[v6,1/9] target/riscv: fix henvcfg potentially containing stale bits

Commit Message

Clément Léger Nov. 28, 2024, 2:12 p.m. UTC

With the current implementation, if we had the following scenario:
- Set bit x in menvcfg
- Set bit x in henvcfg
- Clear bit x in menvcfg
then, the internal variable env->henvcfg would still contain bit x due
to both a wrong menvcfg mask used in write_henvcfg() as well as a
missing update of henvcfg upon menvcfg update.
This can lead to some wrong interpretation of the context. In order to
update henvcfg upon menvcfg writing, call write_henvcfg() after writing
menvcfg. Clearing henvcfg upon writing the new value is also needed in
write_henvcfg() as well as clearing henvcfg upper part when writing it
with write_henvcfgh().

Signed-off-by: Clément Léger <[e-mail]>
---
 target/riscv/csr.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Patch

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 5d8d0d7514..98c683df60 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -2383,6 +2383,8 @@  static RISCVException read_menvcfg(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
+                                    target_ulong val);
 static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
                                     target_ulong val)
 {
@@ -2403,6 +2405,7 @@  static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
         }
     }
     env->menvcfg = (env->menvcfg & ~mask) | (val & mask);
+    write_henvcfg(env, CSR_HENVCFG, env->henvcfg);
 
     return RISCV_EXCP_NONE;
 }
@@ -2414,6 +2417,8 @@  static RISCVException read_menvcfgh(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static RISCVException write_henvcfgh(CPURISCVState *env, int csrno,
+                                    target_ulong val);
 static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
                                      target_ulong val)
 {
@@ -2424,6 +2429,7 @@  static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
     uint64_t valh = (uint64_t)val << 32;
 
     env->menvcfg = (env->menvcfg & ~mask) | (valh & mask);
+    write_henvcfgh(env, CSR_HENVCFGH, env->henvcfg >> 32);
 
     return RISCV_EXCP_NONE;
 }
@@ -2513,7 +2519,7 @@  static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
         }
     }
 
-    env->henvcfg = (env->henvcfg & ~mask) | (val & mask);
+    env->henvcfg = val & mask;
 
     return RISCV_EXCP_NONE;
 }
@@ -2546,7 +2552,7 @@  static RISCVException write_henvcfgh(CPURISCVState *env, int csrno,
         return ret;
     }
 
-    env->henvcfg = (env->henvcfg & ~mask) | (valh & mask);
+    env->henvcfg = (env->henvcfg & 0xFFFFFFFF) | (valh & mask);
     return RISCV_EXCP_NONE;
 }