From 18461960cbf50bf345ef0667d45d5f64de8fb893 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 10 Sep 2013 20:21:10 +1000 Subject: powerpc: Provide for giveup_fpu/altivec to save state in alternate location This provides a facility which is intended for use by KVM, where the contents of the FP/VSX and VMX (Altivec) registers can be saved away to somewhere other than the thread_struct when kernel code wants to use floating point or VMX instructions. This is done by providing a pointer in the thread_struct to indicate where the state should be saved to. The giveup_fpu() and giveup_altivec() functions test these pointers and save state to the indicated location if they are non-NULL. Note that the MSR_FP/VEC bits in task->thread.regs->msr are still used to indicate whether the CPU register state is live, even when an alternate save location is being used. This also provides load_fp_state() and load_vr_state() functions, which load up FP/VSX and VMX state from memory into the CPU registers, and corresponding store_fp_state() and store_vr_state() functions, which store FP/VSX and VMX state into memory from the CPU registers. Signed-off-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/fpu.S | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/kernel/fpu.S') diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S index 34b96e6d2f0d..4dca05e91e95 100644 --- a/arch/powerpc/kernel/fpu.S +++ b/arch/powerpc/kernel/fpu.S @@ -80,6 +80,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX) blr #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ +/* + * Load state from memory into FP registers including FPSCR. + * Assumes the caller has enabled FP in the MSR. + */ +_GLOBAL(load_fp_state) + lfd fr0,FPSTATE_FPSCR(r3) + MTFSF_L(fr0) + REST_32FPVSRS(0, R4, R3) + blr + +/* + * Store FP state into memory, including FPSCR + * Assumes the caller has enabled FP in the MSR. + */ +_GLOBAL(store_fp_state) + SAVE_32FPVSRS(0, R4, R3) + mffs fr0 + stfd fr0,FPSTATE_FPSCR(r3) + blr + /* * This task wants to use the FPU now. * On UP, disable FP for the task which had the FPU previously, @@ -172,9 +192,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX) PPC_LCMPI 0,r3,0 beqlr- /* if no previous owner, done */ addi r3,r3,THREAD /* want THREAD of task */ + PPC_LL r6,THREAD_FPSAVEAREA(r3) PPC_LL r5,PT_REGS(r3) - PPC_LCMPI 0,r5,0 + PPC_LCMPI 0,r6,0 + bne 2f addi r6,r3,THREAD_FPSTATE +2: PPC_LCMPI 0,r5,0 SAVE_32FPVSRS(0, R4, R6) mffs fr0 stfd fr0,FPSTATE_FPSCR(r6) -- cgit v1.2.3-70-g09d2