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qemu/target/riscv/pmp.c

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/*
* QEMU RISC-V PMP (Physical Memory Protection)
*
* Author: Daire McNamara, daire.mcnamara@emdalo.com
* Ivan Griffin, ivan.griffin@emdalo.com
*
* This provides a RISC-V Physical Memory Protection implementation
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* PMP (Physical Memory Protection) is as-of-yet unused and needs testing.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qapi/error.h"
#include "cpu.h"
#include "qemu-common.h"
#ifndef CONFIG_USER_ONLY
#define RISCV_DEBUG_PMP 0
#define PMP_DEBUG(fmt, ...) \
do { \
if (RISCV_DEBUG_PMP) { \
qemu_log_mask(LOG_TRACE, "%s: " fmt "\n", __func__, ##__VA_ARGS__);\
} \
} while (0)
static void pmp_write_cfg(CPURISCVState *env, uint32_t addr_index,
uint8_t val);
static uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t addr_index);
static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index);
/*
* Accessor method to extract address matching type 'a field' from cfg reg
*/
static inline uint8_t pmp_get_a_field(uint8_t cfg)
{
uint8_t a = cfg >> 3;
return a & 0x3;
}
/*
* Check whether a PMP is locked or not.
*/
static inline int pmp_is_locked(CPURISCVState *env, uint32_t pmp_index)
{
if (env->pmp_state.pmp[pmp_index].cfg_reg & PMP_LOCK) {
return 1;
}
/* Top PMP has no 'next' to check */
if ((pmp_index + 1u) >= MAX_RISCV_PMPS) {
return 0;
}
/* In TOR mode, need to check the lock bit of the next pmp
* (if there is a next)
*/
const uint8_t a_field =
pmp_get_a_field(env->pmp_state.pmp[pmp_index + 1].cfg_reg);
if ((env->pmp_state.pmp[pmp_index + 1u].cfg_reg & PMP_LOCK) &&
(PMP_AMATCH_TOR == a_field)) {
return 1;
}
return 0;
}
/*
* Count the number of active rules.
*/
static inline uint32_t pmp_get_num_rules(CPURISCVState *env)
{
return env->pmp_state.num_rules;
}
/*
* Accessor to get the cfg reg for a specific PMP/HART
*/
static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
{
if (pmp_index < MAX_RISCV_PMPS) {
return env->pmp_state.pmp[pmp_index].cfg_reg;
}
return 0;
}
/*
* Accessor to set the cfg reg for a specific PMP/HART
* Bounds checks and relevant lock bit.
*/
static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
{
if (pmp_index < MAX_RISCV_PMPS) {
if (!pmp_is_locked(env, pmp_index)) {
env->pmp_state.pmp[pmp_index].cfg_reg = val;
pmp_update_rule(env, pmp_index);
} else {
PMP_DEBUG("ignoring write - locked");
}
} else {
PMP_DEBUG("ignoring write - out of bounds");
}
}
static void pmp_decode_napot(target_ulong a, target_ulong *sa, target_ulong *ea)
{
/*
aaaa...aaa0 8-byte NAPOT range
aaaa...aa01 16-byte NAPOT range
aaaa...a011 32-byte NAPOT range
...
aa01...1111 2^XLEN-byte NAPOT range
a011...1111 2^(XLEN+1)-byte NAPOT range
0111...1111 2^(XLEN+2)-byte NAPOT range
1111...1111 Reserved
*/
if (a == -1) {
*sa = 0u;
*ea = -1;
return;
} else {
target_ulong t1 = ctz64(~a);
target_ulong base = (a & ~(((target_ulong)1 << t1) - 1)) << 2;
target_ulong range = ((target_ulong)1 << (t1 + 3)) - 1;
*sa = base;
*ea = base + range;
}
}
/* Convert cfg/addr reg values here into simple 'sa' --> start address and 'ea'
* end address values.
* This function is called relatively infrequently whereas the check that
* an address is within a pmp rule is called often, so optimise that one
*/
static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index)
{
int i;
env->pmp_state.num_rules = 0;
uint8_t this_cfg = env->pmp_state.pmp[pmp_index].cfg_reg;
target_ulong this_addr = env->pmp_state.pmp[pmp_index].addr_reg;
target_ulong prev_addr = 0u;
target_ulong sa = 0u;
target_ulong ea = 0u;
if (pmp_index >= 1u) {
prev_addr = env->pmp_state.pmp[pmp_index - 1].addr_reg;
}
switch (pmp_get_a_field(this_cfg)) {
case PMP_AMATCH_OFF:
sa = 0u;
ea = -1;
break;
case PMP_AMATCH_TOR:
sa = prev_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
ea = (this_addr << 2) - 1u;
break;
case PMP_AMATCH_NA4:
sa = this_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
ea = (this_addr + 4u) - 1u;
break;
case PMP_AMATCH_NAPOT:
pmp_decode_napot(this_addr, &sa, &ea);
break;
default:
sa = 0u;
ea = 0u;
break;
}
env->pmp_state.addr[pmp_index].sa = sa;
env->pmp_state.addr[pmp_index].ea = ea;
for (i = 0; i < MAX_RISCV_PMPS; i++) {
const uint8_t a_field =
pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
if (PMP_AMATCH_OFF != a_field) {
env->pmp_state.num_rules++;
}
}
}
static int pmp_is_in_range(CPURISCVState *env, int pmp_index, target_ulong addr)
{
int result = 0;
if ((addr >= env->pmp_state.addr[pmp_index].sa)
&& (addr <= env->pmp_state.addr[pmp_index].ea)) {
result = 1;
} else {
result = 0;
}
return result;
}
/*
* Public Interface
*/
/*
* Check if the address has required RWX privs to complete desired operation
*/
bool pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
target_ulong size, pmp_priv_t privs)
{
int i = 0;
int ret = -1;
target_ulong s = 0;
target_ulong e = 0;
pmp_priv_t allowed_privs = 0;
/* Short cut if no rules */
if (0 == pmp_get_num_rules(env)) {
return true;
}
/* 1.10 draft priv spec states there is an implicit order
from low to high */
for (i = 0; i < MAX_RISCV_PMPS; i++) {
s = pmp_is_in_range(env, i, addr);
e = pmp_is_in_range(env, i, addr + size);
/* partially inside */
if ((s + e) == 1) {
PMP_DEBUG("pmp violation - access is partially inside");
ret = 0;
break;
}
/* fully inside */
const uint8_t a_field =
pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
if ((s + e) == 2) {
if (PMP_AMATCH_OFF == a_field) {
return 1;
}
allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
if ((env->priv != PRV_M) || pmp_is_locked(env, i)) {
allowed_privs &= env->pmp_state.pmp[i].cfg_reg;
}
if ((privs & allowed_privs) == privs) {
ret = 1;
break;
} else {
ret = 0;
break;
}
}
}
/* No rule matched */
if (ret == -1) {
if (env->priv == PRV_M) {
ret = 1; /* Privileged spec v1.10 states if no PMP entry matches an
* M-Mode access, the access succeeds */
} else {
ret = 0; /* Other modes are not allowed to succeed if they don't
* match a rule, but there are rules. We've checked for
* no rule earlier in this function. */
}
}
return ret == 1 ? true : false;
}
/*
* Handle a write to a pmpcfg CSP
*/
void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
target_ulong val)
{
int i;
uint8_t cfg_val;
PMP_DEBUG("hart " TARGET_FMT_ld ": reg%d, val: 0x" TARGET_FMT_lx,
env->mhartid, reg_index, val);
if ((reg_index & 1) && (sizeof(target_ulong) == 8)) {
PMP_DEBUG("ignoring write - incorrect address");
return;
}
for (i = 0; i < sizeof(target_ulong); i++) {
cfg_val = (val >> 8 * i) & 0xff;
pmp_write_cfg(env, (reg_index * sizeof(target_ulong)) + i,
cfg_val);
}
}
/*
* Handle a read from a pmpcfg CSP
*/
target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
{
int i;
target_ulong cfg_val = 0;
target_ulong val = 0;
for (i = 0; i < sizeof(target_ulong); i++) {
val = pmp_read_cfg(env, (reg_index * sizeof(target_ulong)) + i);
cfg_val |= (val << (i * 8));
}
PMP_DEBUG("hart " TARGET_FMT_ld ": reg%d, val: 0x" TARGET_FMT_lx,
env->mhartid, reg_index, cfg_val);
return cfg_val;
}
/*
* Handle a write to a pmpaddr CSP
*/
void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
target_ulong val)
{
PMP_DEBUG("hart " TARGET_FMT_ld ": addr%d, val: 0x" TARGET_FMT_lx,
env->mhartid, addr_index, val);
if (addr_index < MAX_RISCV_PMPS) {
if (!pmp_is_locked(env, addr_index)) {
env->pmp_state.pmp[addr_index].addr_reg = val;
pmp_update_rule(env, addr_index);
} else {
PMP_DEBUG("ignoring write - locked");
}
} else {
PMP_DEBUG("ignoring write - out of bounds");
}
}
/*
* Handle a read from a pmpaddr CSP
*/
target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
{
PMP_DEBUG("hart " TARGET_FMT_ld ": addr%d, val: 0x" TARGET_FMT_lx,
env->mhartid, addr_index,
env->pmp_state.pmp[addr_index].addr_reg);
if (addr_index < MAX_RISCV_PMPS) {
return env->pmp_state.pmp[addr_index].addr_reg;
} else {
PMP_DEBUG("ignoring read - out of bounds");
return 0;
}
}
#endif
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