From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc: Don't handle ALTIVEC/SPE in ASM in _switch(). Do it in C.
Date: Fri, 14 May 2021 13:14:53 +0000 (UTC) [thread overview]
Message-ID: <8ab21fd93d6e0047aa71e6509e5e312f14b2991b.1620998075.git.christophe.leroy@csgroup.eu> (raw)
_switch() saves and restores ALTIVEC and SPE status.
For altivec this is redundant with what __switch_to() does with
save_sprs() and restore_sprs() and giveup_all() before
calling _switch().
Add support for SPI in save_sprs() and restore_sprs() and
remove things from _switch().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/asm-offsets.c | 2 --
arch/powerpc/kernel/entry_32.S | 35 -------------------------------
arch/powerpc/kernel/process.c | 9 ++++++++
3 files changed, 9 insertions(+), 37 deletions(-)
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 28af4efb4587..5573da9a20d1 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -119,7 +119,6 @@ int main(void)
#ifdef CONFIG_ALTIVEC
OFFSET(THREAD_VRSTATE, thread_struct, vr_state.vr);
OFFSET(THREAD_VRSAVEAREA, thread_struct, vr_save_area);
- OFFSET(THREAD_VRSAVE, thread_struct, vrsave);
OFFSET(THREAD_USED_VR, thread_struct, used_vr);
OFFSET(VRSTATE_VSCR, thread_vr_state, vscr);
OFFSET(THREAD_LOAD_VEC, thread_struct, load_vec);
@@ -150,7 +149,6 @@ int main(void)
#ifdef CONFIG_SPE
OFFSET(THREAD_EVR0, thread_struct, evr[0]);
OFFSET(THREAD_ACC, thread_struct, acc);
- OFFSET(THREAD_SPEFSCR, thread_struct, spefscr);
OFFSET(THREAD_USED_SPE, thread_struct, used_spe);
#endif /* CONFIG_SPE */
#endif /* CONFIG_PPC64 */
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 9160285cb2f4..6c09ebb853ec 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -176,28 +176,6 @@ _GLOBAL(_switch)
/* r3-r12 are caller saved -- Cort */
SAVE_NVGPRS(r1)
stw r0,_NIP(r1) /* Return to switch caller */
- mfmsr r11
- li r0,MSR_FP /* Disable floating-point */
-#ifdef CONFIG_ALTIVEC
-BEGIN_FTR_SECTION
- oris r0,r0,MSR_VEC@h /* Disable altivec */
- mfspr r12,SPRN_VRSAVE /* save vrsave register value */
- stw r12,THREAD+THREAD_VRSAVE(r2)
-END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
-BEGIN_FTR_SECTION
- oris r0,r0,MSR_SPE@h /* Disable SPE */
- mfspr r12,SPRN_SPEFSCR /* save spefscr register value */
- stw r12,THREAD+THREAD_SPEFSCR(r2)
-END_FTR_SECTION_IFSET(CPU_FTR_SPE)
-#endif /* CONFIG_SPE */
- and. r0,r0,r11 /* FP or altivec or SPE enabled? */
- beq+ 1f
- andc r11,r11,r0
- mtmsr r11
- isync
-1: stw r11,_MSR(r1)
mfcr r10
stw r10,_CCR(r1)
stw r1,KSP(r3) /* Set old stack pointer */
@@ -218,19 +196,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_SPE)
mr r3,r2
addi r2,r4,-THREAD /* Update current */
-#ifdef CONFIG_ALTIVEC
-BEGIN_FTR_SECTION
- lwz r0,THREAD+THREAD_VRSAVE(r2)
- mtspr SPRN_VRSAVE,r0 /* if G4, restore VRSAVE reg */
-END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
-BEGIN_FTR_SECTION
- lwz r0,THREAD+THREAD_SPEFSCR(r2)
- mtspr SPRN_SPEFSCR,r0 /* restore SPEFSCR reg */
-END_FTR_SECTION_IFSET(CPU_FTR_SPE)
-#endif /* CONFIG_SPE */
-
lwz r0,_CCR(r1)
mtcrf 0xFF,r0
/* r3-r12 are destroyed -- Cort */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 89e34aa273e2..2bd30acc843c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1129,6 +1129,10 @@ static inline void save_sprs(struct thread_struct *t)
if (cpu_has_feature(CPU_FTR_ALTIVEC))
t->vrsave = mfspr(SPRN_VRSAVE);
#endif
+#ifdef CONFIG_SPE
+ if (cpu_has_feature(CPU_FTR_SPE))
+ t->spefscr = mfspr(SPRN_SPEFSCR);
+#endif
#ifdef CONFIG_PPC_BOOK3S_64
if (cpu_has_feature(CPU_FTR_DSCR))
t->dscr = mfspr(SPRN_DSCR);
@@ -1159,6 +1163,11 @@ static inline void restore_sprs(struct thread_struct *old_thread,
old_thread->vrsave != new_thread->vrsave)
mtspr(SPRN_VRSAVE, new_thread->vrsave);
#endif
+#ifdef CONFIG_SPE
+ if (cpu_has_feature(CPU_FTR_SPE) &&
+ old_thread->spefscr != new_thread->spefscr)
+ mtspr(SPRN_SPEFSCR, new_thread->spefscr);
+#endif
#ifdef CONFIG_PPC_BOOK3S_64
if (cpu_has_feature(CPU_FTR_DSCR)) {
u64 dscr = get_paca()->dscr_default;
--
2.25.0
next reply other threads:[~2021-05-14 13:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 13:14 Christophe Leroy [this message]
2021-06-18 3:51 ` [PATCH] powerpc: Don't handle ALTIVEC/SPE in ASM in _switch(). Do it in C Michael Ellerman
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