Re: [PATCH v3] tcg: Sanitize shift constants on ppc64le so that shift operations with large constants don't generate invalid instructions.

2020-06-03 Thread Catherine A. Frederick / mptcultist
Oh dear, I did it to myself again.

On Wed, Jun 3, 2020 at 7:13 PM  wrote:
>
> From: "Catherine A. Frederick" 
>
> Signed-off-by: Catherine A. Frederick 
> ---
>  tcg/ppc/tcg-target.inc.c | 28 ++--
>  1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/tcg/ppc/tcg-target.inc.c b/tcg/ppc/tcg-target.inc.c
> index 7da67086c6..3cab56fe91 100644
> --- a/tcg/ppc/tcg-target.inc.c
> +++ b/tcg/ppc/tcg-target.inc.c
> @@ -790,21 +790,25 @@ static inline void tcg_out_ext32u(TCGContext *s, TCGReg 
> dst, TCGReg src)
>
>  static inline void tcg_out_shli32(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +tcg_debug_assert((c < 32) && (c >= 0));
>  tcg_out_rlw(s, RLWINM, dst, src, c, 0, 31 - c);
>  }
>
>  static inline void tcg_out_shli64(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +tcg_debug_assert((c < 64) && (c >= 0));
>  tcg_out_rld(s, RLDICR, dst, src, c, 63 - c);
>  }
>
>  static inline void tcg_out_shri32(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +tcg_debug_assert((c < 32) && (c >= 0));
>  tcg_out_rlw(s, RLWINM, dst, src, 32 - c, c, 31);
>  }
>
>  static inline void tcg_out_shri64(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +tcg_debug_assert((c < 64) && (c >= 0));
>  tcg_out_rld(s, RLDICL, dst, src, 64 - c, c);
>  }
>
> @@ -2610,21 +2614,27 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
> const TCGArg *args,
>
>  case INDEX_op_shl_i32:
>  if (const_args[2]) {
> -tcg_out_shli32(s, args[0], args[1], args[2]);
> +/* Limit shift immediate to prevent illegal instruction
> +   from bitmask corruption */
> +tcg_out_shli32(s, args[0], args[1], args[2] & 31);
>  } else {
>  tcg_out32(s, SLW | SAB(args[1], args[0], args[2]));
>  }
>  break;
>  case INDEX_op_shr_i32:
>  if (const_args[2]) {
> -tcg_out_shri32(s, args[0], args[1], args[2]);
> +/* Both use RLWINM, which has a 5 bit field for the
> +   shift mask. */
> +tcg_out_shri32(s, args[0], args[1], args[2] & 31);
>  } else {
>  tcg_out32(s, SRW | SAB(args[1], args[0], args[2]));
>  }
>  break;
>  case INDEX_op_sar_i32:
>  if (const_args[2]) {
> -tcg_out32(s, SRAWI | RS(args[1]) | RA(args[0]) | SH(args[2]));
> +/* SRAWI has a 5 bit sized field for the shift mask
> +   as well. */
> +tcg_out32(s, SRAWI | RS(args[1]) | RA(args[0]) | SH(args[2] & 
> 31));
>  } else {
>  tcg_out32(s, SRAW | SAB(args[1], args[0], args[2]));
>  }
> @@ -2696,21 +2706,27 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
> const TCGArg *args,
>
>  case INDEX_op_shl_i64:
>  if (const_args[2]) {
> -tcg_out_shli64(s, args[0], args[1], args[2]);
> +/* Limit shift immediate to prevent illegal instruction from
> +   from bitmask corruption */
> +tcg_out_shli64(s, args[0], args[1], args[2] & 63);
>  } else {
>  tcg_out32(s, SLD | SAB(args[1], args[0], args[2]));
>  }
>  break;
>  case INDEX_op_shr_i64:
>  if (const_args[2]) {
> -tcg_out_shri64(s, args[0], args[1], args[2]);
> +/* Same applies here, as both RLDICL, and RLDICR have a
> +   6 bit large mask for the shift value */
> +tcg_out_shri64(s, args[0], args[1], args[2] & 63);
>  } else {
>  tcg_out32(s, SRD | SAB(args[1], args[0], args[2]));
>  }
>  break;
>  case INDEX_op_sar_i64:
>  if (const_args[2]) {
> -int sh = SH(args[2] & 0x1f) | (((args[2] >> 5) & 1) << 1);
> +/* Same for SRADI, except there's no function
> +   to call into. */
> +int sh = SH(((args[2] & 63) & 0x1f) | args[2] & 63) >> 5) & 
> 1) << 1));
>  tcg_out32(s, SRADI | RA(args[0]) | RS(args[1]) | sh);
>  } else {
>  tcg_out32(s, SRAD | SAB(args[1], args[0], args[2]));
> --
> 2.26.2
>



Re: [PATCH] tcg: Sanitize shift constants on ppc64le so that shift operations with large constants don't generate invalid instructions.

2020-06-02 Thread Catherine A. Frederick / mptcultist
Oh dear, it appears that git send-email ate the formatting, hang on.

On Wed, Jun 3, 2020 at 12:47 AM  wrote:
>
> From: "Catherine A. Frederick" 
>
> ---
>  tcg/ppc/tcg-target.inc.c | 4 
>  1 file changed, 4 insertions(+)
>
> diff --git a/tcg/ppc/tcg-target.inc.c b/tcg/ppc/tcg-target.inc.c
> index ee1f9227c1..a5450a5e67 100644
> --- a/tcg/ppc/tcg-target.inc.c
> +++ b/tcg/ppc/tcg-target.inc.c
> @@ -790,21 +790,25 @@ static inline void tcg_out_ext32u(TCGContext *s, TCGReg 
> dst, TCGReg src)
>
>  static inline void tcg_out_shli32(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +c = ((unsigned)c > 32) ? 32 : c;
>  tcg_out_rlw(s, RLWINM, dst, src, c, 0, 31 - c);
>  }
>
>  static inline void tcg_out_shli64(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +c = ((unsigned)c > 64) ? 64 : c;
>  tcg_out_rld(s, RLDICR, dst, src, c, 63 - c);
>  }
>
>  static inline void tcg_out_shri32(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +c = ((unsigned)c > 32) ? 32 : c;
>  tcg_out_rlw(s, RLWINM, dst, src, 32 - c, c, 31);
>  }
>
>  static inline void tcg_out_shri64(TCGContext *s, TCGReg dst, TCGReg src, int 
> c)
>  {
> +c = ((unsigned)c > 64) ? 64 : c;
>  tcg_out_rld(s, RLDICL, dst, src, 64 - c, c);
>  }
>
> --
> 2.26.2
>