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[PATCH] target/riscv/pmp: fix NAPOT range computation overflow
From: |
Nicolas Pitre |
Subject: |
[PATCH] target/riscv/pmp: fix NAPOT range computation overflow |
Date: |
Fri, 8 Apr 2022 12:25:07 -0400 (EDT) |
There is an overflow with the current code where a pmpaddr value of
0x1fffffff is decoded as sa=0 and ea=0 whereas it should be sa=0 and
ea=0xffffffff.
Fix that by simplifying the computation. There is in fact no need for
ctz64() nor special case for -1 to achieve proper results.
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
---
This is in fact the same patch I posted yesterday but turns out its
scope is far more important than I initially thought.
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 81b61bb65c..151da3fa08 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -141,17 +141,9 @@ static void pmp_decode_napot(target_ulong a, target_ulong
*sa, target_ulong *ea)
0111...1111 2^(XLEN+2)-byte NAPOT range
1111...1111 Reserved
*/
- if (a == -1) {
- *sa = 0u;
- *ea = -1;
- return;
- } else {
- target_ulong t1 = ctz64(~a);
- target_ulong base = (a & ~(((target_ulong)1 << t1) - 1)) << 2;
- target_ulong range = ((target_ulong)1 << (t1 + 3)) - 1;
- *sa = base;
- *ea = base + range;
- }
+ a = (a << 2) | 0x3;
+ *sa = a & (a + 1);
+ *ea = a | (a + 1);
}
void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
- [PATCH] target/riscv/pmp: fix NAPOT range computation overflow,
Nicolas Pitre <=