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linux-user/aarch64: Choose SYNC as the preferred MTE mode

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The API does not generate an error for setting ASYNC | SYNC; that merely
constrains the selection vs the per-cpu default.  For qemu linux-user,
choose SYNC as the default.

Cc: qemu-stable@nongnu.org
Reported-by: Gustavo Romero <gustavo.romero@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Gustavo Romero <gustavo.romero@linaro.org>
Message-id: 20240207025210.8837-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 681dfc0d55)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Richard Henderson 2024-02-15 11:30:44 +00:00 committed by Michael Tokarev
parent 4971891b37
commit bbeeed7102
1 changed files with 17 additions and 12 deletions
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29
linux-user/aarch64/target_prctl.h
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@ -171,21 +171,26 @@ static abi_long do_prctl_set_tagged_addr_ctrl(CPUArchState *env, abi_long arg2)
env->tagged_addr_enable = arg2 & PR_TAGGED_ADDR_ENABLE;
if (cpu_isar_feature(aa64_mte, cpu)) {
switch (arg2 & PR_MTE_TCF_MASK) {
case PR_MTE_TCF_NONE:
case PR_MTE_TCF_SYNC:
case PR_MTE_TCF_ASYNC:
break;
default:
return -EINVAL;
}
/*
* Write PR_MTE_TCF to SCTLR_EL1[TCF0].
* Note that the syscall values are consistent with hw.
*
* 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.
*/
env->cp15.sctlr_el[1] =
deposit64(env->cp15.sctlr_el[1], 38, 2, arg2 >> PR_MTE_TCF_SHIFT);
unsigned tcf = 0;
if (arg2 & PR_MTE_TCF_SYNC) {
tcf = 1;
} else if (arg2 & PR_MTE_TCF_ASYNC) {
tcf = 2;
}
env->cp15.sctlr_el[1] = deposit64(env->cp15.sctlr_el[1], 38, 2, tcf);
/*
* Write PR_MTE_TAG to GCR_EL1[Exclude].