diff options
| author | Paul Mackerras <paulus@samba.org> | 2013-09-10 12:21:10 +0200 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-10-11 08:26:50 +0200 |
| commit | 18461960cbf50bf345ef0667d45d5f64de8fb893 (patch) | |
| tree | 58947fe30598814684f7e33424675e204316e8ef /arch/powerpc/kernel/fpu.S | |
| parent | powerpc: Put FP/VSX and VR state into structures (diff) | |
| download | linux-18461960cbf50bf345ef0667d45d5f64de8fb893.tar.xz linux-18461960cbf50bf345ef0667d45d5f64de8fb893.zip | |
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 <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/fpu.S')
| -rw-r--r-- | arch/powerpc/kernel/fpu.S | 25 |
1 files changed, 24 insertions, 1 deletions
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 @@ -81,6 +81,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX) #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, * and save its floating-point registers in its thread_struct. @@ -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) |