trusty-fiq-arm64.c
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/*
* Copyright (C) 2013 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/percpu.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/trusty/smcall.h>
#include <linux/trusty/trusty.h>
#include <asm/fiq_glue.h>
#include "trusty-fiq.h"
extern void trusty_fiq_glue_arm64(void);
static struct device *trusty_dev;
static DEFINE_PER_CPU(void *, fiq_stack);
static struct fiq_glue_handler *fiq_handlers;
static DEFINE_MUTEX(fiq_glue_lock);
void trusty_fiq_handler(struct pt_regs *regs, void *svc_sp)
{
struct fiq_glue_handler *handler;
for (handler = ACCESS_ONCE(fiq_handlers); handler;
handler = ACCESS_ONCE(handler->next)) {
/* Barrier paired with smp_wmb in fiq_glue_register_handler */
smp_read_barrier_depends();
handler->fiq(handler, regs, svc_sp);
}
}
static void smp_nop_call(void *info)
{
/* If this call is reached, the fiq handler is not currently running */
}
static void fiq_glue_clear_handler(void)
{
int cpu;
int ret;
void *stack;
for_each_possible_cpu(cpu) {
stack = per_cpu(fiq_stack, cpu);
if (!stack)
continue;
ret = trusty_fast_call64(trusty_dev, SMC_FC64_SET_FIQ_HANDLER,
cpu, 0, 0);
if (ret) {
pr_err("%s: SMC_FC_SET_FIQ_HANDLER(%d, 0, 0) failed 0x%x, skip free stack\n",
__func__, cpu, ret);
continue;
}
per_cpu(fiq_stack, cpu) = NULL;
smp_call_function_single(cpu, smp_nop_call, NULL, true);
free_pages((unsigned long)stack, THREAD_SIZE_ORDER);
}
}
static int fiq_glue_set_handler(void)
{
int ret;
int cpu;
void *stack;
unsigned long irqflags;
for_each_possible_cpu(cpu) {
stack = (void *)__get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
if (WARN_ON(!stack)) {
ret = -ENOMEM;
goto err_alloc_fiq_stack;
}
per_cpu(fiq_stack, cpu) = stack;
stack += THREAD_SIZE;
local_irq_save(irqflags);
ret = trusty_fast_call64(trusty_dev, SMC_FC64_SET_FIQ_HANDLER,
cpu, (uintptr_t)trusty_fiq_glue_arm64,
(uintptr_t)stack);
local_irq_restore(irqflags);
if (ret) {
pr_err("%s: SMC_FC_SET_FIQ_HANDLER(%d, %p, %p) failed 0x%x\n",
__func__, cpu, trusty_fiq_glue_arm64,
stack, ret);
ret = -EINVAL;
goto err_set_fiq_handler;
}
}
return 0;
err_alloc_fiq_stack:
err_set_fiq_handler:
fiq_glue_clear_handler();
return ret;
}
int fiq_glue_register_handler(struct fiq_glue_handler *handler)
{
int ret;
if (!handler || !handler->fiq) {
ret = -EINVAL;
goto err_bad_arg;
}
mutex_lock(&fiq_glue_lock);
if (!trusty_dev) {
ret = -ENODEV;
goto err_no_trusty;
}
handler->next = fiq_handlers;
/*
* Write barrier paired with smp_read_barrier_depends in
* trusty_fiq_handler. Make sure next pointer is updated before
* fiq_handlers so trusty_fiq_handler does not see an uninitialized
* value and terminate early or crash.
*/
smp_wmb();
fiq_handlers = handler;
smp_call_function(smp_nop_call, NULL, true);
if (!handler->next) {
ret = fiq_glue_set_handler();
if (ret)
goto err_set_fiq_handler;
}
mutex_unlock(&fiq_glue_lock);
return 0;
err_set_fiq_handler:
fiq_handlers = handler->next;
err_no_trusty:
mutex_unlock(&fiq_glue_lock);
err_bad_arg:
pr_err("%s: failed, %d\n", __func__, ret);
return ret;
}
int trusty_fiq_arch_probe(struct platform_device *pdev)
{
mutex_lock(&fiq_glue_lock);
trusty_dev = pdev->dev.parent;
mutex_unlock(&fiq_glue_lock);
return 0;
}
void trusty_fiq_arch_remove(struct platform_device *pdev)
{
mutex_lock(&fiq_glue_lock);
fiq_glue_clear_handler();
trusty_dev = NULL;
mutex_unlock(&fiq_glue_lock);
}