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firmware: arm_scmi: Relax CLOCK_DESCRIBE_RATES out-of-spec checks

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A reply to CLOCK_DESCRIBE_RATES issued against a non rate-discrete clock
should be composed of a triplet of rates descriptors (min/max/step)
returned all in one reply message.

This is not always the case when dealing with some SCMI server deployed in
the wild: relax such constraint while maintaining memory safety by checking
carefully the returned payload size.

While at that cleanup a stale debug printout.

Link: https://lore.kernel.org/r/20220616170347.2800771-1-cristian.marussi@arm.com
Fixes: 7bc7caafe6 ("firmware: arm_scmi: Use common iterators in the clock protocol")
Tested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
This commit is contained in:
Cristian Marussi 2022-06-16 18:03:47 +01:00 committed by Sudeep Holla
parent 44dbdf3bb3
commit 754f04cac3
3 changed files with 29 additions and 1 deletions
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26
drivers/firmware/arm_scmi/clock.c
View file

@ -194,6 +194,7 @@ static int rate_cmp_func(const void *_r1, const void *_r2)
}
struct scmi_clk_ipriv {
struct device *dev;
u32 clk_id;
struct scmi_clock_info *clk;
};
@ -223,6 +224,29 @@ iter_clk_describe_update_state(struct scmi_iterator_state *st,
st->num_returned = NUM_RETURNED(flags);
p->clk->rate_discrete = RATE_DISCRETE(flags);
/* Warn about out of spec replies ... */
if (!p->clk->rate_discrete &&
(st->num_returned != 3 || st->num_remaining != 0)) {
dev_warn(p->dev,
"Out-of-spec CLOCK_DESCRIBE_RATES reply for %s - returned:%d remaining:%d rx_len:%zd\n",
p->clk->name, st->num_returned, st->num_remaining,
st->rx_len);
/*
* A known quirk: a triplet is returned but num_returned != 3
* Check for a safe payload size and fix.
*/
if (st->num_returned != 3 && st->num_remaining == 0 &&
st->rx_len == sizeof(*r) + sizeof(__le32) * 2 * 3) {
st->num_returned = 3;
st->num_remaining = 0;
} else {
dev_err(p->dev,
"Cannot fix out-of-spec reply !\n");
return -EPROTO;
}
}
return 0;
}
@ -255,7 +279,6 @@ iter_clk_describe_process_response(const struct scmi_protocol_handle *ph,
*rate = RATE_TO_U64(r->rate[st->loop_idx]);
p->clk->list.num_rates++;
//XXX dev_dbg(ph->dev, "Rate %llu Hz\n", *rate);
}
return ret;
@ -275,6 +298,7 @@ scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, u32 clk_id,
struct scmi_clk_ipriv cpriv = {
.clk_id = clk_id,
.clk = clk,
.dev = ph->dev,
};
iter = ph->hops->iter_response_init(ph, &ops, SCMI_MAX_NUM_RATES,

1
drivers/firmware/arm_scmi/driver.c
View file

@ -1223,6 +1223,7 @@ static int scmi_iterator_run(void *iter)
if (ret)
break;
st->rx_len = i->t->rx.len;
ret = iops->update_state(st, i->resp, i->priv);
if (ret)
break;

3
drivers/firmware/arm_scmi/protocols.h
View file

@ -179,6 +179,8 @@ struct scmi_protocol_handle {
* @max_resources: Maximum acceptable number of items, configured by the caller
* depending on the underlying resources that it is querying.
* @loop_idx: The iterator loop index in the current multi-part reply.
* @rx_len: Size in bytes of the currenly processed message; it can be used by
* the user of the iterator to verify a reply size.
* @priv: Optional pointer to some additional state-related private data setup
* by the caller during the iterations.
*/
@ -188,6 +190,7 @@ struct scmi_iterator_state {
unsigned int num_remaining;
unsigned int max_resources;
unsigned int loop_idx;
size_t rx_len;
void *priv;
};