pkey-powerpc.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2
  3#ifndef _PKEYS_POWERPC_H
  4#define _PKEYS_POWERPC_H
  5
  6#include <sys/stat.h>
  7
  8#ifndef SYS_pkey_alloc
  9# define SYS_pkey_alloc		384
 10# define SYS_pkey_free		385
 11#endif
 12#define REG_IP_IDX		PT_NIP
 13#define MCONTEXT_IP(mc)		mc.gp_regs[REG_IP_IDX]
 14#define MCONTEXT_TRAPNO(mc)	mc.gp_regs[REG_TRAPNO]
 15#define REG_TRAPNO		PT_TRAP
 16#define MCONTEXT_FPREGS
 17#define gregs			gp_regs
 18#define fpregs			fp_regs
 19#define si_pkey_offset		0x20
 20
 21#undef PKEY_DISABLE_ACCESS
 22#define PKEY_DISABLE_ACCESS	0x3  /* disable read and write */
 23
 24#undef PKEY_DISABLE_WRITE
 25#define PKEY_DISABLE_WRITE	0x2
 26
 27#define NR_PKEYS		32
 28#define NR_RESERVED_PKEYS_4K	27 /* pkey-0, pkey-1, exec-only-pkey
 29				      and 24 other keys that cannot be
 30				      represented in the PTE */
 31#define NR_RESERVED_PKEYS_64K_3KEYS	3 /* PowerNV and KVM: pkey-0,
 32					     pkey-1 and exec-only key */
 33#define NR_RESERVED_PKEYS_64K_4KEYS	4 /* PowerVM: pkey-0, pkey-1,
 34					     pkey-31 and exec-only key */
 35#define PKEY_BITS_PER_PKEY	2
 36#define HPAGE_SIZE		(1UL << 24)
 37#define PAGE_SIZE		sysconf(_SC_PAGESIZE)
 38
 39static inline u32 pkey_bit_position(int pkey)
 40{
 41	return (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
 42}
 43
 44static inline u64 __read_pkey_reg(void)
 45{
 46	u64 pkey_reg;
 47
 48	asm volatile("mfspr %0, 0xd" : "=r" (pkey_reg));
 49
 50	return pkey_reg;
 51}
 52
 53static inline void __write_pkey_reg(u64 pkey_reg)
 54{
 55	u64 amr = pkey_reg;
 56
 57	dprintf4("%s() changing %016llx to %016llx\n",
 58			 __func__, __read_pkey_reg(), pkey_reg);
 59
 60	asm volatile("isync; mtspr 0xd, %0; isync"
 61		     : : "r" ((unsigned long)(amr)) : "memory");
 62
 63	dprintf4("%s() pkey register after changing %016llx to %016llx\n",
 64			__func__, __read_pkey_reg(), pkey_reg);
 65}
 66
 67static inline int cpu_has_pkeys(void)
 68{
 69	/* No simple way to determine this */
 70	return 1;
 71}
 72
 73static inline bool arch_is_powervm()
 74{
 75	struct stat buf;
 76
 77	if ((stat("/sys/firmware/devicetree/base/ibm,partition-name", &buf) == 0) &&
 78	    (stat("/sys/firmware/devicetree/base/hmc-managed?", &buf) == 0) &&
 79	    (stat("/sys/firmware/devicetree/base/chosen/qemu,graphic-width", &buf) == -1) )
 80		return true;
 81
 82	return false;
 83}
 84
 85static inline int get_arch_reserved_keys(void)
 86{
 87	if (sysconf(_SC_PAGESIZE) == 4096)
 88		return NR_RESERVED_PKEYS_4K;
 89	else
 90		if (arch_is_powervm())
 91			return NR_RESERVED_PKEYS_64K_4KEYS;
 92		else
 93			return NR_RESERVED_PKEYS_64K_3KEYS;
 94}
 95
 96static inline void expect_fault_on_read_execonly_key(void *p1, int pkey)
 97{
 98	/*
 99	 * powerpc does not allow userspace to change permissions of exec-only
100	 * keys since those keys are not allocated by userspace. The signal
101	 * handler wont be able to reset the permissions, which means the code
102	 * will infinitely continue to segfault here.
103	 */
104	return;
105}
106
107#define REPEAT_8(s) s s s s s s s s
108#define REPEAT_64(s) REPEAT_8(s) REPEAT_8(s) REPEAT_8(s) REPEAT_8(s) \
109		     REPEAT_8(s) REPEAT_8(s) REPEAT_8(s) REPEAT_8(s)
110#define REPEAT_512(s) REPEAT_64(s) REPEAT_64(s) REPEAT_64(s) REPEAT_64(s) \
111		      REPEAT_64(s) REPEAT_64(s) REPEAT_64(s) REPEAT_64(s)
112#define REPEAT_4096(s) REPEAT_512(s) REPEAT_512(s) REPEAT_512(s) REPEAT_512(s) \
113		       REPEAT_512(s) REPEAT_512(s) REPEAT_512(s) REPEAT_512(s)
114#define REPEAT_16384(s) REPEAT_4096(s) REPEAT_4096(s) \
115			REPEAT_4096(s) REPEAT_4096(s)
116
117/* 4-byte instructions * 16384 = 64K page */
118#define __page_o_noops() asm(REPEAT_16384("nop\n"))
119
120static inline void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
121{
122	void *ptr;
123	int ret;
124
125	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
126			size, prot, pkey);
127	pkey_assert(pkey < NR_PKEYS);
128	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
129	pkey_assert(ptr != (void *)-1);
130
131	ret = syscall(__NR_subpage_prot, ptr, size, NULL);
132	if (ret) {
133		perror("subpage_perm");
134		return PTR_ERR_ENOTSUP;
135	}
136
137	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
138	pkey_assert(!ret);
139	record_pkey_malloc(ptr, size, prot);
140
141	dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
142	return ptr;
143}
144
145#endif /* _PKEYS_POWERPC_H */