[PATCH 1/2] avr32: setup crt for early panic()

[PATCH 1/2] avr32: setup crt for early panic()

[Andreas Bießmann]

Before the CRT was (fully) set up in kernel_entry (bss cleared before in
_start, but also not before jump to panic() in no_tag_table case).

This patch fixes this up to have a fully working CRT when branching to panic()
in no_tag_table.

Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
---
 arch/avr32/boot/u-boot/head.S |   30 +++++++++++++++++++++++++-----
 arch/avr32/kernel/head.S      |   20 --------------------
 2 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/arch/avr32/boot/u-boot/head.S b/arch/avr32/boot/u-boot/head.S
index 4488fa2..d36d865 100644
--- a/arch/avr32/boot/u-boot/head.S
+++ b/arch/avr32/boot/u-boot/head.S
@@ -8,6 +8,8 @@
  * published by the Free Software Foundation.
  */
 #include <asm/setup.h>
+#include <asm/thread_info.h>
+#include <asm/sysreg.h>
 
 	/*
 	 * The kernel is loaded where we want it to be and all caches
@@ -20,11 +22,6 @@
 	.section .init.text,"ax"
 	.global _start
 _start:
-	/* Check if the boot loader actually provided a tag table */
-	lddpc	r0, magic_number
-	cp.w	r12, r0
-	brne	no_tag_table
-
 	/* Initialize .bss */
 	lddpc	r2, bss_start_addr
 	lddpc   r3, end_addr
@@ -34,6 +31,25 @@ _start:
 	cp      r2, r3
 	brlo    1b
 
+	/* Initialize status register */
+	lddpc	r0, init_sr
+	mtsr	SYSREG_SR, r0
+
+	/* Set initial stack pointer */
+	lddpc	sp, stack_addr
+	sub	sp, -THREAD_SIZE
+
+#ifdef CONFIG_FRAME_POINTER
+	/* Mark last stack frame */
+	mov	lr, 0
+	mov	r7, 0
+#endif
+
+	/* Check if the boot loader actually provided a tag table */
+	lddpc	r0, magic_number
+	cp.w	r12, r0
+	brne	no_tag_table
+
 	/*
 	 * Save the tag table address for later use. This must be done
 	 * _after_ .bss has been initialized...
@@ -53,6 +69,10 @@ bss_start_addr:
 	.long   __bss_start
 end_addr:
 	.long   _end
+init_sr:
+	.long	0x007f0000	/* Supervisor mode, everything masked */
+stack_addr:
+	.long	init_thread_union
 
 no_tag_table:
 	sub	r12, pc, (. - 2f)
diff --git a/arch/avr32/kernel/head.S b/arch/avr32/kernel/head.S
index 6163bd0..59eae6d 100644
--- a/arch/avr32/kernel/head.S
+++ b/arch/avr32/kernel/head.S
@@ -10,33 +10,13 @@
 #include <linux/linkage.h>
 
 #include <asm/page.h>
-#include <asm/thread_info.h>
-#include <asm/sysreg.h>
 
 	.section .init.text,"ax"
 	.global kernel_entry
 kernel_entry:
-	/* Initialize status register */
-	lddpc   r0, init_sr
-	mtsr	SYSREG_SR, r0
-
-	/* Set initial stack pointer */
-	lddpc   sp, stack_addr
-	sub	sp, -THREAD_SIZE
-
-#ifdef CONFIG_FRAME_POINTER
-	/* Mark last stack frame */
-	mov	lr, 0
-	mov	r7, 0
-#endif
-
 	/* Start the show */
 	lddpc   pc, kernel_start_addr
 
 	.align  2
-init_sr:
-	.long   0x007f0000	/* Supervisor mode, everything masked */
-stack_addr:
-	.long   init_thread_union
 kernel_start_addr:
 	.long   start_kernel
-- 
1.7.10.4

[PATCH 2/2] avr32: fix out-of-range jump in large kernels

[Andreas Bießmann]

This patch fixes following error (for big kernels):

---8<---
arch/avr32/boot/u-boot/head.o: In function `no_tag_table':
(.init.text+0x44): relocation truncated to fit: R_AVR32_22H_PCREL against symbol `panic' defined in .text.unlikely section in kernel/built-in.o
arch/avr32/kernel/built-in.o: In function `bad_return':
(.ex.text+0x236): relocation truncated to fit: R_AVR32_22H_PCREL against symbol `panic' defined in .text.unlikely section in kernel/built-in.o
--->8---

It comes up when the kernel increases and 'panic()' is too far away to fit in
the +/- 2MiB range. Which in turn issues from the 21-bit displacement in
'br{cond4}' mnemonic which is one of the two ways to do jumps (rjmp has just
10-bit displacement and therefore a way smaller range). This fact was stated
before in 8d29b7b9f81d6b83d869ff054e6c189d6da73f1f.
One solution to solve this is to add a local storage for the symbol address
and just load the $pc with that value.

Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
---
 arch/avr32/boot/u-boot/head.S    |    5 ++++-
 arch/avr32/kernel/entry-avr32b.S |    3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/avr32/boot/u-boot/head.S b/arch/avr32/boot/u-boot/head.S
index d36d865..2ffc298 100644
--- a/arch/avr32/boot/u-boot/head.S
+++ b/arch/avr32/boot/u-boot/head.S
@@ -73,8 +73,11 @@ init_sr:
 	.long	0x007f0000	/* Supervisor mode, everything masked */
 stack_addr:
 	.long	init_thread_union
+panic_addr:
+	.long	panic
 
 no_tag_table:
 	sub	r12, pc, (. - 2f)
-	bral	panic
+	/* branch to panic() which can be far away with that construct */
+	lddpc	pc, panic_addr
 2:	.asciz	"Boot loader didn't provide correct magic number\n"
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 9899d3c..7301f48 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -401,9 +401,10 @@ handle_critical:
 	/* We should never get here... */
 bad_return:
 	sub	r12, pc, (. - 1f)
-	bral	panic
+	lddpc	pc, 2f
 	.align	2
 1:	.asciz	"Return from critical exception!"
+2:	.long	panic
 
 	.align	1
 do_bus_error_write:
-- 
1.7.10.4