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linux-pinenote/arch/powerpc/kernel/tm.S
Sam bobroff 1739ea9e13 powerpc: Fix regression of per-CPU DSCR setting 
Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)"
it is no longer possible to set the DSCR on a per-CPU basis.

The old behaviour was to minipulate the DSCR SPR directly but this is no
longer sufficient: the value is quickly overwritten by context switching.

This patch stores the per-CPU DSCR value in a kernel variable rather than
directly in the SPR and it is used whenever a process has not set the DSCR
itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged.

Writes to the old global default (/sys/devices/system/cpu/dscr_default)
now set all of the per-CPU values and reads return the last written value.

The new per-CPU default is added to the paca_struct and is used everywhere
outside of sysfs.c instead of the old global default.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-05-28 13:35:40 +10:00

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/*
* 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>
#include <asm/bug.h>
#ifdef CONFIG_VSX
/* See fpu.S, this is borrowed from there */
#define __SAVE_32FPRS_VSRS(n,c,base) \
BEGIN_FTR_SECTION \
b 2f; \
END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
SAVE_32FPRS(n,base); \
b 3f; \
2: SAVE_32VSRS(n,c,base); \
3:
#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(n,c,base) SAVE_32FPRS(n, base)
#define __REST_32FPRS_VSRS(n,c,base) REST_32FPRS(n, base)
#endif
#define SAVE_32FPRS_VSRS(n,c,base) \
__SAVE_32FPRS_VSRS(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
/* 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
stw r6, 8(r1)
std r0, 16(r1)
std r2, STK_GOT(r1)
stdu r1, -TM_FRAME_SIZE(r1)
/* We've a struct pt_regs at [r1+STACK_FRAME_OVERHEAD]. */
std r3, STK_PARAM(R3)(r1)
SAVE_NVGPRS(r1)
/* We need to setup MSR for VSX register save instructions. Here we
* also clear the MSR RI since when we do the treclaim, we won't have a
* valid kernel pointer for a while. We clear RI here as it avoids
* adding another mtmsr closer to the treclaim. This makes the region
* maked as non-recoverable wider than it needs to be but it saves on
* inserting another mtmsrd later.
*/
mfmsr r14
mr r15, r14
ori r15, r15, MSR_FP
li r16, MSR_RI
ori r16, r16, MSR_EE /* IRQs hard off */
andc r15, r15, r16
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
addi r7, r3, THREAD_TRANSACT_VRSTATE
SAVE_32VRS(0, r6, r7) /* r6 scratch, r7 transact vr state */
mfvscr vr0
li r6, VRSTATE_VSCR
stvx vr0, r7, r6
dont_backup_vec:
mfspr r0, SPRN_VRSAVE
std r0, THREAD_TRANSACT_VRSAVE(r3)
andi. r0, r4, MSR_FP
beq dont_backup_fp
addi r7, r3, THREAD_TRANSACT_FPSTATE
SAVE_32FPRS_VSRS(0, R6, R7) /* r6 scratch, r7 transact fp state */
mffs fr0
stfd fr0,FPSTATE_FPSCR(r7)
dont_backup_fp:
/* Do sanity check on MSR to make sure we are suspended */
li r7, (MSR_TS_S)@higher
srdi r6, r14, 32
and r6, r6, r7
1: tdeqi r6, 0
EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,0
/* 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)
/* Store the PPR in r11 and reset to decent value */
std r11, GPR11(r1) /* Temporary stash */
mfspr r11, SPRN_PPR
HMT_MEDIUM
/* Now get some more GPRS free */
std r7, GPR7(r1) /* Temporary stash */
std r12, GPR12(r1) /* '' '' '' */
ld r12, STK_PARAM(R3)(r1) /* Param 0, thread_struct * */
std r11, THREAD_TM_PPR(r12) /* Store PPR and free r11 */
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_GPR(8, r7) /* user r8 */
SAVE_GPR(9, r7) /* user r9 */
SAVE_GPR(10, r7) /* user r10 */
ld r3, PACATMSCRATCH(r13) /* user r1 */
ld r4, GPR7(r1) /* user r7 */
ld r5, GPR11(r1) /* user r11 */
ld r6, GPR12(r1) /* user r12 */
GET_SCRATCH0(8) /* user r13 */
std r3, GPR1(r7)
std r4, GPR7(r7)
std r5, GPR11(r7)
std r6, GPR12(r7)
std r8, 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)
/* ******************** TAR, DSCR ********** */
mfspr r3, SPRN_TAR
mfspr r4, SPRN_DSCR
std r3, THREAD_TM_TAR(r12)
std r4, THREAD_TM_DSCR(r12)
/* 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 is checkpointed too, but is 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
lwz r4, 8(r1)
ld r0, 16(r1)
mtcr r4
mtlr r0
ld r2, STK_GOT(r1)
/* Load CPU's default DSCR */
ld r0, PACA_DSCR(r13)
mtspr SPRN_DSCR, r0
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
stw r5, 8(r1)
std r0, 16(r1)
std r2, STK_GOT(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)
/* 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
#ifdef CONFIG_ALTIVEC
/* 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
addi r8, r3, THREAD_VRSTATE
li r5, VRSTATE_VSCR
lvx vr0, r8, r5
mtvscr vr0
REST_32VRS(0, r5, r8) /* r5 scratch, r8 ptr */
dont_restore_vec:
ld r5, THREAD_VRSAVE(r3)
mtspr SPRN_VRSAVE, r5
#endif
andi. r0, r4, MSR_FP
beq dont_restore_fp
addi r8, r3, THREAD_FPSTATE
lfd fr0, FPSTATE_FPSCR(r8)
MTFSF_L(fr0)
REST_32FPRS_VSRS(0, R4, R8)
dont_restore_fp:
mtmsr r6 /* FP/Vec off again! */
restore_gprs:
/* ******************** CR,LR,CCR,MSR ********** */
ld r4, _CTR(r7)
ld r5, _LINK(r7)
ld r8, _XER(r7)
mtctr r4
mtlr r5
mtxer r8
/* ******************** TAR ******************** */
ld r4, THREAD_TM_TAR(r3)
mtspr SPRN_TAR, r4
/* Load up the PPR and DSCR in GPRs only at this stage */
ld r5, THREAD_TM_DSCR(r3)
ld r6, THREAD_TM_PPR(r3)
/* Clear the MSR RI since we are about to change R1. EE is already off
*/
li r4, 0
mtmsrd r4, 1
REST_GPR(0, r7) /* GPR0 */
REST_2GPRS(2, r7) /* GPR2-3 */
REST_GPR(4, r7) /* GPR4 */
REST_4GPRS(8, r7) /* GPR8-11 */
REST_2GPRS(12, r7) /* GPR12-13 */
REST_NVGPRS(r7) /* GPR14-31 */
/* Load up PPR and DSCR here so we don't run with user values for long
*/
mtspr SPRN_DSCR, r5
mtspr SPRN_PPR, r6
/* Do final sanity check on TEXASR to make sure FS is set. Do this
* here before we load up the userspace r1 so any bugs we hit will get
* a call chain */
mfspr r5, SPRN_TEXASR
srdi r5, r5, 16
li r6, (TEXASR_FS)@h
and r6, r6, r5
1: tdeqi r6, 0
EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,0
/* Do final sanity check on MSR to make sure we are not transactional
* or suspended
*/
mfmsr r6
li r5, (MSR_TS_MASK)@higher
srdi r6, r6, 32
and r6, r6, r5
1: tdnei r6, 0
EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,0
/* Restore CR */
ld r6, _CCR(r7)
mtcr r6
REST_GPR(1, r7) /* GPR1 */
REST_GPR(5, r7) /* GPR5-7 */
REST_GPR(6, r7)
ld r7, GPR7(r7)
/* Commit register state as checkpointed state: */
TRECHKPT
HMT_MEDIUM
/* 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)
/* R1 is restored, so we are recoverable again. EE is still off */
li r4, MSR_RI
mtmsrd r4, 1
REST_NVGPRS(r1)
addi r1, r1, TM_FRAME_SIZE
lwz r4, 8(r1)
ld r0, 16(r1)
mtcr r4
mtlr r0
ld r2, STK_GOT(r1)
/* Load CPU's default DSCR */
ld r0, PACA_DSCR(r13)
mtspr SPRN_DSCR, r0
blr
/* ****************************************************************** */
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