fault-armv.c

内核linux2.4.20,可跟rtlinux3.2打补丁 组成实时linux系统,编译内核

	newaddr += nr_regs;
	if (!LDST_U_BIT(instr))
		eaddr = newaddr;

	if (LDST_P_EQ_U(instr))	/* U = P */
		eaddr += 4;

	/*
	 * This is a "hint" - we already have eaddr worked out by the
	 * processor for us.
	 */
	if (addr != eaddr) {
		printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
			"addr = %08lx, eaddr = %08lx\n",
			 instruction_pointer(regs), instr, addr, eaddr);
		show_regs(regs);
	}

	for (regbits = REGMASK_BITS(instr), rd = 0; regbits; regbits >>= 1, rd += 1)
		if (regbits & 1) {
			if (LDST_L_BIT(instr))
				get32_unaligned_check(regs->uregs[rd], eaddr);
			else
				put32_unaligned_check(regs->uregs[rd], eaddr);
			eaddr += 4;
		}

	if (LDST_W_BIT(instr))
		regs->uregs[rn] = newaddr;
	if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
		regs->ARM_pc -= correction;
	return TYPE_DONE;

fault:
	regs->ARM_pc -= correction;
	return TYPE_FAULT;

bad:
	printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
	return TYPE_ERROR;
}

static int
do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
{
	union offset_union offset;
	unsigned long instr, instrptr;
	int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
	unsigned int type;

	if (user_mode(regs))
		goto user;

	ai_sys += 1;

	instrptr = instruction_pointer(regs);
	instr = *(unsigned long *)instrptr;

	regs->ARM_pc += 4;

	switch (CODING_BITS(instr)) {
	case 0x00000000:	/* ldrh or strh */
		if (LDSTH_I_BIT(instr))
			offset.un = (instr & 0xf00) >> 4 | (instr & 15);
		else
			offset.un = regs->uregs[RM_BITS(instr)];
		handler = do_alignment_ldrhstrh;
		break;

	case 0x04000000:	/* ldr or str immediate */
		offset.un = OFFSET_BITS(instr);
		handler = do_alignment_ldrstr;
		break;

	case 0x06000000:	/* ldr or str register */
		offset.un = regs->uregs[RM_BITS(instr)];

		if (IS_SHIFT(instr)) {
			unsigned int shiftval = SHIFT_BITS(instr);

			switch(SHIFT_TYPE(instr)) {
			case SHIFT_LSL:
				offset.un <<= shiftval;
				break;

			case SHIFT_LSR:
				offset.un >>= shiftval;
				break;

			case SHIFT_ASR:
				offset.sn >>= shiftval;
				break;

			case SHIFT_RORRRX:
				if (shiftval == 0) {
					offset.un >>= 1;
					if (regs->ARM_cpsr & CC_C_BIT)
						offset.un |= 1 << 31;
				} else
					offset.un = offset.un >> shiftval |
							  offset.un << (32 - shiftval);
				break;
			}
		}
		handler = do_alignment_ldrstr;
		break;

	case 0x08000000:	/* ldm or stm */
		handler = do_alignment_ldmstm;
		break;

	default:
		goto bad;
	}

	type = handler(addr, instr, regs);

	if (type == TYPE_ERROR || type == TYPE_FAULT)
		goto bad_or_fault;

	if (type == TYPE_LDST)
		do_alignment_finish_ldst(addr, instr, regs, offset);

	return 0;

bad_or_fault:
	if (type == TYPE_ERROR)
		goto bad;
	regs->ARM_pc -= 4;
	/*
	 * We got a fault - fix it up, or die.
	 */
	do_bad_area(current, current->mm, addr, error_code, regs);
	return 0;

bad:
	/*
	 * Oops, we didn't handle the instruction.
	 */
	printk(KERN_ERR "Alignment trap: not handling instruction "
		"%08lx at [<%08lx>]\n", instr, instrptr);
	ai_skipped += 1;
	return 1;

user:
	set_cr(cr_no_alignment);
	ai_user += 1;
	return 0;
}

#else

#define do_alignment NULL

#endif

/*
 * Some section permission faults need to be handled gracefully, for
 * instance, when they happen due to a __{get,put}_user during an oops).
 */
static int
do_sect_fault(unsigned long addr, int error_code, struct pt_regs *regs)
{
	struct task_struct *tsk = current;
	do_bad_area(tsk, tsk->active_mm, addr, error_code, regs);
	return 0;
}

/*
 * Hook for things that need to trap external faults.  Note that
 * we don't guarantee that this will be the final version of the
 * interface.
 */
int (*external_fault)(unsigned long addr, struct pt_regs *regs);

static int
do_external_fault(unsigned long addr, int error_code, struct pt_regs *regs)
{
	if (external_fault)
		return external_fault(addr, regs);
	return 1;
}

static const struct fsr_info {
	int	(*fn)(unsigned long addr, int error_code, struct pt_regs *regs);
	int	sig;
	char	*name;
} fsr_info[] = {
	{ NULL,			SIGSEGV, "vector exception"		   },
	{ do_alignment,		SIGILL,	 "alignment exception"		   },
	{ NULL,			SIGKILL, "terminal exception"		   },
	{ do_alignment,		SIGILL,	 "alignment exception"		   },
	{ do_external_fault,	SIGBUS,	 "external abort on linefetch"	   },
	{ do_translation_fault,	SIGSEGV, "section translation fault"	   },
	{ do_external_fault,	SIGBUS,	 "external abort on linefetch"	   },
	{ do_page_fault,	SIGSEGV, "page translation fault"	   },
	{ do_external_fault,	SIGBUS,	 "external abort on non-linefetch" },
	{ NULL,			SIGSEGV, "section domain fault"		   },
	{ do_external_fault,	SIGBUS,	 "external abort on non-linefetch" },
	{ NULL,			SIGSEGV, "page domain fault"		   },
	{ NULL,			SIGBUS,	 "external abort on translation"   },
	{ do_sect_fault,	SIGSEGV, "section permission fault"	   },
	{ NULL,			SIGBUS,	 "external abort on translation"   },
	{ do_page_fault,	SIGSEGV, "page permission fault"	   }
};

/*
 * Currently dropped down to debug level
 */
asmlinkage void
do_DataAbort(unsigned long addr, int error_code, struct pt_regs *regs, int fsr)
{
	const struct fsr_info *inf = fsr_info + (fsr & 15);

#if defined(CONFIG_CPU_SA110) || defined(CONFIG_CPU_SA1100) || defined(CONFIG_DEBUG_ERRORS)
	if (addr == regs->ARM_pc)
		goto sa1_weirdness;
#endif

	if (!inf->fn)
		goto bad;

	if (!inf->fn(addr, error_code, regs))
		return;
bad:
	printk(KERN_ALERT "Unhandled fault: %s (%X) at 0x%08lx\n",
		inf->name, fsr, addr);
	show_pte(current->mm, addr);
	force_sig(inf->sig, current);
	die_if_kernel("Oops", regs, 0);
	return;

#if defined(CONFIG_CPU_SA110) || defined(CONFIG_CPU_SA1100) || defined(CONFIG_DEBUG_ERRORS)
sa1_weirdness:
	if (user_mode(regs)) {
		static int first = 1;
		if (first) {
			printk(KERN_DEBUG "Fixing up bad data abort at %08lx\n", addr);
#ifdef CONFIG_DEBUG_ERRORS
			show_pte(current->mm, addr);
#endif
		}
		first = 0;
		return;
	}

	if (!inf->fn || inf->fn(addr, error_code, regs))
		goto bad;
	return;
#endif
}

asmlinkage void
do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
{
	do_translation_fault(addr, 0, regs);
}

/*
 * We take the easy way out of this problem - we make the
 * PTE uncacheable.  However, we leave the write buffer on.
 */
static void adjust_pte(struct vm_area_struct *vma, unsigned long address)
{
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte, entry;

	pgd = pgd_offset(vma->vm_mm, address);
	if (pgd_none(*pgd))
		return;
	if (pgd_bad(*pgd))
		goto bad_pgd;

	pmd = pmd_offset(pgd, address);
	if (pmd_none(*pmd))
		return;
	if (pmd_bad(*pmd))
		goto bad_pmd;

	pte = pte_offset(pmd, address);
	entry = *pte;

	/*
	 * If this page isn't present, or is already setup to
	 * fault (ie, is old), we can safely ignore any issues.
	 */
	if (pte_present(entry) && pte_val(entry) & L_PTE_CACHEABLE) {
		flush_cache_page(vma, address);
		pte_val(entry) &= ~L_PTE_CACHEABLE;
		set_pte(pte, entry);
		flush_tlb_page(vma, address);
	}
	return;

bad_pgd:
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
	return;

bad_pmd:
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
	return;
}

/*
 * Take care of architecture specific things when placing a new PTE into
 * a page table, or changing an existing PTE.  Basically, there are two
 * things that we need to take care of:
 *
 *  1. If PG_dcache_dirty is set for the page, we need to ensure
 *     that any cache entries for the kernels virtual memory
 *     range are written back to the page.
 *  2. If we have multiple shared mappings of the same space in
 *     an object, we need to deal with the cache aliasing issues.
 *
 * Note that the page_table_lock will be held.
 */
void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
{
	struct page *page = pte_page(pte);
	struct vm_area_struct *mpnt;
	struct mm_struct *mm;
	unsigned long pgoff;
	int aliases;

	if (!VALID_PAGE(page) || !page->mapping)
		return;

	if (test_and_clear_bit(PG_dcache_dirty, &page->flags)) {
		unsigned long kvirt = (unsigned long)page_address(page);
		cpu_cache_clean_invalidate_range(kvirt, kvirt + PAGE_SIZE, 0);
	}

	mm = vma->vm_mm;
	pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
	aliases = 0;

	/*
	 * If we have any shared mappings that are in the same mm
	 * space, then we need to handle them specially to maintain
	 * cache coherency.
	 */
	for (mpnt = page->mapping->i_mmap_shared; mpnt;
	     mpnt = mpnt->vm_next_share) {
		unsigned long off;

		/*
		 * If this VMA is not in our MM, we can ignore it.
		 * Note that we intentionally don't mask out the VMA
		 * that we are fixing up.
		 */
		if (mpnt->vm_mm != mm && mpnt != vma)
			continue;

		/*
		 * If the page isn't in this VMA, we can also ignore it.
		 */
		if (pgoff < mpnt->vm_pgoff)
			continue;

		off = pgoff - mpnt->vm_pgoff;
		if (off >= (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT)
			continue;

		/*
		 * Ok, it is within mpnt.  Fix it up.
		 */
		adjust_pte(mpnt, mpnt->vm_start + (off << PAGE_SHIFT));
		aliases ++;
	}
	if (aliases)
		adjust_pte(vma, addr);
}