On 2020-09-18 15:18, Jean-Philippe Brucker wrote:
When building with C=1, sparse reports some issues regarding endianness
annotations:

arm-smmu-v3.c:221:26: warning: cast to restricted __le64
arm-smmu-v3.c:221:24: warning: incorrect type in assignment (different base 
types)
arm-smmu-v3.c:221:24:    expected restricted __le64 [usertype]
arm-smmu-v3.c:221:24:    got unsigned long long [usertype]
arm-smmu-v3.c:229:20: warning: incorrect type in argument 1 (different base 
types)
arm-smmu-v3.c:229:20:    expected restricted __le64 [usertype] *[assigned] dst
arm-smmu-v3.c:229:20:    got unsigned long long [usertype] *ent
arm-smmu-v3.c:229:25: warning: incorrect type in argument 2 (different base 
types)
arm-smmu-v3.c:229:25:    expected unsigned long long [usertype] *[assigned] src
arm-smmu-v3.c:229:25:    got restricted __le64 [usertype] *
arm-smmu-v3.c:396:20: warning: incorrect type in argument 1 (different base 
types)
arm-smmu-v3.c:396:20:    expected restricted __le64 [usertype] *[assigned] dst
arm-smmu-v3.c:396:20:    got unsigned long long *
arm-smmu-v3.c:396:25: warning: incorrect type in argument 2 (different base 
types)
arm-smmu-v3.c:396:25:    expected unsigned long long [usertype] *[assigned] src
arm-smmu-v3.c:396:25:    got restricted __le64 [usertype] *
arm-smmu-v3.c:1349:32: warning: invalid assignment: |=
arm-smmu-v3.c:1349:32:    left side has type restricted __le64
arm-smmu-v3.c:1349:32:    right side has type unsigned long
arm-smmu-v3.c:1396:53: warning: incorrect type in argument 3 (different base 
types)
arm-smmu-v3.c:1396:53:    expected restricted __le64 [usertype] *dst
arm-smmu-v3.c:1396:53:    got unsigned long long [usertype] *strtab
arm-smmu-v3.c:1424:39: warning: incorrect type in argument 1 (different base 
types)
arm-smmu-v3.c:1424:39:    expected unsigned long long [usertype] *[assigned] 
strtab
arm-smmu-v3.c:1424:39:    got restricted __le64 [usertype] *l2ptr

While harmless, they are incorrect and could hide actual errors during
development. Fix them.

Reviewed-by: Robin Murphy <robin.mur...@arm.com>

Signed-off-by: Jean-Philippe Brucker <jean-phili...@linaro.org>
---

There is another false positive due to passing INT_MIN to cmpxchg, and
__cmpxchg* to truncate them to u8 and u16:

arch/arm64/include/asm/cmpxchg.h:172:1: warning: cast truncates bits from 
constant value (ffffffff80000000 becomes 0)
arch/arm64/include/asm/cmpxchg.h:172:1: warning: cast truncates bits from 
constant value (ffffffff80000000 becomes 0)

I haven't found a satisfying fix so far, except adding __force to
__cmpxchg_case* which could hide actual bugs.

I guess that's a general issue with the switch(sizeof()) idiom of sparse not being aware that those cases are unreachable?

Robin.

---
  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c 
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index c192544e874b..83acc1e5888e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -867,7 +867,7 @@ static void queue_write(__le64 *dst, u64 *src, size_t 
n_dwords)
                *dst++ = cpu_to_le64(*src++);
  }
-static void queue_read(__le64 *dst, u64 *src, size_t n_dwords)
+static void queue_read(u64 *dst, __le64 *src, size_t n_dwords)
  {
        int i;
@@ -1939,7 +1939,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
                arm_smmu_cmdq_issue_cmd(smmu, &prefetch_cmd);
  }
-static void arm_smmu_init_bypass_stes(u64 *strtab, unsigned int nent)
+static void arm_smmu_init_bypass_stes(__le64 *strtab, unsigned int nent)
  {
        unsigned int i;
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