From 40b200279c98ea0c223fa5a2bdeb4aee40d4e40e Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 30 Jun 2022 20:41:14 +0100 Subject: [PATCH] target/arm: Suppress debug exceptions when OS Lock set The "OS Lock" in the Arm debug architecture is a way for software to suppress debug exceptions while it is trying to power down a CPU and save the state of the breakpoint and watchpoint registers. In QEMU we implemented the support for writing the OS Lock bit via OSLAR_EL1 and reading it via OSLSR_EL1, but didn't implement the actual behaviour. The required behaviour with the OS Lock set is: * debug exceptions (apart from BKPT insns) are suppressed * some MDSCR_EL1 bits allow write access to the corresponding EDSCR external debug status register that they shadow (we can ignore this because we don't implement external debug) * similarly with the OSECCR_EL1 which shadows the EDECCR (but we don't implement OSECCR_EL1 anyway) Implement the missing behaviour of suppressing debug exceptions. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20220630194116.3438513-4-peter.maydell@linaro.org --- target/arm/debug_helper.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/target/arm/debug_helper.c b/target/arm/debug_helper.c index 9a78c1db96..691b9b74c4 100644 --- a/target/arm/debug_helper.c +++ b/target/arm/debug_helper.c @@ -142,6 +142,9 @@ static bool aa32_generate_debug_exceptions(CPUARMState *env) */ bool arm_generate_debug_exceptions(CPUARMState *env) { + if (env->cp15.oslsr_el1 & 1) { + return false; + } if (is_a64(env)) { return aa64_generate_debug_exceptions(env); } else { -- 2.11.4.GIT