diff options
author | Christoph Lameter <cl@linux.com> | 2014-08-17 12:30:40 -0500 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2014-08-26 13:45:49 -0400 |
commit | 89cbc76768c2fa4ed95545bf961f3a14ddfeed21 (patch) | |
tree | 14a566d17dc886d3330d67404553530f8f979e2d /arch/x86/kernel/cpu/mcheck/mce-inject.c | |
parent | 532d0d0690d1532dcc5a190162ad820b636bcd4d (diff) |
x86: Replace __get_cpu_var uses
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/mcheck/mce-inject.c')
-rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce-inject.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c index 5ac2d1fb28bc..4cfba4371a71 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-inject.c +++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c @@ -83,7 +83,7 @@ static DEFINE_MUTEX(mce_inject_mutex); static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs) { int cpu = smp_processor_id(); - struct mce *m = &__get_cpu_var(injectm); + struct mce *m = this_cpu_ptr(&injectm); if (!cpumask_test_cpu(cpu, mce_inject_cpumask)) return NMI_DONE; cpumask_clear_cpu(cpu, mce_inject_cpumask); @@ -97,7 +97,7 @@ static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs) static void mce_irq_ipi(void *info) { int cpu = smp_processor_id(); - struct mce *m = &__get_cpu_var(injectm); + struct mce *m = this_cpu_ptr(&injectm); if (cpumask_test_cpu(cpu, mce_inject_cpumask) && m->inject_flags & MCJ_EXCEPTION) { @@ -109,7 +109,7 @@ static void mce_irq_ipi(void *info) /* Inject mce on current CPU */ static int raise_local(void) { - struct mce *m = &__get_cpu_var(injectm); + struct mce *m = this_cpu_ptr(&injectm); int context = MCJ_CTX(m->inject_flags); int ret = 0; int cpu = m->extcpu; |