[PATCH 19.11] eal: fix side effect in some pointer arithmetic macros

[Christian Ehrhardt]

On Fri, Nov 11, 2022 at 7:31 PM Dmitry Kozlyuk <dmitry.kozliuk at gmail.com> wrote:
>
> [ upstream commit 1a7374c95678183aef6f40b64074752831a33d26 ]

Thanks, applied to the WIP branch - expect it to be part of 19.11.14
unless some builds stumble over it.

> RTE_PTR_SUB(ptr, x) and RTE_PTR_ALIGN_FLOOR() worked incorrectly
> if "ptr" was an expression:
>
>     uint32_t arr[3];
>
>     RTE_PTR_SUB(arr + 1, sizeof(arr[0]));
>     // expected: (uint32_t *)((uintptr_t)(arr + 1) - 4) == arr
>     // actual:   (uint32_t *)((uintptr_t) arr + 1  - 4) != arr
>
>     RTE_PTR_ALIGN_FLOOR(arr + 2, sizeof(arr[0]));
>     // expected: RTE_ALIGN_FLOOR((uintptr_t)(arr + 2), 4) == &arr[2]
>     // actual:   RTE_ALIGN_FLOOR((uintptr_t) arr + 2,  4) == &arr[0]
>
> Fix the macros and extend the relevant unit test.
> Convert uses of a custom test failure macro to RTE_TEST_ASSERT*().
>
> Fixes: af75078fece3 ("first public release")
> Cc: stable at dpdk.org
>
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk at gmail.com>
> Reviewed-by: Morten Brørup <mb at smartsharesystems.com>
> Acked-by: Bruce Richardson <bruce.richardson at intel.com>
> Acked-by: Chengwen Feng <fengchengwen at huawei.com>
> ---
>  app/test/test_common.c                     | 54 +++++++++++++++-------
>  lib/librte_eal/common/include/rte_common.h |  4 +-
>  2 files changed, 40 insertions(+), 18 deletions(-)
>
> diff --git a/app/test/test_common.c b/app/test/test_common.c
> index 12bd1cad90..181c8be3be 100644
> --- a/app/test/test_common.c
> +++ b/app/test/test_common.c
> @@ -25,27 +25,49 @@ test_macros(int __rte_unused unused_parm)
>  #define SMALLER 0x1000U
>  #define BIGGER 0x2000U
>  #define PTR_DIFF BIGGER - SMALLER
> -#define FAIL_MACRO(x)\
> -       {printf(#x "() test failed!\n");\
> -       return -1;}
>
>         uintptr_t unused = 0;
> +       uint32_t arr[3];
>
>         RTE_SET_USED(unused);
>
> -       if ((uintptr_t)RTE_PTR_ADD(SMALLER, PTR_DIFF) != BIGGER)
> -               FAIL_MACRO(RTE_PTR_ADD);
> -       if ((uintptr_t)RTE_PTR_SUB(BIGGER, PTR_DIFF) != SMALLER)
> -               FAIL_MACRO(RTE_PTR_SUB);
> -       if (RTE_PTR_DIFF(BIGGER, SMALLER) != PTR_DIFF)
> -               FAIL_MACRO(RTE_PTR_DIFF);
> -       if (RTE_MAX(SMALLER, BIGGER) != BIGGER)
> -               FAIL_MACRO(RTE_MAX);
> -       if (RTE_MIN(SMALLER, BIGGER) != SMALLER)
> -               FAIL_MACRO(RTE_MIN);
> -
> -       if (strncmp(RTE_STR(test), "test", sizeof("test")))
> -               FAIL_MACRO(RTE_STR);
> +       RTE_TEST_ASSERT_EQUAL((uintptr_t)RTE_PTR_ADD(SMALLER, PTR_DIFF), BIGGER,
> +               "RTE_PTR_ADD");
> +       RTE_TEST_ASSERT_EQUAL((uintptr_t)RTE_PTR_SUB(BIGGER, PTR_DIFF), SMALLER,
> +               "RTE_PTR_SUB");
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_DIFF(BIGGER, SMALLER), PTR_DIFF,
> +               "RTE_PTR_DIFF");
> +       RTE_TEST_ASSERT_EQUAL(RTE_MAX(SMALLER, BIGGER), BIGGER,
> +               "RTE_MAX");
> +       RTE_TEST_ASSERT_EQUAL(RTE_MIN(SMALLER, BIGGER), SMALLER,
> +               "RTE_MIN");
> +
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_ADD(arr + 1, sizeof(arr[0])), &arr[2],
> +               "RTE_PTR_ADD(expr, x)");
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_SUB(arr + 1, sizeof(arr[0])), &arr[0],
> +               "RTE_PTR_SUB(expr, x)");
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_ALIGN_FLOOR(arr + 2, 4), &arr[2],
> +               "RTE_PTR_ALIGN_FLOOR(expr, x)");
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_ALIGN_CEIL(arr + 2, 4), &arr[2],
> +               "RTE_PTR_ALIGN_CEIL(expr, x)");
> +       RTE_TEST_ASSERT_EQUAL(RTE_PTR_ALIGN(arr + 2, 4), &arr[2],
> +               "RTE_PTR_ALIGN(expr, x)");
> +
> +       RTE_TEST_ASSERT_EQUAL(
> +               RTE_PTR_ALIGN_FLOOR(RTE_PTR_ADD(&arr[1], 1), 4), &arr[1],
> +               "RTE_PTR_ALIGN_FLOOR(x < y/2, y)");
> +       RTE_TEST_ASSERT_EQUAL(
> +               RTE_PTR_ALIGN_FLOOR(RTE_PTR_ADD(&arr[1], 3), 4), &arr[1],
> +               "RTE_PTR_ALIGN_FLOOR(x > y/2, y)");
> +       RTE_TEST_ASSERT_EQUAL(
> +               RTE_PTR_ALIGN_CEIL(RTE_PTR_ADD(&arr[1], 3), 4), &arr[2],
> +               "RTE_PTR_ALIGN_CEIL(x < y/2, y)");
> +       RTE_TEST_ASSERT_EQUAL(
> +               RTE_PTR_ALIGN_CEIL(RTE_PTR_ADD(&arr[1], 1), 4), &arr[2],
> +               "RTE_PTR_ALIGN_CEIL(x > y/2, y)");
> +
> +       RTE_TEST_ASSERT(strncmp(RTE_STR(test), "test", sizeof("test")) == 0,
> +               "RTE_STR");
>
>         return 0;
>  }
> diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
> index fc938eadcd..abe6bc9d15 100644
> --- a/lib/librte_eal/common/include/rte_common.h
> +++ b/lib/librte_eal/common/include/rte_common.h
> @@ -172,7 +172,7 @@ static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
>  /**
>   * subtract a byte-value offset from a pointer
>   */
> -#define RTE_PTR_SUB(ptr, x) ((void*)((uintptr_t)ptr - (x)))
> +#define RTE_PTR_SUB(ptr, x) ((void *)((uintptr_t)(ptr) - (x)))
>
>  /**
>   * get the difference between two pointer values, i.e. how far apart
> @@ -197,7 +197,7 @@ static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
>   * must be a power-of-two value.
>   */
>  #define RTE_PTR_ALIGN_FLOOR(ptr, align) \
> -       ((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)ptr, align))
> +       ((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)(ptr), align))
>
>  /**
>   * Macro to align a value to a given power-of-two. The resultant value
> --
> 2.33.1
>


-- 
Christian Ehrhardt
Senior Staff Engineer, Ubuntu Server
Canonical Ltd