Re: [XEN PATCH] xen: Add SAF deviations for MISRA C:2012 Rule 7.1

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 3 Oct 2023, Nicola Vetrini wrote:
> As specified in rules.rst, these constants can be used
> in the code.
> Their deviation is now accomplished by using a SAF comment,
> rather than an ECLAIR configuration.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

"SAF" discussion aside that can be resolved elsewhere:

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  automation/eclair_analysis/ECLAIR/deviations.ecl | 6 ------
>  docs/misra/safe.json                             | 8 ++++++++
>  xen/arch/x86/hvm/svm/emulate.c                   | 6 +++---
>  xen/arch/x86/hvm/svm/svm.h                       | 9 +++++++++
>  xen/common/inflate.c                             | 4 ++--
>  5 files changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> b/automation/eclair_analysis/ECLAIR/deviations.ecl
> index d8170106b449..fbb806a75d73 100644
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -132,12 +132,6 @@ safe."
>  # Series 7.
>  #
>  
> --doc_begin="Usage of the following constants is safe, since they are given 
> as-is
> -in the inflate algorithm specification and there is therefore no risk of them
> -being interpreted as decimal constants."
> --config=MC3R1.R7.1,literals={safe, 
> "^0(007|37|070|213|236|300|321|330|331|332|333|334|335|337|371)$"}
> --doc_end
> -
>  -doc_begin="Violations in files that maintainers have asked to not modify in 
> the
>  context of R7.2."
>  -file_tag+={adopted_r7_2,"^xen/include/xen/libfdt/.*$"}
> diff --git a/docs/misra/safe.json b/docs/misra/safe.json
> index 39c5c056c7d4..7ea47344ffcc 100644
> --- a/docs/misra/safe.json
> +++ b/docs/misra/safe.json
> @@ -20,6 +20,14 @@
>          },
>          {
>              "id": "SAF-2-safe",
> +            "analyser": {
> +                "eclair": "MC3R1.R7.1"
> +            },
> +            "name": "Rule 7.1: constants defined in specifications, manuals, 
> and algorithm descriptions",
> +            "text": "It is safe to use certain octal constants the way they 
> are defined in specifications, manuals, and algorithm descriptions."
> +        },
> +        {
> +            "id": "SAF-3-safe",
>              "analyser": {},
>              "name": "Sentinel",
>              "text": "Next ID to be used"
> diff --git a/xen/arch/x86/hvm/svm/emulate.c b/xen/arch/x86/hvm/svm/emulate.c
> index aa2c61c433b3..c5e3341c6316 100644
> --- a/xen/arch/x86/hvm/svm/emulate.c
> +++ b/xen/arch/x86/hvm/svm/emulate.c
> @@ -90,9 +90,9 @@ unsigned int svm_get_insn_len(struct vcpu *v, unsigned int 
> instr_enc)
>          if ( !instr_modrm )
>              return emul_len;
>  
> -        if ( modrm_mod       == MASK_EXTR(instr_modrm, 0300) &&
> -             (modrm_reg & 7) == MASK_EXTR(instr_modrm, 0070) &&
> -             (modrm_rm  & 7) == MASK_EXTR(instr_modrm, 0007) )
> +        if ( modrm_mod       == MASK_EXTR(instr_modrm, 0300) && /* 
> SAF-2-safe */
> +             (modrm_reg & 7) == MASK_EXTR(instr_modrm, 0070) && /* 
> SAF-2-safe */
> +             (modrm_rm  & 7) == MASK_EXTR(instr_modrm, 0007) )  /* 
> SAF-2-safe */
>              return emul_len;
>      }
>  
> diff --git a/xen/arch/x86/hvm/svm/svm.h b/xen/arch/x86/hvm/svm/svm.h
> index d2a781fc3fb5..d0623b72ccfa 100644
> --- a/xen/arch/x86/hvm/svm/svm.h
> +++ b/xen/arch/x86/hvm/svm/svm.h
> @@ -57,14 +57,23 @@ static inline void svm_invlpga(unsigned long linear, 
> uint32_t asid)
>  #define INSTR_INT3        INSTR_ENC(X86EMUL_OPC(   0, 0xcc), 0)
>  #define INSTR_ICEBP       INSTR_ENC(X86EMUL_OPC(   0, 0xf1), 0)
>  #define INSTR_HLT         INSTR_ENC(X86EMUL_OPC(   0, 0xf4), 0)
> +/* SAF-2-safe */
>  #define INSTR_XSETBV      INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0321)
> +/* SAF-2-safe */
>  #define INSTR_VMRUN       INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0330)
> +/* SAF-2-safe */
>  #define INSTR_VMCALL      INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0331)
> +/* SAF-2-safe */
>  #define INSTR_VMLOAD      INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0332)
> +/* SAF-2-safe */
>  #define INSTR_VMSAVE      INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0333)
> +/* SAF-2-safe */
>  #define INSTR_STGI        INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0334)
> +/* SAF-2-safe */
>  #define INSTR_CLGI        INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0335)
> +/* SAF-2-safe */
>  #define INSTR_INVLPGA     INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0337)
> +/* SAF-2-safe */
>  #define INSTR_RDTSCP      INSTR_ENC(X86EMUL_OPC(0x0f, 0x01), 0371)
>  #define INSTR_INVD        INSTR_ENC(X86EMUL_OPC(0x0f, 0x08), 0)
>  #define INSTR_WBINVD      INSTR_ENC(X86EMUL_OPC(0x0f, 0x09), 0)
> diff --git a/xen/common/inflate.c b/xen/common/inflate.c
> index 8fa4b96d12a3..be6a9115187e 100644
> --- a/xen/common/inflate.c
> +++ b/xen/common/inflate.c
> @@ -1201,8 +1201,8 @@ static int __init gunzip(void)
>      magic[1] = NEXTBYTE();
>      method   = NEXTBYTE();
>  
> -    if (magic[0] != 037 ||
> -        ((magic[1] != 0213) && (magic[1] != 0236))) {
> +    /* SAF-2-safe */
> +    if (magic[0] != 037 || ((magic[1] != 0213) && (magic[1] != 0236))) {
>          error("bad gzip magic numbers");
>          return -1;
>      }
> -- 
> 2.34.1
>