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linux-2.6/arch/mips/mm/pg-r4k.c
Maciej W. Rozycki 619b6e18fc [MIPS] R4000/R4400 daddiu erratum workaround 
This complements the generic R4000/R4400 errata workaround code and adds 
bits for the daddiu problem.  In most places it just modifies handwritten 
assembly code so that the assembler is allowed to use a temporary register 
as daddiu may now be treated as a macro that expands to a sequence of li 
and daddu.  It is the AT register or, where AT is unavailable or used 
explicitly for another purpose, an explicitly-named register is selected, 
using the .set at=<reg> feature added recently to gas.  This feature is 
only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the 
workaround remains disabled, the required version of binutils stays 
unchanged.

 Similarly, daddiu instructions put in branch delay slots in noreorder 
fragments are now taken out of them and the assembler is allowed to 
reorder them itself as possible (which it does making the whole idea of 
scheduling them into delay slots manually questionable).

 Also in the very few places where such a simple conversion was not 
possible, a handcoded longer sequence is implemented.

 Other than that there are changes to code responsible for building the 
TLB fault and page clear/copy handlers to avoid daddiu as appropriate.  
These are only effective if the erratum is verified to be present at the 
run time.

 Finally there is a trivial update to __delay(), because it uses daddiu in 
a branch delay slot.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-01-29 10:14:55 +00:00

535 lines
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C
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2003, 04, 05 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 2007 Maciej W. Rozycki
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <asm/bugs.h>
#include <asm/cacheops.h>
#include <asm/inst.h>
#include <asm/io.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/prefetch.h>
#include <asm/system.h>
#include <asm/bootinfo.h>
#include <asm/mipsregs.h>
#include <asm/mmu_context.h>
#include <asm/cpu.h>
#include <asm/war.h>
#define half_scache_line_size() (cpu_scache_line_size() >> 1)
#define cpu_is_r4600_v1_x() ((read_c0_prid() & 0xfffffff0) == 0x00002010)
#define cpu_is_r4600_v2_x() ((read_c0_prid() & 0xfffffff0) == 0x00002020)
/*
* Maximum sizes:
*
* R4000 128 bytes S-cache: 0x58 bytes
* R4600 v1.7: 0x5c bytes
* R4600 v2.0: 0x60 bytes
* With prefetching, 16 byte strides 0xa0 bytes
*/
static unsigned int clear_page_array[0x130 / 4];
void clear_page(void * page) __attribute__((alias("clear_page_array")));
EXPORT_SYMBOL(clear_page);
/*
* Maximum sizes:
*
* R4000 128 bytes S-cache: 0x11c bytes
* R4600 v1.7: 0x080 bytes
* R4600 v2.0: 0x07c bytes
* With prefetching, 16 byte strides 0x0b8 bytes
*/
static unsigned int copy_page_array[0x148 / 4];
void copy_page(void *to, void *from) __attribute__((alias("copy_page_array")));
EXPORT_SYMBOL(copy_page);
/*
* This is suboptimal for 32-bit kernels; we assume that R10000 is only used
* with 64-bit kernels. The prefetch offsets have been experimentally tuned
* an Origin 200.
*/
static int pref_offset_clear __initdata = 512;
static int pref_offset_copy __initdata = 256;
static unsigned int pref_src_mode __initdata;
static unsigned int pref_dst_mode __initdata;
static int load_offset __initdata;
static int store_offset __initdata;
static unsigned int __initdata *dest, *epc;
static unsigned int instruction_pending;
static union mips_instruction delayed_mi;
static void __init emit_instruction(union mips_instruction mi)
{
if (instruction_pending)
*epc++ = delayed_mi.word;
instruction_pending = 1;
delayed_mi = mi;
}
static inline void flush_delay_slot_or_nop(void)
{
if (instruction_pending) {
*epc++ = delayed_mi.word;
instruction_pending = 0;
return;
}
*epc++ = 0;
}
static inline unsigned int *label(void)
{
if (instruction_pending) {
*epc++ = delayed_mi.word;
instruction_pending = 0;
}
return epc;
}
static inline void build_insn_word(unsigned int word)
{
union mips_instruction mi;
mi.word = word;
emit_instruction(mi);
}
static inline void build_nop(void)
{
build_insn_word(0); /* nop */
}
static inline void build_src_pref(int advance)
{
if (!(load_offset & (cpu_dcache_line_size() - 1)) && advance) {
union mips_instruction mi;
mi.i_format.opcode = pref_op;
mi.i_format.rs = 5; /* $a1 */
mi.i_format.rt = pref_src_mode;
mi.i_format.simmediate = load_offset + advance;
emit_instruction(mi);
}
}
static inline void __build_load_reg(int reg)
{
union mips_instruction mi;
unsigned int width;
if (cpu_has_64bit_gp_regs) {
mi.i_format.opcode = ld_op;
width = 8;
} else {
mi.i_format.opcode = lw_op;
width = 4;
}
mi.i_format.rs = 5; /* $a1 */
mi.i_format.rt = reg; /* $reg */
mi.i_format.simmediate = load_offset;
load_offset += width;
emit_instruction(mi);
}
static inline void build_load_reg(int reg)
{
if (cpu_has_prefetch)
build_src_pref(pref_offset_copy);
__build_load_reg(reg);
}
static inline void build_dst_pref(int advance)
{
if (!(store_offset & (cpu_dcache_line_size() - 1)) && advance) {
union mips_instruction mi;
mi.i_format.opcode = pref_op;
mi.i_format.rs = 4; /* $a0 */
mi.i_format.rt = pref_dst_mode;
mi.i_format.simmediate = store_offset + advance;
emit_instruction(mi);
}
}
static inline void build_cdex_s(void)
{
union mips_instruction mi;
if ((store_offset & (cpu_scache_line_size() - 1)))
return;
mi.c_format.opcode = cache_op;
mi.c_format.rs = 4; /* $a0 */
mi.c_format.c_op = 3; /* Create Dirty Exclusive */
mi.c_format.cache = 3; /* Secondary Data Cache */
mi.c_format.simmediate = store_offset;
emit_instruction(mi);
}
static inline void build_cdex_p(void)
{
union mips_instruction mi;
if (store_offset & (cpu_dcache_line_size() - 1))
return;
if (R4600_V1_HIT_CACHEOP_WAR && cpu_is_r4600_v1_x()) {
build_nop();
build_nop();
build_nop();
build_nop();
}
if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
build_insn_word(0x8c200000); /* lw $zero, ($at) */
mi.c_format.opcode = cache_op;
mi.c_format.rs = 4; /* $a0 */
mi.c_format.c_op = 3; /* Create Dirty Exclusive */
mi.c_format.cache = 1; /* Data Cache */
mi.c_format.simmediate = store_offset;
emit_instruction(mi);
}
static void __init __build_store_reg(int reg)
{
union mips_instruction mi;
unsigned int width;
if (cpu_has_64bit_gp_regs ||
(cpu_has_64bit_zero_reg && reg == 0)) {
mi.i_format.opcode = sd_op;
width = 8;
} else {
mi.i_format.opcode = sw_op;
width = 4;
}
mi.i_format.rs = 4; /* $a0 */
mi.i_format.rt = reg; /* $reg */
mi.i_format.simmediate = store_offset;
store_offset += width;
emit_instruction(mi);
}
static inline void build_store_reg(int reg)
{
int pref_off = cpu_has_prefetch ?
(reg ? pref_offset_copy : pref_offset_clear) : 0;
if (pref_off)
build_dst_pref(pref_off);
else if (cpu_has_cache_cdex_s)
build_cdex_s();
else if (cpu_has_cache_cdex_p)
build_cdex_p();
__build_store_reg(reg);
}
static inline void build_addiu_rt_rs(unsigned int rt, unsigned int rs,
unsigned long offset)
{
union mips_instruction mi;
BUG_ON(offset > 0x7fff);
if (cpu_has_64bit_gp_regs && DADDI_WAR && r4k_daddiu_bug()) {
mi.i_format.opcode = addiu_op;
mi.i_format.rs = 0; /* $zero */
mi.i_format.rt = 25; /* $t9 */
mi.i_format.simmediate = offset;
emit_instruction(mi);
mi.r_format.opcode = spec_op;
mi.r_format.rs = rs;
mi.r_format.rt = 25; /* $t9 */
mi.r_format.rd = rt;
mi.r_format.re = 0;
mi.r_format.func = daddu_op;
} else {
mi.i_format.opcode = cpu_has_64bit_gp_regs ?
daddiu_op : addiu_op;
mi.i_format.rs = rs;
mi.i_format.rt = rt;
mi.i_format.simmediate = offset;
}
emit_instruction(mi);
}
static inline void build_addiu_a2_a0(unsigned long offset)
{
build_addiu_rt_rs(6, 4, offset); /* $a2, $a0, offset */
}
static inline void build_addiu_a2(unsigned long offset)
{
build_addiu_rt_rs(6, 6, offset); /* $a2, $a2, offset */
}
static inline void build_addiu_a1(unsigned long offset)
{
build_addiu_rt_rs(5, 5, offset); /* $a1, $a1, offset */
load_offset -= offset;
}
static inline void build_addiu_a0(unsigned long offset)
{
build_addiu_rt_rs(4, 4, offset); /* $a0, $a0, offset */
store_offset -= offset;
}
static inline void build_bne(unsigned int *dest)
{
union mips_instruction mi;
mi.i_format.opcode = bne_op;
mi.i_format.rs = 6; /* $a2 */
mi.i_format.rt = 4; /* $a0 */
mi.i_format.simmediate = dest - epc - 1;
*epc++ = mi.word;
flush_delay_slot_or_nop();
}
static inline void build_jr_ra(void)
{
union mips_instruction mi;
mi.r_format.opcode = spec_op;
mi.r_format.rs = 31;
mi.r_format.rt = 0;
mi.r_format.rd = 0;
mi.r_format.re = 0;
mi.r_format.func = jr_op;
*epc++ = mi.word;
flush_delay_slot_or_nop();
}
void __init build_clear_page(void)
{
unsigned int loop_start;
unsigned long off;
int i;
epc = (unsigned int *) &clear_page_array;
instruction_pending = 0;
store_offset = 0;
if (cpu_has_prefetch) {
switch (current_cpu_type()) {
case CPU_TX49XX:
/* TX49 supports only Pref_Load */
pref_offset_clear = 0;
pref_offset_copy = 0;
break;
case CPU_RM9000:
/*
* As a workaround for erratum G105 which make the
* PrepareForStore hint unusable we fall back to
* StoreRetained on the RM9000. Once it is known which
* versions of the RM9000 we'll be able to condition-
* alize this.
*/
case CPU_R10000:
case CPU_R12000:
case CPU_R14000:
pref_src_mode = Pref_LoadStreamed;
pref_dst_mode = Pref_StoreStreamed;
break;
default:
pref_src_mode = Pref_LoadStreamed;
pref_dst_mode = Pref_PrepareForStore;
break;
}
}
off = PAGE_SIZE - (cpu_has_prefetch ? pref_offset_clear : 0);
if (off > 0x7fff) {
build_addiu_a2_a0(off >> 1);
build_addiu_a2(off >> 1);
} else
build_addiu_a2_a0(off);
if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
build_insn_word(0x3c01a000); /* lui $at, 0xa000 */
dest = label();
do {
build_store_reg(0);
build_store_reg(0);
build_store_reg(0);
build_store_reg(0);
} while (store_offset < half_scache_line_size());
build_addiu_a0(2 * store_offset);
loop_start = store_offset;
do {
build_store_reg(0);
build_store_reg(0);
build_store_reg(0);
build_store_reg(0);
} while ((store_offset - loop_start) < half_scache_line_size());
build_bne(dest);
if (cpu_has_prefetch && pref_offset_clear) {
build_addiu_a2_a0(pref_offset_clear);
dest = label();
loop_start = store_offset;
do {
__build_store_reg(0);
__build_store_reg(0);
__build_store_reg(0);
__build_store_reg(0);
} while ((store_offset - loop_start) < half_scache_line_size());
build_addiu_a0(2 * store_offset);
loop_start = store_offset;
do {
__build_store_reg(0);
__build_store_reg(0);
__build_store_reg(0);
__build_store_reg(0);
} while ((store_offset - loop_start) < half_scache_line_size());
build_bne(dest);
}
build_jr_ra();
BUG_ON(epc > clear_page_array + ARRAY_SIZE(clear_page_array));
pr_info("Synthesized clear page handler (%u instructions).\n",
(unsigned int)(epc - clear_page_array));
pr_debug("\t.set push\n");
pr_debug("\t.set noreorder\n");
for (i = 0; i < (epc - clear_page_array); i++)
pr_debug("\t.word 0x%08x\n", clear_page_array[i]);
pr_debug("\t.set pop\n");
}
void __init build_copy_page(void)
{
unsigned int loop_start;
unsigned long off;
int i;
epc = (unsigned int *) &copy_page_array;
store_offset = load_offset = 0;
instruction_pending = 0;
off = PAGE_SIZE - (cpu_has_prefetch ? pref_offset_copy : 0);
if (off > 0x7fff) {
build_addiu_a2_a0(off >> 1);
build_addiu_a2(off >> 1);
} else
build_addiu_a2_a0(off);
if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
build_insn_word(0x3c01a000); /* lui $at, 0xa000 */
dest = label();
loop_start = store_offset;
do {
build_load_reg( 8);
build_load_reg( 9);
build_load_reg(10);
build_load_reg(11);
build_store_reg( 8);
build_store_reg( 9);
build_store_reg(10);
build_store_reg(11);
} while ((store_offset - loop_start) < half_scache_line_size());
build_addiu_a0(2 * store_offset);
build_addiu_a1(2 * load_offset);
loop_start = store_offset;
do {
build_load_reg( 8);
build_load_reg( 9);
build_load_reg(10);
build_load_reg(11);
build_store_reg( 8);
build_store_reg( 9);
build_store_reg(10);
build_store_reg(11);
} while ((store_offset - loop_start) < half_scache_line_size());
build_bne(dest);
if (cpu_has_prefetch && pref_offset_copy) {
build_addiu_a2_a0(pref_offset_copy);
dest = label();
loop_start = store_offset;
do {
__build_load_reg( 8);
__build_load_reg( 9);
__build_load_reg(10);
__build_load_reg(11);
__build_store_reg( 8);
__build_store_reg( 9);
__build_store_reg(10);
__build_store_reg(11);
} while ((store_offset - loop_start) < half_scache_line_size());
build_addiu_a0(2 * store_offset);
build_addiu_a1(2 * load_offset);
loop_start = store_offset;
do {
__build_load_reg( 8);
__build_load_reg( 9);
__build_load_reg(10);
__build_load_reg(11);
__build_store_reg( 8);
__build_store_reg( 9);
__build_store_reg(10);
__build_store_reg(11);
} while ((store_offset - loop_start) < half_scache_line_size());
build_bne(dest);
}
build_jr_ra();
BUG_ON(epc > copy_page_array + ARRAY_SIZE(copy_page_array));
pr_info("Synthesized copy page handler (%u instructions).\n",
(unsigned int)(epc - copy_page_array));
pr_debug("\t.set push\n");
pr_debug("\t.set noreorder\n");
for (i = 0; i < (epc - copy_page_array); i++)
pr_debug("\t.word 0x%08x\n", copy_page_array[i]);
pr_debug("\t.set pop\n");
}
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