linux-kernel - [tip: x86/cache] x86/resctrl: Initialize on-stack struct rmid

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Message-ID: <171994825415.2215.13170170224791872909.tip-bot2@tip-bot2>
Date: Tue, 02 Jul 2024 19:24:14 -0000
From: "tip-bot2 for Tony Luck" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Tony Luck <tony.luck@...el.com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
 Reinette Chatre <reinette.chatre@...el.com>, Babu Moger <babu.moger@....com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: x86/cache] x86/resctrl: Initialize on-stack struct rmid_read instances

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     587edd7069b9e7dc7993d2df9371e7c37a4d2133
Gitweb:        https://git.kernel.org/tip/587edd7069b9e7dc7993d2df9371e7c37a4d2133
Author:        Tony Luck <tony.luck@...el.com>
AuthorDate:    Fri, 28 Jun 2024 14:56:10 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Tue, 02 Jul 2024 19:49:54 +02:00

x86/resctrl: Initialize on-stack struct rmid_read instances

New semantics rely on some struct rmid_read members having NULL values to
distinguish between the SNC and non-SNC scenarios.  resctrl can thus no longer
rely on this struct not being initialized properly.

Initialize all on-stack declarations of struct rmid_read:

  rdtgroup_mondata_show()
  mbm_update()
  mkdir_mondata_subdir()

to ensure that garbage values from the stack are not passed down to other
functions.

  [ bp: Massage commit message. ]

Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Tested-by: Babu Moger <babu.moger@....com>
Link: https://lore.kernel.org/r/20240628215619.76401-11-tony.luck@intel.com
---
 arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 3 +--
 arch/x86/kernel/cpu/resctrl/monitor.c     | 3 +--
 arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 2 +-
 3 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 3b93836..4d76ff3 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -529,7 +529,6 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
 	rr->evtid = evtid;
 	rr->r = r;
 	rr->d = d;
-	rr->val = 0;
 	rr->first = first;
 	rr->arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, evtid);
 	if (IS_ERR(rr->arch_mon_ctx)) {
@@ -557,12 +556,12 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 {
 	struct kernfs_open_file *of = m->private;
 	struct rdt_domain_hdr *hdr;
+	struct rmid_read rr = {0};
 	struct rdt_mon_domain *d;
 	u32 resid, evtid, domid;
 	struct rdtgroup *rdtgrp;
 	struct rdt_resource *r;
 	union mon_data_bits md;
-	struct rmid_read rr;
 	int ret = 0;
 
 	rdtgrp = rdtgroup_kn_lock_live(of->kn);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index ff4e745..ca309c9 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -780,9 +780,8 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
 static void mbm_update(struct rdt_resource *r, struct rdt_mon_domain *d,
 		       u32 closid, u32 rmid)
 {
-	struct rmid_read rr;
+	struct rmid_read rr = {0};
 
-	rr.first = false;
 	rr.r = r;
 	rr.d = d;
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 70d41a8..d044358 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3029,10 +3029,10 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 				struct rdt_mon_domain *d,
 				struct rdt_resource *r, struct rdtgroup *prgrp)
 {
+	struct rmid_read rr = {0};
 	union mon_data_bits priv;
 	struct kernfs_node *kn;
 	struct mon_evt *mevt;
-	struct rmid_read rr;
 	char name[32];
 	int ret;