syscall: Introduce __syscall_always_inline

Sometimes we want to force the inlining of a __syscall. Introduce a new
__syscall_always_inline symbol to do that.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>

.clang-format

@@ -24,6 +24,7 @@ AttributeMacros:
   - __packed
   - __printf_like
   - __syscall
+  - __syscall_always_inline
   - __subsystem
 BitFieldColonSpacing: After
 BreakBeforeBraces: Linux

doc/conf.py

@@ -232,6 +232,7 @@ breathe_default_members = ("members", )
 
 cpp_id_attributes = [
     "__syscall",
+    "__syscall_always_inline",
     "__deprecated",
     "__may_alias",
     "__used",

doc/zephyr.doxyfile.in

@@ -2397,6 +2397,7 @@ PREDEFINED             = __DOXYGEN__ \
                          "__printf_like(x, y)=" \
                          __attribute__(x)= \
                          __syscall= \
+                         __syscall_always_inline= \
                          __must_check= \
                          "ATOMIC_DEFINE(x, y)=atomic_t x[ATOMIC_BITMAP_SIZE(y)]"
 

include/zephyr/toolchain/common.h

@@ -143,8 +143,10 @@
  */
 #ifndef ZTEST_UNITTEST
 #define __syscall static inline
+#define __syscall_always_inline static inline __attribute__((always_inline))
 #else
 #define __syscall
+#define __syscall_always_inline
 #endif /* ZTEST_UNITTEST */
 
 /* Definitions for struct declaration tags. These are sentinel values used by

scripts/build/parse_syscalls.py

@@ -33,11 +33,11 @@ import json
 regex_flags = re.MULTILINE | re.VERBOSE
 
 syscall_regex = re.compile(r'''
-__syscall\s+                    # __syscall attribute, must be first
-([^(]+)                         # type and name of system call (split later)
-[(]                             # Function opening parenthesis
-([^)]*)                         # Arg list (split later)
-[)]                             # Closing parenthesis
+(?:__syscall|__syscall_always_inline)\s+   # __syscall attribute, must be first
+([^(]+)                                    # type and name of system call (split later)
+[(]                                        # Function opening parenthesis
+([^)]*)                                    # Arg list (split later)
+[)]                                        # Closing parenthesis
 ''', regex_flags)
 
 struct_tags = ["__subsystem", "__net_socket"]