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From: Jordan Niethe <jniethe5@gmail.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2 04/12] powerpc/inst: Avoid pointer dereferencing in ppc_inst_equal()
Date: Tue, 15 Jun 2021 13:38:06 +1000	[thread overview]
Message-ID: <CACzsE9pYG2=FWnxb=gkd2WAFjfy3sLXN8mxsEP26zc7OHgX0Nw@mail.gmail.com> (raw)
In-Reply-To: <d8b155e930b7a9708ca110e8ff0ace6713a7af75.1621516826.git.christophe.leroy@csgroup.eu>

On Thu, May 20, 2021 at 11:50 PM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
> Avoid casting/dereferencing ppc_inst() as u64* , check each member
> of the struct when relevant.
>
> And remove the 0xff initialisation of the suffix for non
> prefixed instruction. An instruction with 0xff as a suffix
> might be invalid, but still is a prefixed instruction and
> has to be considered as this.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  arch/powerpc/include/asm/inst.h | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
> index fc6adef528a5..5a0740ebf132 100644
> --- a/arch/powerpc/include/asm/inst.h
> +++ b/arch/powerpc/include/asm/inst.h
> @@ -61,7 +61,7 @@ static inline int ppc_inst_primary_opcode(struct ppc_inst x)
>  }
>
>  #ifdef CONFIG_PPC64
> -#define ppc_inst(x) ((struct ppc_inst){ .val = (x), .suffix = 0xff })
> +#define ppc_inst(x) ((struct ppc_inst){ .val = (x) })
>
>  #define ppc_inst_prefix(x, y) ((struct ppc_inst){ .val = (x), .suffix = (y) })
>
> @@ -72,7 +72,7 @@ static inline u32 ppc_inst_suffix(struct ppc_inst x)
>
>  static inline bool ppc_inst_prefixed(struct ppc_inst x)
>  {
> -       return ppc_inst_primary_opcode(x) == OP_PREFIX && ppc_inst_suffix(x) != 0xff;
> +       return ppc_inst_primary_opcode(x) == OP_PREFIX;
>  }
>
>  static inline struct ppc_inst ppc_inst_swab(struct ppc_inst x)
> @@ -93,11 +93,6 @@ static inline struct ppc_inst ppc_inst_read(const struct ppc_inst *ptr)
>         }
>  }
>
> -static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
> -{
> -       return *(u64 *)&x == *(u64 *)&y;
> -}
> -
>  #else
>
>  #define ppc_inst(x) ((struct ppc_inst){ .val = x })
> @@ -124,13 +119,17 @@ static inline struct ppc_inst ppc_inst_read(const struct ppc_inst *ptr)
>         return *ptr;
>  }
>
> +#endif /* CONFIG_PPC64 */
> +
>  static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
>  {
> -       return ppc_inst_val(x) == ppc_inst_val(y);
> +       if (ppc_inst_val(x) != ppc_inst_val(y))
> +               return false;
> +       if (!ppc_inst_prefixed(x))
> +               return true;
> +       return ppc_inst_suffix(x) == ppc_inst_suffix(y);
>  }
>
> -#endif /* CONFIG_PPC64 */
> -
>  static inline int ppc_inst_len(struct ppc_inst x)
>  {
>         return ppc_inst_prefixed(x) ? 8 : 4;
> --
> 2.25.0
>
Reviewed by: Jordan Niethe <jniethe5@gmail.com>

  reply	other threads:[~2021-06-15  3:38 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20 13:50 [PATCH v2 00/12] powerpc: Cleanup use of 'struct ppc_inst' Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 01/12] powerpc/inst: Fix sparse detection on get_user_instr() Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 02/12] powerpc/inst: Reduce casts in get_user_instr() Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 03/12] powerpc/inst: Improve readability of get_user_instr() and friends Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 04/12] powerpc/inst: Avoid pointer dereferencing in ppc_inst_equal() Christophe Leroy
2021-06-15  3:38   ` Jordan Niethe [this message]
2021-05-20 13:50 ` [PATCH v2 05/12] powerpc: Do not dereference code as 'struct ppc_inst' (uprobe, code-patching, feature-fixups) Christophe Leroy
2021-06-15  3:41   ` Jordan Niethe
2021-05-20 13:50 ` [PATCH v2 06/12] powerpc/lib/code-patching: Make instr_is_branch_to_addr() static Christophe Leroy
2021-06-15  3:42   ` Jordan Niethe
2021-05-20 13:50 ` [PATCH v2 07/12] powerpc/lib/code-patching: Don't use struct 'ppc_inst' for runnable code in tests Christophe Leroy
2021-06-15  3:42   ` Jordan Niethe
2021-05-20 13:50 ` [PATCH v2 08/12] powerpc: Don't use 'struct ppc_inst' to reference instruction location Christophe Leroy
2021-06-15  2:01   ` Michael Ellerman
2021-06-15  3:47     ` Jordan Niethe
2021-05-20 13:50 ` [PATCH v2 09/12] powerpc/inst: Refactor PPC32 and PPC64 versions Christophe Leroy
2021-06-15  3:48   ` Jordan Niethe
2021-05-20 13:50 ` [PATCH v2 10/12] powerpc/optprobes: Minimise casts Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 11/12] powerpc/optprobes: Compact code source a bit Christophe Leroy
2021-05-20 13:50 ` [PATCH v2 12/12] powerpc/optprobes: use PPC_RAW_ macros Christophe Leroy
2021-06-08 12:46 ` [PATCH v2 00/12] powerpc: Cleanup use of 'struct ppc_inst' Christophe Leroy
2021-06-15  7:18 ` Michael Ellerman
2021-06-15  7:24   ` Christophe Leroy
2021-06-16 13:05     ` Michael Ellerman
2021-06-18  3:51 ` Michael Ellerman

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