/*
* Copyright (c) 2007 Petr Stepan, Pavel Jancik
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup kernel_arm32
* @{
*/
/** @file
* @brief Userspace switch.
*/
#include <stdbool.h>
#include <userspace.h>
#include <arch/ras.h>
/** Struct for holding all general purpose registers.
*
* Used to set registers when going to userspace.
*/
typedef struct {
uint32_t r0;
uint32_t r1;
uint32_t r2;
uint32_t r3;
uint32_t r4;
uint32_t r5;
uint32_t r6;
uint32_t r7;
uint32_t r8;
uint32_t r9;
uint32_t r10;
uint32_t r11;
uint32_t r12;
uint32_t sp;
uint32_t lr;
uint32_t pc;
} ustate_t;
uintptr_t arch_get_initial_sp(uintptr_t stack_base, uintptr_t stack_size)
{
return stack_base + stack_size;
}
/** Change processor mode
*
* @param kernel_uarg Userspace settings (entry point, stack, ...).
*
*/
void userspace(uintptr_t pc, uintptr_t sp)
{
volatile ustate_t ustate = { };
/* pass the RAS page address in %r2 */
ustate.r2 = (uintptr_t) ras_page;
ustate.sp = sp;
ustate.pc = pc;
/* status register in user mode */
ipl_t user_mode = current_status_reg_read() &
(~STATUS_REG_MODE_MASK | USER_MODE);
/* set user mode, set registers, jump */
asm volatile (
"mov sp, %[ustate]\n"
"msr spsr_c, %[user_mode]\n"
"ldmfd sp, {r0-r12, sp, lr}^\n"
"nop\n" /* Cannot access sp immediately after ldm(2) */
"add sp, sp, #(15*4)\n"
"ldmfd sp!, {pc}^\n"
:: [ustate] "r" (&ustate), [user_mode] "r" (user_mode)
);
unreachable();
}
/** @}
*/