android_kernel_xiaomi_sm8350/arch/x86/mm/fault_64.c
Harvey Harrison 318aa296c3 x86: more users of PF_ constants in fault_32|64.c
Should be the last of the error_code tests that could use
the PF_ defines.  Makes X86_32|64 a little closer.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:32:59 +01:00

738 lines
20 KiB
C

/*
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/compiler.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
#include <asm/system.h>
#include <asm/pgalloc.h>
#include <asm/smp.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm-generic/sections.h>
/*
* Page fault error code bits
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
* bit 2 == 0 means kernel, 1 means user-mode
* bit 3 == 1 means use of reserved bit detected
* bit 4 == 1 means fault was an instruction fetch
*/
#define PF_PROT (1<<0)
#define PF_WRITE (1<<1)
#define PF_USER (1<<2)
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
static inline int notify_page_fault(struct pt_regs *regs)
{
#ifdef CONFIG_KPROBES
int ret = 0;
/* kprobe_running() needs smp_processor_id() */
if (!user_mode(regs)) {
preempt_disable();
if (kprobe_running() && kprobe_fault_handler(regs, 14))
ret = 1;
preempt_enable();
}
return ret;
#else
return 0;
#endif
}
#ifdef CONFIG_X86_32
/*
* Return EIP plus the CS segment base. The segment limit is also
* adjusted, clamped to the kernel/user address space (whichever is
* appropriate), and returned in *eip_limit.
*
* The segment is checked, because it might have been changed by another
* task between the original faulting instruction and here.
*
* If CS is no longer a valid code segment, or if EIP is beyond the
* limit, or if it is a kernel address when CS is not a kernel segment,
* then the returned value will be greater than *eip_limit.
*
* This is slow, but is very rarely executed.
*/
static inline unsigned long get_segment_eip(struct pt_regs *regs,
unsigned long *eip_limit)
{
unsigned long ip = regs->ip;
unsigned seg = regs->cs & 0xffff;
u32 seg_ar, seg_limit, base, *desc;
/* Unlikely, but must come before segment checks. */
if (unlikely(regs->flags & VM_MASK)) {
base = seg << 4;
*eip_limit = base + 0xffff;
return base + (ip & 0xffff);
}
/* The standard kernel/user address space limit. */
*eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg;
/* By far the most common cases. */
if (likely(SEGMENT_IS_FLAT_CODE(seg)))
return ip;
/* Check the segment exists, is within the current LDT/GDT size,
that kernel/user (ring 0..3) has the appropriate privilege,
that it's a code segment, and get the limit. */
__asm__("larl %3,%0; lsll %3,%1"
: "=&r" (seg_ar), "=r" (seg_limit) : "0" (0), "rm" (seg));
if ((~seg_ar & 0x9800) || ip > seg_limit) {
*eip_limit = 0;
return 1; /* So that returned ip > *eip_limit. */
}
/* Get the GDT/LDT descriptor base.
When you look for races in this code remember that
LDT and other horrors are only used in user space. */
if (seg & (1<<2)) {
/* Must lock the LDT while reading it. */
mutex_lock(&current->mm->context.lock);
desc = current->mm->context.ldt;
desc = (void *)desc + (seg & ~7);
} else {
/* Must disable preemption while reading the GDT. */
desc = (u32 *)get_cpu_gdt_table(get_cpu());
desc = (void *)desc + (seg & ~7);
}
/* Decode the code segment base from the descriptor */
base = get_desc_base((struct desc_struct *)desc);
if (seg & (1<<2))
mutex_unlock(&current->mm->context.lock);
else
put_cpu();
/* Adjust EIP and segment limit, and clamp at the kernel limit.
It's legitimate for segments to wrap at 0xffffffff. */
seg_limit += base;
if (seg_limit < *eip_limit && seg_limit >= base)
*eip_limit = seg_limit;
return ip + base;
}
#endif
/*
* X86_32
* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
* Check that here and ignore it.
*
* X86_64
* Sometimes the CPU reports invalid exceptions on prefetch.
* Check that here and ignore it.
*
* Opcode checker based on code by Richard Brunner
*/
static int is_prefetch(struct pt_regs *regs, unsigned long addr,
unsigned long error_code)
{
unsigned char *instr;
int scan_more = 1;
int prefetch = 0;
unsigned char *max_instr;
#ifdef CONFIG_X86_32
unsigned long limit;
if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
boot_cpu_data.x86 >= 6)) {
/* Catch an obscure case of prefetch inside an NX page. */
if (nx_enabled && (error_code & PF_INSTR))
return 0;
} else {
return 0;
}
instr = (unsigned char *)get_segment_eip(regs, &limit);
#else
/* If it was a exec fault ignore */
if (error_code & PF_INSTR)
return 0;
instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
#endif
max_instr = instr + 15;
#ifdef CONFIG_X86_64
if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
return 0;
#endif
while (scan_more && instr < max_instr) {
unsigned char opcode;
unsigned char instr_hi;
unsigned char instr_lo;
#ifdef CONFIG_X86_32
if (instr > (unsigned char *)limit)
break;
#endif
if (probe_kernel_address(instr, opcode))
break;
instr_hi = opcode & 0xf0;
instr_lo = opcode & 0x0f;
instr++;
switch (instr_hi) {
case 0x20:
case 0x30:
/*
* Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
* In X86_64 long mode, the CPU will signal invalid
* opcode if some of these prefixes are present so
* X86_64 will never get here anyway
*/
scan_more = ((instr_lo & 7) == 0x6);
break;
#ifdef CONFIG_X86_64
case 0x40:
/*
* In AMD64 long mode 0x40..0x4F are valid REX prefixes
* Need to figure out under what instruction mode the
* instruction was issued. Could check the LDT for lm,
* but for now it's good enough to assume that long
* mode only uses well known segments or kernel.
*/
scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
break;
#endif
case 0x60:
/* 0x64 thru 0x67 are valid prefixes in all modes. */
scan_more = (instr_lo & 0xC) == 0x4;
break;
case 0xF0:
/* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
scan_more = !instr_lo || (instr_lo>>1) == 1;
break;
case 0x00:
/* Prefetch instruction is 0x0F0D or 0x0F18 */
scan_more = 0;
#ifdef CONFIG_X86_32
if (instr > (unsigned char *)limit)
break;
#endif
if (probe_kernel_address(instr, opcode))
break;
prefetch = (instr_lo == 0xF) &&
(opcode == 0x0D || opcode == 0x18);
break;
default:
scan_more = 0;
break;
}
}
return prefetch;
}
static void force_sig_info_fault(int si_signo, int si_code,
unsigned long address, struct task_struct *tsk)
{
siginfo_t info;
info.si_signo = si_signo;
info.si_errno = 0;
info.si_code = si_code;
info.si_addr = (void __user *)address;
force_sig_info(si_signo, &info, tsk);
}
static int bad_address(void *p)
{
unsigned long dummy;
return probe_kernel_address((unsigned long *)p, dummy);
}
void dump_pagetable(unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pgd = (pgd_t *)read_cr3();
pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
pgd += pgd_index(address);
if (bad_address(pgd)) goto bad;
printk("PGD %lx ", pgd_val(*pgd));
if (!pgd_present(*pgd)) goto ret;
pud = pud_offset(pgd, address);
if (bad_address(pud)) goto bad;
printk("PUD %lx ", pud_val(*pud));
if (!pud_present(*pud)) goto ret;
pmd = pmd_offset(pud, address);
if (bad_address(pmd)) goto bad;
printk("PMD %lx ", pmd_val(*pmd));
if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret;
pte = pte_offset_kernel(pmd, address);
if (bad_address(pte)) goto bad;
printk("PTE %lx", pte_val(*pte));
ret:
printk("\n");
return;
bad:
printk("BAD\n");
}
#ifdef CONFIG_X86_64
static const char errata93_warning[] =
KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
KERN_ERR "******* Please consider a BIOS update.\n"
KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
/* Workaround for K8 erratum #93 & buggy BIOS.
BIOS SMM functions are required to use a specific workaround
to avoid corruption of the 64bit RIP register on C stepping K8.
A lot of BIOS that didn't get tested properly miss this.
The OS sees this as a page fault with the upper 32bits of RIP cleared.
Try to work around it here.
Note we only handle faults in kernel here. */
static int is_errata93(struct pt_regs *regs, unsigned long address)
{
static int warned;
if (address != regs->ip)
return 0;
if ((address >> 32) != 0)
return 0;
address |= 0xffffffffUL << 32;
if ((address >= (u64)_stext && address <= (u64)_etext) ||
(address >= MODULES_VADDR && address <= MODULES_END)) {
if (!warned) {
printk(errata93_warning);
warned = 1;
}
regs->ip = address;
return 1;
}
return 0;
}
#endif
static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
unsigned long error_code)
{
unsigned long flags = oops_begin();
struct task_struct *tsk;
printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
current->comm, address);
dump_pagetable(address);
tsk = current;
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
if (__die("Bad pagetable", regs, error_code))
regs = NULL;
oops_end(flags, regs, SIGKILL);
}
/*
* Handle a fault on the vmalloc area
*
* This assumes no large pages in there.
*/
static int vmalloc_fault(unsigned long address)
{
pgd_t *pgd, *pgd_ref;
pud_t *pud, *pud_ref;
pmd_t *pmd, *pmd_ref;
pte_t *pte, *pte_ref;
/* Copy kernel mappings over when needed. This can also
happen within a race in page table update. In the later
case just flush. */
pgd = pgd_offset(current->mm ?: &init_mm, address);
pgd_ref = pgd_offset_k(address);
if (pgd_none(*pgd_ref))
return -1;
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
else
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
/* Below here mismatches are bugs because these lower tables
are shared */
pud = pud_offset(pgd, address);
pud_ref = pud_offset(pgd_ref, address);
if (pud_none(*pud_ref))
return -1;
if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
BUG();
pmd = pmd_offset(pud, address);
pmd_ref = pmd_offset(pud_ref, address);
if (pmd_none(*pmd_ref))
return -1;
if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
BUG();
pte_ref = pte_offset_kernel(pmd_ref, address);
if (!pte_present(*pte_ref))
return -1;
pte = pte_offset_kernel(pmd, address);
/* Don't use pte_page here, because the mappings can point
outside mem_map, and the NUMA hash lookup cannot handle
that. */
if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
BUG();
return 0;
}
int show_unhandled_signals = 1;
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long address;
int write, fault;
unsigned long flags;
int si_code;
/*
* We can fault from pretty much anywhere, with unknown IRQ state.
*/
trace_hardirqs_fixup();
tsk = current;
mm = tsk->mm;
prefetchw(&mm->mmap_sem);
/* get the address */
address = read_cr2();
si_code = SEGV_MAPERR;
/*
* 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.
*
* This verifies that the fault happens in kernel space
* (error_code & 4) == 0, and that the fault was not a
* protection error (error_code & 9) == 0.
*/
if (unlikely(address >= TASK_SIZE64)) {
/*
* Don't check for the module range here: its PML4
* is always initialized because it's shared with the main
* kernel text. Only vmalloc may need PML4 syncups.
*/
if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
((address >= VMALLOC_START && address < VMALLOC_END))) {
if (vmalloc_fault(address) >= 0)
return;
}
if (notify_page_fault(regs))
return;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
* fault we could otherwise deadlock.
*/
goto bad_area_nosemaphore;
}
if (notify_page_fault(regs))
return;
if (likely(regs->flags & X86_EFLAGS_IF))
local_irq_enable();
if (unlikely(error_code & PF_RSVD))
pgtable_bad(address, regs, error_code);
/*
* If we're in an interrupt, have no user context or are running in an
* atomic region then we must not take the fault.
*/
if (unlikely(in_atomic() || !mm))
goto bad_area_nosemaphore;
/*
* User-mode registers count as a user access even for any
* potential system fault or CPU buglet.
*/
if (user_mode_vm(regs))
error_code |= PF_USER;
again:
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
* erroneous fault occurring in a code path which already holds mmap_sem
* we will deadlock attempting to validate the fault against the
* address space. Luckily the kernel only validly references user
* space from well defined areas of code, which are listed in the
* exceptions table.
*
* As the vast majority of faults will be valid we will only perform
* the source reference check when there is a possibility of a deadlock.
* Attempt to lock the address space, if we cannot we then validate the
* source. If this is invalid we can skip the address space check,
* thus avoiding the deadlock.
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if ((error_code & PF_USER) == 0 &&
!search_exception_tables(regs->ip))
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
}
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (likely(vma->vm_start <= address))
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (error_code & PF_USER) {
/* Allow userspace just enough access below the stack pointer
* to let the 'enter' instruction work.
*/
if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp)
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;
write = 0;
switch (error_code & (PF_PROT|PF_WRITE)) {
default: /* 3: write, present */
/* fall through */
case PF_WRITE: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
write++;
break;
case PF_PROT: /* read, present */
goto bad_area;
case 0: /* read, not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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.
*/
fault = handle_mm_fault(mm, vma, address, write);
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 (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
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 (error_code & PF_USER) {
/*
* It's possible to have interrupts off here.
*/
local_irq_enable();
if (is_prefetch(regs, address, error_code))
return;
/* Work around K8 erratum #100 K8 in compat mode
occasionally jumps to illegal addresses >4GB. We
catch this here in the page fault handler because
these addresses are not reachable. Just detect this
case and return. Any code segment in LDT is
compatibility mode. */
if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
(address >> 32))
return;
if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
printk_ratelimit()) {
printk(
"%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, tsk->pid, address, regs->ip,
regs->sp, error_code);
}
tsk->thread.cr2 = address;
/* Kernel addresses are always protection faults */
tsk->thread.error_code = error_code | (address >= TASK_SIZE);
tsk->thread.trap_no = 14;
force_sig_info_fault(SIGSEGV, si_code, address, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* Hall of shame of CPU/BIOS bugs.
*/
if (is_prefetch(regs, address, error_code))
return;
if (is_errata93(regs, address))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
flags = oops_begin();
if (address < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel paging request");
printk(" at %016lx RIP: \n" KERN_ALERT, address);
printk_address(regs->ip);
dump_pagetable(address);
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
if (__die("Oops", regs, error_code))
regs = NULL;
/* Executive summary in case the body of the oops scrolled away */
printk(KERN_EMERG "CR2: %016lx\n", address);
oops_end(flags, regs, 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);
if (is_global_init(current)) {
yield();
goto again;
}
printk("VM: killing process %s\n", tsk->comm);
if (error_code & PF_USER)
do_group_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
if (!(error_code & PF_USER))
goto no_context;
tsk->thread.cr2 = address;
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 14;
force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
return;
}
DEFINE_SPINLOCK(pgd_lock);
LIST_HEAD(pgd_list);
void vmalloc_sync_all(void)
{
/* Note that races in the updates of insync and start aren't
problematic:
insync can only get set bits added, and updates to start are only
improving performance (without affecting correctness if undone). */
static DECLARE_BITMAP(insync, PTRS_PER_PGD);
static unsigned long start = VMALLOC_START & PGDIR_MASK;
unsigned long address;
for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
if (!test_bit(pgd_index(address), insync)) {
const pgd_t *pgd_ref = pgd_offset_k(address);
struct page *page;
if (pgd_none(*pgd_ref))
continue;
spin_lock(&pgd_lock);
list_for_each_entry(page, &pgd_list, lru) {
pgd_t *pgd;
pgd = (pgd_t *)page_address(page) + pgd_index(address);
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
else
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
}
spin_unlock(&pgd_lock);
set_bit(pgd_index(address), insync);
}
if (address == start)
start = address + PGDIR_SIZE;
}
/* Check that there is no need to do the same for the modules area. */
BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
(__START_KERNEL & PGDIR_MASK)));
}