| /* |
| * r2300_switch.S: R2300 specific task switching code. |
| * |
| * Copyright (C) 1994, 1995, 1996, 1999 by Ralf Baechle |
| * Copyright (C) 1994, 1995, 1996 by Andreas Busse |
| * |
| * Multi-cpu abstraction and macros for easier reading: |
| * Copyright (C) 1996 David S. Miller (davem@davemloft.net) |
| * |
| * Further modifications to make this work: |
| * Copyright (c) 1998-2000 Harald Koerfgen |
| */ |
| #include <asm/asm.h> |
| #include <asm/cachectl.h> |
| #include <asm/fpregdef.h> |
| #include <asm/mipsregs.h> |
| #include <asm/asm-offsets.h> |
| #include <asm/page.h> |
| #include <asm/regdef.h> |
| #include <asm/stackframe.h> |
| #include <asm/thread_info.h> |
| |
| #include <asm/asmmacro.h> |
| |
| .set mips1 |
| .align 5 |
| |
| /* |
| * Offset to the current process status flags, the first 32 bytes of the |
| * stack are not used. |
| */ |
| #define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS) |
| |
| /* |
| * FPU context is saved iff the process has used it's FPU in the current |
| * time slice as indicated by TIF_USEDFPU. In any case, the CU1 bit for user |
| * space STATUS register should be 0, so that a process *always* starts its |
| * userland with FPU disabled after each context switch. |
| * |
| * FPU will be enabled as soon as the process accesses FPU again, through |
| * do_cpu() trap. |
| */ |
| |
| /* |
| * task_struct *resume(task_struct *prev, task_struct *next, |
| * struct thread_info *next_ti, int usedfpu) |
| */ |
| LEAF(resume) |
| mfc0 t1, CP0_STATUS |
| sw t1, THREAD_STATUS(a0) |
| cpu_save_nonscratch a0 |
| sw ra, THREAD_REG31(a0) |
| |
| beqz a3, 1f |
| |
| PTR_L t3, TASK_THREAD_INFO(a0) |
| |
| /* |
| * clear saved user stack CU1 bit |
| */ |
| lw t0, ST_OFF(t3) |
| li t1, ~ST0_CU1 |
| and t0, t0, t1 |
| sw t0, ST_OFF(t3) |
| |
| fpu_save_single a0, t0 # clobbers t0 |
| |
| 1: |
| /* |
| * The order of restoring the registers takes care of the race |
| * updating $28, $29 and kernelsp without disabling ints. |
| */ |
| move $28, a2 |
| cpu_restore_nonscratch a1 |
| |
| addiu t1, $28, _THREAD_SIZE - 32 |
| sw t1, kernelsp |
| |
| mfc0 t1, CP0_STATUS /* Do we really need this? */ |
| li a3, 0xff01 |
| and t1, a3 |
| lw a2, THREAD_STATUS(a1) |
| nor a3, $0, a3 |
| and a2, a3 |
| or a2, t1 |
| mtc0 a2, CP0_STATUS |
| move v0, a0 |
| jr ra |
| END(resume) |
| |
| /* |
| * Save a thread's fp context. |
| */ |
| LEAF(_save_fp) |
| fpu_save_single a0, t1 # clobbers t1 |
| jr ra |
| END(_save_fp) |
| |
| /* |
| * Restore a thread's fp context. |
| */ |
| LEAF(_restore_fp) |
| fpu_restore_single a0, t1 # clobbers t1 |
| jr ra |
| END(_restore_fp) |
| |
| /* |
| * Load the FPU with signalling NANS. This bit pattern we're using has |
| * the property that no matter whether considered as single or as double |
| * precision represents signaling NANS. |
| * |
| * We initialize fcr31 to rounding to nearest, no exceptions. |
| */ |
| |
| #define FPU_DEFAULT 0x00000000 |
| |
| LEAF(_init_fpu) |
| mfc0 t0, CP0_STATUS |
| li t1, ST0_CU1 |
| or t0, t1 |
| mtc0 t0, CP0_STATUS |
| |
| li t1, FPU_DEFAULT |
| ctc1 t1, fcr31 |
| |
| li t0, -1 |
| |
| mtc1 t0, $f0 |
| mtc1 t0, $f1 |
| mtc1 t0, $f2 |
| mtc1 t0, $f3 |
| mtc1 t0, $f4 |
| mtc1 t0, $f5 |
| mtc1 t0, $f6 |
| mtc1 t0, $f7 |
| mtc1 t0, $f8 |
| mtc1 t0, $f9 |
| mtc1 t0, $f10 |
| mtc1 t0, $f11 |
| mtc1 t0, $f12 |
| mtc1 t0, $f13 |
| mtc1 t0, $f14 |
| mtc1 t0, $f15 |
| mtc1 t0, $f16 |
| mtc1 t0, $f17 |
| mtc1 t0, $f18 |
| mtc1 t0, $f19 |
| mtc1 t0, $f20 |
| mtc1 t0, $f21 |
| mtc1 t0, $f22 |
| mtc1 t0, $f23 |
| mtc1 t0, $f24 |
| mtc1 t0, $f25 |
| mtc1 t0, $f26 |
| mtc1 t0, $f27 |
| mtc1 t0, $f28 |
| mtc1 t0, $f29 |
| mtc1 t0, $f30 |
| mtc1 t0, $f31 |
| jr ra |
| END(_init_fpu) |
