automation/eclair: tag function calls to address violations of MISRA C:2012 Rule 13.1

Rule 13.1: Initializer lists shall not contain persistent side effects

Invocations of functions in initializer lists cause violations of rule
13.1 if the called functions are not tagged with __attribute_pure__ or
__attribute_const__ as they can produce persistent side effects.

Handling these violations with  attributes is not always possible: the
pure and const attributes may cause unwanted and potentially dangerous
optimisations.

To avoid this problem ECLAIR allows using the same attributes in the
-call_properties setting. Additionally, it adds the noeffect attribute
with the following definition:
"like pure but can also read volatile variable not triggering side effects"

These patch tags some functions used in initializer lists to address
violations of Rule 13.1.

No functional changes.

Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

automation/eclair_analysis/ECLAIR/call_properties.ecl

@@ -73,6 +73,17 @@
 -call_properties+={"macro(^va_start$)", {"pointee_write(1=always)", "pointee_read(1=never)", "taken()"}}
 -call_properties+={"macro(^memcmp$)", {"pointee_write(1..2=never)", "taken()"}}
 -call_properties+={"macro(^memcpy$)", {"pointee_write(1=always&&2..=never)", "pointee_read(1=never&&2..=always)", "taken()"}}
+-call_properties+={"name(get_cpu_info)",{pure}}
+-call_properties+={"name(pdx_to_pfn)",{pure}}
+-call_properties+={"name(is_pci_passthrough_enabled)",{const}}
+-call_properties+={"name(get_cycles)", {"noeffect"}}
+-call_properties+={"name(msi_gflags)",{const}}
+-call_properties+={"name(hvm_save_size)",{pure}}
+-call_properties+={"name(cpu_has)",{pure}}
+-call_properties+={"name(boot_cpu_has)",{pure}}
+-call_properties+={"name(get_cpu_info)",{pure}}
+-call_properties+={"name(put_pte_flags)",{const}}
+-call_properties+={"name(is_pv_vcpu)",{pure}}
 
 -doc_begin="Property inferred as a consequence of the semantics of device_tree_get_reg"
 -call_properties+={"name(acquire_static_memory_bank)", {"pointee_write(4..=always)", "pointee_read(4..=never)", "taken()"}}
@@ -104,3 +115,14 @@ Furthermore, their uses do initialize the involved variables as needed by futher
 -call_properties+={"macro(^(__)?(raw_)?copy_from_(paddr|guest|compat)(_offset)?$)", {"pointee_write(1=always)", "pointee_read(1=never)", "taken()"}}
 -call_properties+={"macro(^(__)?copy_to_(guest|compat)(_offset)?$)", {"pointee_write(2=always)", "pointee_read(2=never)", "taken()"}}
 -doc_end
+
+-doc_begin="Functions generated by build_atomic_read cannot be considered pure
+since the input pointer is volatile, but they do not produce any persistent side
+effect."
+-call_properties+={"^read_u(8|16|32|64|int)_atomic.*$", {noeffect}}
+-doc_end
+
+-doc_begin="Functions generated by TYPE_SAFE are const."
+-call_properties+={"^(mfn|gfn|pfn)_x\\(.*$",{const}}
+-call_properties+={"^_(mfn|gfn|pfn)\\(.*$",{const}}
+-doc_end