From: Felix Fietkau <nbd@openwrt.org>
Date: Wed, 8 Jul 2015 13:56:37 +0200
Subject: [PATCH] Add PowerPC soft-float support

Some PowerPC CPUs (e.g. Freescale MPC85xx) have a completely different
instruction set for floating point operations (SPE).
Executing regular PowerPC floating point instructions results in
"Illegal instruction" errors.

Make it possible to run these devices in soft-float mode.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 create mode 100644 src/fenv/powerpc-sf/fenv.sub
 create mode 100644 src/setjmp/powerpc-sf/longjmp.s
 create mode 100644 src/setjmp/powerpc-sf/longjmp.sub
 create mode 100644 src/setjmp/powerpc-sf/setjmp.s
 create mode 100644 src/setjmp/powerpc-sf/setjmp.sub

--- a/arch/powerpc/reloc.h
+++ b/arch/powerpc/reloc.h
@@ -1,4 +1,10 @@
-#define LDSO_ARCH "powerpc"
+#ifdef _SOFT_FLOAT
+#define FP_SUFFIX "-sf"
+#else
+#define FP_SUFFIX ""
+#endif
+
+#define LDSO_ARCH "powerpc" FP_SUFFIX
 
 #define TPOFF_K (-0x7000)
 
--- a/configure
+++ b/configure
@@ -538,6 +538,10 @@ trycppif "_MIPSEL || __MIPSEL || __MIPSE
 trycppif __mips_soft_float "$t" && SUBARCH=${SUBARCH}-sf
 fi
 
+if test "$ARCH" = "powerpc" ; then
+trycppif _SOFT_FLOAT "$t" && SUBARCH=${SUBARCH}-sf
+fi
+
 test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
 && SUBARCH=${SUBARCH}el
 
--- /dev/null
+++ b/src/fenv/powerpc-sf/fenv.sub
@@ -0,0 +1 @@
+../fenv.c
--- /dev/null
+++ b/src/setjmp/powerpc-sf/longjmp.s
@@ -0,0 +1,47 @@
+	.global _longjmp
+	.global longjmp
+	.type   _longjmp,@function
+	.type   longjmp,@function
+_longjmp:
+longjmp:
+# void longjmp(jmp_buf env, int val);
+# put val into return register and restore the env saved in setjmp
+# if val(r4) is 0, put 1 there.
+	# 0) move old return address into r0
+	lwz 0, 0(3)
+	# 1) put it into link reg
+	mtlr 0
+	#2 ) restore stack ptr
+	lwz 1, 4(3)
+	#3) restore control reg
+	lwz 0, 8(3)
+	mtcr 0
+	#4) restore r14-r31
+	lwz 14, 12(3)
+	lwz 15, 16(3)
+	lwz 16, 20(3)
+	lwz 17, 24(3)
+	lwz 18, 28(3)
+	lwz 19, 32(3)
+	lwz 20, 36(3)
+	lwz 21, 40(3)
+	lwz 22, 44(3)
+	lwz 23, 48(3)
+	lwz 24, 52(3)
+	lwz 25, 56(3)
+	lwz 26, 60(3)
+	lwz 27, 64(3)
+	lwz 28, 68(3)
+	lwz 29, 72(3)
+	lwz 30, 76(3)
+	lwz 31, 80(3)
+	#5) put val into return reg r3
+	mr 3, 4
+
+	#6) check if return value is 0, make it 1 in that case
+	cmpwi cr7, 4, 0
+	bne cr7, 1f
+	li 3, 1
+1:
+	blr
+
--- /dev/null
+++ b/src/setjmp/powerpc-sf/longjmp.sub
@@ -0,0 +1 @@
+longjmp.s
--- /dev/null
+++ b/src/setjmp/powerpc-sf/setjmp.s
@@ -0,0 +1,43 @@
+	.global ___setjmp
+	.hidden ___setjmp
+	.global __setjmp
+	.global _setjmp
+	.global setjmp
+	.type   __setjmp,@function
+	.type   _setjmp,@function
+	.type   setjmp,@function
+___setjmp:
+__setjmp:
+_setjmp:
+setjmp:
+	# 0) store IP int 0, then into the jmpbuf pointed to by r3 (first arg)
+	mflr 0
+	stw 0, 0(3)
+	# 1) store reg1 (SP)
+	stw 1, 4(3)
+	# 2) store cr
+	mfcr 0
+	stw 0, 8(3)
+	# 3) store r14-31
+	stw 14, 12(3)
+	stw 15, 16(3)
+	stw 16, 20(3)
+	stw 17, 24(3)
+	stw 18, 28(3)
+	stw 19, 32(3)
+	stw 20, 36(3)
+	stw 21, 40(3)
+	stw 22, 44(3)
+	stw 23, 48(3)
+	stw 24, 52(3)
+	stw 25, 56(3)
+	stw 26, 60(3)
+	stw 27, 64(3)
+	stw 28, 68(3)
+	stw 29, 72(3)
+	stw 30, 76(3)
+	stw 31, 80(3)
+	# 4) set return value to 0
+	li 3, 0
+	# 5) return
+	blr
--- /dev/null
+++ b/src/setjmp/powerpc-sf/setjmp.sub
@@ -0,0 +1 @@
+setjmp.s