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linux-next/arch/avr32/kernel/vmlinux.lds.S
Haavard Skinnemoen 2507bc1338 [AVR32] Follow the rules when dealing with the OCD system
The current debug trap handling code does a number of things that are
illegal according to the AVR32 Architecture manual. Most importantly,
it may try to schedule from Debug Mode, thus clearing the D bit, which
can lead to "undefined behaviour".

It seems like this works in most cases, but several people have
observed somewhat unstable behaviour when debugging programs,
including soft lockups. So there's definitely something which is not
right with the existing code.

The new code will never schedule from Debug mode, it will always exit
Debug mode with a "retd" instruction, and if something not running in
Debug mode needs to do something debug-related (like doing a single
step), it will enter debug mode through a "breakpoint" instruction.
The monitor code will then return directly to user space, bypassing
its own saved registers if necessary (since we don't actually care
about the trapped context, only the one that came before.)

This adds three instructions to the common exception handling code,
including one branch. It does not touch super-hot paths like the TLB
miss handler.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-12-07 14:54:46 +01:00

144 lines
2.7 KiB
ArmAsm

/*
* AVR32 linker script for the Linux kernel
*
* Copyright (C) 2004-2006 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define LOAD_OFFSET 0x00000000
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
OUTPUT_FORMAT("elf32-avr32", "elf32-avr32", "elf32-avr32")
OUTPUT_ARCH(avr32)
ENTRY(_start)
/* Big endian */
jiffies = jiffies_64 + 4;
SECTIONS
{
. = CONFIG_ENTRY_ADDRESS;
.init : AT(ADDR(.init) - LOAD_OFFSET) {
_stext = .;
__init_begin = .;
_sinittext = .;
*(.text.reset)
*(.init.text)
/*
* .exit.text is discarded at runtime, not
* link time, to deal with references from
* __bug_table
*/
*(.exit.text)
_einittext = .;
. = ALIGN(4);
__tagtable_begin = .;
*(.taglist.init)
__tagtable_end = .;
*(.init.data)
. = ALIGN(16);
__setup_start = .;
*(.init.setup)
__setup_end = .;
. = ALIGN(4);
__initcall_start = .;
INITCALLS
__initcall_end = .;
__con_initcall_start = .;
*(.con_initcall.init)
__con_initcall_end = .;
__security_initcall_start = .;
*(.security_initcall.init)
__security_initcall_end = .;
#ifdef CONFIG_BLK_DEV_INITRD
. = ALIGN(32);
__initramfs_start = .;
*(.init.ramfs)
__initramfs_end = .;
#endif
. = ALIGN(PAGE_SIZE);
__init_end = .;
}
.text : AT(ADDR(.text) - LOAD_OFFSET) {
_evba = .;
_text = .;
*(.ex.text)
. = 0x50;
*(.tlbx.ex.text)
. = 0x60;
*(.tlbr.ex.text)
. = 0x70;
*(.tlbw.ex.text)
. = 0x100;
*(.scall.text)
*(.irq.text)
KPROBES_TEXT
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
_etext = .;
} = 0xd703d703
. = ALIGN(4);
__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
__start___ex_table = .;
*(__ex_table)
__stop___ex_table = .;
}
BUG_TABLE
RODATA
. = ALIGN(THREAD_SIZE);
.data : AT(ADDR(.data) - LOAD_OFFSET) {
_data = .;
_sdata = .;
/*
* First, the init task union, aligned to an 8K boundary.
*/
*(.data.init_task)
/* Then, the cacheline aligned data */
. = ALIGN(L1_CACHE_BYTES);
*(.data.cacheline_aligned)
/* And the rest... */
*(.data.rel*)
DATA_DATA
CONSTRUCTORS
_edata = .;
}
. = ALIGN(8);
.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
__bss_start = .;
*(.bss)
*(COMMON)
. = ALIGN(8);
__bss_stop = .;
_end = .;
}
/* When something in the kernel is NOT compiled as a module, the module
* cleanup code and data are put into these segments. Both can then be
* thrown away, as cleanup code is never called unless it's a module.
*/
/DISCARD/ : {
*(.exit.data)
*(.exitcall.exit)
}
DWARF_DEBUG
}