Keil Logo

Technical Support

On-Line Manuals

Compiler Reference Guide

Preface armclang Command-line Options Compiler-specific Keywords and Operators Compiler-specific Function, Variable, and Type Att Function attributes __attribute__((always_inline)) function attribute __attribute__((cmse_nonsecure_call)) function attr __attribute__((cmse_nonsecure_entry)) function att __attribute__((const)) function attribute __attribute__((constructor(priority))) function at __attribute__((format_arg(string-index))) function __attribute__((interrupt("type"))) function attrib __attribute__((malloc)) function attribute __attribute__((naked)) function attribute __attribute__((noinline)) function attribute __attribute__((nonnull)) function attribute __attribute__((noreturn)) function attribute __attribute__((nothrow)) function attribute __attribute__((pcs("calling_convention"))) functio __attribute__((pure)) function attribute __attribute__((section("name"))) function attribut __attribute__((unused)) function attribute __attribute__((used)) function attribute __attribute__((value_in_regs)) function attribute __attribute__((visibility("visibility_type"))) fun __attribute__((weak)) function attribute __attribute__((weakref("target"))) function attrib Type attributes __attribute__((aligned)) type attribute __attribute__((packed)) type attribute __attribute__((transparent_union)) type attribute Variable attributes __attribute__((alias)) variable attribute __attribute__((aligned)) variable attribute __attribute__((deprecated)) variable attribute __attribute__((packed)) variable attribute __attribute__((section("name"))) variable attribut __attribute__((unused)) variable attribute __attribute__((used)) variable attribute __attribute__((visibility("visibility_type"))) var __attribute__((weak)) variable attribute __attribute__((weakref("target"))) variable attrib Compiler-specific Intrinsics Compiler-specific Pragmas Other Compiler-specific Features Standard C Implementation Definition Standard C++ Implementation Definition armclang Integrated Assembler armclang Inline Assembler

__attribute__((cmse_nonsecure_call)) function attribute

3.3 __attribute__((cmse_nonsecure_call)) function attribute

Declares a non-secure function type

A call to a function that switches state from Secure to Non-secure is called a non-secure function call. A non-secure function call can only happen through function pointers. This is a consequence of separating secure and non-secure code into separate executable files.

A non-secure function type must only be used as a base type of a pointer.

Example

#include <arm_cmse.h>
typedef void __attribute__((cmse_nonsecure_call)) nsfunc(void);

void default_callback(void) { … }

// fp can point to a secure function or a non-secure function
nsfunc *fp = (nsfunc *) default_callback;   // secure function pointer

void __attribute__((cmse_nonsecure_entry)) entry(nsfunc *callback) {
    fp = cmse_nsfptr_create(callback);      // non-secure function pointer
}

void call_callback(void) {
    if (cmse_is_nsfptr(fp)){
	   fp();           // non-secure function call
    }
    else {
        ((void (*)(void)) fp)();           // normal function call
    }
}
Non-ConfidentialPDF file icon PDF version100067_0612_00_en
Copyright © 2014–2019 Arm Limited or its affiliates. All rights reserved. 
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.