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authorIngo Molnar <mingo@kernel.org>2014-04-17 10:25:53 +0200
committerIngo Molnar <mingo@kernel.org>2014-04-17 10:28:42 +0200
commitea431643d6c38728195e2c456801c3ef66bb9991 (patch)
tree00a65a9939a45dc15064853da648fb38720c5ef7 /arch/x86
parent5be44a6fb1edb57d7d2d77151870dcd79c8c0e58 (diff)
downloadlinux-ea431643d6c38728195e2c456801c3ef66bb9991.tar.bz2
x86/mce: Fix CMCI preemption bugs
The following commit: 27f6c573e0f7 ("x86, CMCI: Add proper detection of end of CMCI storms") Added two preemption bugs: - machine_check_poll() does a get_cpu_var() without a matching put_cpu_var(), which causes preemption imbalance and crashes upon bootup. - it does percpu ops without disabling preemption. Preemption is not disabled due to the mistaken use of a raw spinlock. To fix these bugs fix the imbalance and change cmci_discover_lock to a regular spinlock. Reported-by: Owen Kibel <qmewlo@gmail.com> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Chen, Gong <gong.chen@linux.intel.com> Cc: Josh Boyer <jwboyer@fedoraproject.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alexander Todorov <atodorov@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Link: http://lkml.kernel.org/n/tip-jtjptvgigpfkpvtQxpEk1at2@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> -- arch/x86/kernel/cpu/mcheck/mce.c | 4 +--- arch/x86/kernel/cpu/mcheck/mce_intel.c | 18 +++++++++--------- 2 files changed, 10 insertions(+), 12 deletions(-)
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/mcheck/mce.c4
-rw-r--r--arch/x86/kernel/cpu/mcheck/mce_intel.c18
2 files changed, 10 insertions, 12 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index eeee23ff75ef..68317c80de7f 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -598,7 +598,6 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
{
struct mce m;
int i;
- unsigned long *v;
this_cpu_inc(mce_poll_count);
@@ -618,8 +617,7 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
if (!(m.status & MCI_STATUS_VAL))
continue;
- v = &get_cpu_var(mce_polled_error);
- set_bit(0, v);
+ this_cpu_write(mce_polled_error, 1);
/*
* Uncorrected or signalled events are handled by the exception
* handler when it is enabled, so don't process those here.
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index 3bdb95ae8c43..9a316b21df8b 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -42,7 +42,7 @@ static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
* cmci_discover_lock protects against parallel discovery attempts
* which could race against each other.
*/
-static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
+static DEFINE_SPINLOCK(cmci_discover_lock);
#define CMCI_THRESHOLD 1
#define CMCI_POLL_INTERVAL (30 * HZ)
@@ -144,14 +144,14 @@ static void cmci_storm_disable_banks(void)
int bank;
u64 val;
- raw_spin_lock_irqsave(&cmci_discover_lock, flags);
+ spin_lock_irqsave(&cmci_discover_lock, flags);
owned = __get_cpu_var(mce_banks_owned);
for_each_set_bit(bank, owned, MAX_NR_BANKS) {
rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
val &= ~MCI_CTL2_CMCI_EN;
wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
}
- raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
+ spin_unlock_irqrestore(&cmci_discover_lock, flags);
}
static bool cmci_storm_detect(void)
@@ -211,7 +211,7 @@ static void cmci_discover(int banks)
int i;
int bios_wrong_thresh = 0;
- raw_spin_lock_irqsave(&cmci_discover_lock, flags);
+ spin_lock_irqsave(&cmci_discover_lock, flags);
for (i = 0; i < banks; i++) {
u64 val;
int bios_zero_thresh = 0;
@@ -266,7 +266,7 @@ static void cmci_discover(int banks)
WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
}
}
- raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
+ spin_unlock_irqrestore(&cmci_discover_lock, flags);
if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) {
pr_info_once(
"bios_cmci_threshold: Some banks do not have valid thresholds set\n");
@@ -316,10 +316,10 @@ void cmci_clear(void)
if (!cmci_supported(&banks))
return;
- raw_spin_lock_irqsave(&cmci_discover_lock, flags);
+ spin_lock_irqsave(&cmci_discover_lock, flags);
for (i = 0; i < banks; i++)
__cmci_disable_bank(i);
- raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
+ spin_unlock_irqrestore(&cmci_discover_lock, flags);
}
static void cmci_rediscover_work_func(void *arg)
@@ -360,9 +360,9 @@ void cmci_disable_bank(int bank)
if (!cmci_supported(&banks))
return;
- raw_spin_lock_irqsave(&cmci_discover_lock, flags);
+ spin_lock_irqsave(&cmci_discover_lock, flags);
__cmci_disable_bank(bank);
- raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
+ spin_unlock_irqrestore(&cmci_discover_lock, flags);
}
static void intel_init_cmci(void)