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/* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $
* fault.c: Page fault handlers for the Sparc.
*
* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
* Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
#include <asm/head.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/threads.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/memreg.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/smp.h>
#include <asm/traps.h>
#include <asm/kdebug.h>
#include <asm/uaccess.h>
#define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))
extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];
extern int prom_node_root;
/* At boot time we determine these two values necessary for setting
* up the segment maps and page table entries (pte's).
*/
int num_segmaps, num_contexts;
int invalid_segment;
/* various Virtual Address Cache parameters we find at boot time... */
int vac_size, vac_linesize, vac_do_hw_vac_flushes;
int vac_entries_per_context, vac_entries_per_segment;
int vac_entries_per_page;
/* Nice, simple, prom library does all the sweating for us. ;) */
int prom_probe_memory (void)
{
register struct linux_mlist_v0 *mlist;
register unsigned long bytes, base_paddr, tally;
register int i;
i = 0;
mlist= *prom_meminfo()->v0_available;
bytes = tally = mlist->num_bytes;
base_paddr = (unsigned long) mlist->start_adr;
sp_banks[0].base_addr = base_paddr;
sp_banks[0].num_bytes = bytes;
while (mlist->theres_more != (void *) 0){
i++;
mlist = mlist->theres_more;
bytes = mlist->num_bytes;
tally += bytes;
if (i >= SPARC_PHYS_BANKS-1) {
printk ("The machine has more banks than "
"this kernel can support\n"
"Increase the SPARC_PHYS_BANKS "
"setting (currently %d)\n",
SPARC_PHYS_BANKS);
i = SPARC_PHYS_BANKS-1;
break;
}
sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
sp_banks[i].num_bytes = mlist->num_bytes;
}
i++;
sp_banks[i].base_addr = 0xdeadbeef;
sp_banks[i].num_bytes = 0;
/* Now mask all bank sizes on a page boundary, it is all we can
* use anyways.
*/
for(i=0; sp_banks[i].num_bytes != 0; i++)
sp_banks[i].num_bytes &= PAGE_MASK;
return tally;
}
/* Traverse the memory lists in the prom to see how much physical we
* have.
*/
unsigned long
probe_memory(void)
{
int total;
total = prom_probe_memory();
/* Oh man, much nicer, keep the dirt in promlib. */
return total;
}
extern void sun4c_complete_all_stores(void);
/* Whee, a level 15 NMI interrupt memory error. Let's have fun... */
asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
unsigned long svaddr, unsigned long aerr,
unsigned long avaddr)
{
sun4c_complete_all_stores();
printk("FAULT: NMI received\n");
printk("SREGS: Synchronous Error %08lx\n", serr);
printk(" Synchronous Vaddr %08lx\n", svaddr);
printk(" Asynchronous Error %08lx\n", aerr);
printk(" Asynchronous Vaddr %08lx\n", avaddr);
if (sun4c_memerr_reg)
printk(" Memory Parity Error %08lx\n", *sun4c_memerr_reg);
printk("REGISTER DUMP:\n");
show_regs(regs);
prom_halt();
}
static void unhandled_fault(unsigned long, struct task_struct *,
struct pt_regs *) __attribute__ ((noreturn));
static void unhandled_fault(unsigned long address, struct task_struct *tsk,
struct pt_regs *regs)
{
if((unsigned long) address < PAGE_SIZE) {
printk(KERN_ALERT "Unable to handle kernel NULL "
"pointer dereference");
} else {
printk(KERN_ALERT "Unable to handle kernel paging request "
"at virtual address %08lx\n", address);
}
printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
(tsk->mm ? (unsigned long) tsk->mm->pgd :
(unsigned long) tsk->active_mm->pgd));
die_if_kernel("Oops", regs);
}
asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
unsigned long address)
{
struct pt_regs regs;
unsigned long g2;
unsigned int insn;
int i;
i = search_exception_table(ret_pc, &g2);
switch (i) {
case 3:
/* load & store will be handled by fixup */
return 3;
case 1:
/* store will be handled by fixup, load will bump out */
/* for _to_ macros */
insn = *((unsigned int *) pc);
if ((insn >> 21) & 1)
return 1;
break;
case 2:
/* load will be handled by fixup, store will bump out */
/* for _from_ macros */
insn = *((unsigned int *) pc);
if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
return 2;
break;
default:
break;
};
memset(®s, 0, sizeof (regs));
regs.pc = pc;
regs.npc = pc + 4;
__asm__ __volatile__(
"rd %%psr, %0\n\t"
"nop\n\t"
"nop\n\t"
"nop\n" : "=r" (regs.psr));
unhandled_fault(address, current, ®s);
/* Not reached */
return 0;
}
asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
unsigned long address)
{
struct vm_area_struct *vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
unsigned int fixup;
unsigned long g2;
siginfo_t info;
int from_user = !(regs->psr & PSR_PS);
if(text_fault)
address = regs->pc;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
goto vmalloc_fault;
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_interrupt() || !mm)
goto no_context;
down_read(&mm->mmap_sem);
/*
* The kernel referencing a bad kernel pointer can lock up
* a sun4c machine completely, so we must attempt recovery.
*/
if(!from_user && address >= PAGE_OFFSET)
goto bad_area;
vma = find_vma(mm, address);
if(!vma)
goto bad_area;
if(vma->vm_start <= address)
goto good_area;
if(!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if(expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
if(write) {
if(!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
/* Allow reads even for write-only mappings */
if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
case 1:
current->min_flt++;
break;
case 2:
current->maj_flt++;
break;
case 0:
goto do_sigbus;
default:
goto out_of_memory;
}
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if(from_user) {
#if 0
printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
tsk->comm, tsk->pid, address, regs->pc);
#endif
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code set above to make clear whether
this was a SEGV_MAPERR or SEGV_ACCERR fault. */
info.si_addr = (void *)address;
info.si_trapno = 0;
force_sig_info (SIGSEGV, &info, tsk);
return;
}
/* Is this in ex_table? */
no_context:
g2 = regs->u_regs[UREG_G2];
if (!from_user && (fixup = search_exception_table (regs->pc, &g2))) {
if (fixup > 10) { /* Values below are reserved for other things */
extern const unsigned __memset_start[];
extern const unsigned __memset_end[];
extern const unsigned __csum_partial_copy_start[];
extern const unsigned __csum_partial_copy_end[];
#ifdef DEBUG_EXCEPTIONS
printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
regs->pc, fixup, g2);
#endif
if ((regs->pc >= (unsigned long)__memset_start &&
regs->pc < (unsigned long)__memset_end) ||
(regs->pc >= (unsigned long)__csum_partial_copy_start &&
regs->pc < (unsigned long)__csum_partial_copy_end)) {
regs->u_regs[UREG_I4] = address;
regs->u_regs[UREG_I5] = regs->pc;
}
regs->u_regs[UREG_G2] = g2;
regs->pc = fixup;
regs->npc = regs->pc + 4;
return;
}
}
unhandled_fault (address, tsk, regs);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
printk("VM: killing process %s\n", tsk->comm);
if (from_user)
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
info.si_trapno = 0;
force_sig_info (SIGBUS, &info, tsk);
if (!from_user)
goto no_context;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pmd_t *pmd, *pmd_k;
pgd = tsk->active_mm->pgd + offset;
pgd_k = init_mm.pgd + offset;
if (!pgd_present(*pgd)) {
if (!pgd_present(*pgd_k))
goto bad_area_nosemaphore;
pgd_val(*pgd) = pgd_val(*pgd_k);
return;
}
pmd = pmd_offset(pgd, address);
pmd_k = pmd_offset(pgd_k, address);
if (pmd_present(*pmd) || !pmd_present(*pmd_k))
goto bad_area_nosemaphore;
pmd_val(*pmd) = pmd_val(*pmd_k);
return;
}
}
asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
unsigned long address)
{
extern void sun4c_update_mmu_cache(struct vm_area_struct *,
unsigned long,pte_t);
extern pte_t *sun4c_pte_offset(pmd_t *,unsigned long);
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
pgd_t *pgdp;
pte_t *ptep;
if (text_fault) {
address = regs->pc;
} else if (!write &&
!(regs->psr & PSR_PS)) {
unsigned int insn, *ip;
ip = (unsigned int *)regs->pc;
if (! get_user(insn, ip)) {
if ((insn & 0xc1680000) == 0xc0680000)
write = 1;
}
}
pgdp = pgd_offset(mm, address);
ptep = sun4c_pte_offset((pmd_t *) pgdp, address);
if (pgd_val(*pgdp)) {
if (write) {
if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
== (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
unsigned long flags;
*ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
_SUN4C_PAGE_MODIFIED |
_SUN4C_PAGE_VALID |
_SUN4C_PAGE_DIRTY);
save_and_cli(flags);
if (sun4c_get_segmap(address) != invalid_segment) {
sun4c_put_pte(address, pte_val(*ptep));
restore_flags(flags);
return;
}
restore_flags(flags);
}
} else {
if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
== (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
unsigned long flags;
*ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
_SUN4C_PAGE_VALID);
save_and_cli(flags);
if (sun4c_get_segmap(address) != invalid_segment) {
sun4c_put_pte(address, pte_val(*ptep));
restore_flags(flags);
return;
}
restore_flags(flags);
}
}
}
/* This conditional is 'interesting'. */
if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
&& (pte_val(*ptep) & _SUN4C_PAGE_VALID))
/* Note: It is safe to not grab the MMAP semaphore here because
* we know that update_mmu_cache() will not sleep for
* any reason (at least not in the current implementation)
* and therefore there is no danger of another thread getting
* on the CPU and doing a shrink_mmap() on this vma.
*/
sun4c_update_mmu_cache (find_vma(current->mm, address), address,
*ptep);
else
do_sparc_fault(regs, text_fault, write, address);
}
/* This always deals with user addresses. */
inline void force_user_fault(unsigned long address, int write)
{
struct vm_area_struct *vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
siginfo_t info;
info.si_code = SEGV_MAPERR;
#if 0
printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
tsk->pid, write, address);
#endif
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if(!vma)
goto bad_area;
if(vma->vm_start <= address)
goto good_area;
if(!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if(expand_stack(vma, address))
goto bad_area;
good_area:
info.si_code = SEGV_ACCERR;
if(write) {
if(!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
if (!handle_mm_fault(mm, vma, address, write))
goto do_sigbus;
up_read(&mm->mmap_sem);
return;
bad_area:
up_read(&mm->mmap_sem);
#if 0
printk("Window whee %s [%d]: segfaults at %08lx\n",
tsk->comm, tsk->pid, address);
#endif
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code set above to make clear whether
this was a SEGV_MAPERR or SEGV_ACCERR fault. */
info.si_addr = (void *)address;
info.si_trapno = 0;
force_sig_info (SIGSEGV, &info, tsk);
return;
do_sigbus:
up_read(&mm->mmap_sem);
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
info.si_trapno = 0;
force_sig_info (SIGBUS, &info, tsk);
}
void window_overflow_fault(void)
{
unsigned long sp;
sp = current->thread.rwbuf_stkptrs[0];
if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
force_user_fault(sp + 0x38, 1);
force_user_fault(sp, 1);
}
void window_underflow_fault(unsigned long sp)
{
if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
force_user_fault(sp + 0x38, 0);
force_user_fault(sp, 0);
}
void window_ret_fault(struct pt_regs *regs)
{
unsigned long sp;
sp = regs->u_regs[UREG_FP];
if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
force_user_fault(sp + 0x38, 0);
force_user_fault(sp, 0);
}
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