[Qemu-devel] [PATCH] RISC-V: Fix pmpcfg register indexing

[Luke Nelson <luke.r.nels@gmail.com>]

pmpcfg_csr_{read,write} do not correctly handle accesses to PMP
configurations 8 through 15 (CSR pmpcfg2) on RV64.

The current code computes the pmpcfg index using:

  (reg_index * sizeof(target_ulong))

This is incorrect on RV64.  For example, when reg_index is 2 (i.e.,
pmpcfg2), the computed configuration index will be 16-23, which
should be 8-15.

A correct way is to use (reg_index * 4) instead, which works for
both RV32 and RV64.

Cc: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
---
 target/riscv/pmp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 15a5366616..a1bee56c86 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -311,9 +311,8 @@ void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
     }
 
     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);
+        cfg_val = (val >> (i * 8)) & 0xff;
+        pmp_write_cfg(env, (reg_index * 4) + i, cfg_val);
     }
 }
 
@@ -328,7 +327,7 @@ target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
     target_ulong val = 0;
 
     for (i = 0; i < sizeof(target_ulong); i++) {
-        val = pmp_read_cfg(env, (reg_index * sizeof(target_ulong)) + i);
+        val = pmp_read_cfg(env, (reg_index * 4) + i);
         cfg_val |= (val << (i * 8));
     }
 
-- 
2.19.1