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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: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2 3/3] powerpc: Remove RFI macro
Date: Sun,  8 Nov 2020 16:57:37 +0000 (UTC)	[thread overview]
Message-ID: <f7e9cb9e9240feec63cb330abf40b67d1aad852f.1604854583.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <7719261b0a0d2787772339484c33eb809723bca7.1604854583.git.christophe.leroy@csgroup.eu>

RFI macro is just there to add an infinite loop past
rfi in order to avoid prefetch on 40x in half a dozen
of places in entry_32 and head_32.

Those places are already full of #ifdefs, so just add a
few more to explicitely show those loops and remove RFI.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/ppc_asm.h |  5 -----
 arch/powerpc/kernel/entry_32.S     | 30 ++++++++++++++++++++++++------
 arch/powerpc/kernel/head_32.h      |  5 ++++-
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index bedf3eb52ebc..101986d4a29d 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -498,11 +498,6 @@ END_FTR_SECTION_NESTED(CPU_FTR_CELL_TB_BUG, CPU_FTR_CELL_TB_BUG, 96)
 #define MTMSRD(r)	mtmsrd	r
 #define MTMSR_EERI(reg)	mtmsrd	reg,1
 #else
-#ifndef CONFIG_40x
-#define	RFI		rfi
-#else
-#define RFI		rfi; b .	/* Prevent prefetch past rfi */
-#endif
 #define MTMSRD(r)	mtmsr	r
 #define MTMSR_EERI(reg)	mtmsr	reg
 #endif
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index e10e1167ffb1..c7c28e8acc10 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -234,7 +234,10 @@ transfer_to_handler_cont:
 	mtspr	SPRN_SRR0,r11
 	mtspr	SPRN_SRR1,r10
 	mtlr	r9
-	RFI				/* jump to handler, enable MMU */
+	rfi				/* jump to handler, enable MMU */
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 
 #if defined (CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
 4:	rlwinm	r12,r12,0,~_TLF_NAPPING
@@ -263,7 +266,10 @@ _ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont)
 	LOAD_REG_IMMEDIATE(r0, MSR_KERNEL)
 	mtspr	SPRN_SRR0,r12
 	mtspr	SPRN_SRR1,r0
-	RFI
+	rfi
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 
 reenable_mmu:
 	/*
@@ -321,7 +327,10 @@ stack_ovf:
 #endif
 	mtspr	SPRN_SRR0,r9
 	mtspr	SPRN_SRR1,r10
-	RFI
+	rfi
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 _ASM_NOKPROBE_SYMBOL(stack_ovf)
 #endif
 
@@ -470,7 +479,10 @@ syscall_exit_finish:
 #endif
 	mtspr	SPRN_SRR0,r7
 	mtspr	SPRN_SRR1,r8
-	RFI
+	rfi
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 _ASM_NOKPROBE_SYMBOL(syscall_exit_finish)
 #ifdef CONFIG_44x
 2:	li	r7,0
@@ -600,7 +612,10 @@ ret_from_kernel_syscall:
 #endif
 	mtspr	SPRN_SRR0, r9
 	mtspr	SPRN_SRR1, r10
-	RFI
+	rfi
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 _ASM_NOKPROBE_SYMBOL(ret_from_kernel_syscall)
 
 /*
@@ -803,7 +818,10 @@ fast_exception_return:
 	REST_GPR(9, r11)
 	REST_GPR(12, r11)
 	lwz	r11,GPR11(r11)
-	RFI
+	rfi
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 _ASM_NOKPROBE_SYMBOL(fast_exception_return)
 
 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 7c767765071d..232000742c9a 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -222,7 +222,10 @@
 #endif
 	mtspr	SPRN_SRR1,r10
 	mtspr	SPRN_SRR0,r11
-	RFI				/* jump to handler, enable MMU */
+	rfi				/* jump to handler, enable MMU */
+#ifdef CONFIG_40x
+	b .	/* Prevent prefetch past rfi */
+#endif
 99:	b	ret_from_kernel_syscall
 .endm
 
-- 
2.25.0


  parent reply	other threads:[~2020-11-08 16:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-08 16:57 [PATCH v2 1/3] powerpc/64s: Replace RFI by RFI_TO_KERNEL and remove RFI Christophe Leroy
2020-11-08 16:57 ` [PATCH v2 2/3] powerpc: Replace RFI by rfi on book3s/32 and booke Christophe Leroy
2020-11-08 16:57 ` Christophe Leroy [this message]
2020-11-10  8:45 ` [PATCH v2 1/3] powerpc/64s: Replace RFI by RFI_TO_KERNEL and remove RFI Nicholas Piggin
2020-11-25 11:57 ` Michael Ellerman

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