35000870fc
Add two optimisations to enable_kernel_altivec: - enable_kernel_altivec has already determined if we need to save the previous task's state but we call giveup_altivec in both cases, requiring an extra branch in giveup_altivec. Create giveup_altivec_notask which only turns on the VMX bit in the MSR. - We write the VMX MSR bit each time we call enable_kernel_altivec even it was already set. Check the bit and branch out if we have already set it. The classic case for this is vectored IO where we have to copy multiple buffers to or from userspace. The following testcase was used to confirm this patch improves performance: http://ozlabs.org/~anton/junkcode/copy_to_user.c Since the current breakpoint for using VMX in copy_tofrom_user is 4096 bytes, I'm using buffers of 4096 + 1 cacheline (4224) bytes. A benchmark of 16 entry readvs (-s 16): time copy_to_user -l 4224 -s 16 -i 1000000 completes 5.2% faster on a POWER7 PS700. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
418 lines
8.7 KiB
ArmAsm
418 lines
8.7 KiB
ArmAsm
#include <asm/processor.h>
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#include <asm/ppc_asm.h>
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#include <asm/reg.h>
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#include <asm/asm-offsets.h>
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#include <asm/cputable.h>
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#include <asm/thread_info.h>
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#include <asm/page.h>
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#include <asm/ptrace.h>
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/*
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* load_up_altivec(unused, unused, tsk)
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* Disable VMX for the task which had it previously,
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* and save its vector registers in its thread_struct.
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* Enables the VMX for use in the kernel on return.
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* On SMP we know the VMX is free, since we give it up every
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* switch (ie, no lazy save of the vector registers).
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*/
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_GLOBAL(load_up_altivec)
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mfmsr r5 /* grab the current MSR */
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oris r5,r5,MSR_VEC@h
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MTMSRD(r5) /* enable use of AltiVec now */
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isync
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/*
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* For SMP, we don't do lazy VMX switching because it just gets too
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* horrendously complex, especially when a task switches from one CPU
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* to another. Instead we call giveup_altvec in switch_to.
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* VRSAVE isn't dealt with here, that is done in the normal context
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* switch code. Note that we could rely on vrsave value to eventually
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* avoid saving all of the VREGs here...
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*/
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#ifndef CONFIG_SMP
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LOAD_REG_ADDRBASE(r3, last_task_used_altivec)
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toreal(r3)
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PPC_LL r4,ADDROFF(last_task_used_altivec)(r3)
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PPC_LCMPI 0,r4,0
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beq 1f
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/* Save VMX state to last_task_used_altivec's THREAD struct */
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toreal(r4)
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addi r4,r4,THREAD
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SAVE_32VRS(0,r5,r4)
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mfvscr vr0
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li r10,THREAD_VSCR
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stvx vr0,r10,r4
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/* Disable VMX for last_task_used_altivec */
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PPC_LL r5,PT_REGS(r4)
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toreal(r5)
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PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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lis r10,MSR_VEC@h
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andc r4,r4,r10
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PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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1:
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#endif /* CONFIG_SMP */
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/* Hack: if we get an altivec unavailable trap with VRSAVE
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* set to all zeros, we assume this is a broken application
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* that fails to set it properly, and thus we switch it to
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* all 1's
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*/
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mfspr r4,SPRN_VRSAVE
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cmpwi 0,r4,0
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bne+ 1f
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li r4,-1
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mtspr SPRN_VRSAVE,r4
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1:
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/* enable use of VMX after return */
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#ifdef CONFIG_PPC32
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mfspr r5,SPRN_SPRG_THREAD /* current task's THREAD (phys) */
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oris r9,r9,MSR_VEC@h
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#else
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ld r4,PACACURRENT(r13)
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addi r5,r4,THREAD /* Get THREAD */
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oris r12,r12,MSR_VEC@h
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std r12,_MSR(r1)
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#endif
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li r4,1
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li r10,THREAD_VSCR
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stw r4,THREAD_USED_VR(r5)
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lvx vr0,r10,r5
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mtvscr vr0
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REST_32VRS(0,r4,r5)
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#ifndef CONFIG_SMP
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/* Update last_task_used_altivec to 'current' */
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subi r4,r5,THREAD /* Back to 'current' */
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fromreal(r4)
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PPC_STL r4,ADDROFF(last_task_used_altivec)(r3)
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#endif /* CONFIG_SMP */
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/* restore registers and return */
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blr
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_GLOBAL(giveup_altivec_notask)
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mfmsr r3
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andis. r4,r3,MSR_VEC@h
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bnelr /* Already enabled? */
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oris r3,r3,MSR_VEC@h
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SYNC
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MTMSRD(r3) /* enable use of VMX now */
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isync
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blr
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/*
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* giveup_altivec(tsk)
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* Disable VMX for the task given as the argument,
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* and save the vector registers in its thread_struct.
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* Enables the VMX for use in the kernel on return.
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*/
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_GLOBAL(giveup_altivec)
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mfmsr r5
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oris r5,r5,MSR_VEC@h
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SYNC
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MTMSRD(r5) /* enable use of VMX now */
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isync
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PPC_LCMPI 0,r3,0
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beqlr /* if no previous owner, done */
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addi r3,r3,THREAD /* want THREAD of task */
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PPC_LL r5,PT_REGS(r3)
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PPC_LCMPI 0,r5,0
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SAVE_32VRS(0,r4,r3)
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mfvscr vr0
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li r4,THREAD_VSCR
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stvx vr0,r4,r3
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beq 1f
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PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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lis r3,(MSR_VEC|MSR_VSX)@h
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FTR_SECTION_ELSE
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lis r3,MSR_VEC@h
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ALT_FTR_SECTION_END_IFSET(CPU_FTR_VSX)
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#else
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lis r3,MSR_VEC@h
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#endif
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andc r4,r4,r3 /* disable FP for previous task */
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PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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1:
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#ifndef CONFIG_SMP
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li r5,0
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LOAD_REG_ADDRBASE(r4,last_task_used_altivec)
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PPC_STL r5,ADDROFF(last_task_used_altivec)(r4)
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#endif /* CONFIG_SMP */
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blr
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#ifdef CONFIG_VSX
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#ifdef CONFIG_PPC32
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#error This asm code isn't ready for 32-bit kernels
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#endif
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/*
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* load_up_vsx(unused, unused, tsk)
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* Disable VSX for the task which had it previously,
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* and save its vector registers in its thread_struct.
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* Reuse the fp and vsx saves, but first check to see if they have
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* been saved already.
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*/
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_GLOBAL(load_up_vsx)
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/* Load FP and VSX registers if they haven't been done yet */
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andi. r5,r12,MSR_FP
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beql+ load_up_fpu /* skip if already loaded */
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andis. r5,r12,MSR_VEC@h
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beql+ load_up_altivec /* skip if already loaded */
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#ifndef CONFIG_SMP
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ld r3,last_task_used_vsx@got(r2)
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ld r4,0(r3)
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cmpdi 0,r4,0
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beq 1f
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/* Disable VSX for last_task_used_vsx */
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addi r4,r4,THREAD
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ld r5,PT_REGS(r4)
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ld r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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lis r6,MSR_VSX@h
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andc r6,r4,r6
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std r6,_MSR-STACK_FRAME_OVERHEAD(r5)
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1:
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#endif /* CONFIG_SMP */
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ld r4,PACACURRENT(r13)
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addi r4,r4,THREAD /* Get THREAD */
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li r6,1
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stw r6,THREAD_USED_VSR(r4) /* ... also set thread used vsr */
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/* enable use of VSX after return */
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oris r12,r12,MSR_VSX@h
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std r12,_MSR(r1)
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#ifndef CONFIG_SMP
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/* Update last_task_used_vsx to 'current' */
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ld r4,PACACURRENT(r13)
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std r4,0(r3)
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#endif /* CONFIG_SMP */
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b fast_exception_return
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/*
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* __giveup_vsx(tsk)
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* Disable VSX for the task given as the argument.
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* Does NOT save vsx registers.
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* Enables the VSX for use in the kernel on return.
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*/
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_GLOBAL(__giveup_vsx)
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mfmsr r5
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oris r5,r5,MSR_VSX@h
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mtmsrd r5 /* enable use of VSX now */
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isync
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cmpdi 0,r3,0
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beqlr- /* if no previous owner, done */
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addi r3,r3,THREAD /* want THREAD of task */
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ld r5,PT_REGS(r3)
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cmpdi 0,r5,0
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beq 1f
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ld r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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lis r3,MSR_VSX@h
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andc r4,r4,r3 /* disable VSX for previous task */
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std r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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1:
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#ifndef CONFIG_SMP
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li r5,0
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ld r4,last_task_used_vsx@got(r2)
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std r5,0(r4)
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#endif /* CONFIG_SMP */
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blr
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#endif /* CONFIG_VSX */
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/*
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* The routines below are in assembler so we can closely control the
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* usage of floating-point registers. These routines must be called
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* with preempt disabled.
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*/
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#ifdef CONFIG_PPC32
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.data
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fpzero:
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.long 0
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fpone:
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.long 0x3f800000 /* 1.0 in single-precision FP */
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fphalf:
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.long 0x3f000000 /* 0.5 in single-precision FP */
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#define LDCONST(fr, name) \
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lis r11,name@ha; \
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lfs fr,name@l(r11)
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#else
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.section ".toc","aw"
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fpzero:
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.tc FD_0_0[TC],0
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fpone:
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.tc FD_3ff00000_0[TC],0x3ff0000000000000 /* 1.0 */
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fphalf:
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.tc FD_3fe00000_0[TC],0x3fe0000000000000 /* 0.5 */
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#define LDCONST(fr, name) \
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lfd fr,name@toc(r2)
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#endif
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.text
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/*
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* Internal routine to enable floating point and set FPSCR to 0.
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* Don't call it from C; it doesn't use the normal calling convention.
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*/
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fpenable:
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#ifdef CONFIG_PPC32
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stwu r1,-64(r1)
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#else
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stdu r1,-64(r1)
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#endif
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mfmsr r10
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ori r11,r10,MSR_FP
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mtmsr r11
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isync
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stfd fr0,24(r1)
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stfd fr1,16(r1)
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stfd fr31,8(r1)
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LDCONST(fr1, fpzero)
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mffs fr31
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MTFSF_L(fr1)
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blr
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fpdisable:
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mtlr r12
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MTFSF_L(fr31)
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lfd fr31,8(r1)
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lfd fr1,16(r1)
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lfd fr0,24(r1)
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mtmsr r10
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isync
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addi r1,r1,64
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blr
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/*
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* Vector add, floating point.
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*/
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_GLOBAL(vaddfp)
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mflr r12
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bl fpenable
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li r0,4
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mtctr r0
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li r6,0
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1: lfsx fr0,r4,r6
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lfsx fr1,r5,r6
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fadds fr0,fr0,fr1
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stfsx fr0,r3,r6
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addi r6,r6,4
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bdnz 1b
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b fpdisable
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/*
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* Vector subtract, floating point.
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*/
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_GLOBAL(vsubfp)
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mflr r12
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bl fpenable
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li r0,4
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mtctr r0
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li r6,0
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1: lfsx fr0,r4,r6
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lfsx fr1,r5,r6
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fsubs fr0,fr0,fr1
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stfsx fr0,r3,r6
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addi r6,r6,4
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bdnz 1b
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b fpdisable
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/*
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* Vector multiply and add, floating point.
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*/
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_GLOBAL(vmaddfp)
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mflr r12
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bl fpenable
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stfd fr2,32(r1)
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li r0,4
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mtctr r0
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li r7,0
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1: lfsx fr0,r4,r7
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lfsx fr1,r5,r7
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lfsx fr2,r6,r7
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fmadds fr0,fr0,fr2,fr1
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stfsx fr0,r3,r7
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addi r7,r7,4
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bdnz 1b
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lfd fr2,32(r1)
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b fpdisable
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/*
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* Vector negative multiply and subtract, floating point.
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*/
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_GLOBAL(vnmsubfp)
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mflr r12
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bl fpenable
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stfd fr2,32(r1)
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li r0,4
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mtctr r0
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li r7,0
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1: lfsx fr0,r4,r7
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lfsx fr1,r5,r7
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lfsx fr2,r6,r7
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fnmsubs fr0,fr0,fr2,fr1
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stfsx fr0,r3,r7
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addi r7,r7,4
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bdnz 1b
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lfd fr2,32(r1)
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b fpdisable
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/*
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* Vector reciprocal estimate. We just compute 1.0/x.
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* r3 -> destination, r4 -> source.
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*/
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_GLOBAL(vrefp)
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mflr r12
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bl fpenable
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li r0,4
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LDCONST(fr1, fpone)
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mtctr r0
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li r6,0
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1: lfsx fr0,r4,r6
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fdivs fr0,fr1,fr0
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stfsx fr0,r3,r6
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addi r6,r6,4
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bdnz 1b
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b fpdisable
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/*
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* Vector reciprocal square-root estimate, floating point.
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* We use the frsqrte instruction for the initial estimate followed
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* by 2 iterations of Newton-Raphson to get sufficient accuracy.
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* r3 -> destination, r4 -> source.
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*/
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_GLOBAL(vrsqrtefp)
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mflr r12
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bl fpenable
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stfd fr2,32(r1)
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stfd fr3,40(r1)
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stfd fr4,48(r1)
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stfd fr5,56(r1)
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li r0,4
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LDCONST(fr4, fpone)
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LDCONST(fr5, fphalf)
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mtctr r0
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li r6,0
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1: lfsx fr0,r4,r6
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frsqrte fr1,fr0 /* r = frsqrte(s) */
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fmuls fr3,fr1,fr0 /* r * s */
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fmuls fr2,fr1,fr5 /* r * 0.5 */
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fnmsubs fr3,fr1,fr3,fr4 /* 1 - s * r * r */
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fmadds fr1,fr2,fr3,fr1 /* r = r + 0.5 * r * (1 - s * r * r) */
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fmuls fr3,fr1,fr0 /* r * s */
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fmuls fr2,fr1,fr5 /* r * 0.5 */
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fnmsubs fr3,fr1,fr3,fr4 /* 1 - s * r * r */
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fmadds fr1,fr2,fr3,fr1 /* r = r + 0.5 * r * (1 - s * r * r) */
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stfsx fr1,r3,r6
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addi r6,r6,4
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bdnz 1b
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lfd fr5,56(r1)
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lfd fr4,48(r1)
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lfd fr3,40(r1)
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lfd fr2,32(r1)
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b fpdisable
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