> From: Morten Brørup [mailto:mb@smartsharesystems.com]
> Sent: Saturday, 3 December 2022 15.23
>
> Add "nonnull" function attribute to help the compiler detect a NULL
> pointer being passed to a function not accepting NULL pointers as an
> argument at build time.
>
> Add "access" function attribute to tell the compiler how a function
> accesses its pointer arguments.
>
> Add these attributes to the rte_memcpy() function, as the first in
> hopefully many to come.
Notes about Warnings/Errors reported in Patchwork [1]:
* The checkpatch warning is about the attributes being defined. This is the purpose of the patch, and I don't know how to do it without getting a checkpatch warning.
* The errors are previously uncaught bugs elsewhere, now being caught by GCC versions >= 10.4.0 due to these new attributes. I have reported these as [Bug 1146]. It shows some actual usefulness of the attributes in this patch, and provides a good example of why we should decorate many more functions with them.
[1]: https://patchwork.dpdk.org/project/dpdk/patch/20221203142244.17135-1-mb@smartsharesystems.com/
[Bug 1146]: https://bugs.dpdk.org/show_bug.cgi?id=1146
Example of previously uncaught bug:
../drivers/net/bnx2x/bnx2x_vfpf.c: In function ‘bnx2x_check_bull’:
../drivers/net/bnx2x/bnx2x_vfpf.c:57:17: error: ‘rte_memcpy’ writing 4 bytes into a region of size 2 overflows the destination [-Werror=stringop-overflow=]
57 | rte_memcpy(&bull->vlan, &sc->old_bulletin.vlan, RTE_VLAN_HLEN);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../drivers/net/bnx2x/bnx2x.h:29,
from ../drivers/net/bnx2x/bnx2x_vfpf.c:8:
../drivers/net/bnx2x/bnx2x_vfpf.h:297:18: note: destination object ‘vlan’ of size 2
297 | uint16_t vlan;
| ^~~~
../drivers/net/bnx2x/bnx2x_vfpf.c:57:17: error: ‘rte_memcpy’ reading 4 bytes from a region of size 2 [-Werror=stringop-overread]
57 | rte_memcpy(&bull->vlan, &sc->old_bulletin.vlan, RTE_VLAN_HLEN);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/net/bnx2x/bnx2x_vfpf.h:297:18: note: source object ‘vlan’ of size 2
297 | uint16_t vlan;
| ^~~~
In file included from ../lib/mempool/rte_mempool.h:48,
from ../lib/mbuf/rte_mbuf.h:38,
from ../lib/net/rte_ether.h:22,
from ../lib/ethdev/rte_eth_ctrl.h:10,
from ../lib/ethdev/rte_ethdev.h:1419,
from ../lib/ethdev/ethdev_driver.h:24,
from ../drivers/net/bnx2x/bnx2x_ethdev.h:34,
from ../drivers/net/bnx2x/bnx2x.h:23:
../lib/eal/x86/include/rte_memcpy.h:869:1: note: in a call to function ‘rte_memcpy’ declared with attribute ‘access (read_only, 2, 3)’
869 | rte_memcpy(void *dst, const void *src, size_t n)
| ^~~~~~~~~~
@@ -14,6 +14,8 @@ extern "C" {
#include "generic/rte_memcpy.h"
+#include <rte_common.h>
+
#ifdef RTE_ARCH_ARM_NEON_MEMCPY
#ifndef __ARM_NEON
@@ -125,6 +127,9 @@ rte_mov256(uint8_t *dst, const uint8_t *src)
memcpy((dst), (src), (n)) : \
rte_memcpy_func((dst), (src), (n)); })
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static inline void *
rte_memcpy_func(void *dst, const void *src, size_t n)
{
@@ -290,6 +295,9 @@ rte_mov256(uint8_t *dst, const uint8_t *src)
memcpy(dst, src, 256);
}
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static inline void *
rte_memcpy(void *dst, const void *src, size_t n)
{
@@ -282,6 +282,9 @@ void rte_memcpy_ge64(uint8_t *dst, const uint8_t *src, size_t n)
}
#if RTE_CACHE_LINE_SIZE >= 128
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static __rte_always_inline
void *rte_memcpy(void *dst, const void *src, size_t n)
{
@@ -303,6 +306,9 @@ void *rte_memcpy(void *dst, const void *src, size_t n)
}
#else
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static __rte_always_inline
void *rte_memcpy(void *dst, const void *src, size_t n)
{
@@ -149,6 +149,35 @@ typedef uint16_t unaligned_uint16_t;
__attribute__((format(printf, format_index, first_arg)))
#endif
+/**
+ * Check pointer arguments at compile-time.
+ *
+ * @param ...
+ * Comma separated list of parameter indexes of pointer arguments.
+ */
+#if defined(RTE_CC_GCC) || defined(RTE_CC_CLANG)
+#define __rte_nonnull_params(...) \
+ __attribute__((nonnull(__VA_ARGS__)))
+#else
+#define __rte_nonnull_params(...)
+#endif
+
+/**
+ * Tells compiler about the access mode of a pointer argument.
+ *
+ * @param access_mode
+ * Access mode: read_only, read_write, write_only, or none.
+ * @param ...
+ * Parameter index of pointer argument.
+ * Optionally followeded by comma and parameter index of size argument.
+ */
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 100400)
+#define __rte_access_param(access_mode, ...) \
+ __attribute__((access(access_mode, __VA_ARGS__)))
+#else
+#define __rte_access_param(access_mode, ...)
+#endif
+
/**
* Tells compiler that the function returns a value that points to
* memory, where the size is given by the one or two arguments.
@@ -84,6 +84,9 @@ rte_mov256(uint8_t *dst, const uint8_t *src)
memcpy((dst), (src), (n)) : \
rte_memcpy_func((dst), (src), (n)); })
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static inline void *
rte_memcpy_func(void *dst, const void *src, size_t n)
{
@@ -42,6 +42,9 @@ extern "C" {
* @return
* Pointer to the destination data.
*/
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static __rte_always_inline void *
rte_memcpy(void *dst, const void *src, size_t n);
@@ -859,6 +862,9 @@ rte_memcpy_aligned(void *dst, const void *src, size_t n)
return ret;
}
+__rte_nonnull_params(1, 2)
+__rte_access_param(write_only, 1, 3)
+__rte_access_param(read_only, 2, 3)
static __rte_always_inline void *
rte_memcpy(void *dst, const void *src, size_t n)
{