MISRA C Rule 20.12 states: "A macro parameter used as an operand to
the # or ## operators, which is itself subject to further macro replacement,
shall only be used as an operand to these operators".

In this case, builds where CONFIG_COMPAT=y the fpu_ctxt
macro is used both as a regular macro argument and as an operand for
stringification in the expansion of CHECK_FIELD_.
This is deviated using a SAF-x-safe comment.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
---
 xen/arch/x86/domain.c | 1 +
 xen/arch/x86/domctl.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 536542841ef5..ccadfe0c9e70 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1084,6 +1084,7 @@ void arch_domain_creation_finished(struct domain *d)
 #ifdef CONFIG_COMPAT
 #define xen_vcpu_guest_context vcpu_guest_context
 #define fpu_ctxt fpu_ctxt.x
+/* SAF-6-safe Rule 20.12 expansion of macro fpu_ctxt with CONFIG_COMPAT */
 CHECK_FIELD_(struct, vcpu_guest_context, fpu_ctxt);
 #undef fpu_ctxt
 #undef xen_vcpu_guest_context
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 9a72d57333e9..335aedf46d03 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1326,6 +1326,7 @@ long arch_do_domctl(
 #ifdef CONFIG_COMPAT
 #define xen_vcpu_guest_context vcpu_guest_context
 #define fpu_ctxt fpu_ctxt.x
+/* SAF-6-safe Rule 20.12 expansion of macro fpu_ctxt with CONFIG_COMPAT */
 CHECK_FIELD_(struct, vcpu_guest_context, fpu_ctxt);
 #undef fpu_ctxt
 #undef xen_vcpu_guest_context
-- 
2.34.1

On 01.06.2024 12:16, Nicola Vetrini wrote:
> MISRA C Rule 20.12 states: "A macro parameter used as an operand to
> the # or ## operators, which is itself subject to further macro replacement,
> shall only be used as an operand to these operators".
> 
> In this case, builds where CONFIG_COMPAT=y the fpu_ctxt
> macro is used both as a regular macro argument and as an operand for
> stringification in the expansion of CHECK_FIELD_.
> This is deviated using a SAF-x-safe comment.
> 
> No functional change.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

At least for the time being; plans that Andrew vaguely described my
render this unnecessary down the road.

Jan

> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -1084,6 +1084,7 @@ void arch_domain_creation_finished(struct domain *d)
>  #ifdef CONFIG_COMPAT
>  #define xen_vcpu_guest_context vcpu_guest_context
>  #define fpu_ctxt fpu_ctxt.x
> +/* SAF-6-safe Rule 20.12 expansion of macro fpu_ctxt with CONFIG_COMPAT */
>  CHECK_FIELD_(struct, vcpu_guest_context, fpu_ctxt);
>  #undef fpu_ctxt
>  #undef xen_vcpu_guest_context
> diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
> index 9a72d57333e9..335aedf46d03 100644
> --- a/xen/arch/x86/domctl.c
> +++ b/xen/arch/x86/domctl.c
> @@ -1326,6 +1326,7 @@ long arch_do_domctl(
>  #ifdef CONFIG_COMPAT
>  #define xen_vcpu_guest_context vcpu_guest_context
>  #define fpu_ctxt fpu_ctxt.x
> +/* SAF-6-safe Rule 20.12 expansion of macro fpu_ctxt with CONFIG_COMPAT */
>  CHECK_FIELD_(struct, vcpu_guest_context, fpu_ctxt);
>  #undef fpu_ctxt
>  #undef xen_vcpu_guest_context