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SubjectRe: [RFC v2 03/12] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call.
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Hi Ram,

Ram Pai <linuxram@us.ibm.com> writes:
> Sys_pkey_alloc() allocates and returns available pkey
> Sys_pkey_free() frees up the pkey.
>
> Total 32 keys are supported on powerpc. However pkey 0,1 and 31
> are reserved. So effectively we have 29 pkeys.
>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
> include/linux/mm.h | 31 ++++---
> include/uapi/asm-generic/mman-common.h | 2 +-

Those changes need to be split out and acked by mm folks.

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7cb17c6..34ddac7 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -204,26 +204,35 @@ extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *,
> #define VM_MERGEABLE 0x80000000 /* KSM may merge identical pages */
>
> #ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
> -#define VM_HIGH_ARCH_BIT_0 32 /* bit only usable on 64-bit architectures */
> -#define VM_HIGH_ARCH_BIT_1 33 /* bit only usable on 64-bit architectures */
> -#define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit architectures */
> -#define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit architectures */
> +#define VM_HIGH_ARCH_BIT_0 32 /* bit only usable on 64-bit arch */
> +#define VM_HIGH_ARCH_BIT_1 33 /* bit only usable on 64-bit arch */
> +#define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit arch */
> +#define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit arch */

Please don't change the comments, it makes the diff harder to read.

You're actually just adding this AFAICS:

> +#define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit arch */

> #define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0)
> #define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1)
> #define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2)
> #define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3)
> +#define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4)
> #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
>
> #if defined(CONFIG_X86)
^
> # define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */
> -#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)
> -# define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
> -# define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 4-bit value */
> -# define VM_PKEY_BIT1 VM_HIGH_ARCH_1
> -# define VM_PKEY_BIT2 VM_HIGH_ARCH_2
> -# define VM_PKEY_BIT3 VM_HIGH_ARCH_3
> -#endif
> +#if defined(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) \
> + || defined(CONFIG_PPC64_MEMORY_PROTECTION_KEYS)
> +#define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
> +#define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 5-bit value */
^ 4?
> +#define VM_PKEY_BIT1 VM_HIGH_ARCH_1
> +#define VM_PKEY_BIT2 VM_HIGH_ARCH_2
> +#define VM_PKEY_BIT3 VM_HIGH_ARCH_3
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */

That appears to be inside an #if defined(CONFIG_X86) ?

> #elif defined(CONFIG_PPC)
^
Should be CONFIG_PPC64_MEMORY_PROTECTION_KEYS no?

> +#define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 5-bit value */
> +#define VM_PKEY_BIT1 VM_HIGH_ARCH_1
> +#define VM_PKEY_BIT2 VM_HIGH_ARCH_2
> +#define VM_PKEY_BIT3 VM_HIGH_ARCH_3
> +#define VM_PKEY_BIT4 VM_HIGH_ARCH_4 /* intel does not use this bit */
> + /* but reserved for future expansion */

But this hunk is for PPC ?

Is it OK for the other arches & generic code to add another VM_PKEY_BIT4 ?

Do you need to update show_smap_vma_flags() ?

> # define VM_SAO VM_ARCH_1 /* Strong Access Ordering (powerpc) */
> #elif defined(CONFIG_PARISC)
> # define VM_GROWSUP VM_ARCH_1

> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index 8c27db0..b13ecc6 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -76,5 +76,5 @@
> #define PKEY_DISABLE_WRITE 0x2
> #define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS |\
> PKEY_DISABLE_WRITE)
> -
> +#define PKEY_DISABLE_EXECUTE 0x4

How you can set that if it's not in PKEY_ACCESS_MASK?

See:

SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
{
int pkey;
int ret;

/* No flags supported yet. */
if (flags)
return -EINVAL;
/* check for unsupported init values */
if (init_val & ~PKEY_ACCESS_MASK)
return -EINVAL;


cheers

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