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linux/arch/sparc64/kernel/head.S
David S. Miller 56fb4df6da [SPARC64]: Elminate all usage of hard-coded trap globals. 
UltraSPARC has special sets of global registers which are switched to
for certain trap types.  There is one set for MMU related traps, one
set of Interrupt Vector processing, and another set (called the
Alternate globals) for all other trap types.

For what seems like forever we've hard coded the values in some of
these trap registers.  Some examples include:

1) Interrupt Vector global %g6 holds current processors interrupt
   work struct where received interrupts are managed for IRQ handler
   dispatch.

2) MMU global %g7 holds the base of the page tables of the currently
   active address space.

3) Alternate global %g6 held the current_thread_info() value.

Such hardcoding has resulted in some serious issues in many areas.
There are some code sequences where having another register available
would help clean up the implementation.  Taking traps such as
cross-calls from the OBP firmware requires some trick code sequences
wherein we have to save away and restore all of the special sets of
global registers when we enter/exit OBP.

We were also using the IMMU TSB register on SMP to hold the per-cpu
area base address, which doesn't work any longer now that we actually
use the TSB facility of the cpu.

The implementation is pretty straight forward.  One tricky bit is
getting the current processor ID as that is different on different cpu
variants.  We use a stub with a fancy calling convention which we
patch at boot time.  The calling convention is that the stub is
branched to and the (PC - 4) to return to is in register %g1.  The cpu
number is left in %g6.  This stub can be invoked by using the
__GET_CPUID macro.

We use an array of per-cpu trap state to store the current thread and
physical address of the current address space's page tables.  The
TRAP_LOAD_THREAD_REG loads %g6 with the current thread from this
table, it uses __GET_CPUID and also clobbers %g1.

TRAP_LOAD_IRQ_WORK is used by the interrupt vector processing to load
the current processor's IRQ software state into %g6.  It also uses
__GET_CPUID and clobbers %g1.

Finally, TRAP_LOAD_PGD_PHYS loads the physical address base of the
current address space's page tables into %g7, it clobbers %g1 and uses
__GET_CPUID.

Many refinements are possible, as well as some tuning, with this stuff
in place.

Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 01:11:16 -08:00

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/* $Id: head.S,v 1.87 2002/02/09 19:49:31 davem Exp $
* head.S: Initial boot code for the Sparc64 port of Linux.
*
* Copyright (C) 1996,1997 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1996 David Sitsky (David.Sitsky@anu.edu.au)
* Copyright (C) 1997,1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
* Copyright (C) 1997 Miguel de Icaza (miguel@nuclecu.unam.mx)
*/
#include <linux/config.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <asm/thread_info.h>
#include <asm/asi.h>
#include <asm/pstate.h>
#include <asm/ptrace.h>
#include <asm/spitfire.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/errno.h>
#include <asm/signal.h>
#include <asm/processor.h>
#include <asm/lsu.h>
#include <asm/dcr.h>
#include <asm/dcu.h>
#include <asm/head.h>
#include <asm/ttable.h>
#include <asm/mmu.h>
#include <asm/cpudata.h>
/* This section from from _start to sparc64_boot_end should fit into
* 0x0000000000404000 to 0x0000000000408000.
*/
.text
.globl start, _start, stext, _stext
_start:
start:
_stext:
stext:
! 0x0000000000404000
b sparc64_boot
flushw /* Flush register file. */
/* This stuff has to be in sync with SILO and other potential boot loaders
* Fields should be kept upward compatible and whenever any change is made,
* HdrS version should be incremented.
*/
.global root_flags, ram_flags, root_dev
.global sparc_ramdisk_image, sparc_ramdisk_size
.global sparc_ramdisk_image64
.ascii "HdrS"
.word LINUX_VERSION_CODE
/* History:
*
* 0x0300 : Supports being located at other than 0x4000
* 0x0202 : Supports kernel params string
* 0x0201 : Supports reboot_command
*/
.half 0x0301 /* HdrS version */
root_flags:
.half 1
root_dev:
.half 0
ram_flags:
.half 0
sparc_ramdisk_image:
.word 0
sparc_ramdisk_size:
.word 0
.xword reboot_command
.xword bootstr_info
sparc_ramdisk_image64:
.xword 0
.word _end
/* PROM cif handler code address is in %o4. */
sparc64_boot:
1: rd %pc, %g7
set 1b, %g1
cmp %g1, %g7
be,pn %xcc, sparc64_boot_after_remap
mov %o4, %l7
/* We need to remap the kernel. Use position independant
* code to remap us to KERNBASE.
*
* SILO can invoke us with 32-bit address masking enabled,
* so make sure that's clear.
*/
rdpr %pstate, %g1
andn %g1, PSTATE_AM, %g1
wrpr %g1, 0x0, %pstate
ba,a,pt %xcc, 1f
.globl prom_finddev_name, prom_chosen_path
.globl prom_getprop_name, prom_mmu_name
.globl prom_callmethod_name, prom_translate_name
.globl prom_map_name, prom_unmap_name, prom_mmu_ihandle_cache
.globl prom_boot_mapped_pc, prom_boot_mapping_mode
.globl prom_boot_mapping_phys_high, prom_boot_mapping_phys_low
prom_finddev_name:
.asciz "finddevice"
prom_chosen_path:
.asciz "/chosen"
prom_getprop_name:
.asciz "getprop"
prom_mmu_name:
.asciz "mmu"
prom_callmethod_name:
.asciz "call-method"
prom_translate_name:
.asciz "translate"
prom_map_name:
.asciz "map"
prom_unmap_name:
.asciz "unmap"
.align 4
prom_mmu_ihandle_cache:
.word 0
prom_boot_mapped_pc:
.word 0
prom_boot_mapping_mode:
.word 0
.align 8
prom_boot_mapping_phys_high:
.xword 0
prom_boot_mapping_phys_low:
.xword 0
1:
rd %pc, %l0
mov (1b - prom_finddev_name), %l1
mov (1b - prom_chosen_path), %l2
mov (1b - prom_boot_mapped_pc), %l3
sub %l0, %l1, %l1
sub %l0, %l2, %l2
sub %l0, %l3, %l3
stw %l0, [%l3]
sub %sp, (192 + 128), %sp
/* chosen_node = prom_finddevice("/chosen") */
stx %l1, [%sp + 2047 + 128 + 0x00] ! service, "finddevice"
mov 1, %l3
stx %l3, [%sp + 2047 + 128 + 0x08] ! num_args, 1
stx %l3, [%sp + 2047 + 128 + 0x10] ! num_rets, 1
stx %l2, [%sp + 2047 + 128 + 0x18] ! arg1, "/chosen"
stx %g0, [%sp + 2047 + 128 + 0x20] ! ret1
call %l7
add %sp, (2047 + 128), %o0 ! argument array
ldx [%sp + 2047 + 128 + 0x20], %l4 ! chosen device node
mov (1b - prom_getprop_name), %l1
mov (1b - prom_mmu_name), %l2
mov (1b - prom_mmu_ihandle_cache), %l5
sub %l0, %l1, %l1
sub %l0, %l2, %l2
sub %l0, %l5, %l5
/* prom_mmu_ihandle_cache = prom_getint(chosen_node, "mmu") */
stx %l1, [%sp + 2047 + 128 + 0x00] ! service, "getprop"
mov 4, %l3
stx %l3, [%sp + 2047 + 128 + 0x08] ! num_args, 4
mov 1, %l3
stx %l3, [%sp + 2047 + 128 + 0x10] ! num_rets, 1
stx %l4, [%sp + 2047 + 128 + 0x18] ! arg1, chosen_node
stx %l2, [%sp + 2047 + 128 + 0x20] ! arg2, "mmu"
stx %l5, [%sp + 2047 + 128 + 0x28] ! arg3, &prom_mmu_ihandle_cache
mov 4, %l3
stx %l3, [%sp + 2047 + 128 + 0x30] ! arg4, sizeof(arg3)
stx %g0, [%sp + 2047 + 128 + 0x38] ! ret1
call %l7
add %sp, (2047 + 128), %o0 ! argument array
mov (1b - prom_callmethod_name), %l1
mov (1b - prom_translate_name), %l2
sub %l0, %l1, %l1
sub %l0, %l2, %l2
lduw [%l5], %l5 ! prom_mmu_ihandle_cache
stx %l1, [%sp + 2047 + 128 + 0x00] ! service, "call-method"
mov 3, %l3
stx %l3, [%sp + 2047 + 128 + 0x08] ! num_args, 3
mov 5, %l3
stx %l3, [%sp + 2047 + 128 + 0x10] ! num_rets, 5
stx %l2, [%sp + 2047 + 128 + 0x18] ! arg1: "translate"
stx %l5, [%sp + 2047 + 128 + 0x20] ! arg2: prom_mmu_ihandle_cache
/* PAGE align */
srlx %l0, 13, %l3
sllx %l3, 13, %l3
stx %l3, [%sp + 2047 + 128 + 0x28] ! arg3: vaddr, our PC
stx %g0, [%sp + 2047 + 128 + 0x30] ! res1
stx %g0, [%sp + 2047 + 128 + 0x38] ! res2
stx %g0, [%sp + 2047 + 128 + 0x40] ! res3
stx %g0, [%sp + 2047 + 128 + 0x48] ! res4
stx %g0, [%sp + 2047 + 128 + 0x50] ! res5
call %l7
add %sp, (2047 + 128), %o0 ! argument array
ldx [%sp + 2047 + 128 + 0x40], %l1 ! translation mode
mov (1b - prom_boot_mapping_mode), %l4
sub %l0, %l4, %l4
stw %l1, [%l4]
mov (1b - prom_boot_mapping_phys_high), %l4
sub %l0, %l4, %l4
ldx [%sp + 2047 + 128 + 0x48], %l2 ! physaddr high
stx %l2, [%l4 + 0x0]
ldx [%sp + 2047 + 128 + 0x50], %l3 ! physaddr low
/* 4MB align */
srlx %l3, 22, %l3
sllx %l3, 22, %l3
stx %l3, [%l4 + 0x8]
/* Leave service as-is, "call-method" */
mov 7, %l3
stx %l3, [%sp + 2047 + 128 + 0x08] ! num_args, 7
mov 1, %l3
stx %l3, [%sp + 2047 + 128 + 0x10] ! num_rets, 1
mov (1b - prom_map_name), %l3
sub %l0, %l3, %l3
stx %l3, [%sp + 2047 + 128 + 0x18] ! arg1: "map"
/* Leave arg2 as-is, prom_mmu_ihandle_cache */
mov -1, %l3
stx %l3, [%sp + 2047 + 128 + 0x28] ! arg3: mode (-1 default)
sethi %hi(8 * 1024 * 1024), %l3
stx %l3, [%sp + 2047 + 128 + 0x30] ! arg4: size (8MB)
sethi %hi(KERNBASE), %l3
stx %l3, [%sp + 2047 + 128 + 0x38] ! arg5: vaddr (KERNBASE)
stx %g0, [%sp + 2047 + 128 + 0x40] ! arg6: empty
mov (1b - prom_boot_mapping_phys_low), %l3
sub %l0, %l3, %l3
ldx [%l3], %l3
stx %l3, [%sp + 2047 + 128 + 0x48] ! arg7: phys addr
call %l7
add %sp, (2047 + 128), %o0 ! argument array
add %sp, (192 + 128), %sp
sparc64_boot_after_remap:
BRANCH_IF_CHEETAH_BASE(g1,g7,cheetah_boot)
BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,g7,cheetah_plus_boot)
ba,pt %xcc, spitfire_boot
nop
cheetah_plus_boot:
/* Preserve OBP chosen DCU and DCR register settings. */
ba,pt %xcc, cheetah_generic_boot
nop
cheetah_boot:
mov DCR_BPE | DCR_RPE | DCR_SI | DCR_IFPOE | DCR_MS, %g1
wr %g1, %asr18
sethi %uhi(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g7
or %g7, %ulo(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g7
sllx %g7, 32, %g7
or %g7, DCU_DM | DCU_IM | DCU_DC | DCU_IC, %g7
stxa %g7, [%g0] ASI_DCU_CONTROL_REG
membar #Sync
cheetah_generic_boot:
mov TSB_EXTENSION_P, %g3
stxa %g0, [%g3] ASI_DMMU
stxa %g0, [%g3] ASI_IMMU
membar #Sync
mov TSB_EXTENSION_S, %g3
stxa %g0, [%g3] ASI_DMMU
membar #Sync
mov TSB_EXTENSION_N, %g3
stxa %g0, [%g3] ASI_DMMU
stxa %g0, [%g3] ASI_IMMU
membar #Sync
ba,a,pt %xcc, jump_to_sun4u_init
spitfire_boot:
/* Typically PROM has already enabled both MMU's and both on-chip
* caches, but we do it here anyway just to be paranoid.
*/
mov (LSU_CONTROL_IC|LSU_CONTROL_DC|LSU_CONTROL_IM|LSU_CONTROL_DM), %g1
stxa %g1, [%g0] ASI_LSU_CONTROL
membar #Sync
jump_to_sun4u_init:
/*
* Make sure we are in privileged mode, have address masking,
* using the ordinary globals and have enabled floating
* point.
*
* Again, typically PROM has left %pil at 13 or similar, and
* (PSTATE_PRIV | PSTATE_PEF | PSTATE_IE) in %pstate.
*/
wrpr %g0, (PSTATE_PRIV|PSTATE_PEF|PSTATE_IE), %pstate
wr %g0, 0, %fprs
set sun4u_init, %g2
jmpl %g2 + %g0, %g0
nop
sun4u_init:
/* Set ctx 0 */
mov PRIMARY_CONTEXT, %g7
stxa %g0, [%g7] ASI_DMMU
membar #Sync
mov SECONDARY_CONTEXT, %g7
stxa %g0, [%g7] ASI_DMMU
membar #Sync
BRANCH_IF_ANY_CHEETAH(g1,g7,cheetah_tlb_fixup)
ba,pt %xcc, spitfire_tlb_fixup
nop
cheetah_tlb_fixup:
mov 2, %g2 /* Set TLB type to cheetah+. */
BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,g7,1f)
mov 1, %g2 /* Set TLB type to cheetah. */
1: sethi %hi(tlb_type), %g1
stw %g2, [%g1 + %lo(tlb_type)]
/* Patch copy/page operations to cheetah optimized versions. */
call cheetah_patch_copyops
nop
call cheetah_patch_copy_page
nop
call cheetah_patch_cachetlbops
nop
ba,pt %xcc, tlb_fixup_done
nop
spitfire_tlb_fixup:
/* Set TLB type to spitfire. */
mov 0, %g2
sethi %hi(tlb_type), %g1
stw %g2, [%g1 + %lo(tlb_type)]
tlb_fixup_done:
sethi %hi(init_thread_union), %g6
or %g6, %lo(init_thread_union), %g6
ldx [%g6 + TI_TASK], %g4
mov %sp, %l6
mov %o4, %l7
wr %g0, ASI_P, %asi
mov 1, %g1
sllx %g1, THREAD_SHIFT, %g1
sub %g1, (STACKFRAME_SZ + STACK_BIAS), %g1
add %g6, %g1, %sp
mov 0, %fp
/* Set per-cpu pointer initially to zero, this makes
* the boot-cpu use the in-kernel-image per-cpu areas
* before setup_per_cpu_area() is invoked.
*/
clr %g5
wrpr %g0, 0, %wstate
wrpr %g0, 0x0, %tl
/* Clear the bss */
sethi %hi(__bss_start), %o0
or %o0, %lo(__bss_start), %o0
sethi %hi(_end), %o1
or %o1, %lo(_end), %o1
call __bzero
sub %o1, %o0, %o1
mov %l6, %o1 ! OpenPROM stack
call prom_init
mov %l7, %o0 ! OpenPROM cif handler
/* Off we go.... */
call start_kernel
nop
/* Not reached... */
/* This is meant to allow the sharing of this code between
* boot processor invocation (via setup_tba() below) and
* secondary processor startup (via trampoline.S). The
* former does use this code, the latter does not yet due
* to some complexities. That should be fixed up at some
* point.
*
* There used to be enormous complexity wrt. transferring
* over from the firwmare's trap table to the Linux kernel's.
* For example, there was a chicken & egg problem wrt. building
* the OBP page tables, yet needing to be on the Linux kernel
* trap table (to translate PAGE_OFFSET addresses) in order to
* do that.
*
* We now handle OBP tlb misses differently, via linear lookups
* into the prom_trans[] array. So that specific problem no
* longer exists. Yet, unfortunately there are still some issues
* preventing trampoline.S from using this code... ho hum.
*/
.globl setup_trap_table
setup_trap_table:
save %sp, -192, %sp
/* Force interrupts to be disabled. */
rdpr %pstate, %o1
andn %o1, PSTATE_IE, %o1
wrpr %o1, 0x0, %pstate
wrpr %g0, 15, %pil
/* Make the firmware call to jump over to the Linux trap table. */
call prom_set_trap_table
sethi %hi(sparc64_ttable_tl0), %o0
/* Start using proper page size encodings in ctx register. */
sethi %hi(sparc64_kern_pri_context), %g3
ldx [%g3 + %lo(sparc64_kern_pri_context)], %g2
mov PRIMARY_CONTEXT, %g1
stxa %g2, [%g1] ASI_DMMU
membar #Sync
/* Kill PROM timer */
sethi %hi(0x80000000), %o2
sllx %o2, 32, %o2
wr %o2, 0, %tick_cmpr
BRANCH_IF_ANY_CHEETAH(o2,o3,1f)
ba,pt %xcc, 2f
nop
/* Disable STICK_INT interrupts. */
1:
sethi %hi(0x80000000), %o2
sllx %o2, 32, %o2
wr %o2, %asr25
2:
wrpr %g0, %g0, %wstate
call init_irqwork_curcpu
nop
/* Now we can turn interrupts back on. */
rdpr %pstate, %o1
or %o1, PSTATE_IE, %o1
wrpr %o1, 0, %pstate
wrpr %g0, 0x0, %pil
ret
restore
.globl setup_tba
setup_tba: /* i0 = is_starfire */
save %sp, -192, %sp
/* The boot processor is the only cpu which invokes this
* routine, the other cpus set things up via trampoline.S.
* So save the OBP trap table address here.
*/
rdpr %tba, %g7
sethi %hi(prom_tba), %o1
or %o1, %lo(prom_tba), %o1
stx %g7, [%o1]
call setup_trap_table
nop
ret
restore
sparc64_boot_end:
#include "systbls.S"
#include "ktlb.S"
#include "tsb.S"
#include "etrap.S"
#include "rtrap.S"
#include "winfixup.S"
#include "entry.S"
/*
* The following skip makes sure the trap table in ttable.S is aligned
* on a 32K boundary as required by the v9 specs for TBA register.
*/
1:
.skip 0x4000 + _start - 1b
#ifdef CONFIG_SBUS
/* This is just a hack to fool make depend config.h discovering
strategy: As the .S files below need config.h, but
make depend does not find it for them, we include config.h
in head.S */
#endif
! 0x0000000000408000
#include "ttable.S"
.data
.align 8
.globl prom_tba, tlb_type
prom_tba: .xword 0
tlb_type: .word 0 /* Must NOT end up in BSS */
.section ".fixup",#alloc,#execinstr
.globl __ret_efault, __retl_efault
__ret_efault:
ret
restore %g0, -EFAULT, %o0
__retl_efault:
retl
mov -EFAULT, %o0
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