MIPS: Tidy up FPU context switching
Rather than saving the scalar FP or vector context in the assembly resume function, reuse the existing C code we have in fpu.h to do exactly that. This reduces duplication, results in a much easier to read resume function & should allow the compiler to optimise out more MSA code due to is_msa_enabled()/cpu_has_msa being known-zero at compile time for kernels without MSA support. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-kernel@vger.kernel.org Cc: James Hogan <james.hogan@imgtec.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Cc: Manuel Lauss <manuel.lauss@gmail.com> Patchwork: https://patchwork.linux-mips.org/patch/10830/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton
Ralf Baechle
Родитель
23eb6f4016
Коммит
1a3d59579b
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@ -164,25 +164,30 @@ static inline int own_fpu(int restore)
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return ret;
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}
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static inline void lose_fpu(int save)
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static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
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{
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preempt_disable();
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if (is_msa_enabled()) {
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if (save) {
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save_msa(current);
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current->thread.fpu.fcr31 =
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save_msa(tsk);
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tsk->thread.fpu.fcr31 =
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read_32bit_cp1_register(CP1_STATUS);
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}
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disable_msa();
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clear_thread_flag(TIF_USEDMSA);
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clear_tsk_thread_flag(tsk, TIF_USEDMSA);
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__disable_fpu();
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} else if (is_fpu_owner()) {
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if (save)
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_save_fp(current);
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_save_fp(tsk);
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__disable_fpu();
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}
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KSTK_STATUS(current) &= ~ST0_CU1;
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clear_thread_flag(TIF_USEDFPU);
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KSTK_STATUS(tsk) &= ~ST0_CU1;
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clear_tsk_thread_flag(tsk, TIF_USEDFPU);
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}
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static inline void lose_fpu(int save)
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{
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preempt_disable();
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lose_fpu_inatomic(save, current);
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preempt_enable();
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}
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@ -16,29 +16,21 @@
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#include <asm/watch.h>
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#include <asm/dsp.h>
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#include <asm/cop2.h>
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#include <asm/msa.h>
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#include <asm/fpu.h>
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struct task_struct;
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enum {
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FP_SAVE_NONE = 0,
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FP_SAVE_VECTOR = -1,
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FP_SAVE_SCALAR = 1,
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};
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/**
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* resume - resume execution of a task
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* @prev: The task previously executed.
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* @next: The task to begin executing.
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* @next_ti: task_thread_info(next).
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* @fp_save: Which, if any, FP context to save for prev.
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*
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* This function is used whilst scheduling to save the context of prev & load
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* the context of next. Returns prev.
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*/
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extern asmlinkage struct task_struct *resume(struct task_struct *prev,
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struct task_struct *next, struct thread_info *next_ti,
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s32 fp_save);
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struct task_struct *next, struct thread_info *next_ti);
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extern unsigned int ll_bit;
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extern struct task_struct *ll_task;
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@ -91,8 +83,8 @@ do { if (cpu_has_rw_llb) { \
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*/
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#define switch_to(prev, next, last) \
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do { \
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s32 __fpsave = FP_SAVE_NONE; \
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__mips_mt_fpaff_switch_to(prev); \
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lose_fpu_inatomic(1, prev); \
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if (cpu_has_dsp) { \
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__save_dsp(prev); \
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__restore_dsp(next); \
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@ -111,15 +103,10 @@ do { \
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clear_c0_status(ST0_CU2); \
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} \
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__clear_software_ll_bit(); \
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if (test_and_clear_tsk_thread_flag(prev, TIF_USEDFPU)) \
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__fpsave = FP_SAVE_SCALAR; \
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if (test_and_clear_tsk_thread_flag(prev, TIF_USEDMSA)) \
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__fpsave = FP_SAVE_VECTOR; \
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if (cpu_has_userlocal) \
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write_c0_userlocal(task_thread_info(next)->tp_value); \
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__restore_watch(); \
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disable_msa(); \
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(last) = resume(prev, next, task_thread_info(next), __fpsave); \
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(last) = resume(prev, next, task_thread_info(next)); \
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} while (0)
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#endif /* _ASM_SWITCH_TO_H */
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@ -34,7 +34,7 @@
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#ifndef USE_ALTERNATE_RESUME_IMPL
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/*
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* task_struct *resume(task_struct *prev, task_struct *next,
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* struct thread_info *next_ti, s32 fp_save)
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* struct thread_info *next_ti)
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*/
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.align 5
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LEAF(resume)
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@ -43,45 +43,6 @@
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cpu_save_nonscratch a0
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LONG_S ra, THREAD_REG31(a0)
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/*
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* Check whether we need to save any FP context. FP context is saved
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* iff the process has used the context with the scalar FPU or the MSA
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* ASE in the current time slice, as indicated by _TIF_USEDFPU and
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* _TIF_USEDMSA respectively. switch_to will have set fp_save
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* accordingly to an FP_SAVE_ enum value.
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*/
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beqz a3, 2f
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/*
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* We do. Clear the saved CU1 bit for prev, such that next time it is
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* scheduled it will start in userland with the FPU disabled. If the
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* task uses the FPU then it will be enabled again via the do_cpu trap.
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* This allows us to lazily restore the FP context.
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*/
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PTR_L t3, TASK_THREAD_INFO(a0)
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LONG_L t0, ST_OFF(t3)
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li t1, ~ST0_CU1
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and t0, t0, t1
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LONG_S t0, ST_OFF(t3)
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/* Check whether we're saving scalar or vector context. */
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bgtz a3, 1f
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/* Save 128b MSA vector context + scalar FP control & status. */
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.set push
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SET_HARDFLOAT
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cfc1 t1, fcr31
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msa_save_all a0
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.set pop /* SET_HARDFLOAT */
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sw t1, THREAD_FCR31(a0)
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b 2f
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1: /* Save 32b/64b scalar FP context. */
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fpu_save_double a0 t0 t1 # c0_status passed in t0
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# clobbers t1
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2:
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#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
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PTR_LA t8, __stack_chk_guard
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LONG_L t9, TASK_STACK_CANARY(a1)
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