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/** @addtogroup arm32
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/** @addtogroup arm32
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 * @{
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 * @{
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 */
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 */
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/** @file
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/** @file
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 *  @brief Userspace.
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 *  @brief Userspace switch.
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 */
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 */
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#include <userspace.h>
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#include <userspace.h>
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- 
 
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/** Struct to hold general purpose register values */
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/** Struct for holding all general purpose registers.
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 *  
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 *  Used to set registers when going to userspace.
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 */
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typedef struct {
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typedef struct {
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    uint32_t r0;
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    uint32_t r0;
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    uint32_t r1;
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    uint32_t r1;
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    uint32_t r2;
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    uint32_t r2;
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    uint32_t r3;
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    uint32_t r3;
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    ustate.r1 = ustate.r2  = ustate.r3  = ustate.r4  =
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    ustate.r1 = ustate.r2  = ustate.r3  = ustate.r4  =
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        ustate.r5 = ustate.r6  = ustate.r7  = ustate.r8  =
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        ustate.r5 = ustate.r6  = ustate.r7  = ustate.r8  =
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        ustate.r9 = ustate.r10 = ustate.r11 = ustate.r12 =
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        ustate.r9 = ustate.r10 = ustate.r11 = ustate.r12 =
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        ustate.lr = 0;
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        ustate.lr = 0;
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    //set user stack
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    // set user stack
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    ustate.sp = ((uint32_t)kernel_uarg->uspace_stack) +
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    ustate.sp = ((uint32_t)kernel_uarg->uspace_stack) + PAGE_SIZE;
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            PAGE_SIZE - sizeof(void*);
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    //set where uspace execution starts
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    // set where uspace execution starts
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    ustate.pc = (uintptr_t) kernel_uarg->uspace_entry;
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    ustate.pc = (uintptr_t) kernel_uarg->uspace_entry;
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    //status register in user mode
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    // status register in user mode
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    ipl_t cpsr = current_status_reg_read();
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    cpsr &= ~STATUS_REG_MODE_MASK | USER_MODE;
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    ipl_t tmpsr = (cpsr & ~STATUS_REG_MODE_MASK) | SUPERVISOR_MODE;
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    ipl_t user_mode = current_status_reg_read() & (~STATUS_REG_MODE_MASK | USER_MODE);
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    // set user mode, set registers, jump
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    asm __volatile__ (
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    asm __volatile__ (
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        // save pointer into ustate struct
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        "mov r0, %0         \n"
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        "mov r0, %0         \n"    
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        // save cspr
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        "mov r1, %1         \n"
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        // change mode into any exception mode
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        "msr cpsr_c, %2         \n"
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        // set saved cpsr
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        "msr spsr_c, r1 \n"
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        "msr spsr_c, %1     \n"
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        "mov sp, r0 \n"
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        // replace almost all registers
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        "ldmfd sp!, {r0-r12, sp, lr}^\n"
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        "ldmfd r0!, {r0-r12, sp, lr}^  \n"
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        //jump to the usermode
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        "ldmfd sp!, {pc}^"
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        "ldmfd r0!, {pc}^"
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    : // no output
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        :
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    : "r"(&ustate), "r"(cpsr), "r"(tmpsr) //
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        : "r"(&ustate), "r"(user_mode)
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    : "r0","r1"
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        : "r0", "r1"
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    );
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    );
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    // unreachable
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    // unreachable
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    while(1) ;
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    while(1) ;
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}
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}