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From: Anton Blanchard <anton@samba.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 11/39] powerpc: endian safe trampoline
Date: Mon, 23 Sep 2013 12:04:45 +1000	[thread overview]
Message-ID: <1379901913-5945-12-git-send-email-anton@samba.org> (raw)
In-Reply-To: <1379901913-5945-1-git-send-email-anton@samba.org>

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Create a trampoline that works in either endian and flips to
the expected endian. Use it for primary and secondary thread
entry as well as RTAS and OF call return.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anton Blanchard <anton@samba.org>
---
 arch/powerpc/include/asm/ppc_asm.h | 31 ++++++++++++++++++++++++++++++-
 arch/powerpc/kernel/entry_64.S     | 36 ++++++++++++++++++++----------------
 arch/powerpc/kernel/head_64.S      |  3 +++
 3 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 0c51fb4..ce05bba 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -845,6 +845,35 @@ END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,946)
 #define N_SLINE	68
 #define N_SO	100
 
-#endif /*  __ASSEMBLY__ */
+/*
+ * Create an endian fixup trampoline
+ *
+ * This starts with a "tdi 0,0,0x48" instruction which is
+ * essentially a "trap never", and thus akin to a nop.
+ *
+ * The opcode for this instruction read with the wrong endian
+ * however results in a b . + 8
+ *
+ * So essentially we use that trick to execute the following
+ * trampoline in "reverse endian" if we are running with the
+ * MSR_LE bit set the "wrong" way for whatever endianness the
+ * kernel is built for.
+ */
 
+#ifdef CONFIG_PPC_BOOK3E
+#define FIXUP_ENDIAN
+#else
+#define FIXUP_ENDIAN						   \
+	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
+	b     $+36;	  /* Skip trampoline if endian is good	*/ \
+	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
+	.long 0xa602487d; /* mflr r10				*/ \
+	.long 0x1c004a39; /* addi r10,r10,28			*/ \
+	.long 0xa600607d; /* mfmsr r11				*/ \
+	.long 0x01006b69; /* xori r11,r11,1			*/ \
+	.long 0xa6035a7d; /* mtsrr0 r10				*/ \
+	.long 0xa6037b7d; /* mtsrr1 r11				*/ \
+	.long 0x2400004c  /* rfid				*/
+#endif /* !CONFIG_PPC_BOOK3E */
+#endif /*  __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_PPC_ASM_H */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index c04cdf7..889ea2b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -1017,7 +1017,7 @@ _GLOBAL(enter_rtas)
 	
         li      r9,1
         rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
-	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI
+	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE
 	andc	r6,r0,r9
 	sync				/* disable interrupts so SRR0/1 */
 	mtmsrd	r0			/* don't get trashed */
@@ -1032,6 +1032,8 @@ _GLOBAL(enter_rtas)
 	b	.	/* prevent speculative execution */
 
 _STATIC(rtas_return_loc)
+	FIXUP_ENDIAN
+
 	/* relocation is off at this point */
 	GET_PACA(r4)
 	clrldi	r4,r4,2			/* convert to realmode address */
@@ -1103,28 +1105,30 @@ _GLOBAL(enter_prom)
 	std	r10,_CCR(r1)
 	std	r11,_MSR(r1)
 
-	/* Get the PROM entrypoint */
-	mtlr	r4
+	/* Put PROM address in SRR0 */
+	mtsrr0	r4
+
+	/* Setup our trampoline return addr in LR */
+	bcl	20,31,$+4
+0:	mflr	r4
+	addi	r4,r4,(1f - 0b)
+       	mtlr	r4
 
-	/* Switch MSR to 32 bits mode
+	/* Prepare a 32-bit mode big endian MSR
 	 */
 #ifdef CONFIG_PPC_BOOK3E
 	rlwinm	r11,r11,0,1,31
-	mtmsr	r11
+	mtsrr1	r11
+	rfi
 #else /* CONFIG_PPC_BOOK3E */
-        mfmsr   r11
-        li      r12,1
-        rldicr  r12,r12,MSR_SF_LG,(63-MSR_SF_LG)
-        andc    r11,r11,r12
-        li      r12,1
-        rldicr  r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG)
-        andc    r11,r11,r12
-        mtmsrd  r11
+	LOAD_REG_IMMEDIATE(r12, MSR_SF | MSR_ISF | MSR_LE)
+	andc	r11,r11,r12
+	mtsrr1	r11
+	rfid
 #endif /* CONFIG_PPC_BOOK3E */
-        isync
 
-	/* Enter PROM here... */
-	blrl
+1:	/* Return from OF */
+	FIXUP_ENDIAN
 
 	/* Just make sure that r1 top 32 bits didn't get
 	 * corrupt by OF
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 3d11d80..2ae41ab 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -68,6 +68,7 @@ _stext:
 _GLOBAL(__start)
 	/* NOP this out unconditionally */
 BEGIN_FTR_SECTION
+	FIXUP_ENDIAN
 	b	.__start_initialization_multiplatform
 END_FTR_SECTION(0, 1)
 
@@ -115,6 +116,7 @@ __run_at_load:
  */
 	.globl	__secondary_hold
 __secondary_hold:
+	FIXUP_ENDIAN
 #ifndef CONFIG_PPC_BOOK3E
 	mfmsr	r24
 	ori	r24,r24,MSR_RI
@@ -205,6 +207,7 @@ _GLOBAL(generic_secondary_thread_init)
  * as SCOM before entry).
  */
 _GLOBAL(generic_secondary_smp_init)
+	FIXUP_ENDIAN
 	mr	r24,r3
 	mr	r25,r4
 
-- 
1.8.1.2

  parent reply	other threads:[~2013-09-23  2:04 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-23  2:04 [PATCH 00/39] Second round of 64bit PowerPC little endian patches Anton Blanchard
2013-09-23  2:04 ` [PATCH 01/39] powerpc: Fix endian issues in VMX copy loops Anton Blanchard
2013-09-23  2:04 ` [PATCH 02/39] powerpc: Book 3S MMU little endian support Anton Blanchard
2013-09-23  2:04 ` [PATCH 03/39] powerpc: Fix offset of FPRs in VSX registers in little endian builds Anton Blanchard
2013-09-23  2:04 ` [PATCH 04/39] powerpc: PTRACE_PEEKUSR/PTRACE_POKEUSER of FPR " Anton Blanchard
2013-09-23  2:04 ` [PATCH 05/39] powerpc: Little endian builds double word swap VSX state during context save/restore Anton Blanchard
2013-09-23  2:04 ` [PATCH 06/39] powerpc: Support endian agnostic MMIO Anton Blanchard
2013-09-23  2:04 ` [PATCH 07/39] powerpc: Add little endian support for word-at-a-time functions Anton Blanchard
2013-09-23  2:04 ` [PATCH 08/39] powerpc: Set MSR_LE bit on little endian builds Anton Blanchard
2013-09-23  2:04 ` [PATCH 09/39] powerpc: Reset MSR_LE on signal entry Anton Blanchard
2013-09-23  2:04 ` [PATCH 10/39] powerpc: Include the appropriate endianness header Anton Blanchard
2013-09-23  2:04 ` Anton Blanchard [this message]
2013-12-28  7:24   ` [PATCH 11/39] powerpc: endian safe trampoline Olof Johansson
2013-12-28  7:58     ` Benjamin Herrenschmidt
2013-09-23  2:04 ` [PATCH 12/39] powerpc: Remove open coded byte swap macro in alignment handler Anton Blanchard
2013-09-23  2:04 ` [PATCH 13/39] powerpc: Remove hard coded FP offsets " Anton Blanchard
2013-09-23  2:04 ` [PATCH 14/39] powerpc: Alignment handler shouldn't access VSX registers with TS_FPR Anton Blanchard
2013-09-23  2:04 ` [PATCH 15/39] powerpc: Add little endian support to alignment handler Anton Blanchard
2013-09-23  2:04 ` [PATCH 16/39] powerpc: Handle VSX alignment faults in little endian mode Anton Blanchard
2013-09-23  2:04 ` [PATCH 17/39] powerpc: Use generic checksum code in little endian Anton Blanchard
2013-09-23  2:04 ` [PATCH 18/39] powerpc: Use generic memcpy " Anton Blanchard
2013-09-23  2:04 ` [PATCH 19/39] powerpc: uname should return ppc64le/ppcle on little endian builds Anton Blanchard
2013-09-23  2:04 ` [PATCH 20/39] powerpc: Little endian fixes for platforms/powernv/opal.c Anton Blanchard
2013-09-23  2:04 ` [PATCH 21/39] powerpc: Little endian fix for arch/powerpc/platforms/powernv/pci.c Anton Blanchard
2013-09-23  2:04 ` [PATCH 22/39] powerpc: Little endian fix for arch/powerpc/platforms/powernv/pci-p5ioc2.c Anton Blanchard
2013-09-23  2:04 ` [PATCH 23/39] powerpc: Little endian sparse clean up for arch/powerpc/platforms/powernv/pci-ioda.c Anton Blanchard
2013-09-23  2:04 ` [PATCH 24/39] powerpc/powernv: Fix endian issues in OPAL RTC driver Anton Blanchard
2013-09-23  2:04 ` [PATCH 25/39] powerpc/powernv: Fix endian issues in OPAL ICS backend Anton Blanchard
2013-09-23  2:05 ` [PATCH 26/39] powerpc/powernv: Make OPAL NVRAM device tree accesses endian safe Anton Blanchard
2013-09-23  2:05 ` [PATCH 27/39] powerpc/powernv: Fix endian issues in powernv PCI code Anton Blanchard
2013-09-23  2:05 ` [PATCH 28/39] powerpc/powernv: Fix endian issues in OPAL console and udbg backend Anton Blanchard
2013-09-23  2:05 ` [PATCH 29/39] powerpc/powernv: Fix OPAL entry and exit in little endian mode Anton Blanchard
2013-09-23  2:05 ` [PATCH 30/39] powerpc/powernv: Don't register exception handlers " Anton Blanchard
2013-09-23  2:05 ` [PATCH 31/39] powerpc/powernv: More little endian issues in OPAL RTC driver Anton Blanchard
2013-09-23  2:05 ` [PATCH 32/39] powerpc/powernv: Fix some PCI sparse errors and one LE bug Anton Blanchard
2013-09-23  2:05 ` [PATCH 33/39] powerpc/hvsi: Fix endian issues in HVSI driver Anton Blanchard
2013-09-23  2:05 ` [PATCH 34/39] tty/hvc_opal: powerpc: Make OPAL HVC device tree accesses endian safe Anton Blanchard
2013-09-23  2:05 ` [PATCH 35/39] KVM: PPC: Disable KVM on little endian builds Anton Blanchard
2013-09-23  2:05 ` [PATCH 36/39] powerpc/kvm/book3s_hv: Add little endian guest support Anton Blanchard
2013-09-25 12:10   ` [PATCH] powerpc/kvmbook3s_hv: propagate H_SET_MODE to the host Laurent Dufour
2013-09-25 12:27     ` Greg Kurz
2013-09-25 22:31     ` Paul Mackerras
2013-09-27  8:14       ` Laurent Dufour
2013-09-27 13:59       ` [PATCH V2] powerpc/kvm/book3s_hv: propagate H_SET_MODE_RESOURCE_LE " Laurent Dufour
2013-09-27 14:45         ` Greg Kurz
2013-09-30 18:40   ` [PATCH 36/39] powerpc/kvm/book3s_hv: Add little endian guest support Alexander Graf
2013-09-23  2:05 ` [PATCH 37/39] powerpc: Add ability to build little endian kernels Anton Blanchard
2013-09-23  2:05 ` [PATCH 38/39] powerpc: Don't set HAVE_EFFICIENT_UNALIGNED_ACCESS on little endian builds Anton Blanchard
2013-09-23  2:05 ` [PATCH 39/39] powerpc: Work around little endian gcc bug Anton Blanchard

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