[RFC PATCH 12/23] Add powerpc64 ieee1275 trampoline

[Ram Pai <linuxram@us.ibm.com>]

From: Anton Blanchard <anton@samba.org>

Add a trampoline so a 64bit grub can call a 32 bit OF

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
From: Anton Blanchard <anton@samba.org>
---
 grub-core/Makefile.core.def              |   2 +
 grub-core/kern/powerpc/ieee1275/entry.S  | 150 +++++++++++++++++++++++++++++++
 include/grub/powerpc/ieee1275/ieee1275.h |   6 ++
 3 files changed, 158 insertions(+)
 create mode 100644 grub-core/kern/powerpc/ieee1275/entry.S

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index c6e70bb..0c80fe4 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -256,9 +256,11 @@ kernel = {
 
   powerpc_ieee1275 = kern/powerpc/cache.S;
   powerpc_ieee1275 = kern/powerpc/dl.c;
+  powerpc_ieee1275 = kern/powerpc/ieee1275/entry.S;
 
   powerpc64le_ieee1275 = kern/powerpc/cache.S;
   powerpc64le_ieee1275 = kern/powerpc/dl.c;
+  powerpc64le_ieee1275 = kern/powerpc/ieee1275/entry.S;
 
   sparc64_ieee1275 = kern/sparc64/cache.S;
   sparc64_ieee1275 = kern/sparc64/dl.c;
diff --git a/grub-core/kern/powerpc/ieee1275/entry.S b/grub-core/kern/powerpc/ieee1275/entry.S
new file mode 100644
index 0000000..5d58149
--- /dev/null
+++ b/grub-core/kern/powerpc/ieee1275/entry.S
@@ -0,0 +1,150 @@
+/* entry.S - open firmware call entry and return  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2004,2007,2010,2014  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <ppc-asm.h>
+
+#define STACK_FRAME_SIZE	(48 + 64 + 16 + 144)
+#define MSR_OFFSET		(48 + 64)
+#define R13_OFFSET		(MSR_OFFSET + 8)
+#define NVREG_OFFSET(i)		(STACK_FRAME_SIZE - (32-(i))*8)
+#define SAVE_NVGPR(A)	std	(A),NVREG_OFFSET(A)(r1)
+#define REST_NVGPR(A)	ld	(A),NVREG_OFFSET(A)(r1)
+#define SPRN_SRR0	0x01A
+#define SPRN_SRR1	0x01B
+#define r1	sp
+
+
+#if defined(_CALL_ELF) && _CALL_ELF == 1  /* BIG ENDIAN */
+#define TOC_OFFSET		40
+#define r2	toc
+#endif
+
+/*
+ * OF runs in 32 bit mode so it clobbers the high 32 bits of all registers
+ * it saves. We save and restore all the non volatile registers to avoid
+ * this issue.
+ *
+ * unsigned int ieee1275_call_entry_fn(void *args, unsigned long entry);
+ */
+FUNC_START(ieee1275_call_entry_fn)
+	mflr	r0
+	std	r0,16(r1)
+	stdu	r1,-STACK_FRAME_SIZE(r1)
+
+#if defined(_CALL_ELF) && _CALL_ELF == 1  /* BIG ENDIAN */
+	std	r2,TOC_OFFSET(r1)
+#endif
+	std	r13,R13_OFFSET(r1)
+
+	SAVE_NVGPR(r14)
+	SAVE_NVGPR(r15)
+	SAVE_NVGPR(r16)
+	SAVE_NVGPR(r17)
+	SAVE_NVGPR(r18)
+	SAVE_NVGPR(r19)
+	SAVE_NVGPR(r20)
+	SAVE_NVGPR(r21)
+	SAVE_NVGPR(r22)
+	SAVE_NVGPR(r23)
+	SAVE_NVGPR(r24)
+	SAVE_NVGPR(r25)
+	SAVE_NVGPR(r26)
+	SAVE_NVGPR(r27)
+	SAVE_NVGPR(r28)
+	SAVE_NVGPR(r29)
+	SAVE_NVGPR(r30)
+	SAVE_NVGPR(r31)
+
+	mfmsr	r31
+	std	r31, MSR_OFFSET(r1)
+
+	/* Clear 64bit mode */
+	rldicl r31,r31,0,1
+
+#if defined(_CALL_ELF) && _CALL_ELF == 2  /* LITTLE ENDIAN */
+	/* Clear LE mode */
+	rldicr r31,r31,0,62
+#endif
+
+	mtspr	SPRN_SRR0,r4
+	mtspr	SPRN_SRR1,r31
+
+	/* Point the LR at our return code */
+	bl	1f
+1:	mflr	r30
+	addi	r30,r30,(2f - 1b)
+	mtlr	r30
+
+	/* Call OF */
+	rfid
+
+#if defined(_CALL_ELF) && _CALL_ELF == 2  /* LITTLE ENDIAN */
+2:     .long 0x05009f42        /* bcl     20,31,$+4 */
+       .long 0xa602487d        /* mflr    r10 */
+       .long 0x1c004a39        /* addi    r10,r10,28 */
+       .long 0xa6035a7d        /* mtsrr0  r10 */
+       .long 0xa600407d        /* mfmsr   r10 */
+       .long 0x01004a69        /* xori    r10,r10,1 */
+       .long 0xa6035b7d        /* mtsrr1  r10 */
+       .long 0x2400004c        /* rfid */
+#endif
+
+	/* Clear the top 32 bits of r1, just in case */
+2:	rldicl	r1,r1,0,32
+
+	/* Reset our MSR */
+	ld	r31,MSR_OFFSET(r1)
+	mtspr	SPRN_SRR1,r31
+
+	bl	3f
+3:	mflr	r30
+	addi	r30,r30,(4f - 3b)
+	mtspr	SPRN_SRR0,r30
+
+	rfid
+
+#if defined(_CALL_ELF) && _CALL_ELF == 1  /* BIG ENDIAN */
+4:	ld	r2,TOC_OFFSET(r1)
+#endif
+4:	ld	r13,R13_OFFSET(r1)
+
+	REST_NVGPR(r14)
+	REST_NVGPR(r15)
+	REST_NVGPR(r16)
+	REST_NVGPR(r17)
+	REST_NVGPR(r18)
+	REST_NVGPR(r19)
+	REST_NVGPR(r20)
+	REST_NVGPR(r21)
+	REST_NVGPR(r22)
+	REST_NVGPR(r23)
+	REST_NVGPR(r24)
+	REST_NVGPR(r25)
+	REST_NVGPR(r26)
+	REST_NVGPR(r27)
+	REST_NVGPR(r28)
+	REST_NVGPR(r29)
+	REST_NVGPR(r30)
+	REST_NVGPR(r31)
+
+	addi	r1,r1,STACK_FRAME_SIZE
+	ld	r0,16(r1)
+	mtlr	r0
+	blr
+FUNC_END(ieee1275_call_entry_fn)
diff --git a/include/grub/powerpc/ieee1275/ieee1275.h b/include/grub/powerpc/ieee1275/ieee1275.h
index 3c7683f..14bdc43 100644
--- a/include/grub/powerpc/ieee1275/ieee1275.h
+++ b/include/grub/powerpc/ieee1275/ieee1275.h
@@ -25,4 +25,10 @@
 #define GRUB_IEEE1275_CELL_SIZEOF 4
 typedef grub_uint32_t grub_ieee1275_cell_t;
 
+#ifdef __powerpc64__
+int EXPORT_FUNC(ieee1275_call_entry_fn)(void *args, void *entry);
+#define	IEEE1275_CALL_ENTRY_FN(args)	\
+		ieee1275_call_entry_fn((args), grub_ieee1275_entry_fn)
+#endif
+
 #endif /* ! GRUB_IEEE1275_MACHINE_HEADER */
-- 
1.8.5.3