On 2017-07-19 14:44, James Hogan wrote:
> On Wed, Jul 19, 2017 at 12:27:50PM +0200, Aurelien Jarno wrote:
> > On 2017-07-18 12:55, James Hogan wrote:
> > > Using MFC0 to read CP0_UserLocal uses tcg_gen_ld32s_tl, however
> > > CP0_UserLocal is a target_ulong. On a big endian host with a MIPS64
> > > target this reads and sign extends the more significant half of the
> > > 64-bit register.
> > >
> > > Fix this by using ld_tl to load the whole target_ulong and ext32s_tl to
> > > sign extend it, as done for various other target_ulong COP0 registers.
> > >
> > > Fixes: d279279e2b5c ("target-mips: implement UserLocal Register")
> > > Signed-off-by: James Hogan <[email protected]>
> > > Cc: Yongbok Kim <[email protected]>
> > > Cc: Aurelien Jarno <[email protected]>
> > > Cc: Petar Jovanovic <[email protected]>
> > > ---
> > > Changes in v2:
> > > - New patch.
> > > ---
> > > target/mips/translate.c | 5 +++--
> > > 1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/target/mips/translate.c b/target/mips/translate.c
> > > index 3022f349cb2a..556aba969a12 100644
> > > --- a/target/mips/translate.c
> > > +++ b/target/mips/translate.c
> > > @@ -5138,8 +5138,9 @@ static void gen_mfc0(DisasContext *ctx, TCGv arg,
> > > int reg, int sel)
> > > goto cp0_unimplemented;
> > > case 2:
> > > CP0_CHECK(ctx->ulri);
> > > - tcg_gen_ld32s_tl(arg, cpu_env,
> > > - offsetof(CPUMIPSState,
> > > active_tc.CP0_UserLocal));
> > > + tcg_gen_ld_tl(arg, cpu_env,
> > > + offsetof(CPUMIPSState,
> > > active_tc.CP0_UserLocal));
> > > + tcg_gen_ext32s_tl(arg, arg);
> > > rn = "UserLocal";
> > > break;
> > > default:
> >
> > I think this is what gen_mfc0_load64() does, that said this whole area
>
> Ah yes, that could do with some wider use (and possibly s/64/tl/ or
> something).
>
> > probably need a rework (see for example how inefficiently
> > gen_mfc0_load32 is implemented). So:
>
> Erm, doesn't gen_mfc0_load32() fail to sign extend as it should when
> used for mfc0...?Yes, this is correct. tcg_gen_ext_i32_tl sign-extends the value when converting it from TCGv_i32 to TCGv_tl. tcg_gen_extu_i32_tl is the op which zero-extends the value. Basically TCG sign-extends the value "by default", like for MIPS. Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B [email protected] http://www.aurel32.net
signature.asc
Description: PGP signature
