qemu

pmp.c (18779B)

---

 /*
  * 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/>.
  */
 
 #include "qemu/osdep.h"
 #include "qemu/log.h"
 #include "qapi/error.h"
 #include "cpu.h"
 #include "trace.h"
 #include "exec/exec-all.h"
 
 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;
     }
 
     return 0;
 }
 
 /*
  * Count the number of active rules.
  */
 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) {
         bool locked = true;
 
         if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
             /* mseccfg.RLB is set */
             if (MSECCFG_RLB_ISSET(env)) {
                 locked = false;
             }
 
             /* mseccfg.MML is not set */
             if (!MSECCFG_MML_ISSET(env) && !pmp_is_locked(env, pmp_index)) {
                 locked = false;
             }
 
             /* mseccfg.MML is set */
             if (MSECCFG_MML_ISSET(env)) {
                 /* not adding execute bit */
                 if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) != PMP_EXEC) {
                     locked = false;
                 }
                 /* shared region and not adding X bit */
                 if ((val & PMP_LOCK) != PMP_LOCK &&
                     (val & 0x7) != (PMP_WRITE | PMP_EXEC)) {
                     locked = false;
                 }
             }
         } else {
             if (!pmp_is_locked(env, pmp_index)) {
                 locked = false;
             }
         }
 
         if (locked) {
             qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
         } else {
             env->pmp_state.pmp[pmp_index].cfg_reg = val;
             pmp_update_rule(env, pmp_index);
         }
     } else {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "ignoring pmpcfg write - out of bounds\n");
     }
 }
 
 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
     */
     a = (a << 2) | 0x3;
     *sa = a & (a + 1);
     *ea = a | (a + 1);
 }
 
 void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
 {
     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;
         if (sa > ea) {
             sa = ea = 0u;
         }
         break;
 
     case PMP_AMATCH_NA4:
         sa = this_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
         ea = (sa + 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;
 }
 
 void pmp_update_rule_nums(CPURISCVState *env)
 {
     int i;
 
     env->pmp_state.num_rules = 0;
     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++;
         }
     }
 }
 
 /* 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)
 {
     pmp_update_rule_addr(env, pmp_index);
     pmp_update_rule_nums(env);
 }
 
 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;
 }
 
 /*
  * Check if the address has required RWX privs when no PMP entry is matched.
  */
 static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr,
     target_ulong size, pmp_priv_t privs, pmp_priv_t *allowed_privs,
     target_ulong mode)
 {
     bool ret;
 
     if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
         if (MSECCFG_MMWP_ISSET(env)) {
             /*
              * The Machine Mode Whitelist Policy (mseccfg.MMWP) is set
              * so we default to deny all, even for M-mode.
              */
             *allowed_privs = 0;
             return false;
         } else if (MSECCFG_MML_ISSET(env)) {
             /*
              * The Machine Mode Lockdown (mseccfg.MML) bit is set
              * so we can only execute code in M-mode with an applicable
              * rule. Other modes are disabled.
              */
             if (mode == PRV_M && !(privs & PMP_EXEC)) {
                 ret = true;
                 *allowed_privs = PMP_READ | PMP_WRITE;
             } else {
                 ret = false;
                 *allowed_privs = 0;
             }
 
             return ret;
         }
     }
 
     if ((!riscv_feature(env, RISCV_FEATURE_PMP)) || (mode == PRV_M)) {
         /*
          * Privileged spec v1.10 states if HW doesn't implement any PMP entry
          * or no PMP entry matches an M-Mode access, the access succeeds.
          */
         ret = true;
         *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
     } else {
         /*
          * 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.
          */
         ret = false;
         *allowed_privs = 0;
     }
 
     return ret;
 }
 
 
 /*
  * 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, pmp_priv_t *allowed_privs,
     target_ulong mode)
 {
     int i = 0;
     int ret = -1;
     int pmp_size = 0;
     target_ulong s = 0;
     target_ulong e = 0;
 
     /* Short cut if no rules */
     if (0 == pmp_get_num_rules(env)) {
         return pmp_hart_has_privs_default(env, addr, size, privs,
                                           allowed_privs, mode);
     }
 
     if (size == 0) {
         if (riscv_feature(env, RISCV_FEATURE_MMU)) {
             /*
              * If size is unknown (0), assume that all bytes
              * from addr to the end of the page will be accessed.
              */
             pmp_size = -(addr | TARGET_PAGE_MASK);
         } else {
             pmp_size = sizeof(target_ulong);
         }
     } else {
         pmp_size = size;
     }
 
     /* 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 + pmp_size - 1);
 
         /* partially inside */
         if ((s + e) == 1) {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "pmp violation - access is partially inside\n");
             ret = 0;
             break;
         }
 
         /* fully inside */
         const uint8_t a_field =
             pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
 
         /*
          * Convert the PMP permissions to match the truth table in the
          * ePMP spec.
          */
         const uint8_t epmp_operation =
             ((env->pmp_state.pmp[i].cfg_reg & PMP_LOCK) >> 4) |
             ((env->pmp_state.pmp[i].cfg_reg & PMP_READ) << 2) |
             (env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) |
             ((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2);
 
         if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) {
             /*
              * If the PMP entry is not off and the address is in range,
              * do the priv check
              */
             if (!MSECCFG_MML_ISSET(env)) {
                 /*
                  * If mseccfg.MML Bit is not set, do pmp priv check
                  * This will always apply to regular PMP.
                  */
                 *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
                 if ((mode != PRV_M) || pmp_is_locked(env, i)) {
                     *allowed_privs &= env->pmp_state.pmp[i].cfg_reg;
                 }
             } else {
                 /*
                  * If mseccfg.MML Bit set, do the enhanced pmp priv check
                  */
                 if (mode == PRV_M) {
                     switch (epmp_operation) {
                     case 0:
                     case 1:
                     case 4:
                     case 5:
                     case 6:
                     case 7:
                     case 8:
                         *allowed_privs = 0;
                         break;
                     case 2:
                     case 3:
                     case 14:
                         *allowed_privs = PMP_READ | PMP_WRITE;
                         break;
                     case 9:
                     case 10:
                         *allowed_privs = PMP_EXEC;
                         break;
                     case 11:
                     case 13:
                         *allowed_privs = PMP_READ | PMP_EXEC;
                         break;
                     case 12:
                     case 15:
                         *allowed_privs = PMP_READ;
                         break;
                     default:
                         g_assert_not_reached();
                     }
                 } else {
                     switch (epmp_operation) {
                     case 0:
                     case 8:
                     case 9:
                     case 12:
                     case 13:
                     case 14:
                         *allowed_privs = 0;
                         break;
                     case 1:
                     case 10:
                     case 11:
                         *allowed_privs = PMP_EXEC;
                         break;
                     case 2:
                     case 4:
                     case 15:
                         *allowed_privs = PMP_READ;
                         break;
                     case 3:
                     case 6:
                         *allowed_privs = PMP_READ | PMP_WRITE;
                         break;
                     case 5:
                         *allowed_privs = PMP_READ | PMP_EXEC;
                         break;
                     case 7:
                         *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
                         break;
                     default:
                         g_assert_not_reached();
                     }
                 }
             }
 
             ret = ((privs & *allowed_privs) == privs);
             break;
         }
     }
 
     /* No rule matched */
     if (ret == -1) {
         return pmp_hart_has_privs_default(env, addr, size, privs,
                                           allowed_privs, mode);
     }
 
     return ret == 1 ? true : false;
 }
 
 /*
  * Handle a write to a pmpcfg CSR
  */
 void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
     target_ulong val)
 {
     int i;
     uint8_t cfg_val;
     int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
 
     trace_pmpcfg_csr_write(env->mhartid, reg_index, val);
 
     for (i = 0; i < pmpcfg_nums; i++) {
         cfg_val = (val >> 8 * i)  & 0xff;
         pmp_write_cfg(env, (reg_index * 4) + i, cfg_val);
     }
 
     /* If PMP permission of any addr has been changed, flush TLB pages. */
     tlb_flush(env_cpu(env));
 }
 
 
 /*
  * Handle a read from a pmpcfg CSR
  */
 target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
 {
     int i;
     target_ulong cfg_val = 0;
     target_ulong val = 0;
     int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
 
     for (i = 0; i < pmpcfg_nums; i++) {
         val = pmp_read_cfg(env, (reg_index * 4) + i);
         cfg_val |= (val << (i * 8));
     }
     trace_pmpcfg_csr_read(env->mhartid, reg_index, cfg_val);
 
     return cfg_val;
 }
 
 
 /*
  * Handle a write to a pmpaddr CSR
  */
 void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
     target_ulong val)
 {
     trace_pmpaddr_csr_write(env->mhartid, addr_index, val);
 
     if (addr_index < MAX_RISCV_PMPS) {
         /*
          * In TOR mode, need to check the lock bit of the next pmp
          * (if there is a next).
          */
         if (addr_index + 1 < MAX_RISCV_PMPS) {
             uint8_t pmp_cfg = env->pmp_state.pmp[addr_index + 1].cfg_reg;
 
             if (pmp_cfg & PMP_LOCK &&
                 PMP_AMATCH_TOR == pmp_get_a_field(pmp_cfg)) {
                 qemu_log_mask(LOG_GUEST_ERROR,
                               "ignoring pmpaddr write - pmpcfg + 1 locked\n");
                 return;
             }
         }
 
         if (!pmp_is_locked(env, addr_index)) {
             env->pmp_state.pmp[addr_index].addr_reg = val;
             pmp_update_rule(env, addr_index);
         } else {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "ignoring pmpaddr write - locked\n");
         }
     } else {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "ignoring pmpaddr write - out of bounds\n");
     }
 }
 
 
 /*
  * Handle a read from a pmpaddr CSR
  */
 target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
 {
     target_ulong val = 0;
 
     if (addr_index < MAX_RISCV_PMPS) {
         val = env->pmp_state.pmp[addr_index].addr_reg;
         trace_pmpaddr_csr_read(env->mhartid, addr_index, val);
     } else {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "ignoring pmpaddr read - out of bounds\n");
     }
 
     return val;
 }
 
 /*
  * Handle a write to a mseccfg CSR
  */
 void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
 {
     int i;
 
     trace_mseccfg_csr_write(env->mhartid, val);
 
     /* RLB cannot be enabled if it's already 0 and if any regions are locked */
     if (!MSECCFG_RLB_ISSET(env)) {
         for (i = 0; i < MAX_RISCV_PMPS; i++) {
             if (pmp_is_locked(env, i)) {
                 val &= ~MSECCFG_RLB;
                 break;
             }
         }
     }
 
     /* Sticky bits */
     val |= (env->mseccfg & (MSECCFG_MMWP | MSECCFG_MML));
 
     env->mseccfg = val;
 }
 
 /*
  * Handle a read from a mseccfg CSR
  */
 target_ulong mseccfg_csr_read(CPURISCVState *env)
 {
     trace_mseccfg_csr_read(env->mhartid, env->mseccfg);
     return env->mseccfg;
 }
 
 /*
  * Calculate the TLB size if the start address or the end address of
  * PMP entry is presented in the TLB page.
  */
 static target_ulong pmp_get_tlb_size(CPURISCVState *env, int pmp_index,
                                      target_ulong tlb_sa, target_ulong tlb_ea)
 {
     target_ulong pmp_sa = env->pmp_state.addr[pmp_index].sa;
     target_ulong pmp_ea = env->pmp_state.addr[pmp_index].ea;
 
     if (pmp_sa >= tlb_sa && pmp_ea <= tlb_ea) {
         return pmp_ea - pmp_sa + 1;
     }
 
     if (pmp_sa >= tlb_sa && pmp_sa <= tlb_ea && pmp_ea >= tlb_ea) {
         return tlb_ea - pmp_sa + 1;
     }
 
     if (pmp_ea <= tlb_ea && pmp_ea >= tlb_sa && pmp_sa <= tlb_sa) {
         return pmp_ea - tlb_sa + 1;
     }
 
     return 0;
 }
 
 /*
  * Check is there a PMP entry which range covers this page. If so,
  * try to find the minimum granularity for the TLB size.
  */
 bool pmp_is_range_in_tlb(CPURISCVState *env, hwaddr tlb_sa,
                          target_ulong *tlb_size)
 {
     int i;
     target_ulong val;
     target_ulong tlb_ea = (tlb_sa + TARGET_PAGE_SIZE - 1);
 
     for (i = 0; i < MAX_RISCV_PMPS; i++) {
         val = pmp_get_tlb_size(env, i, tlb_sa, tlb_ea);
         if (val) {
             if (*tlb_size == 0 || *tlb_size > val) {
                 *tlb_size = val;
             }
         }
     }
 
     if (*tlb_size != 0) {
         /*
          * At this point we have a tlb_size that is the smallest possible size
          * That fits within a TARGET_PAGE_SIZE and the PMP region.
          *
          * If the size is less then TARGET_PAGE_SIZE we drop the size to 1.
          * This means the result isn't cached in the TLB and is only used for
          * a single translation.
          */
         if (*tlb_size < TARGET_PAGE_SIZE) {
             *tlb_size = 1;
         }
 
         return true;
     }
 
     return false;
 }
 
 /*
  * Convert PMP privilege to TLB page privilege.
  */
 int pmp_priv_to_page_prot(pmp_priv_t pmp_priv)
 {
     int prot = 0;
 
     if (pmp_priv & PMP_READ) {
         prot |= PAGE_READ;
     }
     if (pmp_priv & PMP_WRITE) {
         prot |= PAGE_WRITE;
     }
     if (pmp_priv & PMP_EXEC) {
         prot |= PAGE_EXEC;
     }
 
     return prot;
 }