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avr32: fix out-of-range jump in large kernels

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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 8d29b7b9f8.
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>
Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Andreas Bießmann 2013-10-24 12:31:04 +02:00 committed by Hans-Christian Egtvedt
parent 7a2a74f4b8
commit d617b338bb
2 changed files with 6 additions and 2 deletions
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5
arch/avr32/boot/u-boot/head.S
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@ -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"

3
arch/avr32/kernel/entry-avr32b.S
View File

@ -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: