/*
* arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
*
* Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
* Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)
*/
#include <asm/head.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/perf_event.h>
#include <linux/interrupt.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/percpu.h>
#include <linux/context_tracking.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/uaccess.h>
#include <asm/asi.h>
#include <asm/lsu.h>
#include <asm/sections.h>
#include <asm/mmu_context.h>
int show_unhandled_signals = 1;
static inline __kprobes int notify_page_fault(struct pt_regs *regs)
{
int ret = 0;
/* kprobe_running() needs smp_processor_id() */
if (kprobes_built_in() && !user_mode(regs)) {
preempt_disable();
if (kprobe_running() && kprobe_fault_handler(regs, 0))
ret = 1;
preempt_enable();
}
return ret;
}
static void __kprobes 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\n");
} else {
printk(KERN_ALERT "Unable to handle kernel paging request "
"at virtual address %016lx\n", (unsigned long)address);
}
printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
(tsk->mm ?
CTX_HWBITS(tsk->mm->context) :
CTX_HWBITS(tsk->active_mm->context)));
printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
(tsk->mm ? (unsigned long) tsk->mm->pgd :
(unsigned long) tsk->active_mm->pgd));
die_if_kernel("Oops", regs);
}
static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
{
printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
regs->tpc);
printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
dump_stack();
unhandled_fault(regs->tpc, current, regs);
}
/*
* We now make sure that mmap_sem is held in all paths that call
* this. Additionally, to prevent kswapd from ripping ptes from
* under us, raise interrupts around the time that we look at the
* pte, kswapd will have to wait to get his smp ipi response from
* us. vmtruncate likewise. This saves us having to get pte lock.
*/
static unsigned int get_user_insn(unsigned long tpc)
{
pgd_t *pgdp = pgd_offset(current->mm, tpc);
pud_t *pudp;
pmd_t *pmdp;
pte_t *ptep, pte;
unsigned long pa;
u32 insn = 0;
unsigned long pstate;
if (pgd_none(*pgdp))
goto outret;
pudp = pud_offset(pgdp, tpc);
if (pud_none(*pudp))
goto outret;
pmdp = pmd_offset(pudp, tpc);
if (pmd_none(*pmdp))
goto outret;
/* This disables preemption for us as well. */
__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
__asm__ __volatile__("wrpr %0, %1, %%pstate"
: : "r" (pstate), "i" (PSTATE_IE));
ptep = pte_offset_map(pmdp, tpc);
pte = *ptep;
if (!pte_present(pte))
goto out;
pa = (pte_pfn(pte) << PAGE_SHIFT);
pa += (tpc & ~PAGE_MASK);
/* Use phys bypass so we don't pollute dtlb/dcache. */
__asm__ __volatile__("lduwa [%1] %2, %0"
: "=r" (insn)
: "r" (pa), "i" (ASI_PHYS_USE_EC));
out:
pte_unmap(ptep);
__asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
outret:
return insn;
}
static inline void
show_signal_msg(struct pt_regs *regs, int sig, int code,
unsigned long address, struct task_struct *tsk)
{
if (!unhandled_signal(tsk, sig))
return;
if (!printk_ratelimit())
return;
printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, task_pid_nr(tsk), address,
(void *)regs->tpc, (void *)regs->u_regs[UREG_I7],
(void *)regs->u_regs[UREG_FP], code);
print_vma_addr(KERN_CONT " in ", regs->tpc);
printk(KERN_CONT "\n");
}
static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
unsigned int insn, int fault_code)
{
unsigned long addr;
siginfo_t info;
info.si_code = code;
info.si_signo = sig;
info.si_errno = 0;
if (fault_code & FAULT_CODE_ITLB)
addr = regs->tpc;
else
addr = compute_effective_address(regs, insn, 0);
info.si_addr = (void __user *) addr;
info.si_trapno = 0;
if (unlikely(show_unhandled_signals))
show_signal_msg(regs, sig, code, addr, current);
force_sig_info(sig, &info, current);
}
extern int handle_ldf_stq(u32, struct pt_regs *);
extern int handle_ld_nf(u32, struct pt_regs *);
static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
{
if (!insn) {
if (!regs->tpc || (regs->tpc & 0x3))
return 0;
if (regs->tstate & TSTATE_PRIV) {
insn = *(unsigned int *) regs->tpc;
} else {
insn = get_user_insn(regs->tpc);
}
}
return insn;
}
static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
int fault_code, unsigned int insn,
unsigned long address)
{
unsigned char asi = ASI_P;
if ((!insn) && (regs->tstate & TSTATE_PRIV))
goto cannot_handle;
/* If user insn could be read (thus insn is zero), that
* is fine. We will just gun down the process with a signal
* in that case.
*/
if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
(insn & 0xc0800000) == 0xc0800000) {
if (insn & 0x2000)
asi = (regs->tstate >> 24);
else
asi = (insn >> 5);
if ((asi & 0xf2) == 0x82) {
if (insn & 0x1000000) {
handle_ldf_stq(insn, regs);
} else {
/* This was a non-faulting load. Just clear the
* destination register(s) and continue with the next
* instruction. -jj
*/
handle_ld_nf(insn, regs);
}
return;
}
}
/* Is this in ex_table? */
if (regs->tstate & TSTATE_PRIV) {
const struct exception_table_entry *entry;
entry = search_exception_tables(regs->tpc);
if (entry) {
regs->tpc = entry->fixup;
regs->tnpc = regs->tpc + 4;
return;
}
} else {
/* The si_code was set to make clear whether
* this was a SEGV_MAPERR or SEGV_ACCERR fault.
*/
do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
return;
}
cannot_handle:
unhandled_fault (address, current, regs);
}
static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs)
{
static int times;
if (times++ < 10)
printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
"64-bit TPC [%lx]\n",
current->comm, current->pid,
regs->tpc);
show_regs(regs);
}
static void noinline __kprobes bogus_32bit_fault_address(struct pt_regs *regs,
unsigned long addr)
{
static int times;
if (times++ < 10)
printk(KERN_ERR "FAULT[%s:%d]: 32-bit process "
"reports 64-bit fault address [%lx]\n",
current->comm, current->pid, addr);
show_regs(regs);
}
asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
{
enum ctx_state prev_state = exception_enter();
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned int insn = 0;
int si_code, fault_code, fault;
unsigned long address, mm_rss;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
fault_code = get_thread_fault_code();
if (notify_page_fault(regs))
goto exit_exception;
si_code = SEGV_MAPERR;
address = current_thread_info()->fault_address;
if ((fault_code & FAULT_CODE_ITLB) &&
(fault_code & FAULT_CODE_DTLB))
BUG();
if (test_thread_flag(TIF_32BIT)) {
if (!(regs->tstate & TSTATE_PRIV)) {
if (unlikely((regs->tpc >> 32) != 0)) {
bogus_32bit_fault_tpc(regs);
goto intr_or_no_mm;
}
}
if (unlikely((address >> 32) != 0)) {
bogus_32bit_fault_address(regs, address);
goto intr_or_no_mm;
}
}
if (regs->tstate & TSTATE_PRIV) {
unsigned long tpc = regs->tpc;
/* Sanity check the PC. */
if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) ||
(tpc >= MODULES_VADDR && tpc < MODULES_END)) {
/* Valid, no problems... */
} else {
bad_kernel_pc(regs, address);
goto exit_exception;
}
} else
flags |= FAULT_FLAG_USER;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto intr_or_no_mm;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (!down_read_trylock(&mm->mmap_sem)) {
if ((regs->tstate & TSTATE_PRIV) &&
!search_exception_tables(regs->tpc)) {
insn = get_fault_insn(regs, insn);
goto handle_kernel_fault;
}
retry:
down_read(&mm->mmap_sem);
}
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
/* Pure DTLB misses do not tell us whether the fault causing
* load/store/atomic was a write or not, it only says that there
* was no match. So in such a case we (carefully) read the
* instruction to try and figure this out. It's an optimization
* so it's ok if we can't do this.
*
* Special hack, window spill/fill knows the exact fault type.
*/
if (((fault_code &
(FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
(vma->vm_flags & VM_WRITE) != 0) {
insn = get_fault_insn(regs, 0);
if (!insn)
goto continue_fault;
/* All loads, stores and atomics have bits 30 and 31 both set
* in the instruction. Bit 21 is set in all stores, but we
* have to avoid prefetches which also have bit 21 set.
*/
if ((insn & 0xc0200000) == 0xc0200000 &&
(insn & 0x01780000) != 0x01680000) {
/* Don't bother updating thread struct value,
* because update_mmu_cache only cares which tlb
* the access came from.
*/
fault_code |= FAULT_CODE_WRITE;
}
}
continue_fault:
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (!(fault_code & FAULT_CODE_WRITE)) {
/* Non-faulting loads shouldn't expand stack. */
insn = get_fault_insn(regs, insn);
if ((insn & 0xc0800000) == 0xc0800000) {
unsigned char asi;
if (insn & 0x2000)
asi = (regs->tstate >> 24);
else
asi = (insn >> 5);
if ((asi & 0xf2) == 0x82)
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:
si_code = SEGV_ACCERR;
/* If we took a ITLB miss on a non-executable page, catch
* that here.
*/
if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
BUG_ON(address != regs->tpc);
BUG_ON(regs->tstate & TSTATE_PRIV);
goto bad_area;
}
if (fault_code & FAULT_CODE_WRITE) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
/* Spitfire has an icache which does not snoop
* processor stores. Later processors do...
*/
if (tlb_type == spitfire &&
(vma->vm_flags & VM_EXEC) != 0 &&
vma->vm_file != NULL)
set_thread_fault_code(fault_code |
FAULT_CODE_BLKCOMMIT);
flags |= FAULT_FLAG_WRITE;
} else {
/* Allow reads even for write-only mappings */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
fault = handle_mm_fault(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
goto exit_exception;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
current->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
1, regs, address);
} else {
current->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
1, regs, address);
}
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
mm_rss = get_mm_rss(mm);
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE));
#endif
if (unlikely(mm_rss >
mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
tsb_grow(mm, MM_TSB_BASE, mm_rss);
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
mm_rss = mm->context.huge_pte_count;
if (unlikely(mm_rss >
mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) {
if (mm->context.tsb_block[MM_TSB_HUGE].tsb)
tsb_grow(mm, MM_TSB_HUGE, mm_rss);
else
hugetlb_setup(regs);
}
#endif
exit_exception:
exception_exit(prev_state);
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:
insn = get_fault_insn(regs, insn);
up_read(&mm->mmap_sem);
handle_kernel_fault:
do_kernel_fault(regs, si_code, fault_code, insn, address);
goto exit_exception;
/*
* 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:
insn = get_fault_insn(regs, insn);
up_read(&mm->mmap_sem);
if (!(regs->tstate & TSTATE_PRIV)) {
pagefault_out_of_memory();
goto exit_exception;
}
goto handle_kernel_fault;
intr_or_no_mm:
insn = get_fault_insn(regs, 0);
goto handle_kernel_fault;
do_sigbus:
insn = get_fault_insn(regs, insn);
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);
/* Kernel mode? Handle exceptions or die */
if (regs->tstate & TSTATE_PRIV)
goto handle_kernel_fault;
}