs.h>
>  #include <asm/processor.h>
> diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
> new file mode 100644
> index 0000000..418a05b
> --- /dev/null
> +++ b/arch/powerpc/mm/pkeys.c
> @@ -0,0 +1,33 @@
> +/*
> + * PowerPC Memory Protection Keys management
> + * Copyright (c) 2015, Intel Corporation.
> + * Copyright (c) 2017, IBM Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +#include <linux/pkeys.h>                /* PKEY_*                       */
> +
> +bool pkey_inited;
> +bool pkey_execute_disable_support;
> +
> +void __init pkey_initialize(void)
> +{
> +	/* disable the pkey system till everything
> +	 * is in place. A patch further down the
> +	 * line will enable it.
> +	 */

Comment style is broken

> +	pkey_inited = false;
> +
> +	/*
> +	 * disable execute_disable support for now.
> +	 * A patch further down will enable it.
> +	 */
> +	pkey_execute_disable_support = false;
> +}

Balbir Singh.