From: "Cédric Le Goater" <clg@kaod.org>
To: David Gibson <david@gibson.dropbear.id.au>, Greg Kurz <groug@kaod.org>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
"Cédric Le Goater" <clg@kaod.org>
Subject: [PATCH] target/ppc: Fix 64-bit decrementer
Date: Mon, 13 Sep 2021 18:27:58 +0200 [thread overview]
Message-ID: <20210913162758.3806730-1-clg@kaod.org> (raw)
The current way the mask is built can overflow with a 64-bit decrementer.
Use MAKE_64BIT_MASK instead.
Fixes: a8dafa525181 ("target/ppc: Implement large decrementer support for TCG")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
This was found with the QEMU Microwatt machine which uses a 64bit
decrementer. Here is an experimental tree:
https://github.com/legoater/qemu/tree/microwatt
hw/ppc/ppc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index 7375bf4fa910..a86125c50ff9 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -876,7 +876,7 @@ static void __cpu_ppc_store_decr(PowerPCCPU *cpu, uint64_t *nextp,
bool negative;
/* Truncate value to decr_width and sign extend for simplicity */
- value &= ((1ULL << nr_bits) - 1);
+ value &= MAKE_64BIT_MASK(0, nr_bits);
negative = !!(value & (1ULL << (nr_bits - 1)));
if (negative) {
value |= (0xFFFFFFFFULL << nr_bits);
--
2.31.1
next reply other threads:[~2021-09-13 16:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 16:27 Cédric Le Goater [this message]
2021-09-13 17:07 ` [PATCH] target/ppc: Fix 64-bit decrementer Philippe Mathieu-Daudé
2021-09-13 17:22 ` Luis Fernando Fujita Pires
2021-09-13 17:29 ` Luis Fernando Fujita Pires
2021-09-13 18:05 ` Luis Fernando Fujita Pires
2021-09-13 19:55 ` Cédric Le Goater
2021-09-13 20:19 ` Peter Maydell
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