ARM: move exception vectors away from start of binary

Traditionally U-Boot and barebox have the exception vectors at
the start of the binary. There is no real reason in doing so,
because in the majority of cases this data will not be at 0x0
where it could be used as vectors directly anyway.
This patch puts the vectors into a separate linker section and
defines an head function which is placed at the start of the
image instead. Putting this in a separate function also has
the advantage that it can be placed at the start of images
which require an additional header like several Freescale i.MX
images. As the head function contains the barebox arm magic
those images can now also be detected as barebox images.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

13 files changed, 55 insertions, 18 deletions

diff --git a/arch/arm/boards/eukrea_cpuimx25/eukrea_cpuimx25.c b/arch/arm/boards/eukrea_cpuimx25/eukrea_cpuimx25.c
index 73e54f2f54..695e75f288 100644
--- a/arch/arm/boards/eukrea_cpuimx25/eukrea_cpuimx25.c
+++ b/arch/arm/boards/eukrea_cpuimx25/eukrea_cpuimx25.c
@@ -46,13 +46,14 @@
 #include <usb/fsl_usb2.h>
 #include <mach/usb.h>
 #include <mach/devices-imx25.h>
+#include <asm/barebox-arm-head.h>
 
 extern unsigned long _stext;
 extern void exception_vectors(void);
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/eukrea_cpuimx35/flash_header.c b/arch/arm/boards/eukrea_cpuimx35/flash_header.c
index 93c8348209..f8ed5d483e 100644
--- a/arch/arm/boards/eukrea_cpuimx35/flash_header.c
+++ b/arch/arm/boards/eukrea_cpuimx35/flash_header.c
@@ -1,12 +1,13 @@
 #include <common.h>
 #include <mach/imx-flash-header.h>
 #include <mach/imx-regs.h>
+#include <asm/barebox-arm-head.h>
 
 extern void exception_vectors(void);
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/eukrea_cpuimx51/flash_header.c b/arch/arm/boards/eukrea_cpuimx51/flash_header.c
index f953b09bde..ac6bbdcc0f 100644
--- a/arch/arm/boards/eukrea_cpuimx51/flash_header.c
+++ b/arch/arm/boards/eukrea_cpuimx51/flash_header.c
@@ -1,11 +1,12 @@
 #include <common.h>
 #include <mach/imx-flash-header.h>
+#include <asm/barebox-arm-head.h>
 
 extern unsigned long _stext;
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/freescale-mx25-3-stack/3stack.c b/arch/arm/boards/freescale-mx25-3-stack/3stack.c
index 5aa54e43ff..d7e24cf3e7 100644
--- a/arch/arm/boards/freescale-mx25-3-stack/3stack.c
+++ b/arch/arm/boards/freescale-mx25-3-stack/3stack.c
@@ -42,13 +42,14 @@
 #include <i2c/i2c.h>
 #include <mfd/mc34704.h>
 #include <mach/devices-imx25.h>
+#include <asm/barebox-arm-head.h>
 
 extern unsigned long _stext;
 extern void exception_vectors(void);
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/freescale-mx35-3-stack/flash_header.c b/arch/arm/boards/freescale-mx35-3-stack/flash_header.c
index 92f214202e..85b52a25ca 100644
--- a/arch/arm/boards/freescale-mx35-3-stack/flash_header.c
+++ b/arch/arm/boards/freescale-mx35-3-stack/flash_header.c
@@ -1,12 +1,13 @@
 #include <common.h>
 #include <mach/imx-flash-header.h>
 #include <mach/imx-regs.h>
+#include <asm/barebox-arm-head.h>
 
 extern void exception_vectors(void);
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/freescale-mx51-pdk/flash_header.c b/arch/arm/boards/freescale-mx51-pdk/flash_header.c
index 5f94506b69..297dca1c29 100644
--- a/arch/arm/boards/freescale-mx51-pdk/flash_header.c
+++ b/arch/arm/boards/freescale-mx51-pdk/flash_header.c
@@ -1,11 +1,12 @@
 #include <common.h>
 #include <mach/imx-flash-header.h>
+#include <asm/barebox-arm-head.h>
 
 extern unsigned long _stext;
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/freescale-mx53-loco/flash_header.c b/arch/arm/boards/freescale-mx53-loco/flash_header.c
index 490e223f0e..b45964059a 100644
--- a/arch/arm/boards/freescale-mx53-loco/flash_header.c
+++ b/arch/arm/boards/freescale-mx53-loco/flash_header.c
@@ -16,10 +16,11 @@
 #include <common.h>
 #include <asm/byteorder.h>
 #include <mach/imx-flash-header.h>
+#include <asm/barebox-arm-head.h>
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_v2_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/boards/freescale-mx53-smd/flash_header.c b/arch/arm/boards/freescale-mx53-smd/flash_header.c
index 490e223f0e..b45964059a 100644
--- a/arch/arm/boards/freescale-mx53-smd/flash_header.c
+++ b/arch/arm/boards/freescale-mx53-smd/flash_header.c
@@ -16,10 +16,11 @@
 #include <common.h>
 #include <asm/byteorder.h>
 #include <mach/imx-flash-header.h>
+#include <asm/barebox-arm-head.h>
 
 void __naked __flash_header_start go(void)
 {
-	__asm__ __volatile__("b exception_vectors\n");
+	barebox_arm_head();
 }
 
 struct imx_dcd_v2_entry __dcd_entry_section dcd_entry[] = {
diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index 6d9b1e0231..c19f9311cd 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -4,6 +4,7 @@
 #include <errno.h>
 #include <sizes.h>
 #include <asm/memory.h>
+#include <asm/barebox-arm.h>
 #include <asm/system.h>
 #include <memory.h>
 
@@ -182,7 +183,6 @@ static void vectors_init(void)
 {
 	u32 *exc, *zero = NULL;
 	void *vectors;
-	extern unsigned long exception_vectors;
 	u32 cr;
 
 	cr = get_cr();
@@ -210,7 +210,7 @@ static void vectors_init(void)
 
 	vectors = xmemalign(PAGE_SIZE, PAGE_SIZE);
 	memset(vectors, 0, PAGE_SIZE);
-	memcpy(vectors, &exception_vectors, ARM_VECTORS_SIZE);
+	memcpy(vectors, __exceptions_start, __exceptions_stop - __exceptions_start);
 
 	if (cr & CR_V)
 		exc[256 - 16] = (u32)vectors | PTE_TYPE_SMALL | PTE_FLAGS_CACHED;
diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 61d7e3e5d5..1a1538e5e3 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -23,11 +23,17 @@
 #include <common.h>
 #include <init.h>
 #include <asm/barebox-arm.h>
+#include <asm/barebox-arm-head.h>
 #include <asm/system.h>
 #include <asm-generic/memory_layout.h>
 #include <asm/sections.h>
 
-void __naked __section(.text_entry) exception_vectors(void)
+void __naked __section(.text_entry) start(void)
+{
+	barebox_arm_head();
+}
+
+void __naked __section(.text_exceptions) exception_vectors(void)
 {
 	__asm__ __volatile__ (
 		"b reset\n"				/* reset */
@@ -48,12 +54,6 @@ void __naked __section(.text_entry) exception_vectors(void)
 		"1: bne 1b\n"				/* irq (interrupt) */
 		"1: bne 1b\n"				/* fiq (fast interrupt) */
 #endif
-		".word 0x65726162\n"			/* 'bare' */
-		".word 0x00786f62\n"			/* 'box' */
-		".word _text\n"				/* text base. If copied there,
-							 * barebox can skip relocation
-							 */
-		".word _barebox_image_size\n"		/* image size to copy */
 	);
 }
 
diff --git a/arch/arm/include/asm/barebox-arm-head.h b/arch/arm/include/asm/barebox-arm-head.h
new file mode 100644
index 0000000000..fdbee8cdda
--- /dev/null
+++ b/arch/arm/include/asm/barebox-arm-head.h
@@ -0,0 +1,24 @@
+#ifndef __ASM_ARM_HEAD_H
+#define __ASM_ARM_HEAD_H
+
+static inline void barebox_arm_head(void)
+{
+	__asm__ __volatile__ (
+		"b reset\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		"1: b 1b\n"
+		".word 0x65726162\n"			/* 'bare' */
+		".word 0x00786f62\n"			/* 'box' */
+		".word _text\n"				/* text base. If copied there,
+							 * barebox can skip relocation
+							 */
+		".word _barebox_image_size\n"		/* image size to copy */
+	);
+}
+
+#endif /* __ASM_ARM_HEAD_H */
diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 7bb1af1606..333978241c 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -36,6 +36,8 @@ int	cleanup_before_linux(void);
 int	board_init(void);
 int	dram_init (void);
 
+extern char __exceptions_start[], __exceptions_stop[];
+
 void board_init_lowlevel(void);
 void board_init_lowlevel_return(void);
 void arch_init_lowlevel(void);
diff --git a/arch/arm/lib/barebox.lds.S b/arch/arm/lib/barebox.lds.S
index e9f62107f9..531e3d0e87 100644
--- a/arch/arm/lib/barebox.lds.S
+++ b/arch/arm/lib/barebox.lds.S
@@ -26,7 +26,7 @@
 
 OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
 OUTPUT_ARCH(arm)
-ENTRY(exception_vectors)
+ENTRY(start)
 SECTIONS
 {
 	. = TEXT_BASE;
@@ -47,6 +47,9 @@ SECTIONS
 		__bare_init_start = .;
 		*(.text_bare_init*)
 		__bare_init_end = .;
+		__exceptions_start = .;
+		KEEP(*(.text_exceptions*))
+		__exceptions_stop = .;
 		*(.text*)
 	}
 	BAREBOX_BARE_INIT_SIZE