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Commit 2ddc53f3 authored by Ram Pai's avatar Ram Pai Committed by Michael Ellerman
Browse files

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: default avatarThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 0685f217

arch/powerpc/include/asm/pkeys.h

+5 −1
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/mm/pkeys.c

+40 −0
Original line number Diff line number Diff line
@@ -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;

}