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linux/arch/powerpc/kernel/setup_32.c
Benjamin Herrenschmidt 0909c8c2d5 [POWERPC] Support feature fixups in vdso's 
This patch reworks the feature fixup mecanism so vdso's can be fixed up.
The main issue was that the construct:

        .long   label  (or .llong on 64 bits)

will not work in the case of a shared library like the vdso. It will
generate an empty placeholder in the fixup table along with a reloc,
which is not something we can deal with in the vdso.

The idea here (thanks Alan Modra !) is to instead use something like:

1:
        .long   label - 1b

That is, the feature fixup tables no longer contain addresses of bits of
code to patch, but offsets of such code from the fixup table entry
itself. That is properly resolved by ld when building the .so's. I've
modified the fixup mecanism generically to use that method for the rest
of the kernel as well.

Another trick is that the 32 bits vDSO included in the 64 bits kernel
need to have a table in the 64 bits format. However, gas does not
support 32 bits code with a statement of the form:

        .llong  label - 1b  (Or even just .llong label)

That is, it cannot emit the right fixup/relocation for the linker to use
to assign a 32 bits address to an .llong field. Thus, in the specific
case of the 32 bits vdso built as part of the 64 bits kernel, we are
using a modified macro that generates:

        .long   0xffffffff
        .llong  label - 1b

Note that is assumes that the value is negative which is enforced by
the .lds (those offsets are always negative as the .text is always
before the fixup table and gas doesn't support emiting the reloc the
other way around).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-10-25 11:54:07 +10:00

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/*
* Common prep/pmac/chrp boot and setup code.
*/
#include <linux/module.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/initrd.h>
#include <linux/ide.h>
#include <linux/tty.h>
#include <linux/bootmem.h>
#include <linux/seq_file.h>
#include <linux/root_dev.h>
#include <linux/cpu.h>
#include <linux/console.h>
#include <asm/residual.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
#include <asm/amigappc.h>
#include <asm/smp.h>
#include <asm/elf.h>
#include <asm/cputable.h>
#include <asm/bootx.h>
#include <asm/btext.h>
#include <asm/machdep.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/pmac_feature.h>
#include <asm/sections.h>
#include <asm/nvram.h>
#include <asm/xmon.h>
#include <asm/time.h>
#include <asm/serial.h>
#include <asm/udbg.h>
#include "setup.h"
#define DBG(fmt...)
#if defined CONFIG_KGDB
#include <asm/kgdb.h>
#endif
extern void bootx_init(unsigned long r4, unsigned long phys);
struct ide_machdep_calls ppc_ide_md;
int boot_cpuid;
EXPORT_SYMBOL_GPL(boot_cpuid);
int boot_cpuid_phys;
unsigned long ISA_DMA_THRESHOLD;
unsigned int DMA_MODE_READ;
unsigned int DMA_MODE_WRITE;
int have_of = 1;
#ifdef CONFIG_PPC_MULTIPLATFORM
dev_t boot_dev;
#endif /* CONFIG_PPC_MULTIPLATFORM */
#ifdef CONFIG_VGA_CONSOLE
unsigned long vgacon_remap_base;
#endif
/*
* These are used in binfmt_elf.c to put aux entries on the stack
* for each elf executable being started.
*/
int dcache_bsize;
int icache_bsize;
int ucache_bsize;
/*
* We're called here very early in the boot. We determine the machine
* type and call the appropriate low-level setup functions.
* -- Cort <cort@fsmlabs.com>
*
* Note that the kernel may be running at an address which is different
* from the address that it was linked at, so we must use RELOC/PTRRELOC
* to access static data (including strings). -- paulus
*/
unsigned long __init early_init(unsigned long dt_ptr)
{
unsigned long offset = reloc_offset();
struct cpu_spec *spec;
/* First zero the BSS -- use memset_io, some platforms don't have
* caches on yet */
memset_io((void __iomem *)PTRRELOC(&__bss_start), 0, _end - __bss_start);
/*
* Identify the CPU type and fix up code sections
* that depend on which cpu we have.
*/
spec = identify_cpu(offset);
do_feature_fixups(spec->cpu_features,
PTRRELOC(&__start___ftr_fixup),
PTRRELOC(&__stop___ftr_fixup));
return KERNELBASE + offset;
}
/*
* Find out what kind of machine we're on and save any data we need
* from the early boot process (devtree is copied on pmac by prom_init()).
* This is called very early on the boot process, after a minimal
* MMU environment has been set up but before MMU_init is called.
*/
void __init machine_init(unsigned long dt_ptr, unsigned long phys)
{
/* If btext is enabled, we might have a BAT setup for early display,
* thus we do enable some very basic udbg output
*/
#ifdef CONFIG_BOOTX_TEXT
udbg_putc = btext_drawchar;
#endif
/* Do some early initialization based on the flat device tree */
early_init_devtree(__va(dt_ptr));
probe_machine();
#ifdef CONFIG_6xx
if (cpu_has_feature(CPU_FTR_CAN_DOZE) ||
cpu_has_feature(CPU_FTR_CAN_NAP))
ppc_md.power_save = ppc6xx_idle;
#endif
if (ppc_md.progress)
ppc_md.progress("id mach(): done", 0x200);
}
#ifdef CONFIG_BOOKE_WDT
/* Checks wdt=x and wdt_period=xx command-line option */
int __init early_parse_wdt(char *p)
{
if (p && strncmp(p, "0", 1) != 0)
booke_wdt_enabled = 1;
return 0;
}
early_param("wdt", early_parse_wdt);
int __init early_parse_wdt_period (char *p)
{
if (p)
booke_wdt_period = simple_strtoul(p, NULL, 0);
return 0;
}
early_param("wdt_period", early_parse_wdt_period);
#endif /* CONFIG_BOOKE_WDT */
/* Checks "l2cr=xxxx" command-line option */
int __init ppc_setup_l2cr(char *str)
{
if (cpu_has_feature(CPU_FTR_L2CR)) {
unsigned long val = simple_strtoul(str, NULL, 0);
printk(KERN_INFO "l2cr set to %lx\n", val);
_set_L2CR(0); /* force invalidate by disable cache */
_set_L2CR(val); /* and enable it */
}
return 1;
}
__setup("l2cr=", ppc_setup_l2cr);
#ifdef CONFIG_GENERIC_NVRAM
/* Generic nvram hooks used by drivers/char/gen_nvram.c */
unsigned char nvram_read_byte(int addr)
{
if (ppc_md.nvram_read_val)
return ppc_md.nvram_read_val(addr);
return 0xff;
}
EXPORT_SYMBOL(nvram_read_byte);
void nvram_write_byte(unsigned char val, int addr)
{
if (ppc_md.nvram_write_val)
ppc_md.nvram_write_val(addr, val);
}
EXPORT_SYMBOL(nvram_write_byte);
void nvram_sync(void)
{
if (ppc_md.nvram_sync)
ppc_md.nvram_sync();
}
EXPORT_SYMBOL(nvram_sync);
#endif /* CONFIG_NVRAM */
static struct cpu cpu_devices[NR_CPUS];
int __init ppc_init(void)
{
int i;
/* clear the progress line */
if ( ppc_md.progress ) ppc_md.progress(" ", 0xffff);
/* register CPU devices */
for_each_possible_cpu(i)
register_cpu(&cpu_devices[i], i);
/* call platform init */
if (ppc_md.init != NULL) {
ppc_md.init();
}
return 0;
}
arch_initcall(ppc_init);
/* Warning, IO base is not yet inited */
void __init setup_arch(char **cmdline_p)
{
*cmdline_p = cmd_line;
/* so udelay does something sensible, assume <= 1000 bogomips */
loops_per_jiffy = 500000000 / HZ;
unflatten_device_tree();
check_for_initrd();
if (ppc_md.init_early)
ppc_md.init_early();
find_legacy_serial_ports();
smp_setup_cpu_maps();
/* Register early console */
register_early_udbg_console();
xmon_setup();
#if defined(CONFIG_KGDB)
if (ppc_md.kgdb_map_scc)
ppc_md.kgdb_map_scc();
set_debug_traps();
if (strstr(cmd_line, "gdb")) {
if (ppc_md.progress)
ppc_md.progress("setup_arch: kgdb breakpoint", 0x4000);
printk("kgdb breakpoint activated\n");
breakpoint();
}
#endif
/*
* Set cache line size based on type of cpu as a default.
* Systems with OF can look in the properties on the cpu node(s)
* for a possibly more accurate value.
*/
if (cpu_has_feature(CPU_FTR_SPLIT_ID_CACHE)) {
dcache_bsize = cur_cpu_spec->dcache_bsize;
icache_bsize = cur_cpu_spec->icache_bsize;
ucache_bsize = 0;
} else
ucache_bsize = dcache_bsize = icache_bsize
= cur_cpu_spec->dcache_bsize;
/* reboot on panic */
panic_timeout = 180;
if (ppc_md.panic)
setup_panic();
init_mm.start_code = PAGE_OFFSET;
init_mm.end_code = (unsigned long) _etext;
init_mm.end_data = (unsigned long) _edata;
init_mm.brk = klimit;
/* set up the bootmem stuff with available memory */
do_init_bootmem();
if ( ppc_md.progress ) ppc_md.progress("setup_arch: bootmem", 0x3eab);
#ifdef CONFIG_DUMMY_CONSOLE
conswitchp = &dummy_con;
#endif
ppc_md.setup_arch();
if ( ppc_md.progress ) ppc_md.progress("arch: exit", 0x3eab);
paging_init();
}
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