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powerpc: implementation for arch_set_user_pkey_access() 

This patch provides the detailed implementation for
a user to allocate a key and enable it in the hardware.

It provides the plumbing, but it cannot be used till
the system call is implemented. The next patch  will
do so.

Reviewed-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ram Pai 2018-01-18 17:50:29 -08:00 committed by Michael Ellerman
parent 0685f217af
commit 2ddc53f3a7
2 changed files with 45 additions and 1 deletions
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6
arch/powerpc/include/asm/pkeys.h
View File

@ -128,10 +128,14 @@ static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
return 0;
}
extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val);
static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val)
{
return 0;
if (static_branch_likely(&pkey_disabled))
return -EINVAL;
return __arch_set_user_pkey_access(tsk, pkey, init_val);
}
extern void pkey_mm_init(struct mm_struct *mm);

40
arch/powerpc/mm/pkeys.c
View File

@ -5,6 +5,7 @@
* Copyright 2017, Ram Pai, IBM Corporation.
*/
#include <asm/mman.h>
#include <linux/pkeys.h>
DEFINE_STATIC_KEY_TRUE(pkey_disabled);
@ -13,6 +14,9 @@ int pkeys_total; /* Total pkeys as per device tree */
u32 initial_allocation_mask; /* Bits set for reserved keys */
#define AMR_BITS_PER_PKEY 2
#define AMR_RD_BIT 0x1UL
#define AMR_WR_BIT 0x2UL
#define IAMR_EX_BIT 0x1UL
#define PKEY_REG_BITS (sizeof(u64)*8)
#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY))
@ -108,6 +112,20 @@ static inline void write_uamor(u64 value)
mtspr(SPRN_UAMOR, value);
}
static bool is_pkey_enabled(int pkey)
{
u64 uamor = read_uamor();
u64 pkey_bits = 0x3ul << pkeyshift(pkey);
u64 uamor_pkey_bits = (uamor & pkey_bits);
/*
* Both the bits in UAMOR corresponding to the key should be set or
* reset.
*/
WARN_ON(uamor_pkey_bits && (uamor_pkey_bits != pkey_bits));
return !!(uamor_pkey_bits);
}
static inline void init_amr(int pkey, u8 init_bits)
{
u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
@ -150,3 +168,25 @@ void __arch_deactivate_pkey(int pkey)
{
pkey_status_change(pkey, false);
}
/*
* Set the access rights in AMR IAMR and UAMOR registers for @pkey to that
* specified in @init_val.
*/
int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val)
{
u64 new_amr_bits = 0x0ul;
if (!is_pkey_enabled(pkey))
return -EINVAL;
/* Set the bits we need in AMR: */
if (init_val & PKEY_DISABLE_ACCESS)
new_amr_bits |= AMR_RD_BIT | AMR_WR_BIT;
else if (init_val & PKEY_DISABLE_WRITE)
new_amr_bits |= AMR_WR_BIT;
init_amr(pkey, new_amr_bits);
return 0;
}