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Re: [XEN PATCH v3 2/2] MISRA C Rule 20.7 states: "The features of `<stdarg.h>' shall not be used"


  • To: Simone Ballarin <simone.ballarin@xxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 28 Mar 2024 11:31:47 +0100
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: consulting@xxxxxxxxxxx, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 28 Mar 2024 10:32:04 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 28.03.2024 11:29, Simone Ballarin wrote:
> The Xen community wants to avoid using variadic functions except for
> specific circumstances where it feels appropriate by strict code review.

In the title, s/20.7/17.1/ I suppose?

Jan

> Functions hypercall_create_continuation and hypercall_xlat_continuation
> are internal helper functions made to break long running hypercalls into
> multiple calls. They take a variable number of arguments depending on the
> original hypercall they are trying to continue.
> 
> Add SAF deviations for the aforementioned functions.
> 
> Signed-off-by: Simone Ballarin <simone.ballarin@xxxxxxxxxxx>
> 
> ---
> Changes in v3:
> - rebase: change SAF-3-safe to SAF-4-safe.
> Changes in v2:
> - replaced "special hypercalls" with "internal helper functions".
> ---
>  docs/misra/safe.json     | 8 ++++++++
>  xen/arch/arm/domain.c    | 1 +
>  xen/arch/x86/hypercall.c | 2 ++
>  3 files changed, 11 insertions(+)
> 
> diff --git a/docs/misra/safe.json b/docs/misra/safe.json
> index d361d0e65c..fe2bc18509 100644
> --- a/docs/misra/safe.json
> +++ b/docs/misra/safe.json
> @@ -36,6 +36,14 @@
>          },
>          {
>              "id": "SAF-4-safe",
> +            "analyser": {
> +                "eclair": "MC3R1.R17.1"
> +            },
> +            "name": "Rule 17.1: internal helper functions made to break long 
> running hypercalls into multiple calls.",
> +            "text": "They need to take a variable number of arguments 
> depending on the original hypercall they are trying to continue."
> +        },
> +        {
> +            "id": "SAF-5-safe",
>              "analyser": {},
>              "name": "Sentinel",
>              "text": "Next ID to be used"
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index f38cb5e04c..34cbfe699a 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -382,6 +382,7 @@ unsigned long hypercall_create_continuation(
>      const char *p = format;
>      unsigned long arg, rc;
>      unsigned int i;
> +    /* SAF-4-safe allowed variadic function */
>      va_list args;
>  
>      current->hcall_preempted = true;
> diff --git a/xen/arch/x86/hypercall.c b/xen/arch/x86/hypercall.c
> index 01cd73040d..133e9f221c 100644
> --- a/xen/arch/x86/hypercall.c
> +++ b/xen/arch/x86/hypercall.c
> @@ -31,6 +31,7 @@ unsigned long hypercall_create_continuation(
>      const char *p = format;
>      unsigned long arg;
>      unsigned int i;
> +    /* SAF-4-safe allowed variadic function */
>      va_list args;
>  
>      curr->hcall_preempted = true;
> @@ -115,6 +116,7 @@ int hypercall_xlat_continuation(unsigned int *id, 
> unsigned int nr,
>      struct cpu_user_regs *regs;
>      unsigned int i, cval = 0;
>      unsigned long nval = 0;
> +    /* SAF-4-safe allowed variadic function */
>      va_list args;
>  
>      ASSERT(nr <= ARRAY_SIZE(mcs->call.args));




 


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