path: root/arch/mips/mm/tlbex.c

/*
 * 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.
 *
 * Synthesize TLB refill handlers at runtime.
 *
 * Copyright (C) 2004, 2005, 2006, 2008  Thiemo Seufer
 * Copyright (C) 2005, 2007  Maciej W. Rozycki
 * Copyright (C) 2006  Ralf Baechle (ralf@linux-mips.org)
 *
 * ... and the days got worse and worse and now you see
 * I've gone completly out of my mind.
 *
 * They're coming to take me a away haha
 * they're coming to take me a away hoho hihi haha
 * to the funny farm where code is beautiful all the time ...
 *
 * (Condolences to Napoleon XIV)
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/init.h>

#include <asm/mmu_context.h>
#include <asm/war.h>

#include "uasm.h"

static inline int r45k_bvahwbug(void)
{
	/* XXX: We should probe for the presence of this bug, but we don't. */
	return 0;
}

static inline int r4k_250MHZhwbug(void)
{
	/* XXX: We should probe for the presence of this bug, but we don't. */
	return 0;
}

static inline int __maybe_unused bcm1250_m3_war(void)
{
	return BCM1250_M3_WAR;
}

static inline int __maybe_unused r10000_llsc_war(void)
{
	return R10000_LLSC_WAR;
}

/*
 * Found by experiment: At least some revisions of the 4kc throw under
 * some circumstances a machine check exception, triggered by invalid
 * values in the index register.  Delaying the tlbp instruction until
 * after the next branch,  plus adding an additional nop in front of
 * tlbwi/tlbwr avoids the invalid index register values. Nobody knows
 * why; it's not an issue caused by the core RTL.
 *
 */
static int __cpuinit m4kc_tlbp_war(void)
{
	return (current_cpu_data.processor_id & 0xffff00) ==
	       (PRID_COMP_MIPS | PRID_IMP_4KC);
}

/* Handle labels (which must be positive integers). */
enum label_id {
	label_second_part = 1,
	label_leave,
#ifdef MODULE_START
	label_module_alloc,
#endif
	label_vmalloc,
	label_vmalloc_done,
	label_tlbw_hazard,
	label_split,
	label_nopage_tlbl,
	label_nopage_tlbs,
	label_nopage_tlbm,
	label_smp_pgtable_change,
	label_r3000_write_probe_fail,
};

UASM_L_LA(_second_part)
UASM_L_LA(_leave)
#ifdef MODULE_START
UASM_L_LA(_module_alloc)
#endif
UASM_L_LA(_vmalloc)
UASM_L_LA(_vmalloc_done)
UASM_L_LA(_tlbw_hazard)
UASM_L_LA(_split)
UASM_L_LA(_nopage_tlbl)
UASM_L_LA(_nopage_tlbs)
UASM_L_LA(_nopage_tlbm)
UASM_L_LA(_smp_pgtable_change)
UASM_L_LA(_r3000_write_probe_fail)

/*
 * For debug purposes.
 */
static inline void dump_handler(const u32 *handler, int count)
{
	int i;

	pr_debug("\t.set push\n");
	pr_debug("\t.set noreorder\n");

	for (i = 0; i < count; i++)
		pr_debug("\t%p\t.word 0x%08x\n", &handler[i], handler[i]);

	pr_debug("\t.set pop\n");
}

/* The only general purpose registers allowed in TLB handlers. */
#define K0		26
#define K1		27

/* Some CP0 registers */
#define C0_INDEX	0, 0
#define C0_ENTRYLO0	2, 0
#define C0_TCBIND	2, 2
#define C0_ENTRYLO1	3, 0
#define C0_CONTEXT	4, 0
#define C0_BADVADDR	8, 0
#define C0_ENTRYHI	10, 0
#define C0_EPC		14, 0
#define C0_XCONTEXT	20, 0

#ifdef CONFIG_64BIT
# define GET_CONTEXT(buf, reg) UASM_i_MFC0(buf, reg, C0_XCONTEXT)
#else
# define GET_CONTEXT(buf, reg) UASM_i_MFC0(buf, reg, C0_CONTEXT)
#endif

/* The worst case length of the handler is around 18 instructions for
 * R3000-style TLBs and up to 63 instructions for R4000-style TLBs.
 * Maximum space available is 32 instructions for R3000 and 64
 * instructions for R4000.
 *
 * We deliberately chose a buffer size of 128, so we won't scribble
 * over anything important on overflow before we panic.
 */
static u3