Re: [PATCH] align gdbstub with QEMU

[Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>]

Jan Kiszka wrote:
> We've noticed some problems with current gdbstub in kvm's qemu:
> 
> # qemu-system-x86_64 -hda myimage -S -s &
> # gdb
> (gdb) tar re :1234
> Remote debugging using :1234
> Remote 'g' packet reply is too long:
> 000000000000000000000000000000000000[...]
> 
> This issue did not occur with QEMU from CVS. As I was aware of an
> x86_64-related problem in QEMU's gdbstub, I merged its current state
> into kvm - and things start to work again. Find the update patch below.

Any feedback on this? Any chance to see this patch (or some similar
version) in kvm-57?

Thanks,
Jan

> 
> Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
> 
> ---
>  qemu/gdbstub.c |  290 ++++++++++++++++++++++++++++-----------------------------
>  1 file changed, 143 insertions(+), 147 deletions(-)
> 
> Index: kvm-54/qemu/gdbstub.c
> ===================================================================
> --- kvm-54.orig/qemu/gdbstub.c
> +++ kvm-54/qemu/gdbstub.c
> @@ -222,146 +222,60 @@ static int put_packet(GDBState *s, char 
>      return 0;
>  }
>  
> -#if defined(TARGET_X86_64)
> +#if defined(TARGET_I386)
>  
>  static int cpu_gdb_read_registers(CPUState *env, uint8_t *mem_buf)
>  {
> -    uint8_t *p = mem_buf;
>      int i, fpus;
> +    uint32_t *registers = (uint32_t *)mem_buf;
>  
> -#define PUTREG(x) do { \
> -	target_ulong reg = tswapl(x); \
> -	memcpy(p, &reg, sizeof reg); \
> -	p += sizeof reg; \
> -    } while (0)
> -#define PUTREG32(x) do { \
> -	uint32_t reg = tswap32(x);		\
> -	memcpy(p, &reg, sizeof reg); \
> -	p += sizeof reg; \
> -    } while (0)
> -#define PUTREGF(x) do { \
> -	memcpy(p, &(x), 10);			\
> -	p += sizeof (x);			\
> -    } while (0)
> -
> -    PUTREG(env->regs[R_EAX]);
> -    PUTREG(env->regs[R_EBX]);
> -    PUTREG(env->regs[R_ECX]);
> -    PUTREG(env->regs[R_EDX]);
> -    PUTREG(env->regs[R_ESI]);
> -    PUTREG(env->regs[R_EDI]);
> -    PUTREG(env->regs[R_EBP]);
> -    PUTREG(env->regs[R_ESP]);
> -    PUTREG(env->regs[8]);
> -    PUTREG(env->regs[9]);
> -    PUTREG(env->regs[10]);
> -    PUTREG(env->regs[11]);
> -    PUTREG(env->regs[12]);
> -    PUTREG(env->regs[13]);
> -    PUTREG(env->regs[14]);
> -    PUTREG(env->regs[15]);
> -
> -    PUTREG(env->eip);
> -    PUTREG32(env->eflags);
> -    PUTREG32(env->segs[R_CS].selector);
> -    PUTREG32(env->segs[R_SS].selector);
> -    PUTREG32(env->segs[R_DS].selector);
> -    PUTREG32(env->segs[R_ES].selector);
> -    PUTREG32(env->segs[R_FS].selector);
> -    PUTREG32(env->segs[R_GS].selector);
> -    /* XXX: convert floats */
> -    for(i = 0; i < 8; i++) {
> -        PUTREGF(env->fpregs[i]);
> -    }
> -    PUTREG32(env->fpuc);
> -    fpus = (env->fpus & ~0x3800) | (env->fpstt & 0x7) << 11;
> -    PUTREG32(fpus);
> -    PUTREG32(0); /* XXX: convert tags */
> -    PUTREG32(0); /* fiseg */
> -    PUTREG32(0); /* fioff */
> -    PUTREG32(0); /* foseg */
> -    PUTREG32(0); /* fooff */
> -    PUTREG32(0); /* fop */
> -
> -#undef PUTREG
> -#undef PUTREG32
> -#undef PUTREGF
> -
> -    return p - mem_buf;
> -}
> +#ifdef TARGET_X86_64
> +    /* This corresponds with amd64_register_info[] in gdb/amd64-tdep.c */
> +    uint64_t *registers64 = (uint64_t *)mem_buf;
> +
> +    if (env->hflags & HF_CS64_MASK) {
> +        registers64[0] = tswap64(env->regs[R_EAX]);
> +        registers64[1] = tswap64(env->regs[R_EBX]);
> +        registers64[2] = tswap64(env->regs[R_ECX]);
> +        registers64[3] = tswap64(env->regs[R_EDX]);
> +        registers64[4] = tswap64(env->regs[R_ESI]);
> +        registers64[5] = tswap64(env->regs[R_EDI]);
> +        registers64[6] = tswap64(env->regs[R_EBP]);
> +        registers64[7] = tswap64(env->regs[R_ESP]);
> +        for(i = 8; i < 16; i++) {
> +            registers64[i] = tswap64(env->regs[i]);
> +        }
> +        registers64[16] = tswap64(env->eip);
>  
> -static void cpu_gdb_write_registers(CPUState *env, uint8_t *mem_buf, int size)
> -{
> -    uint8_t *p = mem_buf;
> -    uint32_t junk;
> -    int i, fpus;
> +        registers = (uint32_t *)&registers64[17];
> +        registers[0] = tswap32(env->eflags);
> +        registers[1] = tswap32(env->segs[R_CS].selector);
> +        registers[2] = tswap32(env->segs[R_SS].selector);
> +        registers[3] = tswap32(env->segs[R_DS].selector);
> +        registers[4] = tswap32(env->segs[R_ES].selector);
> +        registers[5] = tswap32(env->segs[R_FS].selector);
> +        registers[6] = tswap32(env->segs[R_GS].selector);
> +        /* XXX: convert floats */
> +        for(i = 0; i < 8; i++) {
> +            memcpy(mem_buf + 16 * 8 + 7 * 4 + i * 10, &env->fpregs[i], 10);
> +        }
> +        registers[27] = tswap32(env->fpuc); /* fctrl */
> +        fpus = (env->fpus & ~0x3800) | (env->fpstt & 0x7) << 11;
> +        registers[28] = tswap32(fpus); /* fstat */
> +        registers[29] = 0; /* ftag */
> +        registers[30] = 0; /* fiseg */
> +        registers[31] = 0; /* fioff */
> +        registers[32] = 0; /* foseg */
> +        registers[33] = 0; /* fooff */
> +        registers[34] = 0; /* fop */
> +        for(i = 0; i < 16; i++) {
> +            memcpy(mem_buf + 16 * 8 + 35 * 4 + i * 16, &env->xmm_regs[i], 16);
> +        }
> +        registers[99] = tswap32(env->mxcsr);
>  
> -#define GETREG(x) do { \
> -	target_ulong reg; \
> -    	memcpy(&reg, p, sizeof reg);     \
> -	x = tswapl(reg);		 \
> -	p += sizeof reg;                 \
> -    } while (0)
> -#define GETREG32(x) do { \
> -	uint32_t reg; \
> -    	memcpy(&reg, p, sizeof reg);     \
> -	x = tswap32(reg);		 \
> -	p += sizeof reg;                 \
> -    } while (0)
> -#define GETREGF(x) do { \
> -    	memcpy(&(x), p, 10);		 \
> -	p += 10;                         \
> -    } while (0)
> -
> -    GETREG(env->regs[R_EAX]);
> -    GETREG(env->regs[R_EBX]);
> -    GETREG(env->regs[R_ECX]);
> -    GETREG(env->regs[R_EDX]);
> -    GETREG(env->regs[R_ESI]);
> -    GETREG(env->regs[R_EDI]);
> -    GETREG(env->regs[R_EBP]);
> -    GETREG(env->regs[R_ESP]);
> -    GETREG(env->regs[8]);
> -    GETREG(env->regs[9]);
> -    GETREG(env->regs[10]);
> -    GETREG(env->regs[11]);
> -    GETREG(env->regs[12]);
> -    GETREG(env->regs[13]);
> -    GETREG(env->regs[14]);
> -    GETREG(env->regs[15]);
> -
> -    GETREG(env->eip);
> -    GETREG32(env->eflags);
> -    GETREG32(env->segs[R_CS].selector);
> -    GETREG32(env->segs[R_SS].selector);
> -    GETREG32(env->segs[R_DS].selector);
> -    GETREG32(env->segs[R_ES].selector);
> -    GETREG32(env->segs[R_FS].selector);
> -    GETREG32(env->segs[R_GS].selector);
> -    /* XXX: convert floats */
> -    for(i = 0; i < 8; i++) {
> -        GETREGF(env->fpregs[i]);
> +        return 8 * 17 + 4 * 7 + 10 * 8 + 4 * 8 + 16 * 16 + 4;
>      }
> -    GETREG32(env->fpuc);
> -    GETREG32(fpus); /* XXX: convert fpus */
> -    GETREG32(junk); /* XXX: convert tags */
> -    GETREG32(junk); /* fiseg */
> -    GETREG32(junk); /* fioff */
> -    GETREG32(junk); /* foseg */
> -    GETREG32(junk); /* fooff */
> -    GETREG32(junk); /* fop */
> -
> -#undef GETREG
> -#undef GETREG32
> -#undef GETREGF
> -}
> -
> -#elif defined(TARGET_I386)
> -
> -static int cpu_gdb_read_registers(CPUState *env, uint8_t *mem_buf)
> -{
> -    uint32_t *registers = (uint32_t *)mem_buf;
> -    int i, fpus;
> +#endif
>  
>      for(i = 0; i < 8; i++) {
>          registers[i] = env->regs[i];
> @@ -435,7 +349,7 @@ static int cpu_gdb_read_registers(CPUSta
>      }
>      /* nip, msr, ccr, lnk, ctr, xer, mq */
>      registers[96] = tswapl(env->nip);
> -    registers[97] = tswapl(do_load_msr(env));
> +    registers[97] = tswapl(env->msr);
>      tmp = 0;
>      for (i = 0; i < 8; i++)
>          tmp |= env->crf[i] << (32 - ((i + 1) * 4));
> @@ -464,7 +378,7 @@ static void cpu_gdb_write_registers(CPUS
>      }
>      /* nip, msr, ccr, lnk, ctr, xer, mq */
>      env->nip = tswapl(registers[96]);
> -    do_store_msr(env, tswapl(registers[97]));
> +    ppc_store_msr(env, tswapl(registers[97]));
>      registers[98] = tswapl(registers[98]);
>      for (i = 0; i < 8; i++)
>          env->crf[i] = (registers[98] >> (32 - ((i + 1) * 4))) & 0xF;
> @@ -698,7 +612,7 @@ static int cpu_gdb_read_registers(CPUSta
>          ptr += sizeof(target_ulong);
>        }
>  
> -    *(target_ulong *)ptr = tswapl(env->CP0_Status);
> +    *(target_ulong *)ptr = (int32_t)tswap32(env->CP0_Status);
>      ptr += sizeof(target_ulong);
>  
>      *(target_ulong *)ptr = tswapl(env->LO[0][env->current_tc]);
> @@ -710,7 +624,7 @@ static int cpu_gdb_read_registers(CPUSta
>      *(target_ulong *)ptr = tswapl(env->CP0_BadVAddr);
>      ptr += sizeof(target_ulong);
>  
> -    *(target_ulong *)ptr = tswapl(env->CP0_Cause);
> +    *(target_ulong *)ptr = (int32_t)tswap32(env->CP0_Cause);
>      ptr += sizeof(target_ulong);
>  
>      *(target_ulong *)ptr = tswapl(env->PC[env->current_tc]);
> @@ -720,19 +634,34 @@ static int cpu_gdb_read_registers(CPUSta
>        {
>          for (i = 0; i < 32; i++)
>            {
> -            *(target_ulong *)ptr = tswapl(env->fpu->fpr[i].fs[FP_ENDIAN_IDX]);
> +            if (env->CP0_Status & (1 << CP0St_FR))
> +              *(target_ulong *)ptr = tswapl(env->fpu->fpr[i].d);
> +            else
> +              *(target_ulong *)ptr = tswap32(env->fpu->fpr[i].w[FP_ENDIAN_IDX]);
>              ptr += sizeof(target_ulong);
>            }
>  
> -        *(target_ulong *)ptr = tswapl(env->fpu->fcr31);
> +        *(target_ulong *)ptr = (int32_t)tswap32(env->fpu->fcr31);
> +        ptr += sizeof(target_ulong);
> +
> +        *(target_ulong *)ptr = (int32_t)tswap32(env->fpu->fcr0);
>          ptr += sizeof(target_ulong);
> +      }
> +
> +    /* "fp", pseudo frame pointer. Not yet implemented in gdb. */
> +    *(target_ulong *)ptr = 0;
> +    ptr += sizeof(target_ulong);
>  
> -        *(target_ulong *)ptr = tswapl(env->fpu->fcr0);
> +    /* Registers for embedded use, we just pad them. */
> +    for (i = 0; i < 16; i++)
> +      {
> +        *(target_ulong *)ptr = 0;
>          ptr += sizeof(target_ulong);
>        }
>  
> -    /* 32 FP registers, fsr, fir, fp.  Not yet implemented.  */
> -    /* what's 'fp' mean here?  */
> +    /* Processor ID. */
> +    *(target_ulong *)ptr = (int32_t)tswap32(env->CP0_PRid);
> +    ptr += sizeof(target_ulong);
>  
>      return ptr - mem_buf;
>  }
> @@ -782,15 +711,17 @@ static void cpu_gdb_write_registers(CPUS
>        {
>          for (i = 0; i < 32; i++)
>            {
> -            env->fpu->fpr[i].fs[FP_ENDIAN_IDX] = tswapl(*(target_ulong *)ptr);
> +            if (env->CP0_Status & (1 << CP0St_FR))
> +              env->fpu->fpr[i].d = tswapl(*(target_ulong *)ptr);
> +            else
> +              env->fpu->fpr[i].w[FP_ENDIAN_IDX] = tswapl(*(target_ulong *)ptr);
>              ptr += sizeof(target_ulong);
>            }
>  
> -        env->fpu->fcr31 = tswapl(*(target_ulong *)ptr) & 0x0183FFFF;
> +        env->fpu->fcr31 = tswapl(*(target_ulong *)ptr) & 0xFF83FFFF;
>          ptr += sizeof(target_ulong);
>  
> -        env->fpu->fcr0 = tswapl(*(target_ulong *)ptr);
> -        ptr += sizeof(target_ulong);
> +        /* The remaining registers are assumed to be read-only. */
>  
>          /* set rounding mode */
>          RESTORE_ROUNDING_MODE;
> @@ -863,6 +794,66 @@ static void cpu_gdb_write_registers(CPUS
>    for (i = 0; i < 8; i++) LOAD(env->gregs[i]);
>    for (i = 0; i < 8; i++) LOAD(env->gregs[i + 16]);
>  }
> +#elif defined (TARGET_CRIS)
> +
> +static int cris_save_32 (unsigned char *d, uint32_t value)
> +{
> +	*d++ = (value);
> +	*d++ = (value >>= 8);
> +	*d++ = (value >>= 8);
> +	*d++ = (value >>= 8);
> +	return 4;
> +}
> +static int cris_save_16 (unsigned char *d, uint32_t value)
> +{
> +	*d++ = (value);
> +	*d++ = (value >>= 8);
> +	return 2;
> +}
> +static int cris_save_8 (unsigned char *d, uint32_t value)
> +{
> +	*d++ = (value);
> +	return 1;
> +}
> +
> +/* FIXME: this will bug on archs not supporting unaligned word accesses.  */
> +static int cpu_gdb_read_registers(CPUState *env, uint8_t *mem_buf)
> +{
> +  uint8_t *ptr = mem_buf;
> +  uint8_t srs;
> +  int i;
> +
> +  for (i = 0; i < 16; i++)
> +	  ptr += cris_save_32 (ptr, env->regs[i]);
> +
> +  srs = env->pregs[SR_SRS];
> +
> +  ptr += cris_save_8 (ptr, env->pregs[0]);
> +  ptr += cris_save_8 (ptr, env->pregs[1]);
> +  ptr += cris_save_32 (ptr, env->pregs[2]);
> +  ptr += cris_save_8 (ptr, srs);
> +  ptr += cris_save_16 (ptr, env->pregs[4]);
> +
> +  for (i = 5; i < 16; i++)
> +	  ptr += cris_save_32 (ptr, env->pregs[i]);
> +
> +  ptr += cris_save_32 (ptr, env->pc);
> +
> +  for (i = 0; i < 16; i++)
> +	  ptr += cris_save_32 (ptr, env->sregs[srs][i]);
> +
> +  return ((uint8_t *)ptr - mem_buf);
> +}
> +
> +static void cpu_gdb_write_registers(CPUState *env, uint8_t *mem_buf, int size)
> +{
> +  uint32_t *ptr = (uint32_t *)mem_buf;
> +  int i;
> +
> +#define LOAD(x) (x)=*ptr++;
> +  for (i = 0; i < 16; i++) LOAD(env->regs[i]);
> +  LOAD (env->pc);
> +}
>  #else
>  static int cpu_gdb_read_registers(CPUState *env, uint8_t *mem_buf)
>  {
> @@ -880,7 +871,7 @@ static int gdb_handle_packet(GDBState *s
>      const char *p;
>      int ch, reg_size, type;
>      char buf[4096];
> -    uint8_t mem_buf[2000];
> +    uint8_t mem_buf[4096];
>      uint32_t *registers;
>      target_ulong addr, len;
>  
> @@ -914,6 +905,8 @@ static int gdb_handle_packet(GDBState *s
>              env->pc = addr;
>  #elif defined (TARGET_MIPS)
>              env->PC[env->current_tc] = addr;
> +#elif defined (TARGET_CRIS)
> +            env->pc = addr;
>  #endif
>          }
>  #ifdef CONFIG_USER_ONLY
> @@ -941,6 +934,8 @@ static int gdb_handle_packet(GDBState *s
>              env->pc = addr;
>  #elif defined (TARGET_MIPS)
>              env->PC[env->current_tc] = addr;
> +#elif defined (TARGET_CRIS)
> +            env->pc = addr;
>  #endif
>          }
>          cpu_single_step(env, 1);
> @@ -1070,7 +1065,8 @@ static int gdb_handle_packet(GDBState *s
>              TaskState *ts = env->opaque;
>  
>              sprintf(buf,
> -                    "Text=" TARGET_FMT_lx ";Data=" TARGET_FMT_lx ";Bss=" TARGET_FMT_lx,
> +                    "Text=" TARGET_ABI_FMT_lx ";Data=" TARGET_ABI_FMT_lx
> +                    ";Bss=" TARGET_ABI_FMT_lx,
>                      ts->info->code_offset,
>                      ts->info->data_offset,
>                      ts->info->data_offset);
> 
> 

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

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