target-arm: implement SCTLR.B, drop bswap_code

bswap_code is a CPU property of sorts ("is the iside endianness the
opposite way round to TARGET_WORDS_BIGENDIAN?") but it is not the
actual CPU state involved here which is SCTLR.B (set for BE32
binaries, clear for BE8).

Replace bswap_code with SCTLR.B, and pass that to arm_ld*_code.
The next patches will make data fetches honor both SCTLR.B and
CPSR.E appropriately.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[PC changes:
 * rebased on master (Jan 2016)
 * s/TARGET_USER_ONLY/CONFIG_USER_ONLY
 * Use bswap_code() for disas_set_info() instead of raw sctlr_b
]
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 39 insertions, 8 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 744f052..61b8b03 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -478,9 +478,6 @@ typedef struct CPUARMState {
         uint32_t cregs[16];
     } iwmmxt;
 
-    /* For mixed endian mode.  */
-    bool bswap_code;
-
 #if defined(CONFIG_USER_ONLY)
     /* For usermode syscall translation.  */
     int eabi;
@@ -1898,6 +1895,19 @@ static inline bool arm_singlestep_active(CPUARMState *env)
         && arm_generate_debug_exceptions(env);
 }
 
+static inline bool arm_sctlr_b(CPUARMState *env)
+{
+    return
+        /* We need not implement SCTLR.ITD in user-mode emulation, so
+         * let linux-user ignore the fact that it conflicts with SCTLR_B.
+         * This lets people run BE32 binaries with "-cpu any".
+         */
+#ifndef CONFIG_USER_ONLY
+        !arm_feature(env, ARM_FEATURE_V7) &&
+#endif
+        (env->cp15.sctlr_el[1] & SCTLR_B) != 0;
+}
+
 #include "exec/cpu-all.h"
 
 /* Bit usage in the TB flags field: bit 31 indicates whether we are
@@ -1928,8 +1938,8 @@ static inline bool arm_singlestep_active(CPUARMState *env)
 #define ARM_TBFLAG_VFPEN_MASK       (1 << ARM_TBFLAG_VFPEN_SHIFT)
 #define ARM_TBFLAG_CONDEXEC_SHIFT   8
 #define ARM_TBFLAG_CONDEXEC_MASK    (0xff << ARM_TBFLAG_CONDEXEC_SHIFT)
-#define ARM_TBFLAG_BSWAP_CODE_SHIFT 16
-#define ARM_TBFLAG_BSWAP_CODE_MASK  (1 << ARM_TBFLAG_BSWAP_CODE_SHIFT)
+#define ARM_TBFLAG_SCTLR_B_SHIFT    16
+#define ARM_TBFLAG_SCTLR_B_MASK     (1 << ARM_TBFLAG_SCTLR_B_SHIFT)
 /* We store the bottom two bits of the CPAR as TB flags and handle
  * checks on the other bits at runtime
  */
@@ -1965,13 +1975,34 @@ static inline bool arm_singlestep_active(CPUARMState *env)
     (((F) & ARM_TBFLAG_VFPEN_MASK) >> ARM_TBFLAG_VFPEN_SHIFT)
 #define ARM_TBFLAG_CONDEXEC(F) \
     (((F) & ARM_TBFLAG_CONDEXEC_MASK) >> ARM_TBFLAG_CONDEXEC_SHIFT)
-#define ARM_TBFLAG_BSWAP_CODE(F) \
-    (((F) & ARM_TBFLAG_BSWAP_CODE_MASK) >> ARM_TBFLAG_BSWAP_CODE_SHIFT)
+#define ARM_TBFLAG_SCTLR_B(F) \
+    (((F) & ARM_TBFLAG_SCTLR_B_MASK) >> ARM_TBFLAG_SCTLR_B_SHIFT)
 #define ARM_TBFLAG_XSCALE_CPAR(F) \
     (((F) & ARM_TBFLAG_XSCALE_CPAR_MASK) >> ARM_TBFLAG_XSCALE_CPAR_SHIFT)
 #define ARM_TBFLAG_NS(F) \
     (((F) & ARM_TBFLAG_NS_MASK) >> ARM_TBFLAG_NS_SHIFT)
 
+static inline bool bswap_code(bool sctlr_b)
+{
+#ifdef CONFIG_USER_ONLY
+    /* BE8 (SCTLR.B = 0, TARGET_WORDS_BIGENDIAN = 1) is mixed endian.
+     * The invalid combination SCTLR.B=1/CPSR.E=1/TARGET_WORDS_BIGENDIAN=0
+     * would also end up as a mixed-endian mode with BE code, LE data.
+     */
+    return
+#ifdef TARGET_WORDS_BIGENDIAN
+        1 ^
+#endif
+        sctlr_b;
+#else
+    /* We do not implement BE32 mode for system-mode emulation, but
+     * anyway it would always do little-endian accesses with
+     * TARGET_WORDS_BIGENDIAN = 0.
+     */
+    return 0;
+#endif
+}
+
 /* Return the exception level to which FP-disabled exceptions should
  * be taken, or 0 if FP is enabled.
  */
@@ -2049,7 +2080,7 @@ static inline void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
             | (env->vfp.vec_len << ARM_TBFLAG_VECLEN_SHIFT)
             | (env->vfp.vec_stride << ARM_TBFLAG_VECSTRIDE_SHIFT)
             | (env->condexec_bits << ARM_TBFLAG_CONDEXEC_SHIFT)
-            | (env->bswap_code << ARM_TBFLAG_BSWAP_CODE_SHIFT);
+            | (arm_sctlr_b(env) << ARM_TBFLAG_SCTLR_B_SHIFT);
         if (!(access_secure_reg(env))) {
             *flags |= ARM_TBFLAG_NS_MASK;
         }