target/arm: Remove CPSR_RESERVED

The only remaining use was in op_helper.c.  Use PSTATE_SS
directly, and move the commentary so that it is more obvious
what is going on.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200208125816.14954-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 694b07429838a0396efbcf8d3c567d277ba27ff2..c6dff1d55b6bf86b055efdb8c801c2b0a2cf4191 100644 (file)
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1186,12 +1186,6 @@ void pmu_init(ARMCPU *cpu);
 #define CPSR_IT_2_7 (0xfc00U)
 #define CPSR_GE (0xfU << 16)
 #define CPSR_IL (1U << 20)
-/* Note that the RESERVED bits include bit 21, which is PSTATE_SS in
- * an AArch64 SPSR but RES0 in AArch32 SPSR and CPSR. In QEMU we use
- * env->uncached_cpsr bit 21 to store PSTATE.SS when executing in AArch32,
- * where it is live state but not accessible to the AArch32 code.
- */
-#define CPSR_RESERVED (0x7U << 21)
 #define CPSR_J (1U << 24)
 #define CPSR_IT_0_1 (3U << 25)
 #define CPSR_Q (1U << 27)

diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index acf1815ea3e9631f6e8efe3a97ee4c4ae460f857..af3020b78f86bfa07a382ba790a021eff419c080 100644 (file)
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -387,7 +387,14 @@ void HELPER(exception_bkpt_insn)(CPUARMState *env, uint32_t syndrome)
 
 uint32_t HELPER(cpsr_read)(CPUARMState *env)
 {
-    return cpsr_read(env) & ~(CPSR_EXEC | CPSR_RESERVED);
+    /*
+     * We store the ARMv8 PSTATE.SS bit in env->uncached_cpsr.
+     * This is convenient for populating SPSR_ELx, but must be
+     * hidden from aarch32 mode, where it is not visible.
+     *
+     * TODO: ARMv8.4-DIT -- need to move SS somewhere else.
+     */
+    return cpsr_read(env) & ~(CPSR_EXEC | PSTATE_SS);
 }
 
 void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)