[v2,0/6] xen: address violations of MISRA C:2012 Rule 11.8

Message

Simone Ballarin Dec. 19, 2023, 11:05 a.m. UTC

From: Maria Celeste Cesario <[e-mail]>

The xen sources contain violations of MISRA C:2012 Rule 11.8 whose
headline states:
"A conversion shall not remove any const, volatile or _Atomic
qualification from the type pointed to by a pointer".

This patch amends or drops casts that unnecessarily
drop const qualifiers.

Example:

int device_tree_for_each_node(const void *fdt);

size_t __init boot_fdt_info(const void *fdt)
{
  int ret = device_tree_for_each_node((void *)fdt); /* Non-compliant */
  int ret = device_tree_for_each_node(fdt);         /* Compliant, proposed change */
}

In this example, the const qualifier is unnecessarily cast away
from the original object, therefore making it non-compliant.

Deviate the following violations:

- removal of const qualifier to comply with function signatures
   A single function could either read or write through a passed in pointer,
   depending on how it is called. It is deemed safe to cast away a const
   qualifier when passing a pointer to such a function, when the other
   parameters guarantee read-only operation.
   A SAF-3-safe comment was added to deviate these violations.

- violations in macro container_of
   Violations caused by this macro are due to pointer arithmetic operations
   with the provided offset. The resulting pointer is then immediately cast back to its
   original type, which preserves the qualifier. This use is deemed safe.

Changes in v2:
- reword SAF-3-safe text;
- merge comments on __hvm_copy;
- add SAF-3-safe comment in x86/hvm.c:3433;
- add SAF-3-safe comment on arm/guestcopy.c raw_copy_to_guest and
  raw_copy_to_guest_flush_dcache;
- remove deviation for function ERR_CAST;
- remove function ERR_CAST;
- move common/version.c to patch xen/common;
- change cast type from const void* to uintptr_t in common/version.c;
- drop redundant cast on fdt.


Maria Celeste Cesario (6):
  xen/arm: address violations of MISRA C:2012 Rule 11.8
  xen/ppc: address violations of MISRA C:2012 Rule 11.8.
  xen: add deviations for Rule 11.8
  xen: add SAF deviation for safe cast removal
  xen: remove unused function ERR_CAST
  xen/common: address violations of MISRA C:2012 Rule 11.8

 automation/eclair_analysis/ECLAIR/deviations.ecl |  7 +++++++
 docs/misra/deviations.rst                        |  7 +++++++
 docs/misra/safe.json                             |  8 ++++++++
 xen/arch/arm/bootfdt.c                           |  6 +++---
 xen/arch/arm/guestcopy.c                         |  2 ++
 xen/arch/arm/include/asm/alternative.h           |  2 +-
 xen/arch/ppc/include/asm/atomic.h                |  2 +-
 xen/arch/x86/hvm/hvm.c                           |  6 ++++--
 xen/common/version.c                             |  2 +-
 xen/include/xen/err.h                            | 13 -------------
 10 files changed, 34 insertions(+), 21 deletions(-)