Re: [Qemu-devel] [PATCH v2 10/27] tcg: Add atomic128 helpers

[Alex Bennée]

Richard Henderson <address@hidden> writes:

> Force the use of cmpxchg16b on x86_64.
>
> Wikipedia suggests that only very old AMD64 (circa 2004) did not have
> this instruction.  Further, it's required by Windows 8 so no new cpus
> will ever omit it.
>
> If we truely care about these, then we could check this at startup time
> and then avoid executing paths that use it.
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  configure             |  29 ++++++++++++-
>  cputlb.c              |   6 +++
>  include/qemu/int128.h |   6 +++
>  softmmu_template.h    | 110 
> +++++++++++++++++++++++++++++++++++++-------------
>  tcg/tcg.h             |  22 ++++++++++
>  5 files changed, 144 insertions(+), 29 deletions(-)
>
<snip>
> diff --git a/softmmu_template.h b/softmmu_template.h
> index 76712b9..0a9f49b 100644
> --- a/softmmu_template.h
> +++ b/softmmu_template.h
> @@ -27,25 +27,30 @@
>
>  #define DATA_SIZE (1 << SHIFT)
>
> -#if DATA_SIZE == 8
> -#define SUFFIX q
> -#define LSUFFIX q
> -#define SDATA_TYPE  int64_t
> +#if DATA_SIZE == 16
> +#define SUFFIX     o
> +#define LSUFFIX    o
> +#define SDATA_TYPE Int128
> +#define DATA_TYPE  Int128
> +#elif DATA_SIZE == 8
> +#define SUFFIX     q
> +#define LSUFFIX    q
> +#define SDATA_TYPE int64_t
>  #define DATA_TYPE  uint64_t
>  #elif DATA_SIZE == 4
> -#define SUFFIX l
> -#define LSUFFIX l
> -#define SDATA_TYPE  int32_t
> +#define SUFFIX     l
> +#define LSUFFIX    l
> +#define SDATA_TYPE int32_t
>  #define DATA_TYPE  uint32_t
>  #elif DATA_SIZE == 2
> -#define SUFFIX w
> -#define LSUFFIX uw
> -#define SDATA_TYPE  int16_t
> +#define SUFFIX     w
> +#define LSUFFIX    uw
> +#define SDATA_TYPE int16_t
>  #define DATA_TYPE  uint16_t
>  #elif DATA_SIZE == 1
> -#define SUFFIX b
> -#define LSUFFIX ub
> -#define SDATA_TYPE  int8_t
> +#define SUFFIX     b
> +#define LSUFFIX    ub
> +#define SDATA_TYPE int8_t
>  #define DATA_TYPE  uint8_t
>  #else
>  #error unsupported data size
> @@ -56,7 +61,7 @@
>     to the register size of the host.  This is tcg_target_long, except in the
>     case of a 32-bit host and 64-bit data, and for that we always have
>     uint64_t.  Don't bother with this widened value for SOFTMMU_CODE_ACCESS.  
> */
> -#if defined(SOFTMMU_CODE_ACCESS) || DATA_SIZE == 8
> +#if defined(SOFTMMU_CODE_ACCESS) || DATA_SIZE >= 8
>  # define WORD_TYPE  DATA_TYPE
>  # define USUFFIX    SUFFIX
>  #else
> @@ -73,7 +78,9 @@
>  #define ADDR_READ addr_read
>  #endif
>
> -#if DATA_SIZE == 8
> +#if DATA_SIZE == 16
> +# define BSWAP(X)  bswap128(X)
> +#elif DATA_SIZE == 8
>  # define BSWAP(X)  bswap64(X)
>  #elif DATA_SIZE == 4
>  # define BSWAP(X)  bswap32(X)
> @@ -140,6 +147,7 @@
>      vidx >= 0;                                                               
>  \
>  })

This currently merge conflicts with the current master due to the move
of the VICTIM_TLB code.

>
> +#if DATA_SIZE < 16
>  #ifndef SOFTMMU_CODE_ACCESS
>  static inline DATA_TYPE glue(io_read, SUFFIX)(CPUArchState *env,
>                                                CPUIOTLBEntry *iotlbentry,
> @@ -307,9 +315,10 @@ WORD_TYPE helper_be_ld_name(CPUArchState *env, 
> target_ulong addr,
>      return res;
>  }
>  #endif /* DATA_SIZE > 1 */
> +#endif /* DATA_SIZE < 16 */
>
>  #ifndef SOFTMMU_CODE_ACCESS
> -
> +#if DATA_SIZE < 16
>  /* Provide signed versions of the load routines as well.  We can of course
>     avoid this for 64-bit data, or for 32-bit data on 32-bit host.  */
>  #if DATA_SIZE * 8 < TCG_TARGET_REG_BITS
> @@ -507,6 +516,7 @@ void probe_write(CPUArchState *env, target_ulong addr, 
> int mmu_idx,
>      }
>  }
>  #endif
> +#endif /* DATA_SIZE < 16 */
>
>  #if DATA_SIZE == 1
>  # define HE_SUFFIX  _mmu
> @@ -573,9 +583,30 @@ DATA_TYPE glue(glue(helper_atomic_cmpxchg, SUFFIX), 
> HE_SUFFIX)
>       TCGMemOpIdx oi, uintptr_t retaddr)
>  {
>      ATOMIC_MMU_BODY;
> +#if DATA_SIZE < 16
>      return atomic_cmpxchg(haddr, cmpv, newv);
> +#else
> +    __atomic_compare_exchange(haddr, &cmpv, &newv, false,
> +                              __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
> +    return cmpv;
> +#endif
>  }
>
> +#if DATA_SIZE > 1
> +DATA_TYPE glue(glue(helper_atomic_cmpxchg, SUFFIX), RE_SUFFIX)
> +    (CPUArchState *env, target_ulong addr, DATA_TYPE cmpv, DATA_TYPE newv,
> +     TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> +    DATA_TYPE retv;
> +    cmpv = BSWAP(cmpv);
> +    newv = BSWAP(newv);
> +    retv = (glue(glue(helper_atomic_cmpxchg, SUFFIX), HE_SUFFIX)
> +            (env, addr, cmpv, newv, oi, retaddr));
> +    return BSWAP(retv);
> +}
> +#endif
> +
> +#if DATA_SIZE < 16
>  #define GEN_ATOMIC_HELPER(NAME)                                         \
>  DATA_TYPE glue(glue(glue(helper_atomic_, NAME), SUFFIX), HE_SUFFIX)     \
>      (CPUArchState *env, target_ulong addr, DATA_TYPE val,               \
> @@ -600,18 +631,6 @@ GEN_ATOMIC_HELPER(xchg)
>  #undef GEN_ATOMIC_HELPER
>
>  #if DATA_SIZE > 1
> -DATA_TYPE glue(glue(helper_atomic_cmpxchg, SUFFIX), RE_SUFFIX)
> -    (CPUArchState *env, target_ulong addr, DATA_TYPE cmpv, DATA_TYPE newv,
> -     TCGMemOpIdx oi, uintptr_t retaddr)
> -{
> -    DATA_TYPE retv;
> -    cmpv = BSWAP(cmpv);
> -    newv = BSWAP(newv);
> -    retv = (glue(glue(helper_atomic_cmpxchg, SUFFIX), HE_SUFFIX)
> -            (env, addr, cmpv, newv, oi, retaddr));
> -    return BSWAP(retv);
> -}
> -
>  #define GEN_ATOMIC_HELPER(NAME)                                         \
>  DATA_TYPE glue(glue(glue(helper_atomic_, NAME), SUFFIX), RE_SUFFIX)     \
>      (CPUArchState *env, target_ulong addr, DATA_TYPE val,               \
> @@ -676,6 +695,41 @@ DATA_TYPE glue(glue(helper_atomic_add_fetch, SUFFIX), 
> RE_SUFFIX)
>      }
>  }
>  #endif /* DATA_SIZE > 1 */
> +#else /* DATA_SIZE >= 16 */
> +DATA_TYPE glue(glue(helper_atomic_ld, SUFFIX), HE_SUFFIX)
> +    (CPUArchState *env, target_ulong addr, TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> +    DATA_TYPE res;
> +    ATOMIC_MMU_BODY;
> +    __atomic_load(haddr, &res, __ATOMIC_RELAXED);
> +    return res;
> +}
> +
> +DATA_TYPE glue(glue(helper_atomic_ld, SUFFIX), RE_SUFFIX)
> +    (CPUArchState *env, target_ulong addr, TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> +    DATA_TYPE res;
> +    res = (glue(glue(helper_atomic_ld, SUFFIX), HE_SUFFIX)
> +           (env, addr, oi, retaddr));
> +    return BSWAP(res);
> +}
> +
> +void glue(glue(helper_atomic_st, SUFFIX), HE_SUFFIX)
> +    (CPUArchState *env, target_ulong addr, DATA_TYPE val,
> +     TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> +    ATOMIC_MMU_BODY;
> +    __atomic_store(haddr, &val, __ATOMIC_RELAXED);
> +}
> +
> +void glue(glue(helper_atomic_st, SUFFIX), RE_SUFFIX)
> +    (CPUArchState *env, target_ulong addr, DATA_TYPE val,
> +     TCGMemOpIdx oi, uintptr_t retaddr)
> +{
> +    (glue(glue(helper_atomic_st, SUFFIX), HE_SUFFIX)
> +     (env, addr, BSWAP(val), oi, retaddr));
> +}
> +#endif /* DATA_SIZE < 16 */
>
>  #undef ATOMIC_MMU_BODY
>
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index 4e60498..1304a42 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -1216,6 +1216,28 @@ GEN_ATOMIC_HELPER_ALL(xchg)
>  #undef GEN_ATOMIC_HELPER_ALL
>  #undef GEN_ATOMIC_HELPER
>
> +#ifdef CONFIG_ATOMIC128
> +#include "qemu/int128.h"
> +
> +/* These aren't really a "proper" helpers because TCG cannot manage Int128.
> +   However, use the same format as the others, for use by the backends. */
> +Int128 helper_atomic_cmpxchgo_le_mmu(CPUArchState *env, target_ulong addr,
> +                                     Int128 cmpv, Int128 newv,
> +                                     TCGMemOpIdx oi, uintptr_t retaddr);
> +Int128 helper_atomic_cmpxchgo_be_mmu(CPUArchState *env, target_ulong addr,
> +                                     Int128 cmpv, Int128 newv,
> +                                     TCGMemOpIdx oi, uintptr_t retaddr);
> +
> +Int128 helper_atomic_ldo_le_mmu(CPUArchState *env, target_ulong addr,
> +                                TCGMemOpIdx oi, uintptr_t retaddr);
> +Int128 helper_atomic_ldo_be_mmu(CPUArchState *env, target_ulong addr,
> +                                TCGMemOpIdx oi, uintptr_t retaddr);
> +void helper_atomic_sto_le_mmu(CPUArchState *env, target_ulong addr, Int128 
> val,
> +                              TCGMemOpIdx oi, uintptr_t retaddr);
> +void helper_atomic_sto_be_mmu(CPUArchState *env, target_ulong addr, Int128 
> val,
> +                              TCGMemOpIdx oi, uintptr_t retaddr);
> +
> +#endif /* CONFIG_ATOMIC128 */
>  #endif /* CONFIG_SOFTMMU */
>
>  #endif /* TCG_H */


--
Alex Bennée