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>
diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index 04cbbde3..92cd051 100644
--- a/arch/mips/kernel/r4k_switch.S
+++ b/arch/mips/kernel/r4k_switch.S
@@ -34,7 +34,7 @@
#ifndef USE_ALTERNATE_RESUME_IMPL
/*
* task_struct *resume(task_struct *prev, task_struct *next,
- * struct thread_info *next_ti, s32 fp_save)
+ * struct thread_info *next_ti)
*/
.align 5
LEAF(resume)
@@ -43,45 +43,6 @@
cpu_save_nonscratch a0
LONG_S ra, THREAD_REG31(a0)
- /*
- * Check whether we need to save any FP context. FP context is saved
- * iff the process has used the context with the scalar FPU or the MSA
- * ASE in the current time slice, as indicated by _TIF_USEDFPU and
- * _TIF_USEDMSA respectively. switch_to will have set fp_save
- * accordingly to an FP_SAVE_ enum value.
- */
- beqz a3, 2f
-
- /*
- * We do. Clear the saved CU1 bit for prev, such that next time it is
- * scheduled it will start in userland with the FPU disabled. If the
- * task uses the FPU then it will be enabled again via the do_cpu trap.
- * This allows us to lazily restore the FP context.
- */
- PTR_L t3, TASK_THREAD_INFO(a0)
- LONG_L t0, ST_OFF(t3)
- li t1, ~ST0_CU1
- and t0, t0, t1
- LONG_S t0, ST_OFF(t3)
-
- /* Check whether we're saving scalar or vector context. */
- bgtz a3, 1f
-
- /* Save 128b MSA vector context + scalar FP control & status. */
- .set push
- SET_HARDFLOAT
- cfc1 t1, fcr31
- msa_save_all a0
- .set pop /* SET_HARDFLOAT */
-
- sw t1, THREAD_FCR31(a0)
- b 2f
-
-1: /* Save 32b/64b scalar FP context. */
- fpu_save_double a0 t0 t1 # c0_status passed in t0
- # clobbers t1
-2:
-
#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
PTR_LA t8, __stack_chk_guard
LONG_L t9, TASK_STACK_CANARY(a1)
