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authorSven Schnelle <svens@stackframe.org>2019-01-29 20:14:02 +0100
committerRichard Henderson <richard.henderson@linaro.org>2019-02-06 10:49:21 +0000
commit68aa851aa21741ab0a3c019b641d6ce72f68b3d5 (patch)
treed9e8ac235202070473020f2fcb63d0a59a839145 /target
parent5c41496dd780fed67eadd64c59fc2cf21717ecf0 (diff)
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>
Diffstat (limited to 'target')
-rw-r--r--target/hppa/op_helper.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/target/hppa/op_helper.c b/target/hppa/op_helper.c
index 912e8d5be4..6bf478e7b0 100644
--- a/target/hppa/op_helper.c
+++ b/target/hppa/op_helper.c
@@ -665,11 +665,15 @@ void HELPER(reset)(CPUHPPAState *env)
target_ureg HELPER(swap_system_mask)(CPUHPPAState *env, target_ureg nsm)
{
target_ulong psw = env->psw;
- /* ??? On second reading this condition simply seems
- to be undefined rather than a diagnosed trap. */
- if (nsm & ~psw & PSW_Q) {
- hppa_dynamic_excp(env, EXCP_ILL, GETPC());
- }
+ /*
+ * Setting the PSW Q bit to 1, if it was not already 1, is an
+ * undefined operation.
+ *
+ * However, HP-UX 10.20 does this with the SSM instruction.
+ * Tested this on HP9000/712 and HP9000/785/C3750 and both
+ * machines set the Q bit from 0 to 1 without an exception,
+ * so let this go without comment.
+ */
env->psw = (psw & ~PSW_SM) | (nsm & PSW_SM);
return psw & PSW_SM;
}