Re: [Qemu-devel] [PATCH 04/12] ARM: Add AArch64 translation stub

[Laurent Desnogues]

(This mail was previously sent by accident to Alexander only.)

On Wed, Mar 6, 2013 at 3:01 AM, Alexander Graf <address@hidden> wrote:
> We should translate AArch64 mode separately from AArch32 mode. In AArch64 
> mode,
> registers look vastly different, instruction encoding is completely different,
> basically the system turns into a different machine.
>
> So let's do a simple if() in translate.c to decide whether we can handle the
> current code in the legacy AArch32 code or in the new AArch64 code.
>
> So far, the translation always complains about unallocated instructions. There
> is no emulator functionality in this patch!
>
> Signed-off-by: Alexander Graf <address@hidden>
> ---
>  target-arm/Makefile.objs   |    1 +
>  target-arm/translate-a64.c |  139 
> ++++++++++++++++++++++++++++++++++++++++++++
>  target-arm/translate.c     |   15 +++++
>  target-arm/translate.h     |    6 ++
>  4 files changed, 161 insertions(+), 0 deletions(-)
>  create mode 100644 target-arm/translate-a64.c
>
> diff --git a/target-arm/Makefile.objs b/target-arm/Makefile.objs
> index d89b57c..f9f0de4 100644
> --- a/target-arm/Makefile.objs
> +++ b/target-arm/Makefile.objs
> @@ -3,3 +3,4 @@ obj-$(CONFIG_SOFTMMU) += machine.o
>  obj-$(CONFIG_KVM) += kvm.o
>  obj-y += translate.o op_helper.o helper.o cpu.o
>  obj-y += neon_helper.o iwmmxt_helper.o
> +obj-$(TARGET_ARM64) += translate-a64.o
> diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
> new file mode 100644
> index 0000000..f354d08
> --- /dev/null
> +++ b/target-arm/translate-a64.c
> @@ -0,0 +1,139 @@
> +/*
> + *  AArch64 translation
> + *
> + *  Copyright (c) 2013 Alexander Graf <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +#include <stdarg.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <inttypes.h>
> +
> +#include "cpu.h"
> +#include "tcg-op.h"
> +#include "qemu/log.h"
> +#include "translate.h"
> +#include "qemu/host-utils.h"
> +
> +#include "helper.h"
> +#define GEN_HELPER 1
> +#include "helper.h"
> +
> +static TCGv_i64 cpu_X[32];
> +static TCGv_i64 cpu_pc;
> +static TCGv_i64 cpu_sp;
> +static TCGv_i32 pstate;
> +
> +static const char *regnames[] =
> +    { "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
> +      "x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
> +      "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
> +      "x24", "x25", "x26", "x27", "x28", "x29", "lr", "xzr" };

Wouldn't it be better to use sp instead of xzr?  I would
expect the translator not to emit TCG ops with reg 31
meaning zero :-)


Laurent

> +
> +/* initialize TCG globals.  */
> +void a64_translate_init(void)
> +{
> +    int i;
> +
> +    cpu_pc = tcg_global_mem_new_i64(TCG_AREG0,
> +                                    offsetof(CPUARMState, pc),
> +                                    "pc");
> +    cpu_sp = tcg_global_mem_new_i64(TCG_AREG0,
> +                                    offsetof(CPUARMState, sp),
> +                                    "sp");
> +    for (i = 0; i < 32; i++) {
> +        cpu_X[i] = tcg_global_mem_new_i64(TCG_AREG0,
> +                                          offsetof(CPUARMState, xregs[i]),
> +                                          regnames[i]);
> +    }
> +
> +    pstate = tcg_global_mem_new_i32(TCG_AREG0,
> +                                    offsetof(CPUARMState, pstate),
> +                                    "pstate");
> +}
> +
> +void cpu_dump_state_a64(CPUARMState *env, FILE *f, fprintf_function 
> cpu_fprintf,
> +                        int flags)
> +{
> +    int i;
> +
> +    cpu_fprintf(f, "PC=%016"PRIx64"  SP=%016"PRIx64"\n", env->pc, env->sp);
> +    for(i = 0; i < 31; i++) {
> +        cpu_fprintf(f, "X%02d=%016"PRIx64, i, env->xregs[i]);
> +        if ((i % 4) == 3)
> +            cpu_fprintf(f, "\n");
> +        else
> +            cpu_fprintf(f, " ");
> +    }
> +    cpu_fprintf(f, "XZR=%016"PRIx64"\n", env->xregs[31]);
> +    cpu_fprintf(f, "PSTATE=%c%c%c%c\n",
> +        env->pstate & PSTATE_N ? 'n' : '.',
> +        env->pstate & PSTATE_Z ? 'z' : '.',
> +        env->pstate & PSTATE_C ? 'c' : '.',
> +        env->pstate & PSTATE_V ? 'v' : '.');
> +    cpu_fprintf(f, "\n");
> +}
> +
> +void gen_a64_set_pc_im(uint64_t val)
> +{
> +    tcg_gen_movi_i64(cpu_pc, val);
> +}
> +
> +static void gen_exception(int excp)
> +{
> +    TCGv_i32 tmp = tcg_temp_new_i32();
> +    tcg_gen_movi_i32(tmp, excp);
> +    gen_helper_exception(cpu_env, tmp);
> +    tcg_temp_free_i32(tmp);
> +}
> +
> +static void gen_exception_insn(DisasContext *s, int offset, int excp)
> +{
> +    gen_a64_set_pc_im(s->pc - offset);
> +    gen_exception(excp);
> +    s->is_jmp = DISAS_JUMP;
> +}
> +
> +static void real_unallocated_encoding(DisasContext *s)
> +{
> +    fprintf(stderr, "Unknown instruction: %#x\n",
> +            arm_ldl_code(cpu_single_env, s->pc - 4, s->bswap_code));
> +    gen_exception_insn(s, 4, EXCP_UDEF);
> +}
> +
> +#define unallocated_encoding(s) do { \
> +    fprintf(stderr, "unallocated encoding at line: %d\n", __LINE__); \
> +    real_unallocated_encoding(s); \
> +    } while(0)
> +
> +void disas_a64_insn(CPUARMState *env, DisasContext *s)
> +{
> +    uint32_t insn;
> +
> +    insn = arm_ldl_code(env, s->pc, s->bswap_code);
> +    s->pc += 4;
> +
> +    switch ((insn >> 24) & 0x1f) {
> +    default:
> +        unallocated_encoding(s);
> +        break;
> +    }
> +
> +    if (unlikely(s->singlestep_enabled) && (s->is_jmp == DISAS_TB_JUMP)) {
> +        /* go through the main loop for single step */
> +        s->is_jmp = DISAS_JUMP;
> +    }
> +}
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index de04a0c..a3cb5ee 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -112,6 +112,10 @@ void arm_translate_init(void)
>          offsetof(CPUARMState, exclusive_info), "exclusive_info");
>  #endif
>
> +#ifdef TARGET_ARM64
> +    a64_translate_init();
> +#endif
> +
>  #define GEN_HELPER 2
>  #include "helper.h"
>  }
> @@ -9944,6 +9948,9 @@ static inline void 
> gen_intermediate_code_internal(CPUARMState *env,
>              gen_set_label(dc->condlabel);
>          }
>          if (dc->condjmp || !dc->is_jmp) {
> +            if (is_a64(env)) {
> +                gen_a64_set_pc_im(dc->pc);
> +            }
>              gen_set_pc_im(dc->pc);
>              dc->condjmp = 0;
>          }
> @@ -9967,6 +9974,9 @@ static inline void 
> gen_intermediate_code_internal(CPUARMState *env,
>          gen_set_condexec(dc);
>          switch(dc->is_jmp) {
>          case DISAS_NEXT:
> +            if (is_a64(env)) {
> +                gen_a64_set_pc_im(dc->pc);
> +            }
>              gen_goto_tb(dc, 1, dc->pc);
>              break;
>          default:
> @@ -10038,6 +10048,11 @@ void cpu_dump_state(CPUARMState *env, FILE *f, 
> fprintf_function cpu_fprintf,
>      int i;
>      uint32_t psr;
>
> +    if (is_a64(env)) {
> +        cpu_dump_state_a64(env, f, cpu_fprintf, flags);
> +        return;
> +    }
> +
>      for(i=0;i<16;i++) {
>          cpu_fprintf(f, "R%02d=%08x", i, env->regs[i]);
>          if ((i % 4) == 3)
> diff --git a/target-arm/translate.h b/target-arm/translate.h
> index 8ba1433..9086e43 100644
> --- a/target-arm/translate.h
> +++ b/target-arm/translate.h
> @@ -26,4 +26,10 @@ typedef struct DisasContext {
>
>  extern TCGv_ptr cpu_env;
>
> +void a64_translate_init(void);
> +void cpu_dump_state_a64(CPUARMState *env, FILE *f,
> +        fprintf_function cpu_fprintf, int flags);
> +void disas_a64_insn(CPUARMState *env, DisasContext *s);
> +void gen_a64_set_pc_im(uint64_t val);
> +
>  #endif /* TARGET_ARM_TRANSLATE_H */
> --
> 1.6.0.2
>
>