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Re: [XEN PATCH 1/3] EFI: address violations of MISRA C Rule 13.6
On 11/09/24 16:57, Jan Beulich wrote:
On 11.09.2024 16:27, Nicola Vetrini wrote:
On 2024-09-11 16:10, Jan Beulich wrote:
On 11.09.2024 15:16, Marek Marczykowski-Górecki wrote:
On Wed, Sep 11, 2024 at 02:50:03PM +0200, Jan Beulich wrote:
On 10.09.2024 21:06, Federico Serafini wrote:
Refactor the code to improve readability
I question this aspect. I'm not the maintainer of this code anymore,
so
my view probably doesn't matter much here.
and address violations of
MISRA C:2012 Rule 13.6 ("The operand of the `sizeof' operator shall
not contain any expression which has potential side effect").
Where's the potential side effect? Since you move ...
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -250,14 +250,20 @@ int efi_get_info(uint32_t idx, union
xenpf_efi_info *info)
info->cfg.addr = __pa(efi_ct);
info->cfg.nent = efi_num_ct;
break;
+
case XEN_FW_EFI_VENDOR:
+ {
+ XEN_GUEST_HANDLE_PARAM(CHAR16) vendor_name =
+ guest_handle_cast(info->vendor.name, CHAR16);
.. this out, it must be the one. I've looked at it, yet I can't spot
anything:
#define guest_handle_cast(hnd, type) ({ \
type *_x = (hnd).p; \
(XEN_GUEST_HANDLE_PARAM(type)) { _x }; \
})
As a rule of thumb, when things aren't obvious, please call out the
specific aspect / property in descriptions of such patches.
I guess it's because guest_handle_cast() is a macro, yet it's
lowercase
so looks like a function?
If Eclair didn't look at the macro-expanded code, it wouldn't even see
the sizeof(). Hence I don't expect the thing to be mistaken for a
function
call.
Looking at the fully preprocessed code [1], there is an assignment to
CHAR *_x inside a sizeof(), therefore compat_handle_cast is triggering
the violation when used in such a way to be inside the sizeof().
I can see a number of initializers, but no assignment.
+ Stefano in CC.
MISRA considers the initialization (even of a local variable)
a side effect. This is the reason of the violations.
I will send a V2 with a better description.
if ( !((!!((((get_cpu_info()->current_vcpu))->domain)->arch.paging.mode
& ((1 << 4) << 10))) || (
__builtin_expect(!!(((n)) < (~0U / (sizeof(**(({ CHAR16 *_x =
(__typeof__(**(info->vendor.name)._) *)(full_ptr_t)(info->
vendor.name).c; (__compat_handle_CHAR16) { (full_ptr_t)_x };
}))._)))),1) && ((unsigned long)((unsigned long)((void *)(
full_ptr_t)(({ CHAR16 *_x = (__typeof__(**(info->vendor.name)._)
*)(full_ptr_t)(info->vendor.name).c; (
__compat_handle_CHAR16) { (full_ptr_t)_x }; })).c) + ((0 + ((n)) *
(sizeof(**(({ CHAR16 *_x = (__typeof__(**(info->
vendor.name)._) *)(full_ptr_t)(info->vendor.name).c;
(__compat_handle_CHAR16) { (full_ptr_t)_x }; }))._))) ? (0 + ((n))
* (sizeof(**(({ CHAR16 *_x = (__typeof__(**(info->vendor.name)._)
*)(full_ptr_t)(info->vendor.name).c; (
__compat_handle_CHAR16) { (full_ptr_t)_x }; }))._))) - 1 : 0)) <
((void)(((get_cpu_info()->current_vcpu))->domain), 0)))
) )
--
Federico Serafini, M.Sc.
Software Engineer, BUGSENG (http://bugseng.com)
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