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Blackfin: add an early shadow console
Add a memory based shadow console to keep a copy of the printk buffer in a location which can be found externally. This allows bootloaders to locate and utilize the log buffer in case of silent (early/resume/etc...) crashes. Signed-off-by: Robin Getz <robin.getz@analog.com> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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4 changed files with 83 additions and 0 deletions
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@ -23,6 +23,8 @@
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#ifdef CONFIG_EARLY_PRINTK
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extern int setup_early_printk(char *);
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extern void enable_shadow_console(void);
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#else
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#define setup_early_printk(fmt) do { } while (0)
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#define enable_shadow_console(fmt) do { } while (0)
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#endif /* CONFIG_EARLY_PRINTK */
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@ -26,6 +26,7 @@ obj-$(CONFIG_MODULES) += module.o
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obj-$(CONFIG_KGDB) += kgdb.o
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obj-$(CONFIG_KGDB_TESTS) += kgdb_test.o
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obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
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obj-$(CONFIG_EARLY_PRINTK) += shadow_console.o
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obj-$(CONFIG_STACKTRACE) += stacktrace.o
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# the kgdb test puts code into L2 and without linker
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@ -810,6 +810,8 @@ void __init setup_arch(char **cmdline_p)
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{
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unsigned long sclk, cclk;
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enable_shadow_console();
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/* Check to make sure we are running on the right processor */
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if (unlikely(CPUID != bfin_cpuid()))
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printk(KERN_ERR "ERROR: Not running on ADSP-%s: unknown CPUID 0x%04x Rev 0.%d\n",
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78
arch/blackfin/kernel/shadow_console.c
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78
arch/blackfin/kernel/shadow_console.c
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@ -0,0 +1,78 @@
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/*
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* manage a small early shadow of the log buffer which we can pass between the
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* bootloader so early crash messages are communicated properly and easily
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*
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* Copyright 2009 Analog Devices Inc.
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*
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* Enter bugs at http://blackfin.uclinux.org/
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/string.h>
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#include <asm/blackfin.h>
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#include <asm/irq_handler.h>
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#include <asm/early_printk.h>
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#define SHADOW_CONSOLE_START (0x500)
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#define SHADOW_CONSOLE_END (0x1000)
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#define SHADOW_CONSOLE_MAGIC_LOC (0x4F0)
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#define SHADOW_CONSOLE_MAGIC (0xDEADBEEF)
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static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;
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static __init void early_shadow_write(struct console *con, const char *s,
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unsigned int n)
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{
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/*
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* save 2 bytes for the double null at the end
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* once we fail on a long line, make sure we don't write a short line afterwards
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*/
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if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {
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memcpy(shadow_console_buffer, s, n);
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shadow_console_buffer += n;
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shadow_console_buffer[0] = 0;
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shadow_console_buffer[1] = 0;
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} else
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shadow_console_buffer = (char *)SHADOW_CONSOLE_END;
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}
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static __initdata struct console early_shadow_console = {
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.name = "early_shadow",
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.write = early_shadow_write,
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.flags = CON_BOOT | CON_PRINTBUFFER,
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.index = -1,
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.device = 0,
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};
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__init void enable_shadow_console(void)
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{
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int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
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if (!(early_shadow_console.flags & CON_ENABLED)) {
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register_console(&early_shadow_console);
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/* for now, assume things are going to fail */
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*loc = SHADOW_CONSOLE_MAGIC;
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loc++;
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*loc = SHADOW_CONSOLE_START;
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}
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}
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static __init int disable_shadow_console(void)
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{
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/*
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* by the time pure_initcall runs, the standard console is enabled,
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* and the early_console is off, so unset the magic numbers
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* unregistering the console is taken care of in common code (See
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* ./kernel/printk:disable_boot_consoles() )
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*/
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int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
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*loc = 0;
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return 0;
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}
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pure_initcall(disable_shadow_console);
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