target/hppa: fix PSW Q bit behaviour to match hardware
PA-RISC specification says: "Setting the PSW Q-bit, PSW{28}, to 1 with this instruction, if it was not already 1, is an undefined operation." However, at least HP-UX 10.20 sets the Q bit from 0 to 1 with the SSM instruction. Tested this both on HP9000/712 and HP9000/785/C3750, both machines set the Q bit from 0 to 1 without exception. This makes HP-UX 10.20 progress a little bit further. Signed-off-by: Sven Schnelle <svens@stackframe.org> Message-Id: <20190129191402.29539-1-svens@stackframe.org> [rth: Add a comment to the code as well.] Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@ -665,11 +665,15 @@ void HELPER(reset)(CPUHPPAState *env)
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target_ureg HELPER(swap_system_mask)(CPUHPPAState *env, target_ureg nsm)
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target_ureg HELPER(swap_system_mask)(CPUHPPAState *env, target_ureg nsm)
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{
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{
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target_ulong psw = env->psw;
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target_ulong psw = env->psw;
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/* ??? On second reading this condition simply seems
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/*
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to be undefined rather than a diagnosed trap. */
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* Setting the PSW Q bit to 1, if it was not already 1, is an
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if (nsm & ~psw & PSW_Q) {
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* undefined operation.
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hppa_dynamic_excp(env, EXCP_ILL, GETPC());
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*
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}
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* However, HP-UX 10.20 does this with the SSM instruction.
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* Tested this on HP9000/712 and HP9000/785/C3750 and both
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* machines set the Q bit from 0 to 1 without an exception,
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* so let this go without comment.
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*/
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env->psw = (psw & ~PSW_SM) | (nsm & PSW_SM);
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env->psw = (psw & ~PSW_SM) | (nsm & PSW_SM);
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return psw & PSW_SM;
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return psw & PSW_SM;
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}
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}
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