Re: [Qemu-devel] [PATCH] target/alpha: fix tlb_fill trap_arg2 value for instruction fetch

[Peter Maydell]

On Wed, 21 Aug 2019 at 14:42, Aurelien Jarno <address@hidden> wrote:
>
> Commit e41c94529740cc26 ("target/alpha: Convert to CPUClass::tlb_fill")
> slightly changed the way the trap_arg2 value is computed in case of TLB
> fill. The type of the variable used in the ternary operator has been
> changed from an int to an enum. This causes the -1 value to not be
> sign-extended to 64-bit in case of an instruction fetch. The trap_arg2
> ends up with 0xffffffff instead of 0xffffffffffffffff. Fix that by
> changing the -1 into -1LL.
>
> This fixes the execution of user space processes in qemu-system-alpha.
>
> Fixes: e41c94529740cc26
> Cc: address@hidden
> Signed-off-by: Aurelien Jarno <address@hidden>
> ---
>  target/alpha/helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/alpha/helper.c b/target/alpha/helper.c
> index 93b8e788b1..9e9d880c1a 100644
> --- a/target/alpha/helper.c
> +++ b/target/alpha/helper.c
> @@ -283,7 +283,7 @@ bool alpha_cpu_tlb_fill(CPUState *cs, vaddr addr, int 
> size,
>          cs->exception_index = EXCP_MMFAULT;
>          env->trap_arg0 = addr;
>          env->trap_arg1 = fail;
> -        env->trap_arg2 = (access_type == MMU_INST_FETCH ? -1 : access_type);
> +        env->trap_arg2 = (access_type == MMU_INST_FETCH ? -1LL : 
> access_type);
>          cpu_loop_exit_restore(cs, retaddr);
>      }

Oops. Thanks for the catch.

Maybe we should not rely directly on the value of the access_type
enum to set trap_arg2 at all (ie just go for a switch on access_type and
set env->trap_arg2 to the right h/w value in the three cases)?

thanks
-- PMM