6cc0c16d82
Implement the bulk of interrupt return logic in C. The asm return code must handle a few cases: restoring full GPRs, and emulating stack store. The stack store emulation is significantly simplfied, rather than creating a new return frame and switching to that before performing the store, it uses the PACA to keep a scratch register around to perform the store. The asm return code is moved into 64e for now. The new logic has made allowance for 64e, but I don't have a full environment that works well to test it, and even booting in emulated qemu is not great for stress testing. 64e shouldn't be too far off working with this, given a bit more testing and auditing of the logic. This is slightly faster on a POWER9 (page fault speed increases about 1.1%), probably due to reduced mtmsrd. mpe: Includes fixes from Nick for _TIF_EMULATE_STACK_STORE handling (including the fast_interrupt_return path), to remove trace_hardirqs_on(), and fixes the interrupt-return part of the MSR_VSX restore bug caught by tm-unavailable selftest. mpe: Incorporate fix from Nick: The return-to-kernel path has to replay any soft-pending interrupts if it is returning to a context that had interrupts soft-enabled. It has to do this carefully and avoid plain enabling interrupts if this is an irq context, which can cause multiple nesting of interrupts on the stack, and other unexpected issues. The code which avoided this case got the soft-mask state wrong, and marked interrupts as enabled before going around again to retry. This seems to be mostly harmless except when PREEMPT=y, this calls preempt_schedule_irq with irqs apparently enabled and runs into a BUG in kernel/sched/core.c Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Suchanek <msuchanek@suse.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200225173541.1549955-29-npiggin@gmail.com
335 lines
6.7 KiB
ArmAsm
335 lines
6.7 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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#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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#include <asm/export.h>
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#include <asm/asm-compat.h>
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/*
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* Load state from memory into VMX registers including VSCR.
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* Assumes the caller has enabled VMX in the MSR.
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*/
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_GLOBAL(load_vr_state)
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li r4,VRSTATE_VSCR
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lvx v0,r4,r3
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mtvscr v0
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REST_32VRS(0,r4,r3)
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blr
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EXPORT_SYMBOL(load_vr_state)
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_ASM_NOKPROBE_SYMBOL(load_vr_state); /* used by restore_math */
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/*
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* Store VMX state into memory, including VSCR.
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* Assumes the caller has enabled VMX in the MSR.
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*/
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_GLOBAL(store_vr_state)
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SAVE_32VRS(0, r4, r3)
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mfvscr v0
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li r4, VRSTATE_VSCR
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stvx v0, r4, r3
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blr
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EXPORT_SYMBOL(store_vr_state)
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/*
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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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* Note that on 32-bit this can only use registers that will be
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* restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
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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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* While userspace in general ignores VRSAVE, glibc uses it as a boolean
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* to optimise userspace context save/restore. Whenever we take an
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* altivec unavailable exception we must set VRSAVE to something non
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* zero. Set it to all 1s. See also the programming note in the ISA.
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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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#ifdef CONFIG_VMAP_STACK
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tovirt(r5, r5)
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#endif
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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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/* Don't care if r4 overflows, this is desired behaviour */
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lbz r4,THREAD_LOAD_VEC(r5)
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addi r4,r4,1
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stb r4,THREAD_LOAD_VEC(r5)
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addi r6,r5,THREAD_VRSTATE
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li r4,1
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li r10,VRSTATE_VSCR
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stw r4,THREAD_USED_VR(r5)
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lvx v0,r10,r6
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mtvscr v0
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REST_32VRS(0,r4,r6)
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/* restore registers and return */
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blr
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/*
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* save_altivec(tsk)
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* Save the vector registers to its thread_struct
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*/
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_GLOBAL(save_altivec)
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addi r3,r3,THREAD /* want THREAD of task */
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PPC_LL r7,THREAD_VRSAVEAREA(r3)
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PPC_LL r5,PT_REGS(r3)
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PPC_LCMPI 0,r7,0
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bne 2f
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addi r7,r3,THREAD_VRSTATE
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2: SAVE_32VRS(0,r4,r7)
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mfvscr v0
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li r4,VRSTATE_VSCR
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stvx v0,r4,r7
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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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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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b fast_interrupt_return
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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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