arm: Thumb ALL the things!

This patch switches every last part of Coreboot on ARM over to Thumb
mode: libpayload, the internal libgcc, and assorted assembly files. In
combination with the respective depthcharge patch, this will switch to
Thumb mode right after the entry point of the bootblock and not switch
back to ARM until the final assembly stub that jumps to the kernel.

The required changes to make this work include some new headers and
Makefile flags to handle assembly files (using the unified syntax and
the same helper macros as Linux), modifying our custom-written libgcc
code for 64-bit division to support Thumb (removing some stale old files
that were never really used for clarity), and flipping the general
CFLAGS to Thumb (some more cleanup there as well while I'm at it).

BUG=None
TEST=Snow and Nyan still boot.

Original-Change-Id: I80c04281e3adbf74f9f477486a96b9fafeb455b3
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/182212
Original-Reviewed-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 5f65c17cbfae165a95354146ae79e06c512c2c5a)

Conflicts:
	payloads/libpayload/include/arm/arch/asm.h
	src/arch/arm/Makefile.inc
	src/arch/arm/armv7/Makefile.inc

*** There is an issue with what to do with ramstage-S-ccopts, and
*** will need to be covered in additional ARM cleanup patches.

Change-Id: I80c04281e3adbf74f9f477486a96b9fafeb455b3
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-on: http://review.coreboot.org/6930
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

3 files changed, 19 insertions, 353 deletions

diff --git a/src/arch/arm/libgcc/bpabi.c b/src/arch/arm/libgcc/bpabi.c
deleted file mode 100644
index 8cb7ddf129..0000000000
--- a/src/arch/arm/libgcc/bpabi.c
+++ /dev/null
@@ -1,214 +0,0 @@
-/* Miscellaneous BPABI functions.
-
-   Copyright (C) 2003, 2004  Free Software Foundation, Inc.
-   Contributed by CodeSourcery, LLC.
-
-   This file 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 2, or (at your option) any
-   later version.
-
-   In addition to the permissions in the GNU General Public License, the
-   Free Software Foundation gives you unlimited permission to link the
-   compiled version of this file into combinations with other programs,
-   and to distribute those combinations without any restriction coming
-   from the use of this file.  (The General Public License restrictions
-   do apply in other respects; for example, they cover modification of
-   the file, and distribution when not linked into a combine
-   executable.)
-
-   This file 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 this program; see the file COPYING.  If not, write to
-   the Free Software Foundation, 51 Franklin Street, Fifth Floor,
-   Boston, MA 02110-1301, USA.  */
-
-#if defined __GNUC__
-
-#include <stdint.h>
-
-uint64_t __udivmoddi4(uint64_t n, uint64_t d, uint64_t *rp);
-extern int64_t __divdi3(int64_t, int64_t);
-extern uint64_t __udivdi3(uint64_t, uint64_t);
-extern int64_t __gnu_ldivmod_helper(int64_t, int64_t, int64_t *);
-extern uint64_t __gnu_uldivmod_helper(uint64_t, uint64_t, uint64_t *);
-
-typedef union
-{
-	struct {
-		int32_t low;
-		int32_t high;
-	} s;
-	int64_t ll;
-} DWunion;
-
-uint64_t
-__udivmoddi4(uint64_t n, uint64_t d, uint64_t *rp)
-{
-	const DWunion nn = {.ll = n};
-	const DWunion dd = {.ll = d};
-	DWunion rr;
-	uint32_t d0, d1, n0, n1, n2;
-	uint32_t q0, q1;
-	uint32_t b, bm;
-
-	d0 = dd.s.low;
-	d1 = dd.s.high;
-	n0 = nn.s.low;
-	n1 = nn.s.high;
-
-	if (d1 == 0) {
-		if (d0 > n1) {
-			/* 0q = nn / 0D */
-			udiv_qrnnd(q0, n0, n1, n0, d0);
-			q1 = 0;
-			/* Remainder in n0. */
-		} else {
-			/* qq = NN / 0d */
-			if (d0 == 0)
-				d0 = 1 / d0; /* Divide intentionally by zero. */
-
-			udiv_qrnnd(q1, n1, 0, n1, d0);
-			udiv_qrnnd(q0, n0, n1, n0, d0);
-
-			/* Remainder in n0. */
-		}
-
-		if (rp != 0) {
-			rr.s.low = n0;
-			rr.s.high = 0;
-			*rp = rr.ll;
-		}
-	} else {
-		if (d1 > n1) {
-			/* 00 = nn / DD */
-			q0 = 0;
-			q1 = 0;
-
-			/* Remainder in n1n0. */
-			if (rp != 0) {
-				rr.s.low = n0;
-				rr.s.high = n1;
-				*rp = rr.ll;
-			}
-		} else {
-			/* 0q = NN / dd */
-
-			count_leading_zeros(bm, d1);
-			if (bm == 0) {
-				/* From (n1 >= d1) /\ (the most significant
-				   bit of d1 is set), conclude (the most
-				   significant bit of n1 is set) /\ (the
-				   quotient digit q0 = 0 or 1).
-
-				   This special case is necessary, not an
-				   optimization. */
-
-				/* The condition on the next line takes
-				   advantage of that n1 >= d1 (true due to
-				   program flow). */
-				if (n1 > d1 || n0 >= d0) {
-					q0 = 1;
-					sub_ddmmss(n1, n0, n1, n0, d1, d0);
-				} else
-					q0 = 0;
-
-				q1 = 0;
-
-				if (rp != 0) {
-					rr.s.low = n0;
-					rr.s.high = n1;
-					*rp = rr.ll;
-				}
-			} else {
-				uint32_t m1, m0;
-				/* Normalize.  */
-
-				b = 32 - bm;
-
-				d1 = (d1 << bm) | (d0 >> b);
-				d0 = d0 << bm;
-				n2 = n1 >> b;
-				n1 = (n1 << bm) | (n0 >> b);
-				n0 = n0 << bm;
-
-				udiv_qrnnd(q0, n1, n2, n1, d1);
-				umul_ppmm(m1, m0, q0, d0);
-
-				if (m1 > n1 || (m1 == n1 && m0 > n0)) {
-					q0--;
-					sub_ddmmss(m1, m0, m1, m0, d1, d0);
-				}
-
-				q1 = 0;
-
-				/* Remainder in (n1n0 - m1m0) >> bm. */
-				if (rp != 0) {
-					sub_ddmmss(n1, n0, n1, n0, m1, m0);
-					rr.s.low = (n1 << b) | (n0 >> bm);
-					rr.s.high = n1 >> bm;
-					*rp = rr.ll;
-				}
-			}
-		}
-	}
-
-	const DWunion ww = {{.low = q0, .high = q1}};
-	return ww.ll;
-}
-
-int64_t
-__divdi3(int64_t u, int64_t v)
-{
-	int32_t c = 0;
-	DWunion uu = {.ll = u};
-	DWunion vv = {.ll = v};
-	int64_t w;
-
-	if (uu.s.high < 0) {
-		c = ~c;
-		uu.ll = -uu.ll;
-	}
-	if (vv.s.high < 0) {
-		c = ~c;
-		vv.ll = -vv.ll;
-	}
-
-	w = __udivmoddi4(uu.ll, vv.ll, (uint64_t *)0);
-	if (c)
-		w = -w;
-
-	return w;
-}
-
-int64_t
-__gnu_ldivmod_helper (int64_t a, int64_t b, int64_t *remainder)
-{
-	int64_t quotient;
-
-	quotient = __divdi3(a, b);
-	*remainder = a - b * quotient;
-	return quotient;
-}
-
-uint64_t
-__udivdi3(uint64_t n, uint64_t d)
-{
-	return __udivmoddi4(n, d, (uint64_t *)0);
-}
-
-uint64_t
-__gnu_uldivmod_helper(uint64_t a, uint64_t b, uint64_t *remainder)
-{
-	uint64_t quotient;
-
-	quotient = __udivdi3(a, b);
-	*remainder = a - b * quotient;
-	return quotient;
-}
-
-#endif
diff --git a/src/arch/arm/libgcc/bpabi_asm.S b/src/arch/arm/libgcc/bpabi_asm.S
deleted file mode 100644
index 27b4a1cfe8..0000000000
--- a/src/arch/arm/libgcc/bpabi_asm.S
+++ /dev/null
@@ -1,130 +0,0 @@
-/* Miscellaneous BPABI functions.
-
-   Copyright (C) 2003, 2004, 2007, 2008  Free Software Foundation, Inc.
-   Contributed by CodeSourcery, LLC.
-
-   This file 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 2, or (at your option) any
-   later version.
-
-   In addition to the permissions in the GNU General Public License, the
-   Free Software Foundation gives you unlimited permission to link the
-   compiled version of this file into combinations with other programs,
-   and to distribute those combinations without any restriction coming
-   from the use of this file.  (The General Public License restrictions
-   do apply in other respects; for example, they cover modification of
-   the file, and distribution when not linked into a combine
-   executable.)
-
-   This file 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 this program; see the file COPYING.  If not, write to
-   the Free Software Foundation, 51 Franklin Street, Fifth Floor,
-   Boston, MA 02110-1301, USA.  */
-
-
-#include <arch/asm.h>
-
-#ifdef __ARMEB__
-#define xxh r0
-#define xxl r1
-#define yyh r2
-#define yyl r3
-#else
-#define xxh r1
-#define xxl r0
-#define yyh r3
-#define yyl r2
-#endif
-
-#if defined __thumb2__
-
-.macro do_it cond
-	it	\cond
-.endm
-#define do_push push
-#define do_pop pop
-
-#else
-
-.macro do_it cond
-.endm
-#define do_push stmfd sp!,
-#define do_pop ldmfd sp!,
-
-#endif
-
-ENTRY(__aeabi_lcmp)
-
-	cmp	xxh, yyh
-	do_it	lt
-	movlt	r0, #-1
-	do_it	gt
-	movgt	r0, #1
-	do_it	ne
-	movne	pc, lr
-	subs	r0, xxl, yyl
-	do_it	lo
-	movlo	r0, #-1
-	do_it	hi
-	movhi	r0, #1
-	mov	pc, lr
-
-ENDPROC(__aeabi_lcmp)
-
-ENTRY(__aeabi_ulcmp)
-
-	cmp	xxh, yyh
-	do_it	lo
-	movlo	r0, #-1
-	do_it	hi
-	movhi	r0, #1
-	do_it	ne
-	movne	pc, lr
-	cmp	xxl, yyl
-	do_it	lo
-	movlo	r0, #-1
-	do_it	hi
-	movhi	r0, #1
-	do_it	eq
-	moveq	r0, #0
-	mov	pc, lr
-
-ENDPROC(__aeabi_ulcmp)
-
-ENTRY(__aeabi_ldivmod)
-	sub sp, sp, #8
-#if defined(__thumb2__)
-	mov ip, sp
-	push {ip, lr}
-#else
-	do_push {sp, lr}
-#endif
-	bl __gnu_ldivmod_helper
-	ldr lr, [sp, #4]
-	add sp, sp, #8
-	do_pop {r2, r3}
-	mov	pc, lr
-
-ENDPROC(__aeabi_ldivmod)
-
-ENTRY(__aeabi_uldivmod)
-	sub sp, sp, #8
-#if defined(__thumb2__)
-	mov ip, sp
-	push {ip, lr}
-#else
-	do_push {sp, lr}
-#endif
-	bl __gnu_uldivmod_helper
-	ldr lr, [sp, #4]
-	add sp, sp, #8
-	do_pop {r2, r3}
-	mov	pc, lr
-
-ENDPROC(__aeabi_uldivmod)
diff --git a/src/arch/arm/libgcc/uldivmod.S b/src/arch/arm/libgcc/uldivmod.S
index ac267d006e..521a5d1e33 100644
--- a/src/arch/arm/libgcc/uldivmod.S
+++ b/src/arch/arm/libgcc/uldivmod.S
@@ -55,8 +55,12 @@ Q_1	.req	r1
 R_0	.req	r2
 R_1	.req	r3
 
+THUMB(
+TMP	.req	r8
+)
+
 ENTRY(__aeabi_uldivmod)
-	stmfd	sp!, {r4, r5, r6, r7, lr}
+	stmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) lr}
 	@ Test if B == 0
 	orrs	ip, B_0, B_1		@ Z set -> B == 0
 	beq	L_div_by_0
@@ -92,12 +96,16 @@ L_div_64_64:
 	subs	D_1, D_0, #32
 	rsb	ip, D_0, #32
 	movmi	B_1, B_1, lsl D_0
-	orrmi	B_1, B_1, B_0, lsr ip
+ARM(	orrmi	B_1, B_1, B_0, lsr ip	)
+THUMB(	lsrmi	TMP, B_0, ip		)
+THUMB(	orrmi	B_1, B_1, TMP		)
 	movpl	B_1, B_0, lsl D_1
 	mov	B_0, B_0, lsl D_0
 	@ C = 1 << (clz B - clz A)
 	movmi	C_1, C_1, lsl D_0
-	orrmi	C_1, C_1, C_0, lsr ip
+ARM(	orrmi	C_1, C_1, C_0, lsr ip	)
+THUMB(	lsrmi	TMP, C_0, ip		)
+THUMB(	orrmi	C_1, C_1, TMP		)
 	movpl	C_1, C_0, lsl D_1
 	mov	C_0, C_0, lsl D_0
 L_done_shift:
@@ -170,7 +178,7 @@ L_exit:
 	mov	R_1, A_1
 	mov	Q_0, D_0
 	mov	Q_1, D_1
-	ldmfd	sp!, {r4, r5, r6, r7, pc}
+	ldmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) pc}
 
 L_div_32_32:
 	@ Note:	A_0 &	r0 are aliases
@@ -180,7 +188,7 @@ L_div_32_32:
 	mov	R_0, r1
 	mov	R_1, #0
 	mov	Q_1, #0
-	ldmfd	sp!, {r4, r5, r6, r7, pc}
+	ldmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) pc}
 
 L_pow2:
 /* CLZ only exists in ARM architecture version 5 and above. */
@@ -201,12 +209,14 @@ L_pow2:
 	add	D_0, D_0, #32
 L_1:
 	movpl	A_0, A_0, lsr D_0
-	orrpl	A_0, A_0, A_1, lsl D_1
+ARM(	orrpl	A_0, A_0, A_1, lsl D_1	)
+THUMB(	lslpl	TMP, A_1, D_1		)
+THUMB(	orrpl	A_0, A_0, TMP		)
 	mov	A_1, A_1, lsr D_0
 	@ Mov back C to R
 	mov	R_0, C_0
 	mov	R_1, C_1
-	ldmfd	sp!, {r4, r5, r6, r7, pc}
+	ldmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) pc}
 #else
 	@ Note: A, B and Q, R are aliases
 	@ R = A & (B - 1)
@@ -244,7 +254,7 @@ L_1:
 	@ Move C to R
 	mov	R_0, C_0
 	mov	R_1, C_1
-	ldmfd	sp!, {r4, r5, r6, r7, pc}
+	ldmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) pc}
 #endif
 
 L_div_by_0:
@@ -254,5 +264,5 @@ L_div_by_0:
 	mov	Q_1, #0
 	mov	R_0, #0
 	mov	R_1, #0
-	ldmfd	sp!, {r4, r5, r6, r7, pc}
+	ldmfd	sp!, {r4, r5, r6, r7, THUMB(TMP,) pc}
 ENDPROC(__aeabi_uldivmod)