[Qemu-devel] [PATCH v3 03/11] target-arm: implement SCTLR.B, drop bswap_code

[Paolo Bonzini <pbonzini@redhat.com>]

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>
---
 linux-user/main.c          | 14 +++++++++++---
 target-arm/arm_ldst.h      |  8 ++++----
 target-arm/cpu.h           | 38 ++++++++++++++++++++++++++++++--------
 target-arm/helper.c        |  8 ++++----
 target-arm/translate-a64.c |  6 +++---
 target-arm/translate.c     | 14 +++++++-------
 target-arm/translate.h     |  2 +-
 7 files changed, 60 insertions(+), 30 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index fb6c2c0..dbaa42a 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -435,7 +435,7 @@ void cpu_loop(CPUX86State *env)
 
 #define get_user_code_u32(x, gaddr, env)                \
     ({ abi_long __r = get_user_u32((x), (gaddr));       \
-        if (!__r && (env)->bswap_code) {                \
+        if (!__r && bswap_code(arm_sctlr_b(env))) {     \
             (x) = bswap32(x);                           \
         }                                               \
         __r;                                            \
@@ -443,7 +443,7 @@ void cpu_loop(CPUX86State *env)
 
 #define get_user_code_u16(x, gaddr, env)                \
     ({ abi_long __r = get_user_u16((x), (gaddr));       \
-        if (!__r && (env)->bswap_code) {                \
+        if (!__r && bswap_code(arm_sctlr_b(env))) {     \
             (x) = bswap16(x);                           \
         }                                               \
         __r;                                            \
@@ -4191,11 +4191,19 @@ int main(int argc, char **argv, char **envp)
         for(i = 0; i < 16; i++) {
             env->regs[i] = regs->uregs[i];
         }
+#ifdef TARGET_WORDS_BIGENDIAN
         /* Enable BE8.  */
         if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4
             && (info->elf_flags & EF_ARM_BE8)) {
-            env->bswap_code = 1;
+            /* nothing for now, CPSR.E not emulated yet */
+        } else {
+            if (arm_feature(env, ARM_FEATURE_V7)) {
+                fprintf(stderr, "BE32 binaries only supported until ARMv6\n");
+                exit(1);
+            }
+            env->cp15.c1_sys |= SCTLR_B;
         }
+#endif
     }
 #elif defined(TARGET_UNICORE32)
     {
diff --git a/target-arm/arm_ldst.h b/target-arm/arm_ldst.h
index b1ece01..35c2c43 100644
--- a/target-arm/arm_ldst.h
+++ b/target-arm/arm_ldst.h
@@ -25,10 +25,10 @@
 
 /* Load an instruction and return it in the standard little-endian order */
 static inline uint32_t arm_ldl_code(CPUARMState *env, target_ulong addr,
-                                    bool do_swap)
+                                    bool sctlr_b)
 {
     uint32_t insn = cpu_ldl_code(env, addr);
-    if (do_swap) {
+    if (bswap_code(sctlr_b)) {
         return bswap32(insn);
     }
     return insn;
@@ -36,10 +36,10 @@ static inline uint32_t arm_ldl_code(CPUARMState *env, target_ulong addr,
 
 /* Ditto, for a halfword (Thumb) instruction */
 static inline uint16_t arm_lduw_code(CPUARMState *env, target_ulong addr,
-                                     bool do_swap)
+                                     bool sctlr_b)
 {
     uint16_t insn = cpu_lduw_code(env, addr);
-    if (do_swap) {
+    if (bswap_code(sctlr_b)) {
         return bswap16(insn);
     }
     return insn;
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 369d472..4a9d2a8 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -313,9 +313,6 @@ 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;
@@ -1132,8 +1129,8 @@ static inline int cpu_mmu_index (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)
 #define ARM_TBFLAG_CPACR_FPEN_SHIFT 17
 #define ARM_TBFLAG_CPACR_FPEN_MASK  (1 << ARM_TBFLAG_CPACR_FPEN_SHIFT)
 
@@ -1158,8 +1155,8 @@ static inline int cpu_mmu_index (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_CPACR_FPEN(F) \
     (((F) & ARM_TBFLAG_CPACR_FPEN_MASK) >> ARM_TBFLAG_CPACR_FPEN_SHIFT)
 #define ARM_TBFLAG_AA64_EL(F) \
@@ -1167,6 +1164,31 @@ static inline int cpu_mmu_index (CPUARMState *env)
 #define ARM_TBFLAG_AA64_FPEN(F) \
     (((F) & ARM_TBFLAG_AA64_FPEN_MASK) >> ARM_TBFLAG_AA64_FPEN_SHIFT)
 
+static inline bool arm_sctlr_b(CPUARMState *env)
+{
+    return !arm_feature(env, ARM_FEATURE_V7) && (env->cp15.c1_sys & SCTLR_B) != 0;
+}
+
+static inline bool bswap_code(bool sctlr_b)
+{
+#ifdef CONFIG_USER_ONLY
+    /* Mixed-endian modes are BE8 (SCTLR.B = 0, TARGET_WORDS_BIGENDIAN = 1)
+     * and "LE8" (SCTLR.B = 1, TARGET_WORDS_BIGENDIAN = 0).
+     */
+    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
+}
+
 static inline void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
                                         target_ulong *cs_base, int *flags)
 {
@@ -1186,7 +1208,7 @@ 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 (arm_feature(env, ARM_FEATURE_M)) {
             privmode = !((env->v7m.exception == 0) && (env->v7m.control & 1));
         } else {
diff --git a/target-arm/helper.c b/target-arm/helper.c
index ed4d2bb..6e4fc55 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -3312,7 +3312,7 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
     case EXCP_BKPT:
         if (semihosting_enabled) {
             int nr;
-            nr = arm_lduw_code(env, env->regs[15], env->bswap_code) & 0xff;
+            nr = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env)) & 0xff;
             if (nr == 0xab) {
                 env->regs[15] += 2;
                 env->regs[0] = do_arm_semihosting(env);
@@ -3387,10 +3387,10 @@ void arm_cpu_do_interrupt(CPUState *cs)
         if (semihosting_enabled) {
             /* Check for semihosting interrupt.  */
             if (env->thumb) {
-                mask = arm_lduw_code(env, env->regs[15] - 2, env->bswap_code)
+                mask = arm_lduw_code(env, env->regs[15] - 2, arm_sctlr_b(env))
                     & 0xff;
             } else {
-                mask = arm_ldl_code(env, env->regs[15] - 4, env->bswap_code)
+                mask = arm_ldl_code(env, env->regs[15] - 4, arm_sctlr_b(env))
                     & 0xffffff;
             }
             /* Only intercept calls from privileged modes, to provide some
@@ -3412,7 +3412,7 @@ void arm_cpu_do_interrupt(CPUState *cs)
     case EXCP_BKPT:
         /* See if this is a semihosting syscall.  */
         if (env->thumb && semihosting_enabled) {
-            mask = arm_lduw_code(env, env->regs[15], env->bswap_code) & 0xff;
+            mask = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env)) & 0xff;
             if (mask == 0xab
                   && (env->uncached_cpsr & CPSR_M) != ARM_CPU_MODE_USR) {
                 env->regs[15] += 2;
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 33b5025..e4115ba 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -10786,7 +10786,7 @@ static void disas_a64_insn(CPUARMState *env, DisasContext *s)
 {
     uint32_t insn;
 
-    insn = arm_ldl_code(env, s->pc, s->bswap_code);
+    insn = arm_ldl_code(env, s->pc, s->sctlr_b);
     s->insn = insn;
     s->pc += 4;
 
@@ -10853,7 +10853,7 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
 
     dc->aarch64 = 1;
     dc->thumb = 0;
-    dc->bswap_code = 0;
+    dc->sctlr_b = 0;
     dc->condexec_mask = 0;
     dc->condexec_cond = 0;
 #if !defined(CONFIG_USER_ONLY)
@@ -10988,7 +10988,7 @@ done_generating:
         qemu_log("----------------\n");
         qemu_log("IN: %s\n", lookup_symbol(pc_start));
         log_target_disas(env, pc_start, dc->pc - pc_start,
-                         4 | (dc->bswap_code << 1));
+                         4 | (dc->sctlr_b << 1));
         qemu_log("\n");
     }
 #endif
diff --git a/target-arm/translate.c b/target-arm/translate.c
index cf4e767..460150d 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -7484,7 +7484,7 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s)
     TCGv_i32 addr;
     TCGv_i64 tmp64;
 
-    insn = arm_ldl_code(env, s->pc, s->bswap_code);
+    insn = arm_ldl_code(env, s->pc, s->sctlr_b);
     s->pc += 4;
 
     /* M variants do not implement ARM mode.  */
@@ -7552,7 +7552,7 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s)
         if ((insn & 0x0ffffdff) == 0x01010000) {
             ARCH(6);
             /* setend */
-            if (((insn >> 9) & 1) != s->bswap_code) {
+            if (((insn >> 9) & 1) != bswap_code(s->sctlr_b)) {
                 /* Dynamic endianness switching not implemented. */
                 qemu_log_mask(LOG_UNIMP, "arm: unimplemented setend\n");
                 goto illegal_op;
@@ -9024,7 +9024,7 @@ static int disas_thumb2_insn(CPUARMState *env, DisasContext *s, uint16_t insn_hw
         /* Fall through to 32-bit decode.  */
     }
 
-    insn = arm_lduw_code(env, s->pc, s->bswap_code);
+    insn = arm_lduw_code(env, s->pc, s->sctlr_b);
     s->pc += 2;
     insn |= (uint32_t)insn_hw1 << 16;
 
@@ -10149,7 +10149,7 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
         }
     }
 
-    insn = arm_lduw_code(env, s->pc, s->bswap_code);
+    insn = arm_lduw_code(env, s->pc, s->sctlr_b);
     s->pc += 2;
 
     switch (insn >> 12) {
@@ -10719,7 +10719,7 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
             case 2:
                 /* setend */
                 ARCH(6);
-                if (((insn >> 3) & 1) != s->bswap_code) {
+                if (((insn >> 3) & 1) != bswap_code(s->sctlr_b)) {
                     /* Dynamic endianness switching not implemented. */
                     qemu_log_mask(LOG_UNIMP, "arm: unimplemented setend\n");
                     goto illegal_op;
@@ -10899,7 +10899,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
 
     dc->aarch64 = 0;
     dc->thumb = ARM_TBFLAG_THUMB(tb->flags);
-    dc->bswap_code = ARM_TBFLAG_BSWAP_CODE(tb->flags);
+    dc->sctlr_b = ARM_TBFLAG_SCTLR_B(tb->flags);
     dc->condexec_mask = (ARM_TBFLAG_CONDEXEC(tb->flags) & 0xf) << 1;
     dc->condexec_cond = ARM_TBFLAG_CONDEXEC(tb->flags) >> 4;
 #if !defined(CONFIG_USER_ONLY)
@@ -11142,7 +11142,7 @@ done_generating:
         qemu_log("----------------\n");
         qemu_log("IN: %s\n", lookup_symbol(pc_start));
         log_target_disas(env, pc_start, dc->pc - pc_start,
-                         dc->thumb | (dc->bswap_code << 1));
+                         dc->thumb | (dc->sctlr_b << 1));
         qemu_log("\n");
     }
 #endif
diff --git a/target-arm/translate.h b/target-arm/translate.h
index 31a0104..19f794c 100644
--- a/target-arm/translate.h
+++ b/target-arm/translate.h
@@ -16,7 +16,7 @@ typedef struct DisasContext {
     struct TranslationBlock *tb;
     int singlestep_enabled;
     int thumb;
-    int bswap_code;
+    int sctlr_b;
 #if !defined(CONFIG_USER_ONLY)
     int user;
 #endif
-- 
1.9.3