[PATCH 1/3] eal: fix pointer arithmetic with an expression argument

[Dmitry Kozlyuk]

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.

Fixes: af75078fece3 ("first public release")
Cc: stable at dpdk.org

Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk at gmail.com>
---
 app/test/test_common.c       | 11 +++++++++++
 lib/eal/include/rte_common.h |  4 ++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/app/test/test_common.c b/app/test/test_common.c
index ef177cecb1..4194c1208a 100644
--- a/app/test/test_common.c
+++ b/app/test/test_common.c
@@ -31,6 +31,7 @@ test_macros(int __rte_unused unused_parm)
 
 	uintptr_t unused = 0;
 	unsigned int smaller = SMALLER, bigger  = BIGGER;
+	uint32_t arr[3];
 
 	RTE_SET_USED(unused);
 
@@ -41,6 +42,16 @@ test_macros(int __rte_unused unused_parm)
 		FAIL_MACRO(RTE_PTR_ADD);
 	if ((uintptr_t)RTE_PTR_SUB(BIGGER, PTR_DIFF) != SMALLER)
 		FAIL_MACRO(RTE_PTR_SUB);
+	if (RTE_PTR_ADD(arr + 1, sizeof(arr[0])) != &arr[2])
+		FAIL_MACRO(RTE_PTR_ADD);
+	if (RTE_PTR_SUB(arr + 1, sizeof(arr[0])) != &arr[0])
+		FAIL_MACRO(RTE_PTR_SUB);
+	if (RTE_PTR_ALIGN_FLOOR(arr + 2, 4) != &arr[2])
+		FAIL_MACRO(RTE_PTR_ALIGN_FLOOR);
+	if (RTE_PTR_ALIGN_CEIL(arr + 2, 4) != &arr[2])
+		FAIL_MACRO(RTE_PTR_ALIGN_CEIL);
+	if (RTE_PTR_ALIGN(arr + 2, 4) != &arr[2])
+		FAIL_MACRO(RTE_PTR_ALIGN);
 	if (RTE_PTR_DIFF(BIGGER, SMALLER) != PTR_DIFF)
 		FAIL_MACRO(RTE_PTR_DIFF);
 	if (RTE_MAX(SMALLER, BIGGER) != BIGGER)
diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index a96cc2a138..d517e9f75f 100644
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -295,7 +295,7 @@ 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
@@ -320,7 +320,7 @@ 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