1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Non-trivial C macros cannot be used in Rust. Similarly, inlined C functions 4 * cannot be called either. This file explicitly creates functions ("helpers") 5 * that wrap those so that they can be called from Rust. 6 * 7 * Even though Rust kernel modules should never use directly the bindings, some 8 * of these helpers need to be exported because Rust generics and inlined 9 * functions may not get their code generated in the crate where they are 10 * defined. Other helpers, called from non-inline functions, may not be 11 * exported, in principle. However, in general, the Rust compiler does not 12 * guarantee codegen will be performed for a non-inline function either. 13 * Therefore, this file exports all the helpers. In the future, this may be 14 * revisited to reduce the number of exports after the compiler is informed 15 * about the places codegen is required. 16 * 17 * All symbols are exported as GPL-only to guarantee no GPL-only feature is 18 * accidentally exposed. 19 */ 20 21 #include <linux/bug.h> 22 #include <linux/build_bug.h> 23 #include <linux/err.h> 24 #include <linux/refcount.h> 25 26 __noreturn void rust_helper_BUG(void) 27 { 28 BUG(); 29 } 30 EXPORT_SYMBOL_GPL(rust_helper_BUG); 31 32 refcount_t rust_helper_REFCOUNT_INIT(int n) 33 { 34 return (refcount_t)REFCOUNT_INIT(n); 35 } 36 EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT); 37 38 void rust_helper_refcount_inc(refcount_t *r) 39 { 40 refcount_inc(r); 41 } 42 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc); 43 44 bool rust_helper_refcount_dec_and_test(refcount_t *r) 45 { 46 return refcount_dec_and_test(r); 47 } 48 EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); 49 50 __force void *rust_helper_ERR_PTR(long err) 51 { 52 return ERR_PTR(err); 53 } 54 EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR); 55 56 bool rust_helper_IS_ERR(__force const void *ptr) 57 { 58 return IS_ERR(ptr); 59 } 60 EXPORT_SYMBOL_GPL(rust_helper_IS_ERR); 61 62 long rust_helper_PTR_ERR(__force const void *ptr) 63 { 64 return PTR_ERR(ptr); 65 } 66 EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR); 67 68 /* 69 * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type 70 * as the Rust `usize` type, so we can use it in contexts where Rust 71 * expects a `usize` like slice (array) indices. `usize` is defined to be 72 * the same as C's `uintptr_t` type (can hold any pointer) but not 73 * necessarily the same as `size_t` (can hold the size of any single 74 * object). Most modern platforms use the same concrete integer type for 75 * both of them, but in case we find ourselves on a platform where 76 * that's not true, fail early instead of risking ABI or 77 * integer-overflow issues. 78 * 79 * If your platform fails this assertion, it means that you are in 80 * danger of integer-overflow bugs (even if you attempt to remove 81 * `--size_t-is-usize`). It may be easiest to change the kernel ABI on 82 * your platform such that `size_t` matches `uintptr_t` (i.e., to increase 83 * `size_t`, because `uintptr_t` has to be at least as big as `size_t`). 84 */ 85 static_assert( 86 sizeof(size_t) == sizeof(uintptr_t) && 87 __alignof__(size_t) == __alignof__(uintptr_t), 88 "Rust code expects C `size_t` to match Rust `usize`" 89 ); 90