| 30,6 → 30,7 |
|---|
| #include <arch/mm/page.h> |
| #include <arch/asm/boot.h> |
| #include <arch/context_offset.h> |
| #include <arch/stack.h> |
| |
| .text |
| |
| 229,8 → 230,6 |
|---|
| j exception_handler |
| nop |
| |
| |
| |
| exception_handler: |
| KERNEL_STACK_TO_K0 |
| sub $k0, REGISTER_SPACE |
| 256,8 → 255,20 |
|---|
| # The $sp is automatically restored to former value |
| eret |
| |
| # it seems that mips reserves some space on stack for varfuncs??? |
| #define SS_ARG4 16 |
| ## Syscall entry |
| # |
| # Registers: |
| # |
| # @param v0 Syscall number. |
| # @param a0 1st argument. |
| # @param a1 2nd argument. |
| # @param a2 3rd argument. |
| # @param a3 4th argument. |
| # @param t0 5th argument. |
| # @param t1 6th argument. |
| # |
| # @return The return value will be stored in v0. |
| # |
| #define SS_SP EOFFSET_SP |
| #define SS_STATUS EOFFSET_STATUS |
| #define SS_EPC EOFFSET_EPC |
| 264,39 → 275,44 |
|---|
| #define SS_K1 EOFFSET_K1 |
| syscall_shortcut: |
| # We have a lot of space on the stack, with free use |
| mfc0 $t1, $epc |
| mfc0 $t0, $status |
| sw $t1,SS_EPC($sp) # Save EPC |
| sw $k1,SS_K1($sp) # Save k1, which is not saved during context switch |
| mfc0 $t3, $epc |
| mfc0 $t2, $status |
| sw $t3, SS_EPC($sp) # Save EPC |
| sw $k1, SS_K1($sp) # Save k1 not saved on context switch |
| |
| and $t2, $t0, REG_SAVE_MASK # Save only KSU,EXL,ERL,IE |
| li $t3, ~(0x1f) |
| and $t0, $t0, $t3 # Clear KSU,EXL,ERL |
| ori $t0, $t0, 0x1 # Set IE |
| and $t4, $t2, REG_SAVE_MASK # Save only KSU, EXL, ERL, IE |
| li $t5, ~(0x1f) |
| and $t2, $t2, $t5 # Clear KSU, EXL, ERL |
| ori $t2, $t2, 0x1 # Set IE |
| |
| sw $t2,SS_STATUS($sp) |
| mtc0 $t0, $status |
| sw $t4, SS_STATUS($sp) |
| mtc0 $t2, $status |
| |
| # CALL Syscall handler |
| # |
| # Call the higher level system call handler |
| # We are going to reuse part of the unused exception stack frame |
| # |
| sw $t0, STACK_ARG4($sp) # save the 5th argument on the stack |
| sw $t1, STACK_ARG5($sp) # save the 6th argument on the stack |
| jal syscall_handler |
| sw $v0, SS_ARG4($sp) # save v0 - arg4 to stack |
| sw $v0, STACK_ARG6($sp) # save the syscall number on the stack |
| |
| # restore status |
| mfc0 $t0, $status |
| lw $t1,SS_STATUS($sp) |
| mfc0 $t2, $status |
| lw $t3, SS_STATUS($sp) |
| |
| # Change back to EXL=1(from last exception), otherwise |
| # an interrupt could rewrite the CP0-EPC |
| li $t2, ~REG_SAVE_MASK # Mask UM,EXL,ERL,IE |
| and $t0, $t0, $t2 |
| or $t0, $t0, $t1 # Copy UM,EXL,ERL,IE from saved status |
| mtc0 $t0, $status |
| li $t4, ~REG_SAVE_MASK # Mask UM, EXL, ERL, IE |
| and $t2, $t2, $t4 |
| or $t2, $t2, $t3 # Copy saved UM, EXL, ERL, IE |
| mtc0 $t2, $status |
| |
| # restore epc+4 |
| lw $t0,SS_EPC($sp) |
| lw $t2, SS_EPC($sp) |
| lw $k1,SS_K1($sp) |
| addi $t0, $t0, 4 |
| mtc0 $t0, $epc |
| addi $t2, $t2, 4 |
| mtc0 $t2, $epc |
| |
| lw $sp,SS_SP($sp) # restore sp |
| |