[PATCH v3] target/riscv: Fix incorrect PTE merge in walk_pte

[Ralf Ramsauer]

Two non-subsequent PTEs can be mapped to subsequent paddrs. In this
case, walk_pte will erroneously merge them.

Enforce the split up, by tracking the virtual base address.

Let's say we have the mapping:
0x81200000 -> 0x89623000 (4K)
0x8120f000 -> 0x89624000 (4K)

Before, walk_pte would have shown:

vaddr            paddr            size             attr
---------------- ---------------- ---------------- -------
0000000081200000 0000000089623000 0000000000002000 rwxu-ad

as it only checks for subsequent paddrs. With this patch, it becomes:

vaddr            paddr            size             attr
---------------- ---------------- ---------------- -------
0000000081200000 0000000089623000 0000000000001000 rwxu-ad
000000008120f000 0000000089624000 0000000000001000 rwxu-ad

Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
---
[since v2: Adjust comment, rebased to latest master]

 target/riscv/monitor.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/target/riscv/monitor.c b/target/riscv/monitor.c
index 7efb4b62c1..17e63fab00 100644
--- a/target/riscv/monitor.c
+++ b/target/riscv/monitor.c
@@ -84,6 +84,7 @@ static void walk_pte(Monitor *mon, hwaddr base, target_ulong 
start,
 {
     hwaddr pte_addr;
     hwaddr paddr;
+    target_ulong last_start = -1;
     target_ulong pgsize;
     target_ulong pte;
     int ptshift;
@@ -111,12 +112,13 @@ static void walk_pte(Monitor *mon, hwaddr base, 
target_ulong start,
                  * A leaf PTE has been found
                  *
                  * If current PTE's permission bits differ from the last one,
-                 * or current PTE's ppn does not make a contiguous physical
-                 * address block together with the last one, print out the last
-                 * contiguous mapped block details.
+                 * or the current PTE breaks up a contiguous virtual or
+                 * physical mapping, address block together with the last one,
+                 * print out the last contiguous mapped block details.
                  */
                 if ((*last_attr != attr) ||
-                    (*last_paddr + *last_size != paddr)) {
+                    (*last_paddr + *last_size != paddr) ||
+                    (last_start + *last_size != start)) {
                     print_pte(mon, va_bits, *vbase, *pbase,
                               *last_paddr + *last_size - *pbase, *last_attr);
 
@@ -125,6 +127,7 @@ static void walk_pte(Monitor *mon, hwaddr base, 
target_ulong start,
                     *last_attr = attr;
                 }
 
+                last_start = start;
                 *last_paddr = paddr;
                 *last_size = pgsize;
             } else {
-- 
2.36.0