ee43eb788b
The kernel uses SPRG registers for various purposes, typically in low level assembly code as scratch registers or to hold per-cpu global infos such as the PACA or the current thread_info pointer. We want to be able to easily shuffle the usage of those registers as some implementations have specific constraints realted to some of them, for example, some have userspace readable aliases, etc.. and the current choice isn't always the best. This patch should not change any code generation, and replaces the usage of SPRN_SPRGn everywhere in the kernel with a named replacement and adds documentation next to the definition of the names as to what those are used for on each processor family. The only parts that still use the original numbers are bits of KVM or suspend/resume code that just blindly needs to save/restore all the SPRGs. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
187 lines
4.7 KiB
ArmAsm
187 lines
4.7 KiB
ArmAsm
/*
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* FPU support code, moved here from head.S so that it can be used
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* by chips which use other head-whatever.S files.
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*
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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* Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
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* Copyright (C) 1996 Paul Mackerras.
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* Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <asm/reg.h>
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#include <asm/page.h>
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#include <asm/mmu.h>
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#include <asm/pgtable.h>
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#include <asm/cputable.h>
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#include <asm/cache.h>
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#include <asm/thread_info.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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#ifdef CONFIG_VSX
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#define REST_32FPVSRS(n,c,base) \
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BEGIN_FTR_SECTION \
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b 2f; \
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END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
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REST_32FPRS(n,base); \
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b 3f; \
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2: REST_32VSRS(n,c,base); \
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3:
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#define SAVE_32FPVSRS(n,c,base) \
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BEGIN_FTR_SECTION \
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b 2f; \
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END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
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SAVE_32FPRS(n,base); \
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b 3f; \
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2: SAVE_32VSRS(n,c,base); \
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3:
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#else
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#define REST_32FPVSRS(n,b,base) REST_32FPRS(n, base)
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#define SAVE_32FPVSRS(n,b,base) SAVE_32FPRS(n, base)
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#endif
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/*
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* This task wants to use the FPU now.
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* On UP, disable FP for the task which had the FPU previously,
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* and save its floating-point registers in its thread_struct.
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* Load up this task's FP registers from its thread_struct,
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* enable the FPU for the current task and return to the task.
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*/
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_GLOBAL(load_up_fpu)
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mfmsr r5
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ori r5,r5,MSR_FP
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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oris r5,r5,MSR_VSX@h
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END_FTR_SECTION_IFSET(CPU_FTR_VSX)
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#endif
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SYNC
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MTMSRD(r5) /* enable use of fpu now */
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isync
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/*
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* For SMP, we don't do lazy FPU 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_fpu in switch_to.
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*/
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#ifndef CONFIG_SMP
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LOAD_REG_ADDRBASE(r3, last_task_used_math)
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toreal(r3)
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PPC_LL r4,ADDROFF(last_task_used_math)(r3)
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PPC_LCMPI 0,r4,0
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beq 1f
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toreal(r4)
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addi r4,r4,THREAD /* want last_task_used_math->thread */
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SAVE_32FPVSRS(0, r5, r4)
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mffs fr0
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stfd fr0,THREAD_FPSCR(r4)
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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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li r10,MSR_FP|MSR_FE0|MSR_FE1
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andc r4,r4,r10 /* 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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#endif /* CONFIG_SMP */
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/* enable use of FP 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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lwz r4,THREAD_FPEXC_MODE(r5)
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ori r9,r9,MSR_FP /* enable FP for current */
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or r9,r9,r4
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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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lwz r4,THREAD_FPEXC_MODE(r5)
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ori r12,r12,MSR_FP
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or r12,r12,r4
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std r12,_MSR(r1)
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#endif
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lfd fr0,THREAD_FPSCR(r5)
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MTFSF_L(fr0)
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REST_32FPVSRS(0, r4, r5)
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#ifndef CONFIG_SMP
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subi r4,r5,THREAD
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fromreal(r4)
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PPC_STL r4,ADDROFF(last_task_used_math)(r3)
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#endif /* CONFIG_SMP */
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/* restore registers and return */
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/* we haven't used ctr or xer or lr */
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blr
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/*
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* giveup_fpu(tsk)
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* Disable FP for the task given as the argument,
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* and save the floating-point registers in its thread_struct.
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* Enables the FPU for use in the kernel on return.
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*/
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_GLOBAL(giveup_fpu)
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mfmsr r5
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ori r5,r5,MSR_FP
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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oris r5,r5,MSR_VSX@h
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END_FTR_SECTION_IFSET(CPU_FTR_VSX)
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#endif
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SYNC_601
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ISYNC_601
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MTMSRD(r5) /* enable use of fpu now */
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SYNC_601
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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_32FPVSRS(0, r4 ,r3)
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mffs fr0
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stfd fr0,THREAD_FPSCR(r3)
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beq 1f
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PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
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li r3,MSR_FP|MSR_FE0|MSR_FE1
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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oris r3,r3,MSR_VSX@h
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END_FTR_SECTION_IFSET(CPU_FTR_VSX)
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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_math)
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PPC_STL r5,ADDROFF(last_task_used_math)(r4)
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#endif /* CONFIG_SMP */
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blr
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/*
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* These are used in the alignment trap handler when emulating
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* single-precision loads and stores.
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* We restore and save the fpscr so the task gets the same result
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* and exceptions as if the cpu had performed the load or store.
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*/
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_GLOBAL(cvt_fd)
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lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */
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MTFSF_L(0)
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lfs 0,0(r3)
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stfd 0,0(r4)
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mffs 0
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stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */
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blr
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_GLOBAL(cvt_df)
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lfd 0,THREAD_FPSCR(r5) /* load up fpscr value */
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MTFSF_L(0)
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lfd 0,0(r3)
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stfs 0,0(r4)
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mffs 0
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stfd 0,THREAD_FPSCR(r5) /* save new fpscr value */
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blr
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