Re: [Qemu-devel] [PATCH 01/13] target/ppc: Add do_unaligned_access hook

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 26, 2018 at 09:19:09AM -0700, Richard Henderson wrote:
> This allows faults from MO_ALIGN to have the same effect
> as from gen_check_align.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

So, most powerpc cpus can handle most unaligned accesses without an
exception.  I'm assuming this series won't preclude that?

> ---
>  target/ppc/internal.h           |  5 +++++
>  target/ppc/excp_helper.c        | 18 +++++++++++++++++-
>  target/ppc/translate_init.inc.c |  1 +
>  3 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/target/ppc/internal.h b/target/ppc/internal.h
> index 1f441c6483..a9bcadff42 100644
> --- a/target/ppc/internal.h
> +++ b/target/ppc/internal.h
> @@ -252,4 +252,9 @@ static inline void putVSR(int n, ppc_vsr_t *vsr, CPUPPCState *env)
>  void helper_compute_fprf_float16(CPUPPCState *env, float16 arg);
>  void helper_compute_fprf_float32(CPUPPCState *env, float32 arg);
>  void helper_compute_fprf_float128(CPUPPCState *env, float128 arg);
> +
> +/* Raise a data fault alignment exception for the specified virtual address */
> +void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
> +                                 MMUAccessType access_type,
> +                                 int mmu_idx, uintptr_t retaddr);
>  #endif /* PPC_INTERNAL_H */
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index c092fbead0..d6e97a90e0 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -22,7 +22,7 @@
>  #include "exec/helper-proto.h"
>  #include "exec/exec-all.h"
>  #include "exec/cpu_ldst.h"
> -
> +#include "internal.h"
>  #include "helper_regs.h"
>  
>  //#define DEBUG_OP
> @@ -1198,3 +1198,19 @@ void helper_book3s_msgsnd(target_ulong rb)
>      qemu_mutex_unlock_iothread();
>  }
>  #endif
> +
> +void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
> +                                 MMUAccessType access_type,
> +                                 int mmu_idx, uintptr_t retaddr)
> +{
> +    CPUPPCState *env = cs->env_ptr;
> +    uint32_t insn;
> +
> +    /* Restore state and reload the insn we executed, for filling in DSISR.  */
> +    cpu_restore_state(cs, retaddr, true);
> +    insn = cpu_ldl_code(env, env->nip);
> +
> +    cs->exception_index = POWERPC_EXCP_ALIGN;
> +    env->error_code = insn & 0x03FF0000;
> +    cpu_loop_exit(cs);
> +}
> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
> index 76d6f3fd5e..7813b1b004 100644
> --- a/target/ppc/translate_init.inc.c
> +++ b/target/ppc/translate_init.inc.c
> @@ -10457,6 +10457,7 @@ static void ppc_cpu_class_init(ObjectClass *oc, void *data)
>      cc->set_pc = ppc_cpu_set_pc;
>      cc->gdb_read_register = ppc_cpu_gdb_read_register;
>      cc->gdb_write_register = ppc_cpu_gdb_write_register;
> +    cc->do_unaligned_access = ppc_cpu_do_unaligned_access;
>  #ifdef CONFIG_USER_ONLY
>      cc->handle_mmu_fault = ppc_cpu_handle_mmu_fault;
>  #else

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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