[dpdk-dev,v4,04/18] bus/dpaa: solve inconsistent struct alignment
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Commit Message
The actual descriptor for qm_mr_entry is 64-byte aligned.
But the original code plays a trick, and puts a u8 common
to the three descriptor subtypes in the union afterwards
outside their structure definitions.
Unfortunately since they compose a struct qm_fd with
alignment 8, this trick destroys the ability of the compiler
to understand what has happened, resulting in this kind of
problem:
/home/agreen/projects/dpdk/drivers/bus/dpaa/include/
fsl_qman.h:354:3: error: alignment 1 of ‘struct <anonymous>’
is less than 8 [-Werror=packed-not-aligned]
} __packed dcern;
on gcc 8 / Fedora 28 out of the box.
This patch moves the u8 verb into the structure definitions
composed into the union, so the alignment of the parent struct
containing the alignment 8 object can also be seen to be
alignment 8 by the compiler. Uses of .verb are fixed up to use
.ern.verb (the same offset of +0 inside all the structs in
the union).
The final struct layout should be unchanged.
Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Tested-by: Hemant Agrawal <hemant.agrawal@nxp.com>
---
drivers/bus/dpaa/base/qbman/qman.c | 14 +++++++-------
drivers/bus/dpaa/include/fsl_qman.h | 24 +++++++++++++-----------
2 files changed, 20 insertions(+), 18 deletions(-)
Comments
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Andy Green
> Sent: Friday, May 11, 2018 2:46 AM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v4 04/18] bus/dpaa: solve inconsistent struct
> alignment
>
> The actual descriptor for qm_mr_entry is 64-byte aligned.
>
> But the original code plays a trick, and puts a u8 common to the three descriptor
> subtypes in the union afterwards outside their structure definitions.
>
> Unfortunately since they compose a struct qm_fd with alignment 8, this trick
> destroys the ability of the compiler to understand what has happened, resulting
> in this kind of
> problem:
>
> /home/agreen/projects/dpdk/drivers/bus/dpaa/include/
> fsl_qman.h:354:3: error: alignment 1 of ‘struct <anonymous>’
> is less than 8 [-Werror=packed-not-aligned]
> } __packed dcern;
>
> on gcc 8 / Fedora 28 out of the box.
>
> This patch moves the u8 verb into the structure definitions composed into the
> union, so the alignment of the parent struct containing the alignment 8 object
> can also be seen to be alignment 8 by the compiler. Uses of .verb are fixed up to
> use .ern.verb (the same offset of +0 inside all the structs in the union).
>
> The final struct layout should be unchanged.
>
> Signed-off-by: Andy Green <andy@warmcat.com>
> Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
> Tested-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Missing fixes line and CC stable:
Fixes: c47ff048b99a ("bus/dpaa: add QMAN driver core routines")
Fixes: f6fadc3e6310 ("bus/dpaa: add QMAN interface driver")
Cc: stable@dpdk.org
@@ -314,9 +314,9 @@ static int drain_mr_fqrni(struct qm_portal *p)
if (!msg)
return 0;
}
- if ((msg->verb & QM_MR_VERB_TYPE_MASK) != QM_MR_VERB_FQRNI) {
+ if ((msg->ern.verb & QM_MR_VERB_TYPE_MASK) != QM_MR_VERB_FQRNI) {
/* We aren't draining anything but FQRNIs */
- pr_err("Found verb 0x%x in MR\n", msg->verb);
+ pr_err("Found verb 0x%x in MR\n", msg->ern.verb);
return -1;
}
qm_mr_next(p);
@@ -483,7 +483,7 @@ static inline void qm_mr_pvb_update(struct qm_portal *portal)
/* when accessing 'verb', use __raw_readb() to ensure that compiler
* inlining doesn't try to optimise out "excess reads".
*/
- if ((__raw_readb(&res->verb) & QM_MR_VERB_VBIT) == mr->vbit) {
+ if ((__raw_readb(&res->ern.verb) & QM_MR_VERB_VBIT) == mr->vbit) {
mr->pi = (mr->pi + 1) & (QM_MR_SIZE - 1);
if (!mr->pi)
mr->vbit ^= QM_MR_VERB_VBIT;
@@ -832,7 +832,7 @@ static u32 __poll_portal_slow(struct qman_portal *p, u32 is)
goto mr_done;
swapped_msg = *msg;
hw_fd_to_cpu(&swapped_msg.ern.fd);
- verb = msg->verb & QM_MR_VERB_TYPE_MASK;
+ verb = msg->ern.verb & QM_MR_VERB_TYPE_MASK;
/* The message is a software ERN iff the 0x20 bit is set */
if (verb & 0x20) {
switch (verb) {
@@ -1666,7 +1666,7 @@ int qman_retire_fq(struct qman_fq *fq, u32 *flags)
*/
struct qm_mr_entry msg;
- msg.verb = QM_MR_VERB_FQRNI;
+ msg.ern.verb = QM_MR_VERB_FQRNI;
msg.fq.fqs = mcr->alterfq.fqs;
msg.fq.fqid = fq->fqid;
#ifdef CONFIG_FSL_QMAN_FQ_LOOKUP
@@ -2643,7 +2643,7 @@ int qman_shutdown_fq(u32 fqid)
qm_mr_pvb_update(low_p);
msg = qm_mr_current(low_p);
while (msg) {
- if ((msg->verb &
+ if ((msg->ern.verb &
QM_MR_VERB_TYPE_MASK)
== QM_MR_VERB_FQRN)
found_fqrn = 1;
@@ -2711,7 +2711,7 @@ int qman_shutdown_fq(u32 fqid)
qm_mr_pvb_update(low_p);
msg = qm_mr_current(low_p);
while (msg) {
- if ((msg->verb & QM_MR_VERB_TYPE_MASK) ==
+ if ((msg->ern.verb & QM_MR_VERB_TYPE_MASK) ==
QM_MR_VERB_FQRL)
orl_empty = 1;
qm_mr_next(low_p);
@@ -284,20 +284,20 @@ static inline dma_addr_t qm_sg_addr(const struct qm_sg_entry *sg)
} while (0)
/* See 1.5.8.1: "Enqueue Command" */
-struct qm_eqcr_entry {
+struct __rte_aligned(8) qm_eqcr_entry {
u8 __dont_write_directly__verb;
u8 dca;
u16 seqnum;
u32 orp; /* 24-bit */
u32 fqid; /* 24-bit */
u32 tag;
- struct qm_fd fd;
+ struct qm_fd fd; /* this has alignment 8 */
u8 __reserved3[32];
} __packed;
/* "Frame Dequeue Response" */
-struct qm_dqrr_entry {
+struct __rte_aligned(8) qm_dqrr_entry {
u8 verb;
u8 stat;
u16 seqnum; /* 15-bit */
@@ -305,7 +305,7 @@ struct qm_dqrr_entry {
u8 __reserved2[3];
u32 fqid; /* 24-bit */
u32 contextB;
- struct qm_fd fd;
+ struct qm_fd fd; /* this has alignment 8 */
u8 __reserved4[32];
};
@@ -323,18 +323,19 @@ struct qm_dqrr_entry {
/* "ERN Message Response" */
/* "FQ State Change Notification" */
struct qm_mr_entry {
- u8 verb;
union {
struct {
+ u8 verb;
u8 dca;
u16 seqnum;
u8 rc; /* Rejection Code */
u32 orp:24;
u32 fqid; /* 24-bit */
u32 tag;
- struct qm_fd fd;
- } __packed ern;
+ struct qm_fd fd; /* this has alignment 8 */
+ } __packed __rte_aligned(8) ern;
struct {
+ u8 verb;
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
u8 colour:2; /* See QM_MR_DCERN_COLOUR_* */
u8 __reserved1:4;
@@ -349,18 +350,19 @@ struct qm_mr_entry {
u32 __reserved3:24;
u32 fqid; /* 24-bit */
u32 tag;
- struct qm_fd fd;
- } __packed dcern;
+ struct qm_fd fd; /* this has alignment 8 */
+ } __packed __rte_aligned(8) dcern;
struct {
+ u8 verb;
u8 fqs; /* Frame Queue Status */
u8 __reserved1[6];
u32 fqid; /* 24-bit */
u32 contextB;
u8 __reserved2[16];
- } __packed fq; /* FQRN/FQRNI/FQRL/FQPN */
+ } __packed __rte_aligned(8) fq; /* FQRN/FQRNI/FQRL/FQPN */
};
u8 __reserved2[32];
-} __packed;
+} __packed __rte_aligned(8);
#define QM_MR_VERB_VBIT 0x80
/*
* ERNs originating from direct-connect portals ("dcern") use 0x20 as a verb