pkeys.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright 2020, Sandipan Das, IBM Corp.
  4 */
  5
  6#ifndef _SELFTESTS_POWERPC_PKEYS_H
  7#define _SELFTESTS_POWERPC_PKEYS_H
  8
  9#include <sys/mman.h>
 10
 11#include "reg.h"
 12#include "utils.h"
 13
 14/*
 15 * Older versions of libc use the Intel-specific access rights.
 16 * Hence, override the definitions as they might be incorrect.
 17 */
 18#undef PKEY_DISABLE_ACCESS
 19#define PKEY_DISABLE_ACCESS	0x3
 20
 21#undef PKEY_DISABLE_WRITE
 22#define PKEY_DISABLE_WRITE	0x2
 23
 24#undef PKEY_DISABLE_EXECUTE
 25#define PKEY_DISABLE_EXECUTE	0x4
 26
 27#undef PKEY_UNRESTRICTED
 28#define PKEY_UNRESTRICTED	0x0
 29
 30/* Older versions of libc do not define this */
 31#ifndef SEGV_PKUERR
 32#define SEGV_PKUERR	4
 33#endif
 34
 35#define SI_PKEY_OFFSET	0x20
 36
 37#define __NR_pkey_mprotect	386
 38#define __NR_pkey_alloc		384
 39#define __NR_pkey_free		385
 40
 41#ifndef NT_PPC_PKEY
 42#define NT_PPC_PKEY		0x110
 43#endif
 44
 45#define PKEY_BITS_PER_PKEY	2
 46#define NR_PKEYS		32
 47#define PKEY_BITS_MASK		((1UL << PKEY_BITS_PER_PKEY) - 1)
 48
 49#define AMR_BITS_PER_PKEY 2
 50#define PKEY_REG_BITS (sizeof(u64) * 8)
 51#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey + 1) * AMR_BITS_PER_PKEY))
 52
 53inline unsigned long pkeyreg_get(void)
 54{
 55	return mfspr(SPRN_AMR);
 56}
 57
 58inline void pkeyreg_set(unsigned long amr)
 59{
 60	set_amr(amr);
 61}
 62
 63void pkey_set_rights(int pkey, unsigned long rights)
 64{
 65	unsigned long amr, shift;
 66
 67	shift = (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
 68	amr = pkeyreg_get();
 69	amr &= ~(PKEY_BITS_MASK << shift);
 70	amr |= (rights & PKEY_BITS_MASK) << shift;
 71	pkeyreg_set(amr);
 72}
 73
 74int sys_pkey_mprotect(void *addr, size_t len, int prot, int pkey)
 75{
 76	return syscall(__NR_pkey_mprotect, addr, len, prot, pkey);
 77}
 78
 79int sys_pkey_alloc(unsigned long flags, unsigned long rights)
 80{
 81	return syscall(__NR_pkey_alloc, flags, rights);
 82}
 83
 84int sys_pkey_free(int pkey)
 85{
 86	return syscall(__NR_pkey_free, pkey);
 87}
 88
 89int pkeys_unsupported(void)
 90{
 91	bool hash_mmu = false;
 92	int pkey;
 93
 94	/* Protection keys are currently supported on Hash MMU only */
 95	FAIL_IF(using_hash_mmu(&hash_mmu));
 96	SKIP_IF(!hash_mmu);
 97
 98	/* Check if the system call is supported */
 99	pkey = sys_pkey_alloc(0, PKEY_UNRESTRICTED);
100	SKIP_IF(pkey < 0);
101	sys_pkey_free(pkey);
102
103	return 0;
104}
105
106int siginfo_pkey(siginfo_t *si)
107{
108	/*
109	 * In older versions of libc, siginfo_t does not have si_pkey as
110	 * a member.
111	 */
112#ifdef si_pkey
113	return si->si_pkey;
114#else
115	return *((int *)(((char *) si) + SI_PKEY_OFFSET));
116#endif
117}
118
119#define pkey_rights(r) ({						\
120	static char buf[4] = "rwx";					\
121	unsigned int amr_bits;						\
122	if ((r) & PKEY_DISABLE_EXECUTE)					\
123		buf[2] = '-';						\
124	amr_bits = (r) & PKEY_BITS_MASK;				\
125	if (amr_bits & PKEY_DISABLE_WRITE)				\
126		buf[1] = '-';						\
127	if (amr_bits & PKEY_DISABLE_ACCESS & ~PKEY_DISABLE_WRITE)	\
128		buf[0] = '-';						\
129	buf;								\
130})
131
132unsigned long next_pkey_rights(unsigned long rights)
133{
134	if (rights == PKEY_DISABLE_ACCESS)
135		return PKEY_DISABLE_EXECUTE;
136	else if (rights == (PKEY_DISABLE_ACCESS | PKEY_DISABLE_EXECUTE))
137		return 0;
138
139	if ((rights & PKEY_BITS_MASK) == 0)
140		rights |= PKEY_DISABLE_WRITE;
141	else if ((rights & PKEY_BITS_MASK) == PKEY_DISABLE_WRITE)
142		rights |= PKEY_DISABLE_ACCESS;
143
144	return rights;
145}
146
147#endif /* _SELFTESTS_POWERPC_PKEYS_H */