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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2017 Cavium, Inc
*/
#ifndef STACK_H
#define STACK_H
#ifdef __cplusplus
extern "C" {
#endif
#include "lthread_int.h"
/*
* Sets up the initial stack for the lthread.
*/
static inline void
arch_set_stack(struct lthread *lt, void *func)
{
void **stack_top = (void *)((char *)(lt->stack) + lt->stack_size);
/*
* Align stack_top to 16 bytes. Arm64 has the constraint that the
* stack pointer must always be quad-word aligned.
*/
stack_top = (void **)(((unsigned long)(stack_top)) & ~0xfUL);
/*
* First Stack Frame
*/
stack_top[0] = NULL;
stack_top[-1] = NULL;
/*
* Initialize the context
*/
lt->ctx.fp = &stack_top[-1];
lt->ctx.sp = &stack_top[-2];
/*
* Here only the address of _lthread_exec is saved as the link
* register value. The argument to _lthread_exec i.e the address of
* the lthread struct is not saved. This is because the first
* argument to ctx_switch is the address of the new context,
* which also happens to be the address of required lthread struct.
* So while returning from ctx_switch into _thread_exec, parameter
* register x0 will always contain the required value.
*/
lt->ctx.lr = func;
}
#ifdef __cplusplus
}
#endif
#endif /* STACK_H_ */
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