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improve recoverability of OPAL calls

PATCH In review Nicholas Piggin 2 participants 5 messages Oct 23, 2017 – Nov 7, 2017 PowerPC

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Nicholas Piggin

author reviewer
#0 lore raw

cover improve recoverability of OPAL calls

Here's a few patches to improve recoverability for FIXUP_ENDIAN on powernv. We should try to minimise SRR[01] (and MSR[RI]=0) usage as much as possible. Whether that's by using HSRR or mtmsrd, it usually results in faster and smaller code too.

There's a few other places we can improve, but I've had these patches around for a while.

Thanks,
Nick

Nicholas Piggin (3):
powerpc/book3s: use label for FIXUP_ENDIAN macro branch powerpc/book3s: Add an HV variant of FIXUP_ENDIAN that is recoverable powerpc/powernv: Use FIXUP_ENDIAN_HV in OPAL return

 arch/powerpc/include/asm/ppc_asm.h             | 27 ++++++++++++++++++++++++--
 arch/powerpc/platforms/powernv/opal-wrappers.S |  4 ++--
 2 files changed, 27 insertions(+), 4 deletions(-)
Signature · 1 line
2.13.3
author reviewer
#1 lore raw

PATCH 1/3 powerpc/book3s: use label for FIXUP_ENDIAN macro branch

Signed-off-by Nicholas Piggin <[email protected]>
---
 arch/powerpc/include/asm/ppc_asm.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
arch/powerpc/include/asm/ppc_asm.h +3 -2
index 36f3e41c9fbe..d6b56aebe602 100644
@@ -776,7 +776,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 #else
 #define FIXUP_ENDIAN						   \
 	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
-	b     $+44;	  /* Skip trampoline if endian is good	*/ \
+	b     191f;	  /* Skip trampoline if endian is good	*/ \
 	.long 0xa600607d; /* mfmsr r11				*/ \
 	.long 0x01006b69; /* xori r11,r11,1			*/ \
 	.long 0x00004039; /* li r10,0				*/ \

@@ -786,7 +786,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 	.long 0x14004a39; /* addi r10,r10,20			*/ \
 	.long 0xa6035a7d; /* mtsrr0 r10				*/ \
 	.long 0xa6037b7d; /* mtsrr1 r11				*/ \
-	.long 0x2400004c  /* rfid				*/
+	.long 0x2400004c; /* rfid				*/ \
+191:
 
 #endif /* !CONFIG_PPC_BOOK3E */
Signature · 1 line
2.13.3
author reviewer
#3 lore raw

PATCH 2/3 powerpc/book3s: Add an HV variant of FIXUP_ENDIAN that is recoverable

In reply to Nicholas Piggin

Add an HV variant of FIXUP_ENDIAN which uses HSRR[01] and does not clear MSR[RI], which improves recoverability.

Signed-off-by Nicholas Piggin <[email protected]>
---
 arch/powerpc/include/asm/ppc_asm.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
arch/powerpc/include/asm/ppc_asm.h +22 -0
index d6b56aebe602..ae94b3626b6c 100644
@@ -774,6 +774,10 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 #ifdef CONFIG_PPC_BOOK3E
 #define FIXUP_ENDIAN
 #else
+/*
+ * This version may be used in in HV or non-HV context.
+ * MSR[EE] must be disabled.
+ */
 #define FIXUP_ENDIAN						   \
 	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
 	b     191f;	  /* Skip trampoline if endian is good	*/ \

@@ -789,6 +793,24 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 	.long 0x2400004c; /* rfid				*/ \
 191:
 
+/*
+ * This version that may only be used with MSR[HV]=1
+ * - Does not clear MSR[RI], so more robust.
+ * - Slightly smaller and faster.
+ */
+#define FIXUP_ENDIAN_HV						   \
+	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
+	b     191f;	  /* Skip trampoline if endian is good	*/ \
+	.long 0xa600607d; /* mfmsr r11				*/ \
+	.long 0x01006b69; /* xori r11,r11,1			*/ \
+	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
+	.long 0xa602487d; /* mflr r10				*/ \
+	.long 0x14004a39; /* addi r10,r10,20			*/ \
+	.long 0xa64b5a7d; /* mthsrr0 r10			*/ \
+	.long 0xa64b7b7d; /* mthsrr1 r11			*/ \
+	.long 0x2402004c; /* hrfid				*/ \
+191:
+
 #endif /* !CONFIG_PPC_BOOK3E */
 
 #endif /*  __ASSEMBLY__ */
Signature · 1 line
2.13.3
author reviewer
#4 lore raw

PATCH 3/3 powerpc/powernv: Use FIXUP_ENDIAN_HV in OPAL return

In reply to Nicholas Piggin

Close the recoverability gap for OPAL calls by using FIXUP_ENDIAN_HV in the return path.

Signed-off-by Nicholas Piggin <[email protected]>
---
 arch/powerpc/platforms/powernv/opal-wrappers.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
arch/powerpc/platforms/powernv/opal-wrappers.S +2 -2
index 37cd170201a2..6f4b00a2ac46 100644
@@ -94,7 +94,7 @@ opal_return:
 	 * bytes (always BE) since MSR:LE will end up fixed up as a side
 	 * effect of the rfid.
 	 */
-	FIXUP_ENDIAN
+	FIXUP_ENDIAN_HV
 	ld	r2,PACATOC(r13);
 	lwz	r4,8(r1);
 	ld	r5,PPC_LR_STKOFF(r1);

@@ -120,7 +120,7 @@ opal_real_call:
 	hrfid
 
 opal_return_realmode:
-	FIXUP_ENDIAN
+	FIXUP_ENDIAN_HV
 	ld	r2,PACATOC(r13);
 	lwz	r11,8(r1);
 	ld	r12,PPC_LR_STKOFF(r1)
Signature · 1 line
2.13.3