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Subject[tip:x86/urgent] x86, msr: Add support for non-contiguous cpumasks
Commit-ID:  505422517d3f126bb939439e9d15dece94e11d2c
Gitweb: http://git.kernel.org/tip/505422517d3f126bb939439e9d15dece94e11d2c
Author: Borislav Petkov <borislav.petkov@amd.com>
AuthorDate: Fri, 11 Dec 2009 18:14:40 +0100
Committer: H. Peter Anvin <hpa@zytor.com>
CommitDate: Fri, 11 Dec 2009 10:59:21 -0800

x86, msr: Add support for non-contiguous cpumasks

The current rd/wrmsr_on_cpus helpers assume that the supplied
cpumasks are contiguous. However, there are machines out there
like some K8 multinode Opterons which have a non-contiguous core
enumeration on each node (e.g. cores 0,2 on node 0 instead of 0,1), see
http://www.gossamer-threads.com/lists/linux/kernel/1160268.

This patch fixes out-of-bounds writes (see URL above) by adding per-CPU
msr structs which are used on the respective cores.

Additionally, two helpers, msrs_{alloc,free}, are provided for use by
the callers of the MSR accessors.
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20091211171440.GD31998@aftab>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
arch/x86/include/asm/msr.h | 3 ++
arch/x86/lib/msr.c | 26 +++++++++++++++++++++---
drivers/edac/amd64_edac.c | 46 ++++++++++++++++---------------------------
3 files changed, 42 insertions(+), 33 deletions(-)
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 5bef931..2d228fc 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -244,6 +244,9 @@ do { \

#define write_rdtscp_aux(val) wrmsr(0xc0000103, (val), 0)

+struct msr *msrs_alloc(void);
+void msrs_free(struct msr *msrs);
+
#ifdef CONFIG_SMP
int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c
index 41628b1..8728341 100644
--- a/arch/x86/lib/msr.c
+++ b/arch/x86/lib/msr.c
@@ -7,7 +7,6 @@ struct msr_info {
u32 msr_no;
struct msr reg;
struct msr *msrs;
- int off;
int err;
};

@@ -18,7 +17,7 @@ static void __rdmsr_on_cpu(void *info)
int this_cpu = raw_smp_processor_id();

if (rv->msrs)
- reg = &rv->msrs[this_cpu - rv->off];
+ reg = per_cpu_ptr(rv->msrs, this_cpu);
else
reg = &rv->reg;

@@ -32,7 +31,7 @@ static void __wrmsr_on_cpu(void *info)
int this_cpu = raw_smp_processor_id();

if (rv->msrs)
- reg = &rv->msrs[this_cpu - rv->off];
+ reg = per_cpu_ptr(rv->msrs, this_cpu);
else
reg = &rv->reg;

@@ -80,7 +79,6 @@ static void __rwmsr_on_cpus(const struct cpumask *mask, u32 msr_no,

memset(&rv, 0, sizeof(rv));

- rv.off = cpumask_first(mask);
rv.msrs = msrs;
rv.msr_no = msr_no;

@@ -120,6 +118,26 @@ void wrmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs)
}
EXPORT_SYMBOL(wrmsr_on_cpus);

+struct msr *msrs_alloc(void)
+{
+ struct msr *msrs = NULL;
+
+ msrs = alloc_percpu(struct msr);
+ if (!msrs) {
+ pr_warning("%s: error allocating msrs\n", __func__);
+ return NULL;
+ }
+
+ return msrs;
+}
+EXPORT_SYMBOL(msrs_alloc);
+
+void msrs_free(struct msr *msrs)
+{
+ free_percpu(msrs);
+}
+EXPORT_SYMBOL(msrs_free);
+
/* These "safe" variants are slower and should be used when the target MSR
may not actually exist. */
static void __rdmsr_safe_on_cpu(void *info)
diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 5fdd6da..df5b684 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -13,6 +13,8 @@ module_param(report_gart_errors, int, 0644);
static int ecc_enable_override;
module_param(ecc_enable_override, int, 0644);

+static struct msr *msrs;
+
/* Lookup table for all possible MC control instances */
struct amd64_pvt;
static struct mem_ctl_info *mci_lookup[EDAC_MAX_NUMNODES];
@@ -2495,8 +2497,7 @@ static void get_cpus_on_this_dct_cpumask(struct cpumask *mask, int nid)
static bool amd64_nb_mce_bank_enabled_on_node(int nid)
{
cpumask_var_t mask;
- struct msr *msrs;
- int cpu, nbe, idx = 0;
+ int cpu, nbe;
bool ret = false;

if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
@@ -2507,32 +2508,22 @@ static bool amd64_nb_mce_bank_enabled_on_node(int nid)

get_cpus_on_this_dct_cpumask(mask, nid);

- msrs = kzalloc(sizeof(struct msr) * cpumask_weight(mask), GFP_KERNEL);
- if (!msrs) {
- amd64_printk(KERN_WARNING, "%s: error allocating msrs\n",
- __func__);
- free_cpumask_var(mask);
- return false;
- }
-
rdmsr_on_cpus(mask, MSR_IA32_MCG_CTL, msrs);

for_each_cpu(cpu, mask) {
- nbe = msrs[idx].l & K8_MSR_MCGCTL_NBE;
+ struct msr *reg = per_cpu_ptr(msrs, cpu);
+ nbe = reg->l & K8_MSR_MCGCTL_NBE;

debugf0("core: %u, MCG_CTL: 0x%llx, NB MSR is %s\n",
- cpu, msrs[idx].q,
+ cpu, reg->q,
(nbe ? "enabled" : "disabled"));

if (!nbe)
goto out;
-
- idx++;
}
ret = true;

out:
- kfree(msrs);
free_cpumask_var(mask);
return ret;
}
@@ -2540,8 +2531,7 @@ out:
static int amd64_toggle_ecc_err_reporting(struct amd64_pvt *pvt, bool on)
{
cpumask_var_t cmask;
- struct msr *msrs = NULL;
- int cpu, idx = 0;
+ int cpu;

if (!zalloc_cpumask_var(&cmask, GFP_KERNEL)) {
amd64_printk(KERN_WARNING, "%s: error allocating mask\n",
@@ -2551,34 +2541,27 @@ static int amd64_toggle_ecc_err_reporting(struct amd64_pvt *pvt, bool on)

get_cpus_on_this_dct_cpumask(cmask, pvt->mc_node_id);

- msrs = kzalloc(sizeof(struct msr) * cpumask_weight(cmask), GFP_KERNEL);
- if (!msrs) {
- amd64_printk(KERN_WARNING, "%s: error allocating msrs\n",
- __func__);
- return -ENOMEM;
- }
-
rdmsr_on_cpus(cmask, MSR_IA32_MCG_CTL, msrs);

for_each_cpu(cpu, cmask) {

+ struct msr *reg = per_cpu_ptr(msrs, cpu);
+
if (on) {
- if (msrs[idx].l & K8_MSR_MCGCTL_NBE)
+ if (reg->l & K8_MSR_MCGCTL_NBE)
pvt->flags.ecc_report = 1;

- msrs[idx].l |= K8_MSR_MCGCTL_NBE;
+ reg->l |= K8_MSR_MCGCTL_NBE;
} else {
/*
* Turn off ECC reporting only when it was off before
*/
if (!pvt->flags.ecc_report)
- msrs[idx].l &= ~K8_MSR_MCGCTL_NBE;
+ reg->l &= ~K8_MSR_MCGCTL_NBE;
}
- idx++;
}
wrmsr_on_cpus(cmask, MSR_IA32_MCG_CTL, msrs);

- kfree(msrs);
free_cpumask_var(cmask);

return 0;
@@ -3036,6 +3019,8 @@ static int __init amd64_edac_init(void)
if (cache_k8_northbridges() < 0)
return err;

+ msrs = msrs_alloc();
+
err = pci_register_driver(&amd64_pci_driver);
if (err)
return err;
@@ -3071,6 +3056,9 @@ static void __exit amd64_edac_exit(void)
edac_pci_release_generic_ctl(amd64_ctl_pci);

pci_unregister_driver(&amd64_pci_driver);
+
+ msrs_free(msrs);
+ msrs = NULL;
}

module_init(amd64_edac_init);

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