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From ca15b67dc746c13a8231d11a3e2925f128982a7d Mon Sep 17 00:00:00 2001
From: Robin Murphy <robin.murphy@arm.com>
Date: Fri, 3 Dec 2021 11:44:54 +0000
Subject: [PATCH 19/40] perf/arm-cmn: Streamline node iteration
Refactor the places where we scan through the set of nodes to switch
from explicit array indexing to pointer-based iteration. This leads to
slightly simpler object code, but also makes the source less dense and
more pleasant for further development. It also unearths an almost-bug
in arm_cmn_event_init() where we've been depending on the "array index"
of NULL relative to cmn->dns being a sufficiently large number, yuck.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/ee0c9eda9a643f46001ac43aadf3f0b1fd5660dd.1638530442.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Upstream-Status: Backport [https://lore.kernel.org/r/ee0c9eda9a643f46001ac43aadf3f0b1fd5660dd.1638530442.git.robin.murphy@arm.com]
Signed-off-by: Rupinderjit Singh <rupinderjit.singh@arm.com>
---
drivers/perf/arm-cmn.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)
diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index adf50d613734..da7bf779fec2 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -299,11 +299,11 @@ static struct arm_cmn_node *arm_cmn_node_to_xp(struct arm_cmn_node *dn)
static struct arm_cmn_node *arm_cmn_node(const struct arm_cmn *cmn,
enum cmn_node_type type)
{
- int i;
+ struct arm_cmn_node *dn;
- for (i = 0; i < cmn->num_dns; i++)
- if (cmn->dns[i].type == type)
- return &cmn->dns[i];
+ for (dn = cmn->dns; dn->type; dn++)
+ if (dn->type == type)
+ return dn;
return NULL;
}
@@ -941,8 +941,8 @@ static int arm_cmn_event_init(struct perf_event *event)
{
struct arm_cmn *cmn = to_cmn(event->pmu);
struct arm_cmn_hw_event *hw = to_cmn_hw(event);
+ struct arm_cmn_node *dn;
enum cmn_node_type type;
- unsigned int i;
bool bynodeid;
u16 nodeid, eventid;
@@ -974,10 +974,12 @@ static int arm_cmn_event_init(struct perf_event *event)
nodeid = CMN_EVENT_NODEID(event);
hw->dn = arm_cmn_node(cmn, type);
- for (i = hw->dn - cmn->dns; i < cmn->num_dns && cmn->dns[i].type == type; i++) {
+ if (!hw->dn)
+ return -EINVAL;
+ for (dn = hw->dn; dn->type == type; dn++) {
if (!bynodeid) {
hw->num_dns++;
- } else if (cmn->dns[i].id != nodeid) {
+ } else if (dn->id != nodeid) {
hw->dn++;
} else {
hw->num_dns = 1;
@@ -1332,7 +1334,7 @@ static int arm_cmn_init_dtcs(struct arm_cmn *cmn)
cmn->xps = arm_cmn_node(cmn, CMN_TYPE_XP);
- for (dn = cmn->dns; dn < cmn->dns + cmn->num_dns; dn++) {
+ for (dn = cmn->dns; dn->type; dn++) {
if (dn->type != CMN_TYPE_XP)
arm_cmn_init_node_to_xp(cmn, dn);
else if (cmn->num_dtcs == 1)
@@ -1382,6 +1384,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
u32 xp_offset[CMN_MAX_XPS];
u64 reg;
int i, j;
+ size_t sz;
cfg_region = cmn->base + rgn_offset;
reg = readl_relaxed(cfg_region + CMN_CFGM_PERIPH_ID_2);
@@ -1408,14 +1411,13 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
cmn->num_dns += FIELD_GET(CMN_CI_CHILD_COUNT, reg);
}
- /* Cheeky +1 to help terminate pointer-based iteration */
- cmn->dns = devm_kcalloc(cmn->dev, cmn->num_dns + 1,
- sizeof(*cmn->dns), GFP_KERNEL);
- if (!cmn->dns)
+ /* Cheeky +1 to help terminate pointer-based iteration later */
+ dn = devm_kcalloc(cmn->dev, cmn->num_dns + 1, sizeof(*dn), GFP_KERNEL);
+ if (!dn)
return -ENOMEM;
/* Pass 2: now we can actually populate the nodes */
- dn = cmn->dns;
+ cmn->dns = dn;
for (i = 0; i < cmn->num_xps; i++) {
void __iomem *xp_region = cmn->base + xp_offset[i];
struct arm_cmn_node *xp = dn++;
@@ -1484,6 +1486,11 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
/* Correct for any nodes we skipped */
cmn->num_dns = dn - cmn->dns;
+ sz = (void *)(dn + 1) - (void *)cmn->dns;
+ dn = devm_krealloc(cmn->dev, cmn->dns, sz, GFP_KERNEL);
+ if (dn)
+ cmn->dns = dn;
+
/*
* If mesh_x wasn't set during discovery then we never saw
* an XP at (0,1), thus we must have an Nx1 configuration.
--
2.34.1
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