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cpu/x86/mp: pass pointers to structures for AP callbacks 

In order to extend the MP callback infrastructure prepare for
easier changes by making the AP callback get signalled by a
single pointer to a local variable on the signaller's stack.
When the APs see the callback they will copy the structure
to a local variable and then set the acknowledgement by
clearing out the slot.

The reading and writing to the slots were implemented using inline
assembly which forces a memory access and a compiler barrier.

BUG=b:74436746

Change-Id: Ia46133a49c03ce3ce0e73ae3d30547316c7ec43c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/26043
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Aaron Durbin 2018-05-03 13:49:41 -06:00 committed by Patrick Georgi
parent e6cc21e262
commit 223fb436fe
1 changed files with 36 additions and 17 deletions
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53
src/cpu/x86/mp_init.c
View File

@ -40,7 +40,9 @@
#define MAX_APIC_IDS 256
typedef void (*mp_callback_t)(void);
struct mp_callback {
void (*func)(void);
};
/*
* A mp_flight_record details a sequence of calls for the APs to perform
@ -58,8 +60,8 @@ typedef void (*mp_callback_t)(void);
struct mp_flight_record {
atomic_t barrier;
atomic_t cpus_entered;
mp_callback_t ap_call;
mp_callback_t bsp_call;
void (*ap_call)(void);
void (*bsp_call)(void);
} __aligned(CACHELINE_SIZE);
#define _MP_FLIGHT_RECORD(barrier_, ap_func_, bsp_func_) \
@ -851,19 +853,30 @@ static void trigger_smm_relocation(void)
mp_state.ops.per_cpu_smm_trigger();
}
static mp_callback_t ap_callbacks[CONFIG_MAX_CPUS];
static struct mp_callback *ap_callbacks[CONFIG_MAX_CPUS];
static mp_callback_t read_callback(mp_callback_t *slot)
static struct mp_callback *read_callback(struct mp_callback **slot)
{
return *(volatile mp_callback_t *)slot;
struct mp_callback *ret;
asm volatile ("mov %1, %0\n"
: "=r" (ret)
: "m" (*slot)
: "memory"
);
return ret;
}
static void store_callback(mp_callback_t *slot, mp_callback_t value)
static void store_callback(struct mp_callback **slot, struct mp_callback *val)
{
*(volatile mp_callback_t *)slot = value;
asm volatile ("mov %1, %0\n"
: "=m" (*slot)
: "r" (val)
: "memory"
);
}
static int run_ap_work(mp_callback_t func, long expire_us)
static int run_ap_work(struct mp_callback *val, long expire_us)
{
int i;
int cpus_accepted;
@ -879,7 +892,7 @@ static int run_ap_work(mp_callback_t func, long expire_us)
for (i = 0; i < ARRAY_SIZE(ap_callbacks); i++) {
if (cur_cpu == i)
continue;
store_callback(&ap_callbacks[i], func);
store_callback(&ap_callbacks[i], val);
}
mfence();
@ -908,28 +921,34 @@ static int run_ap_work(mp_callback_t func, long expire_us)
static void ap_wait_for_instruction(void)
{
int cur_cpu = cpu_index();
struct mp_callback lcb;
struct mp_callback **per_cpu_slot;
if (!IS_ENABLED(CONFIG_PARALLEL_MP_AP_WORK))
return;
while (1) {
mp_callback_t func = read_callback(&ap_callbacks[cur_cpu]);
per_cpu_slot = &ap_callbacks[cpu_index()];
if (func == NULL) {
while (1) {
struct mp_callback *cb = read_callback(per_cpu_slot);
if (cb == NULL) {
asm ("pause");
continue;
}
store_callback(&ap_callbacks[cur_cpu], NULL);
/* Copy to local variable before signalling consumption. */
memcpy(&lcb, cb, sizeof(lcb));
mfence();
func();
store_callback(per_cpu_slot, NULL);
lcb.func();
}
}
int mp_run_on_aps(void (*func)(void), long expire_us)
{
return run_ap_work(func, expire_us);
struct mp_callback lcb = { .func = func };
return run_ap_work(&lcb, expire_us);
}
int mp_run_on_all_cpus(void (*func)(void), long expire_us)