[5/7] target/sparc: Handle bus errors in mmu_probe()

Commit Message

Peter Maydell Aug. 1, 2019, 6:30 p.m. UTC

Convert the mmu_probe() function to using address_space_ldl()
rather than ldl_phys(), so we can explicitly detect memory
transaction failures.

This makes no practical difference at the moment, because
ldl_phys() will return 0 on a transaction failure, and we
treat transaction failures and 0 PDEs identically. However
the spec says that MMU probe operations are supposed to
update the fault status registers, and if we ever implement
that we'll want to distinguish the difference. For the
moment, just add a TODO comment about the bug.

Signed-off-by: Peter Maydell <[e-mail]>
---
 target/sparc/mmu_helper.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

Comments

Richard Henderson Aug. 1, 2019, 8:40 p.m. UTC | #1

On 8/1/19 11:30 AM, Peter Maydell wrote:
> +    /*
> +     * TODO: MMU probe operations are supposed to set the fault
> +     * status registers, but we don't do this.
> +     */

Well, the todo should be using sparc_cpu_tlb_fill with probe=true, since this
function appears to be otherwise redundant.  Of course, there's currently a big
fixme for that as well.

In the meantime, this does one step better than before.
Reviewed-by: Richard Henderson <[e-mail]>


r~

Patch

diff --git a/target/sparc/mmu_helper.c b/target/sparc/mmu_helper.c
index 351055a09b1..d90aabfa4d2 100644
--- a/target/sparc/mmu_helper.c
+++ b/target/sparc/mmu_helper.c
@@ -287,11 +287,20 @@  target_ulong mmu_probe(CPUSPARCState *env, target_ulong address, int mmulev)
     CPUState *cs = env_cpu(env);
     hwaddr pde_ptr;
     uint32_t pde;
+    MemTxResult result;
+
+    /*
+     * TODO: MMU probe operations are supposed to set the fault
+     * status registers, but we don't do this.
+     */
 
     /* Context base + context number */
     pde_ptr = (hwaddr)(env->mmuregs[1] << 4) +
         (env->mmuregs[2] << 2);
-    pde = ldl_phys(cs->as, pde_ptr);
+    pde = address_space_ldl(cs->as, pde_ptr, MEMTXATTRS_UNSPECIFIED, &result);
+    if (result != MEMTX_OK) {
+        return 0;
+    }
 
     switch (pde & PTE_ENTRYTYPE_MASK) {
     default:
@@ -304,7 +313,11 @@  target_ulong mmu_probe(CPUSPARCState *env, target_ulong address, int mmulev)
             return pde;
         }
         pde_ptr = ((address >> 22) & ~3) + ((pde & ~3) << 4);
-        pde = ldl_phys(cs->as, pde_ptr);
+        pde = address_space_ldl(cs->as, pde_ptr,
+                                MEMTXATTRS_UNSPECIFIED, &result);
+        if (result != MEMTX_OK) {
+            return 0;
+        }
 
         switch (pde & PTE_ENTRYTYPE_MASK) {
         default:
@@ -318,7 +331,11 @@  target_ulong mmu_probe(CPUSPARCState *env, target_ulong address, int mmulev)
                 return pde;
             }
             pde_ptr = ((address & 0xfc0000) >> 16) + ((pde & ~3) << 4);
-            pde = ldl_phys(cs->as, pde_ptr);
+            pde = address_space_ldl(cs->as, pde_ptr,
+                                    MEMTXATTRS_UNSPECIFIED, &result);
+            if (result != MEMTX_OK) {
+                return 0;
+            }
 
             switch (pde & PTE_ENTRYTYPE_MASK) {
             default:
@@ -332,7 +349,11 @@  target_ulong mmu_probe(CPUSPARCState *env, target_ulong address, int mmulev)
                     return pde;
                 }
                 pde_ptr = ((address & 0x3f000) >> 10) + ((pde & ~3) << 4);
-                pde = ldl_phys(cs->as, pde_ptr);
+                pde = address_space_ldl(cs->as, pde_ptr,
+                                        MEMTXATTRS_UNSPECIFIED, &result);
+                if (result != MEMTX_OK) {
+                    return 0;
+                }
 
                 switch (pde & PTE_ENTRYTYPE_MASK) {
                 default: