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authorMichael Neuling <mikey@neuling.org>2013-02-13 16:21:35 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-02-15 16:58:52 +1100
commit98ae22e15b430bfed5def01ac1a88ec9396284c8 (patch)
treedc4119b4c88a094039206851c7f12f42b4ce75df /arch/powerpc/kernel/tm.S
parentafc07701ced6463786d09a3b9baf894c1397e991 (diff)
downloadlinux-stericsson-98ae22e15b430bfed5def01ac1a88ec9396284c8.tar.gz
powerpc: Add helper functions for transactional memory context switching
Here we add the helper functions to be used when context switching. These allow us to fully reclaim and recheckpoint a transaction. We introduce a new paca field called tm_scratch to help us store away register values when doing the low level tm reclaim register save. Signed-off-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/tm.S')
-rw-r--r--arch/powerpc/kernel/tm.S388
1 files changed, 388 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
new file mode 100644
index 000000000000..84dbace657ce
--- /dev/null
+++ b/arch/powerpc/kernel/tm.S
@@ -0,0 +1,388 @@
+/*
+ * Transactional memory support routines to reclaim and recheckpoint
+ * transactional process state.
+ *
+ * Copyright 2012 Matt Evans & Michael Neuling, IBM Corporation.
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/ppc_asm.h>
+#include <asm/ppc-opcode.h>
+#include <asm/ptrace.h>
+#include <asm/reg.h>
+
+#ifdef CONFIG_VSX
+/* See fpu.S, this is very similar but to save/restore checkpointed FPRs/VSRs */
+#define __SAVE_32FPRS_VSRS_TRANSACT(n,c,base) \
+BEGIN_FTR_SECTION \
+ b 2f; \
+END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
+ SAVE_32FPRS_TRANSACT(n,base); \
+ b 3f; \
+2: SAVE_32VSRS_TRANSACT(n,c,base); \
+3:
+/* ...and this is just plain borrowed from there. */
+#define __REST_32FPRS_VSRS(n,c,base) \
+BEGIN_FTR_SECTION \
+ b 2f; \
+END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
+ REST_32FPRS(n,base); \
+ b 3f; \
+2: REST_32VSRS(n,c,base); \
+3:
+#else
+#define __SAVE_32FPRS_VSRS_TRANSACT(n,c,base) SAVE_32FPRS_TRANSACT(n, base)
+#define __REST_32FPRS_VSRS(n,c,base) REST_32FPRS(n, base)
+#endif
+#define SAVE_32FPRS_VSRS_TRANSACT(n,c,base) \
+ __SAVE_32FPRS_VSRS_TRANSACT(n,__REG_##c,__REG_##base)
+#define REST_32FPRS_VSRS(n,c,base) \
+ __REST_32FPRS_VSRS(n,__REG_##c,__REG_##base)
+
+/* Stack frame offsets for local variables. */
+#define TM_FRAME_L0 TM_FRAME_SIZE-16
+#define TM_FRAME_L1 TM_FRAME_SIZE-8
+#define STACK_PARAM(x) (48+((x)*8))
+
+
+/* In order to access the TM SPRs, TM must be enabled. So, do so: */
+_GLOBAL(tm_enable)
+ mfmsr r4
+ li r3, MSR_TM >> 32
+ sldi r3, r3, 32
+ and. r0, r4, r3
+ bne 1f
+ or r4, r4, r3
+ mtmsrd r4
+1: blr
+
+_GLOBAL(tm_save_sprs)
+ mfspr r0, SPRN_TFHAR
+ std r0, THREAD_TM_TFHAR(r3)
+ mfspr r0, SPRN_TEXASR
+ std r0, THREAD_TM_TEXASR(r3)
+ mfspr r0, SPRN_TFIAR
+ std r0, THREAD_TM_TFIAR(r3)
+ blr
+
+_GLOBAL(tm_restore_sprs)
+ ld r0, THREAD_TM_TFHAR(r3)
+ mtspr SPRN_TFHAR, r0
+ ld r0, THREAD_TM_TEXASR(r3)
+ mtspr SPRN_TEXASR, r0
+ ld r0, THREAD_TM_TFIAR(r3)
+ mtspr SPRN_TFIAR, r0
+ blr
+
+ /* Passed an 8-bit failure cause as first argument. */
+_GLOBAL(tm_abort)
+ TABORT(R3)
+ blr
+
+
+/* void tm_reclaim(struct thread_struct *thread,
+ * unsigned long orig_msr,
+ * uint8_t cause)
+ *
+ * - Performs a full reclaim. This destroys outstanding
+ * transactions and updates thread->regs.tm_ckpt_* with the
+ * original checkpointed state. Note that thread->regs is
+ * unchanged.
+ * - FP regs are written back to thread->transact_fpr before
+ * reclaiming. These are the transactional (current) versions.
+ *
+ * Purpose is to both abort transactions of, and preserve the state of,
+ * a transactions at a context switch. We preserve/restore both sets of process
+ * state to restore them when the thread's scheduled again. We continue in
+ * userland as though nothing happened, but when the transaction is resumed
+ * they will abort back to the checkpointed state we save out here.
+ *
+ * Call with IRQs off, stacks get all out of sync for some periods in here!
+ */
+_GLOBAL(tm_reclaim)
+ mfcr r6
+ mflr r0
+ std r6, 8(r1)
+ std r0, 16(r1)
+ std r2, 40(r1)
+ stdu r1, -TM_FRAME_SIZE(r1)
+
+ /* We've a struct pt_regs at [r1+STACK_FRAME_OVERHEAD]. */
+
+ std r3, STACK_PARAM(0)(r1)
+ SAVE_NVGPRS(r1)
+
+ mfmsr r14
+ mr r15, r14
+ ori r15, r15, MSR_FP
+ oris r15, r15, MSR_VEC@h
+#ifdef CONFIG_VSX
+ BEGIN_FTR_SECTION
+ oris r15,r15, MSR_VSX@h
+ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
+#endif
+ mtmsrd r15
+ std r14, TM_FRAME_L0(r1)
+
+ /* Stash the stack pointer away for use after reclaim */
+ std r1, PACAR1(r13)
+
+ /* ******************** FPR/VR/VSRs ************
+ * Before reclaiming, capture the current/transactional FPR/VR
+ * versions /if used/.
+ *
+ * (If VSX used, FP and VMX are implied. Or, we don't need to look
+ * at MSR.VSX as copying FP regs if .FP, vector regs if .VMX covers it.)
+ *
+ * We're passed the thread's MSR as parameter 2.
+ *
+ * We enabled VEC/FP/VSX in the msr above, so we can execute these
+ * instructions!
+ */
+ andis. r0, r4, MSR_VEC@h
+ beq dont_backup_vec
+
+ SAVE_32VRS_TRANSACT(0, r6, r3) /* r6 scratch, r3 thread */
+ mfvscr vr0
+ li r6, THREAD_TRANSACT_VSCR
+ stvx vr0, r3, r6
+ mfspr r0, SPRN_VRSAVE
+ std r0, THREAD_TRANSACT_VRSAVE(r3)
+
+dont_backup_vec:
+ andi. r0, r4, MSR_FP
+ beq dont_backup_fp
+
+ SAVE_32FPRS_VSRS_TRANSACT(0, R6, R3) /* r6 scratch, r3 thread */
+
+ mffs fr0
+ stfd fr0,THREAD_TRANSACT_FPSCR(r3)
+
+dont_backup_fp:
+ /* The moment we treclaim, ALL of our GPRs will switch
+ * to user register state. (FPRs, CCR etc. also!)
+ * Use an sprg and a tm_scratch in the PACA to shuffle.
+ */
+ TRECLAIM(R5) /* Cause in r5 */
+
+ /* ******************** GPRs ******************** */
+ /* Stash the checkpointed r13 away in the scratch SPR and get the real
+ * paca
+ */
+ SET_SCRATCH0(r13)
+ GET_PACA(r13)
+
+ /* Stash the checkpointed r1 away in paca tm_scratch and get the real
+ * stack pointer back
+ */
+ std r1, PACATMSCRATCH(r13)
+ ld r1, PACAR1(r13)
+
+ /* Now get some more GPRS free */
+ std r7, GPR7(r1) /* Temporary stash */
+ std r12, GPR12(r1) /* '' '' '' */
+ ld r12, STACK_PARAM(0)(r1) /* Param 0, thread_struct * */
+
+ addi r7, r12, PT_CKPT_REGS /* Thread's ckpt_regs */
+
+ /* Make r7 look like an exception frame so that we
+ * can use the neat GPRx(n) macros. r7 is NOT a pt_regs ptr!
+ */
+ subi r7, r7, STACK_FRAME_OVERHEAD
+
+ /* Sync the userland GPRs 2-12, 14-31 to thread->regs: */
+ SAVE_GPR(0, r7) /* user r0 */
+ SAVE_GPR(2, r7) /* user r2 */
+ SAVE_4GPRS(3, r7) /* user r3-r6 */
+ SAVE_4GPRS(8, r7) /* user r8-r11 */
+ ld r3, PACATMSCRATCH(r13) /* user r1 */
+ ld r4, GPR7(r1) /* user r7 */
+ ld r5, GPR12(r1) /* user r12 */
+ GET_SCRATCH0(6) /* user r13 */
+ std r3, GPR1(r7)
+ std r4, GPR7(r7)
+ std r5, GPR12(r7)
+ std r6, GPR13(r7)
+
+ SAVE_NVGPRS(r7) /* user r14-r31 */
+
+ /* ******************** NIP ******************** */
+ mfspr r3, SPRN_TFHAR
+ std r3, _NIP(r7) /* Returns to failhandler */
+ /* The checkpointed NIP is ignored when rescheduling/rechkpting,
+ * but is used in signal return to 'wind back' to the abort handler.
+ */
+
+ /* ******************** CR,LR,CCR,MSR ********** */
+ mfctr r3
+ mflr r4
+ mfcr r5
+ mfxer r6
+
+ std r3, _CTR(r7)
+ std r4, _LINK(r7)
+ std r5, _CCR(r7)
+ std r6, _XER(r7)
+
+ /* MSR and flags: We don't change CRs, and we don't need to alter
+ * MSR.
+ */
+
+ /* TM regs, incl TEXASR -- these live in thread_struct. Note they've
+ * been updated by the treclaim, to explain to userland the failure
+ * cause (aborted).
+ */
+ mfspr r0, SPRN_TEXASR
+ mfspr r3, SPRN_TFHAR
+ mfspr r4, SPRN_TFIAR
+ std r0, THREAD_TM_TEXASR(r12)
+ std r3, THREAD_TM_TFHAR(r12)
+ std r4, THREAD_TM_TFIAR(r12)
+
+ /* AMR and PPR are checkpointed too, but are unsupported by Linux. */
+
+ /* Restore original MSR/IRQ state & clear TM mode */
+ ld r14, TM_FRAME_L0(r1) /* Orig MSR */
+ li r15, 0
+ rldimi r14, r15, MSR_TS_LG, (63-MSR_TS_LG)-1
+ mtmsrd r14
+
+ REST_NVGPRS(r1)
+
+ addi r1, r1, TM_FRAME_SIZE
+ ld r4, 8(r1)
+ ld r0, 16(r1)
+ mtcr r4
+ mtlr r0
+ ld r2, 40(r1)
+ blr
+
+
+ /* void tm_recheckpoint(struct thread_struct *thread,
+ * unsigned long orig_msr)
+ * - Restore the checkpointed register state saved by tm_reclaim
+ * when we switch_to a process.
+ *
+ * Call with IRQs off, stacks get all out of sync for
+ * some periods in here!
+ */
+_GLOBAL(tm_recheckpoint)
+ mfcr r5
+ mflr r0
+ std r5, 8(r1)
+ std r0, 16(r1)
+ std r2, 40(r1)
+ stdu r1, -TM_FRAME_SIZE(r1)
+
+ /* We've a struct pt_regs at [r1+STACK_FRAME_OVERHEAD].
+ * This is used for backing up the NVGPRs:
+ */
+ SAVE_NVGPRS(r1)
+
+ std r1, PACAR1(r13)
+
+ /* Load complete register state from ts_ckpt* registers */
+
+ addi r7, r3, PT_CKPT_REGS /* Thread's ckpt_regs */
+
+ /* Make r7 look like an exception frame so that we
+ * can use the neat GPRx(n) macros. r7 is now NOT a pt_regs ptr!
+ */
+ subi r7, r7, STACK_FRAME_OVERHEAD
+
+ SET_SCRATCH0(r1)
+
+ mfmsr r6
+ /* R4 = original MSR to indicate whether thread used FP/Vector etc. */
+
+ /* Enable FP/vec in MSR if necessary! */
+ lis r5, MSR_VEC@h
+ ori r5, r5, MSR_FP
+ and. r5, r4, r5
+ beq restore_gprs /* if neither, skip both */
+
+#ifdef CONFIG_VSX
+ BEGIN_FTR_SECTION
+ oris r5, r5, MSR_VSX@h
+ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
+#endif
+ or r5, r6, r5 /* Set MSR.FP+.VSX/.VEC */
+ mtmsr r5
+
+ /* FP and VEC registers: These are recheckpointed from thread.fpr[]
+ * and thread.vr[] respectively. The thread.transact_fpr[] version
+ * is more modern, and will be loaded subsequently by any FPUnavailable
+ * trap.
+ */
+ andis. r0, r4, MSR_VEC@h
+ beq dont_restore_vec
+
+ li r5, THREAD_VSCR
+ lvx vr0, r3, r5
+ mtvscr vr0
+ REST_32VRS(0, r5, r3) /* r5 scratch, r3 THREAD ptr */
+ ld r5, THREAD_VRSAVE(r3)
+ mtspr SPRN_VRSAVE, r5
+
+dont_restore_vec:
+ andi. r0, r4, MSR_FP
+ beq dont_restore_fp
+
+ lfd fr0, THREAD_FPSCR(r3)
+ MTFSF_L(fr0)
+ REST_32FPRS_VSRS(0, R4, R3)
+
+dont_restore_fp:
+ mtmsr r6 /* FP/Vec off again! */
+
+restore_gprs:
+ /* ******************** CR,LR,CCR,MSR ********** */
+ ld r3, _CTR(r7)
+ ld r4, _LINK(r7)
+ ld r5, _CCR(r7)
+ ld r6, _XER(r7)
+
+ mtctr r3
+ mtlr r4
+ mtcr r5
+ mtxer r6
+
+ /* MSR and flags: We don't change CRs, and we don't need to alter
+ * MSR.
+ */
+
+ REST_4GPRS(0, r7) /* GPR0-3 */
+ REST_GPR(4, r7) /* GPR4-6 */
+ REST_GPR(5, r7)
+ REST_GPR(6, r7)
+ REST_4GPRS(8, r7) /* GPR8-11 */
+ REST_2GPRS(12, r7) /* GPR12-13 */
+
+ REST_NVGPRS(r7) /* GPR14-31 */
+
+ ld r7, GPR7(r7) /* GPR7 */
+
+ /* Commit register state as checkpointed state: */
+ TRECHKPT
+
+ /* Our transactional state has now changed.
+ *
+ * Now just get out of here. Transactional (current) state will be
+ * updated once restore is called on the return path in the _switch-ed
+ * -to process.
+ */
+
+ GET_PACA(r13)
+ GET_SCRATCH0(r1)
+
+ REST_NVGPRS(r1)
+
+ addi r1, r1, TM_FRAME_SIZE
+ ld r4, 8(r1)
+ ld r0, 16(r1)
+ mtcr r4
+ mtlr r0
+ ld r2, 40(r1)
+ blr
+
+ /* ****************************************************************** */