[Qemu-devel] [PATCH 18/26] target-xtensa: implement windowed registers

[Max Filippov <jcmvbkbc@gmail.com>]

See ISA, 4.7.1 for details.

Physical registers and currently visible window are separate fields in
CPUEnv. Only current window is accessible to TCG. On operations that
change window base helpers copy current window to and from physical
registers.

Window overflow check described in 4.7.1.3 is in separate patch.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 target-xtensa/cpu.h       |    8 ++
 target-xtensa/helper.c    |    1 +
 target-xtensa/helpers.h   |    8 ++
 target-xtensa/op_helper.c |  185 +++++++++++++++++++++++++++++++++++++++++++++
 target-xtensa/translate.c |  146 +++++++++++++++++++++++++++++++++--
 5 files changed, 339 insertions(+), 9 deletions(-)

diff --git a/target-xtensa/cpu.h b/target-xtensa/cpu.h
index 52fcf18..223535c 100644
--- a/target-xtensa/cpu.h
+++ b/target-xtensa/cpu.h
@@ -108,6 +108,8 @@ enum {
 enum {
     SAR = 3,
     SCOMPARE1 = 12,
+    WINDOW_BASE = 72,
+    WINDOW_START = 73,
     EPC1 = 177,
     DEPC = 192,
     EXCSAVE1 = 209,
@@ -134,6 +136,8 @@ enum {
 
 #define PS_WOE 0x40000
 
+#define MAX_NAREG 64
+
 enum {
     /* Static vectors */
     EXC_RESET,
@@ -185,6 +189,7 @@ enum {
 typedef struct XtensaConfig {
     const char *name;
     uint64_t options;
+    unsigned nareg;
     int excm_level;
     int ndepc;
     uint32_t exception_vector[EXC_MAX];
@@ -196,6 +201,7 @@ typedef struct CPUXtensaState {
     uint32_t pc;
     uint32_t sregs[256];
     uint32_t uregs[256];
+    uint32_t phys_regs[MAX_NAREG];
 
     int exception_taken;
 
@@ -214,6 +220,8 @@ int cpu_xtensa_exec(CPUXtensaState *s);
 void do_interrupt(CPUXtensaState *s);
 int cpu_xtensa_signal_handler(int host_signum, void *pinfo, void *puc);
 void xtensa_cpu_list(FILE *f, fprintf_function cpu_fprintf);
+void xtensa_sync_window_from_phys(CPUState *env);
+void xtensa_sync_phys_from_window(CPUState *env);
 
 static inline int xtensa_option_enabled(const XtensaConfig *config, int opt)
 {
diff --git a/target-xtensa/helper.c b/target-xtensa/helper.c
index db61bbb..0eb3b9a 100644
--- a/target-xtensa/helper.c
+++ b/target-xtensa/helper.c
@@ -45,6 +45,7 @@ static const XtensaConfig core_config[] = {
     {
         .name = "sample-xtensa-core",
         .options = -1,
+        .nareg = 64,
         .ndepc = 1,
         .excm_level = 16,
         .exception_vector = {
diff --git a/target-xtensa/helpers.h b/target-xtensa/helpers.h
index 6329c43..0971fde 100644
--- a/target-xtensa/helpers.h
+++ b/target-xtensa/helpers.h
@@ -5,5 +5,13 @@ DEF_HELPER_2(exception_cause, void, i32, i32)
 DEF_HELPER_3(exception_cause_vaddr, void, i32, i32, i32)
 DEF_HELPER_1(nsa, i32, i32)
 DEF_HELPER_1(nsau, i32, i32)
+DEF_HELPER_1(wsr_windowbase, void, i32)
+DEF_HELPER_3(entry, void, i32, i32, i32)
+DEF_HELPER_1(retw, i32, i32)
+DEF_HELPER_1(rotw, void, i32)
+DEF_HELPER_2(window_check, void, i32, i32)
+DEF_HELPER_0(restore_owb, void)
+DEF_HELPER_1(movsp, void, i32)
+DEF_HELPER_0(dump_state, void)
 
 #include "def-helper.h"
diff --git a/target-xtensa/op_helper.c b/target-xtensa/op_helper.c
index c10671a..61d82cf 100644
--- a/target-xtensa/op_helper.c
+++ b/target-xtensa/op_helper.c
@@ -99,3 +99,188 @@ uint32_t HELPER(nsau)(uint32_t v)
 {
     return v ? clz32(v) : 32;
 }
+
+static void copy_window_from_phys(CPUState *env,
+        uint32_t window, uint32_t phys, uint32_t n)
+{
+    assert(phys < env->config->nareg);
+    if (phys + n <= env->config->nareg) {
+        memcpy(env->regs + window, env->phys_regs + phys,
+                n * sizeof(uint32_t));
+    } else {
+        uint32_t n1 = env->config->nareg - phys;
+        memcpy(env->regs + window, env->phys_regs + phys,
+                n1 * sizeof(uint32_t));
+        memcpy(env->regs + window + n1, env->phys_regs,
+                (n - n1) * sizeof(uint32_t));
+    }
+}
+
+static void copy_phys_from_window(CPUState *env,
+        uint32_t phys, uint32_t window, uint32_t n)
+{
+    assert(phys < env->config->nareg);
+    if (phys + n <= env->config->nareg) {
+        memcpy(env->phys_regs + phys, env->regs + window,
+                n * sizeof(uint32_t));
+    } else {
+        uint32_t n1 = env->config->nareg - phys;
+        memcpy(env->phys_regs + phys, env->regs + window,
+                n1 * sizeof(uint32_t));
+        memcpy(env->phys_regs, env->regs + window + n1,
+                (n - n1) * sizeof(uint32_t));
+    }
+}
+
+
+#define WINDOWBASE_BOUND(a) ((a) & (env->config->nareg / 4 - 1))
+#define WINDOW_BOUND(a) ((a) & (env->config->nareg - 1))
+#define WINDOWSTART_BIT(a) (1 << WINDOWBASE_BOUND(a))
+
+void xtensa_sync_window_from_phys(CPUState *env)
+{
+    copy_window_from_phys(env, 0, env->sregs[WINDOW_BASE] * 4, 16);
+}
+
+void xtensa_sync_phys_from_window(CPUState *env)
+{
+    copy_phys_from_window(env, env->sregs[WINDOW_BASE] * 4, 0, 16);
+}
+
+static void rotate_window_abs(uint32_t position)
+{
+    xtensa_sync_phys_from_window(env);
+    env->sregs[WINDOW_BASE] = WINDOWBASE_BOUND(position);
+    xtensa_sync_window_from_phys(env);
+}
+
+static void rotate_window(uint32_t delta)
+{
+    rotate_window_abs(env->sregs[WINDOW_BASE] + delta);
+}
+
+void HELPER(wsr_windowbase)(uint32_t v)
+{
+    rotate_window_abs(v);
+}
+
+void HELPER(entry)(uint32_t pc, uint32_t s, uint32_t imm)
+{
+    int callinc = (env->sregs[PS] & PS_CALLINC) >> PS_CALLINC_SHIFT;
+    if (s > 3 || ((env->sregs[PS] & (PS_WOE | PS_EXCM)) ^ PS_WOE) != 0) {
+        qemu_log("Illegal entry instruction(pc = %08x), PS = %08x\n",
+                pc, env->sregs[PS]);
+        HELPER(exception_cause)(pc, ILLEGAL_INSTRUCTION_CAUSE);
+    } else {
+        env->regs[(callinc << 2) | (s & 3)] = env->regs[s] - (imm << 3);
+        rotate_window(callinc);
+        env->sregs[WINDOW_START] |= WINDOWSTART_BIT(env->sregs[WINDOW_BASE]);
+    }
+}
+
+void HELPER(window_check)(uint32_t pc, uint32_t w)
+{
+    uint32_t windowbase = WINDOWBASE_BOUND(env->sregs[WINDOW_BASE]);
+    uint32_t windowstart = env->sregs[WINDOW_START];
+    uint32_t m, n;
+
+    if ((env->sregs[PS] & (PS_WOE | PS_EXCM)) ^ PS_WOE) {
+        return;
+    }
+
+    for (n = 1; ; ++n) {
+        if (n > w) {
+            return;
+        }
+        if (windowstart & WINDOWSTART_BIT(windowbase + n)) {
+            break;
+        }
+    }
+
+    m = WINDOWBASE_BOUND(windowbase + n);
+    rotate_window(n);
+    env->sregs[PS] = (env->sregs[PS] & ~PS_OWB) |
+        (windowbase << PS_OWB_SHIFT) | PS_EXCM;
+    env->sregs[EPC1] = env->pc = pc;
+
+    if (windowstart & WINDOWSTART_BIT(m + 1)) {
+        HELPER(exception)(EXC_WINDOW_OVERFLOW4);
+    } else if (windowstart & WINDOWSTART_BIT(m + 2)) {
+        HELPER(exception)(EXC_WINDOW_OVERFLOW8);
+    } else {
+        HELPER(exception)(EXC_WINDOW_OVERFLOW12);
+    }
+}
+
+uint32_t HELPER(retw)(uint32_t pc)
+{
+    int n = (env->regs[0] >> 30) & 0x3;
+    int m = 0;
+    uint32_t windowbase = WINDOWBASE_BOUND(env->sregs[WINDOW_BASE]);
+    uint32_t windowstart = env->sregs[WINDOW_START];
+    uint32_t ret_pc = 0;
+
+    if (windowstart & WINDOWSTART_BIT(windowbase - 1)) {
+        m = 1;
+    } else if (windowstart & WINDOWSTART_BIT(windowbase - 2)) {
+        m = 2;
+    } else if (windowstart & WINDOWSTART_BIT(windowbase - 3)) {
+        m = 3;
+    }
+
+    if (n == 0 || (m != 0 && m != n) ||
+            ((env->sregs[PS] & (PS_WOE | PS_EXCM)) ^ PS_WOE) != 0) {
+        qemu_log("Illegal retw instruction(pc = %08x), "
+                "PS = %08x, m = %d, n = %d\n",
+                pc, env->sregs[PS], m, n);
+        HELPER(exception_cause)(pc, ILLEGAL_INSTRUCTION_CAUSE);
+    } else {
+        int owb = windowbase;
+
+        ret_pc = (pc & 0xc0000000) | (env->regs[0] & 0x3fffffff);
+
+        rotate_window(-n);
+        if (windowstart & WINDOWSTART_BIT(env->sregs[WINDOW_BASE])) {
+            env->sregs[WINDOW_START] &= ~WINDOWSTART_BIT(owb);
+        } else {
+            /* window underflow */
+            env->sregs[PS] = (env->sregs[PS] & ~PS_OWB) |
+                (windowbase << PS_OWB_SHIFT) | PS_EXCM;
+            env->sregs[EPC1] = env->pc = pc;
+
+            if (n == 1) {
+                HELPER(exception)(EXC_WINDOW_UNDERFLOW4);
+            } else if (n == 2) {
+                HELPER(exception)(EXC_WINDOW_UNDERFLOW8);
+            } else if (n == 3) {
+                HELPER(exception)(EXC_WINDOW_UNDERFLOW12);
+            }
+        }
+    }
+    return ret_pc;
+}
+
+void HELPER(rotw)(uint32_t imm4)
+{
+    rotate_window(imm4);
+}
+
+void HELPER(restore_owb)(void)
+{
+    rotate_window_abs((env->sregs[PS] & PS_OWB) >> PS_OWB_SHIFT);
+}
+
+void HELPER(movsp)(uint32_t pc)
+{
+    if ((env->sregs[WINDOW_START] &
+            (WINDOWSTART_BIT(env->sregs[WINDOW_BASE] - 3) |
+             WINDOWSTART_BIT(env->sregs[WINDOW_BASE] - 2) |
+             WINDOWSTART_BIT(env->sregs[WINDOW_BASE] - 1))) == 0) {
+        HELPER(exception_cause)(pc, ALLOCA_CAUSE);
+    }
+}
+
+void HELPER(dump_state)(void)
+{
+    cpu_dump_state(env, stderr, fprintf, 0);
+}
diff --git a/target-xtensa/translate.c b/target-xtensa/translate.c
index 8933e5a..323d67b 100644
--- a/target-xtensa/translate.c
+++ b/target-xtensa/translate.c
@@ -66,6 +66,8 @@ static TCGv_i32 cpu_UR[256];
 static const char * const sregnames[256] = {
     [SAR] = "SAR",
     [SCOMPARE1] = "SCOMPARE1",
+    [WINDOW_BASE] = "WINDOW_BASE",
+    [WINDOW_START] = "WINDOW_START",
     [EPC1] = "EPC1",
     [DEPC] = "DEPC",
     [EXCSAVE1] = "EXCSAVE1",
@@ -207,6 +209,34 @@ static void gen_jumpi(DisasContext *dc, uint32_t dest, int slot)
     tcg_temp_free(tmp);
 }
 
+static void gen_callw_slot(DisasContext *dc, int _callinc, TCGv_i32 dest,
+        int slot)
+{
+    TCGv_i32 callinc = tcg_const_i32(_callinc);
+
+    tcg_gen_deposit_i32(cpu_SR[PS], cpu_SR[PS],
+            callinc, PS_CALLINC_SHIFT, PS_CALLINC_LEN);
+    tcg_temp_free(callinc);
+    tcg_gen_movi_i32(cpu_R[_callinc << 2],
+            (_callinc << 30) | (dc->next_pc & 0x3fffffff));
+    gen_jump_slot(dc, dest, slot);
+}
+
+static void gen_callw(DisasContext *dc, int callinc, TCGv_i32 dest)
+{
+    gen_callw_slot(dc, callinc, dest, -1);
+}
+
+static void gen_callwi(DisasContext *dc, int callinc, uint32_t dest, int slot)
+{
+    TCGv_i32 tmp = tcg_const_i32(dest);
+    if (((dc->pc ^ dest) & TARGET_PAGE_MASK) != 0) {
+        slot = -1;
+    }
+    gen_callw_slot(dc, callinc, tmp, slot);
+    tcg_temp_free(tmp);
+}
+
 static void gen_brcond(DisasContext *dc, TCGCond cond,
         TCGv_i32 t0, TCGv_i32 t1, uint32_t offset)
 {
@@ -253,11 +283,17 @@ static void gen_wsr_sar(DisasContext *dc, uint32_t sr, TCGv_i32 s)
     dc->sar_m32_5bit = false;
 }
 
+static void gen_wsr_windowbase(DisasContext *dc, uint32_t sr, TCGv_i32 v)
+{
+    gen_helper_wsr_windowbase(v);
+}
+
 static void gen_wsr(DisasContext *dc, uint32_t sr, TCGv_i32 s)
 {
     static void (* const wsr_handler[256])(DisasContext *dc,
             uint32_t sr, TCGv_i32 v) = {
         [SAR] = gen_wsr_sar,
+        [WINDOW_BASE] = gen_wsr_windowbase,
     };
 
     if (sregnames[sr]) {
@@ -405,7 +441,12 @@ static void disas_xtensa_insn(DisasContext *dc)
 
                         case 1: /*RETWw*/
                             HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                            TBD();
+                            {
+                                TCGv_i32 tmp = tcg_const_i32(dc->pc);
+                                gen_helper_retw(tmp, tmp);
+                                gen_jump(dc, tmp);
+                                tcg_temp_free(tmp);
+                            }
                             break;
 
                         case 3: /*reserved*/
@@ -430,7 +471,13 @@ static void disas_xtensa_insn(DisasContext *dc)
                         case 2: /*CALLX8w*/
                         case 3: /*CALLX12w*/
                             HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                            TBD();
+                            {
+                                TCGv_i32 tmp = tcg_temp_new_i32();
+
+                                tcg_gen_mov_i32(tmp, cpu_R[CALLX_S]);
+                                gen_callw(dc, CALLX_N, tmp);
+                                tcg_temp_free(tmp);
+                            }
                             break;
                         }
                         break;
@@ -439,7 +486,12 @@ static void disas_xtensa_insn(DisasContext *dc)
 
                 case 1: /*MOVSPw*/
                     HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                    TBD();
+                    {
+                        TCGv_i32 pc = tcg_const_i32(dc->pc);
+                        gen_helper_movsp(pc);
+                        tcg_gen_mov_i32(cpu_R[RRR_T], cpu_R[RRR_S]);
+                        tcg_temp_free(pc);
+                    }
                     break;
 
                 case 2: /*SYNC*/
@@ -499,7 +551,27 @@ static void disas_xtensa_insn(DisasContext *dc)
                         case 4: /*RFWOw*/
                         case 5: /*RFWUw*/
                             HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                            TBD();
+                            gen_check_privilege(dc);
+                            {
+                                TCGv_i32 tmp = tcg_const_i32(1);
+
+                                tcg_gen_andi_i32(
+                                        cpu_SR[PS], cpu_SR[PS], ~PS_EXCM);
+                                tcg_gen_shl_i32(tmp, tmp, cpu_SR[WINDOW_BASE]);
+
+                                if (RRR_S == 4) {
+                                    tcg_gen_andc_i32(cpu_SR[WINDOW_START],
+                                            cpu_SR[WINDOW_START], tmp);
+                                } else {
+                                    tcg_gen_or_i32(cpu_SR[WINDOW_START],
+                                            cpu_SR[WINDOW_START], tmp);
+                                }
+
+                                gen_helper_restore_owb();
+                                gen_jump(dc, cpu_SR[EPC1]);
+
+                                tcg_temp_free(tmp);
+                            }
                             break;
 
                         default: /*reserved*/
@@ -646,7 +718,13 @@ static void disas_xtensa_insn(DisasContext *dc)
 
                 case 8: /*ROTWw*/
                     HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                    TBD();
+                    gen_check_privilege(dc);
+                    {
+                        TCGv_i32 tmp = tcg_const_i32(
+                                RRR_T | ((RRR_T & 8) ? 0xfffffff0 : 0));
+                        gen_helper_rotw(tmp);
+                        tcg_temp_free(tmp);
+                    }
                     break;
 
                 case 14: /*NSAu*/
@@ -1088,7 +1166,37 @@ static void disas_xtensa_insn(DisasContext *dc)
             break;
 
         case 9: /*LSC4*/
-            TBD();
+            switch (_OP2) {
+            case 0: /*L32E*/
+                HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
+                gen_check_privilege(dc);
+                {
+                    TCGv_i32 addr = tcg_temp_new_i32();
+                    tcg_gen_addi_i32(addr, cpu_R[RRR_S],
+                            (0xffffffc0 | (RRR_R << 2)));
+                    /*TODO protection control*/
+                    tcg_gen_qemu_ld32u(cpu_R[RRR_T], addr, 0);
+                    tcg_temp_free(addr);
+                }
+                break;
+
+            case 4: /*S32E*/
+                HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
+                gen_check_privilege(dc);
+                {
+                    TCGv_i32 addr = tcg_temp_new_i32();
+                    tcg_gen_addi_i32(addr, cpu_R[RRR_S],
+                            (0xffffffc0 | (RRR_R << 2)));
+                    /*TODO protection control*/
+                    tcg_gen_qemu_st32(cpu_R[RRR_T], addr, 0);
+                    tcg_temp_free(addr);
+                }
+                break;
+
+            default:
+                RESERVED();
+                break;
+            }
             break;
 
         case 10: /*FP0*/
@@ -1326,7 +1434,8 @@ static void disas_xtensa_insn(DisasContext *dc)
         case 2: /*CALL8w*/
         case 3: /*CALL12w*/
             HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-            TBD();
+            gen_callwi(dc, CALL_N,
+                    (dc->pc & ~3) + (CALL_OFFSET_SE << 2) + 4, 0);
             break;
         }
         break;
@@ -1369,7 +1478,15 @@ static void disas_xtensa_insn(DisasContext *dc)
             switch (BRI8_M) {
             case 0: /*ENTRYw*/
                 HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                TBD();
+                {
+                    TCGv_i32 pc = tcg_const_i32(dc->pc);
+                    TCGv_i32 s = tcg_const_i32(BRI12_S);
+                    TCGv_i32 imm = tcg_const_i32(BRI12_IMM12);
+                    gen_helper_entry(pc, s, imm);
+                    tcg_temp_free(imm);
+                    tcg_temp_free(s);
+                    tcg_temp_free(pc);
+                }
                 break;
 
             case 1: /*B1*/
@@ -1534,7 +1651,12 @@ static void disas_xtensa_insn(DisasContext *dc)
 
             case 1: /*RETW.Nn*/
                 HAS_OPTION(XTENSA_OPTION_WINDOWED_REGISTER);
-                TBD();
+                {
+                    TCGv_i32 tmp = tcg_const_i32(dc->pc);
+                    gen_helper_retw(tmp, tmp);
+                    gen_jump(dc, tmp);
+                    tcg_temp_free(tmp);
+                }
                 break;
 
             case 2: /*BREAK.Nn*/
@@ -1701,6 +1823,12 @@ void cpu_dump_state(CPUState *env, FILE *f, fprintf_function cpu_fprintf,
     for (i = 0; i < 16; ++i)
         cpu_fprintf(f, "A%02d=%08x%c", i, env->regs[i],
                 (i % 4) == 3 ? '\n' : ' ');
+
+    cpu_fprintf(f, "\n");
+
+    for (i = 0; i < env->config->nareg; ++i)
+        cpu_fprintf(f, "AR%02d=%08x%c", i, env->phys_regs[i],
+                (i % 4) == 3 ? '\n' : ' ');
 }
 
 void restore_state_to_opc(CPUState *env, TranslationBlock *tb, int pc_pos)
-- 
1.7.3.4