On 13/6/24 19:21, Gustavo Romero wrote:
Factor out the code used for setting the MTE TCF0 field from the prctl
code into a convenient function. Other subsystems, like gdbstub, need to
set this field as well, so keep it as a separate function to avoid
duplication and ensure consistency in how this field is set across the
board.
Signed-off-by: Gustavo Romero <gustavo.rom...@linaro.org>
---
linux-user/aarch64/target_prctl.h | 22 ++-----------
target/arm/mte.h | 53 +++++++++++++++++++++++++++++++
2 files changed, 55 insertions(+), 20 deletions(-)
create mode 100644 target/arm/mte.h
diff --git a/target/arm/mte.h b/target/arm/mte.h
new file mode 100644
index 0000000000..89712aad70
--- /dev/null
+++ b/target/arm/mte.h
@@ -0,0 +1,53 @@
+/*
+ * ARM MemTag convenience functions.
+ *
+ * Copyright (c) 2024 Linaro, Ltd.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MTE_H
+#define MTE_H
+
+#ifdef CONFIG_TCG
+#ifdef CONFIG_USER_ONLY
+#include "sys/prctl.h"
+
+static void set_mte_tcf0(CPUArchState *env, abi_long value)
Either declare it inlined (otherwise we'll get multiple symbols
declared if this header is included multiple times), or
preferably only expose the prototype.
Also I'd use the 'arm_' prefix.
+{
+ /*
+ * Write PR_MTE_TCF to SCTLR_EL1[TCF0].
+ *
+ * The kernel has a per-cpu configuration for the sysadmin,
+ * /sys/devices/system/cpu/cpu<N>/mte_tcf_preferred,
+ * which qemu does not implement.
+ *
+ * Because there is no performance difference between the modes, and
+ * because SYNC is most useful for debugging MTE errors, choose SYNC
+ * as the preferred mode. With this preference, and the way the API
+ * uses only two bits, there is no way for the program to select
+ * ASYMM mode.
+ */
+ unsigned tcf = 0;
+ if (value & PR_MTE_TCF_SYNC) {
+ tcf = 1;
+ } else if (value & PR_MTE_TCF_ASYNC) {
+ tcf = 2;
+ }
+ env->cp15.sctlr_el[1] = deposit64(env->cp15.sctlr_el[1], 38, 2, tcf);
+}
+#endif /* CONFIG_USER_ONLY */
+#endif /* CONFIG_TCG */
+
+#endif /* MTE_H */
