[PATCH 2/5 v2] powerpc/boot/fdt: Add little-endian support to libfdt wrappers

[PATCH 2/5 v2] powerpc/boot/fdt: Add little-endian support to libfdt wrappers

[Jeremy Kerr]

For epapr-style boot, we may be little-endian. This change implements
the proper conversion for fdt*_to_cpu and cpu_to_fdt*. We also need the
full cpu_to_* and *_to_cpu macros for this.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

---
 arch/powerpc/boot/libfdt_env.h |   14 ++++++++------
 arch/powerpc/boot/of.h         |    8 ++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/boot/libfdt_env.h b/arch/powerpc/boot/libfdt_env.h
index c89fdb1..8dcd744 100644
--- a/arch/powerpc/boot/libfdt_env.h
+++ b/arch/powerpc/boot/libfdt_env.h
@@ -4,15 +4,17 @@
 #include <types.h>
 #include <string.h>
 
+#include "of.h"
+
 typedef u32 uint32_t;
 typedef u64 uint64_t;
 typedef unsigned long uintptr_t;
 
-#define fdt16_to_cpu(x)		(x)
-#define cpu_to_fdt16(x)		(x)
-#define fdt32_to_cpu(x)		(x)
-#define cpu_to_fdt32(x)		(x)
-#define fdt64_to_cpu(x)		(x)
-#define cpu_to_fdt64(x)		(x)
+#define fdt16_to_cpu(x)		be16_to_cpu(x)
+#define cpu_to_fdt16(x)		cpu_to_be16(x)
+#define fdt32_to_cpu(x)		be32_to_cpu(x)
+#define cpu_to_fdt32(x)		cpu_to_be32(x)
+#define fdt64_to_cpu(x)		be64_to_cpu(x)
+#define cpu_to_fdt64(x)		cpu_to_be64(x)
 
 #endif /* _ARCH_POWERPC_BOOT_LIBFDT_ENV_H */
diff --git a/arch/powerpc/boot/of.h b/arch/powerpc/boot/of.h
index c8c1750..5603320 100644
--- a/arch/powerpc/boot/of.h
+++ b/arch/powerpc/boot/of.h
@@ -24,11 +24,19 @@ void of_console_init(void);
 typedef u32			__be32;
 
 #ifdef __LITTLE_ENDIAN__
+#define cpu_to_be16(x) swab16(x)
+#define be16_to_cpu(x) swab16(x)
 #define cpu_to_be32(x) swab32(x)
 #define be32_to_cpu(x) swab32(x)
+#define cpu_to_be64(x) swab64(x)
+#define be64_to_cpu(x) swab64(x)
 #else
+#define cpu_to_be16(x) (x)
+#define be16_to_cpu(x) (x)
 #define cpu_to_be32(x) (x)
 #define be32_to_cpu(x) (x)
+#define cpu_to_be64(x) (x)
+#define be64_to_cpu(x) (x)
 #endif
 
 #define PROM_ERROR (-1u)

[PATCH 3/5 v2] powerpc/boot/wrapper: use the pseries wrapper for zImage.epapr

[Jeremy Kerr]

We'll likely be entering the zImage.epapr as BE, so include the pseries
implementation of _zimage_start, which adds the endian fixup magic.

Although the endian fixup won't work on Book III-E machines starting LE,
the current entry point doesn't support LE anyway, so we shouldn't be
breaking anything.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

---
 arch/powerpc/boot/wrapper |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/boot/wrapper b/arch/powerpc/boot/wrapper
index ae0f88e..3f50c27 100755
--- a/arch/powerpc/boot/wrapper
+++ b/arch/powerpc/boot/wrapper
@@ -277,7 +277,7 @@ treeboot-iss4xx-mpic)
     platformo="$object/treeboot-iss4xx.o"
     ;;
 epapr)
-    platformo="$object/epapr.o $object/epapr-wrapper.o"
+    platformo="$object/pseries-head.o $object/epapr.o $object/epapr-wrapper.o"
     link_address='0x20000000'
     pie=-pie
     ;;

[PATCH 1/5 v2] powerpc/boot/fdt: Use unsigned long for pointer casts

[Jeremy Kerr]

Now that the wrapper supports 64-bit builds, we see warnings when
attempting to cast pointers to int. Use unsigned long instead.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

---
 arch/powerpc/boot/libfdt-wrapper.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/boot/libfdt-wrapper.c b/arch/powerpc/boot/libfdt-wrapper.c
index bb8b9b3..535e8fd 100644
--- a/arch/powerpc/boot/libfdt-wrapper.c
+++ b/arch/powerpc/boot/libfdt-wrapper.c
@@ -44,12 +44,12 @@
 
 #define offset_devp(off)	\
 	({ \
-		int _offset = (off); \
+		unsigned long _offset = (off); \
 		check_err(_offset) ? NULL : (void *)(_offset+1); \
 	})
 
-#define devp_offset_find(devp)	(((int)(devp))-1)
-#define devp_offset(devp)	(devp ? ((int)(devp))-1 : 0)
+#define devp_offset_find(devp)	(((unsigned long)(devp))-1)
+#define devp_offset(devp)	(devp ? ((unsigned long)(devp))-1 : 0)
 
 static void *fdt;
 static void *buf; /* = NULL */

[PATCH 4/5 v2] powerpc/boot: Fix stack corruption in epapr entry point

[Jeremy Kerr]

Currently, a 64-bit little-endian zImage.epapr won't boot in epapr mode,
as we never return from platform_init.

Before entering C, we initialise our stack by setting r1 16 bytes below
the end of the _bss_stack:

  stwu	r0,-16(r1)	/* establish a stack frame */

However, the called function will save the caller's lr in the caller's
frame's lr save area, at -16(r1) to -32(r1).

This means that writes to the fdt variable will corrupt the saved link
register:

 0000000020c06018 l     O .bss   0000000000001000 _bss_stack
 0000000020c07018 l     O .bss   0000000000000008 fdt

We'll need at least 32 bytes in the initial stack frame, to handle the
LR save area. We bump this to 112 bytes, as that'll be the max required
by ABIv1.

Thanks to Alistair Popple for debugging help.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

---
 arch/powerpc/boot/crt0.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index 14de4f8..e004062 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -218,7 +218,7 @@ p_base:	mflr	r10		/* r10 now points to runtime addr of p_base */
 	beq	6f
 	ld	r1,0(r8)
 	li	r0,0
-	stdu	r0,-16(r1)	/* establish a stack frame */
+	stdu	r0,-112(r1)	/* establish a stack frame */
 6:
 #endif  /* __powerpc64__ */
 	/* Call platform_init() */

[PATCH 5/5 v2] powerpc/boot: don't clobber r6 and r7 in epapr boot

[Jeremy Kerr]

We use r6 and r7 for epapr boot, but the current pre-C init will clobber
both of these.

This change does a simple replacement, of r6 -> r12 and r7 -> r13, so
that we hit platform init with these registers intact.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

---
 arch/powerpc/boot/crt0.S |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index e004062..12866cc 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -155,29 +155,29 @@ p_base:	mflr	r10		/* r10 now points to runtime addr of p_base */
 	ld	r9,(p_rela-p_base)(r10)
 	add	r9,r9,r10
 
-	li	r7,0
+	li	r13,0
 	li	r8,0
-9:	ld	r6,0(r11)       /* get tag */
-	cmpdi	r6,0
+9:	ld	r12,0(r11)       /* get tag */
+	cmpdi	r12,0
 	beq	12f              /* end of list */
-	cmpdi	r6,RELA
+	cmpdi	r12,RELA
 	bne	10f
-	ld	r7,8(r11)       /* get RELA pointer in r7 */
+	ld	r13,8(r11)       /* get RELA pointer in r13 */
 	b	11f
-10:	addis	r6,r6,(-RELACOUNT)@ha
-	cmpdi	r6,RELACOUNT@l
+10:	addis	r12,r12,(-RELACOUNT)@ha
+	cmpdi	r12,RELACOUNT@l
 	bne	11f
 	ld	r8,8(r11)       /* get RELACOUNT value in r8 */
 11:	addi	r11,r11,16
 	b	9b
 12:
-	cmpdi	r7,0            /* check we have both RELA and RELACOUNT */
+	cmpdi	r13,0            /* check we have both RELA and RELACOUNT */
 	cmpdi	cr1,r8,0
 	beq	3f
 	beq	cr1,3f
 
 	/* Calcuate the runtime offset. */
-	subf	r7,r7,r9
+	subf	r13,r13,r9
 
 	/* Run through the list of relocations and process the
 	 * R_PPC64_RELATIVE ones. */
@@ -185,10 +185,10 @@ p_base:	mflr	r10		/* r10 now points to runtime addr of p_base */
 13:	ld	r0,8(r9)        /* ELF64_R_TYPE(reloc->r_info) */
 	cmpdi	r0,22           /* R_PPC64_RELATIVE */
 	bne	3f
-	ld	r6,0(r9)        /* reloc->r_offset */
+	ld	r12,0(r9)        /* reloc->r_offset */
 	ld	r0,16(r9)       /* reloc->r_addend */
-	add	r0,r0,r7
-	stdx	r0,r7,r6
+	add	r0,r0,r13
+	stdx	r0,r13,r12
 	addi	r9,r9,24
 	bdnz	13b
 

Re: [PATCH 2/5 v2] powerpc/boot/fdt: Add little-endian support to libfdt wrappers

[Cedric Le Goater]

On 02/11/2015 05:55 AM, Jeremy Kerr wrote:
> For epapr-style boot, we may be little-endian. This change implements
> the proper conversion for fdt*_to_cpu and cpu_to_fdt*. We also need the
> full cpu_to_* and *_to_cpu macros for this.
> 
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>


I did not work on the little endian epapr wrapper :/

To test the patchset, I used the 'le' branch of git://github.com/jk-ozlabs/linux 
and successfully booted a tuleta and an open-power system using the latest 
skiboot and a LE zImage.epapr. Looks good to me. 

You might want to add CONFIG_IPMI_WATCHDOG to openpower_defconfig 

Thanks.

C.