276 lines
6.5 KiB
C
276 lines
6.5 KiB
C
/*
|
|
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
|
|
* Licensed under the GPL
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/hardirq.h>
|
|
#include <asm/current.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/tlbflush.h>
|
|
#include "arch.h"
|
|
#include "as-layout.h"
|
|
#include "kern_util.h"
|
|
#include "os.h"
|
|
#include "skas.h"
|
|
#include "sysdep/sigcontext.h"
|
|
|
|
/*
|
|
* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
|
|
* segv().
|
|
*/
|
|
int handle_page_fault(unsigned long address, unsigned long ip,
|
|
int is_write, int is_user, int *code_out)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *pte;
|
|
int err = -EFAULT;
|
|
|
|
*code_out = SEGV_MAPERR;
|
|
|
|
/*
|
|
* If the fault was during atomic operation, don't take the fault, just
|
|
* fail.
|
|
*/
|
|
if (in_atomic())
|
|
goto out_nosemaphore;
|
|
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, address);
|
|
if (!vma)
|
|
goto out;
|
|
else if (vma->vm_start <= address)
|
|
goto good_area;
|
|
else if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
goto out;
|
|
else if (is_user && !ARCH_IS_STACKGROW(address))
|
|
goto out;
|
|
else if (expand_stack(vma, address))
|
|
goto out;
|
|
|
|
good_area:
|
|
*code_out = SEGV_ACCERR;
|
|
if (is_write && !(vma->vm_flags & VM_WRITE))
|
|
goto out;
|
|
|
|
/* Don't require VM_READ|VM_EXEC for write faults! */
|
|
if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
|
|
goto out;
|
|
|
|
do {
|
|
int fault;
|
|
|
|
fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
|
|
if (unlikely(fault & VM_FAULT_ERROR)) {
|
|
if (fault & VM_FAULT_OOM) {
|
|
goto out_of_memory;
|
|
} else if (fault & VM_FAULT_SIGBUS) {
|
|
err = -EACCES;
|
|
goto out;
|
|
}
|
|
BUG();
|
|
}
|
|
if (fault & VM_FAULT_MAJOR)
|
|
current->maj_flt++;
|
|
else
|
|
current->min_flt++;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
pud = pud_offset(pgd, address);
|
|
pmd = pmd_offset(pud, address);
|
|
pte = pte_offset_kernel(pmd, address);
|
|
} while (!pte_present(*pte));
|
|
err = 0;
|
|
/*
|
|
* The below warning was added in place of
|
|
* pte_mkyoung(); if (is_write) pte_mkdirty();
|
|
* If it's triggered, we'd see normally a hang here (a clean pte is
|
|
* marked read-only to emulate the dirty bit).
|
|
* However, the generic code can mark a PTE writable but clean on a
|
|
* concurrent read fault, triggering this harmlessly. So comment it out.
|
|
*/
|
|
#if 0
|
|
WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
|
|
#endif
|
|
flush_tlb_page(vma, address);
|
|
out:
|
|
up_read(&mm->mmap_sem);
|
|
out_nosemaphore:
|
|
return err;
|
|
|
|
out_of_memory:
|
|
/*
|
|
* We ran out of memory, call the OOM killer, and return the userspace
|
|
* (which will retry the fault, or kill us if we got oom-killed).
|
|
*/
|
|
up_read(&mm->mmap_sem);
|
|
pagefault_out_of_memory();
|
|
return 0;
|
|
}
|
|
|
|
static void show_segv_info(struct uml_pt_regs *regs)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct faultinfo *fi = UPT_FAULTINFO(regs);
|
|
|
|
if (!unhandled_signal(tsk, SIGSEGV))
|
|
return;
|
|
|
|
if (!printk_ratelimit())
|
|
return;
|
|
|
|
printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
|
|
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
|
|
tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi),
|
|
(void *)UPT_IP(regs), (void *)UPT_SP(regs),
|
|
fi->error_code);
|
|
|
|
print_vma_addr(KERN_CONT " in ", UPT_IP(regs));
|
|
printk(KERN_CONT "\n");
|
|
}
|
|
|
|
static void bad_segv(struct faultinfo fi, unsigned long ip)
|
|
{
|
|
struct siginfo si;
|
|
|
|
si.si_signo = SIGSEGV;
|
|
si.si_code = SEGV_ACCERR;
|
|
si.si_addr = (void __user *) FAULT_ADDRESS(fi);
|
|
current->thread.arch.faultinfo = fi;
|
|
force_sig_info(SIGSEGV, &si, current);
|
|
}
|
|
|
|
void fatal_sigsegv(void)
|
|
{
|
|
force_sigsegv(SIGSEGV, current);
|
|
do_signal();
|
|
/*
|
|
* This is to tell gcc that we're not returning - do_signal
|
|
* can, in general, return, but in this case, it's not, since
|
|
* we just got a fatal SIGSEGV queued.
|
|
*/
|
|
os_dump_core();
|
|
}
|
|
|
|
void segv_handler(int sig, struct uml_pt_regs *regs)
|
|
{
|
|
struct faultinfo * fi = UPT_FAULTINFO(regs);
|
|
|
|
if (UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)) {
|
|
show_segv_info(regs);
|
|
bad_segv(*fi, UPT_IP(regs));
|
|
return;
|
|
}
|
|
segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
|
|
}
|
|
|
|
/*
|
|
* We give a *copy* of the faultinfo in the regs to segv.
|
|
* This must be done, since nesting SEGVs could overwrite
|
|
* the info in the regs. A pointer to the info then would
|
|
* give us bad data!
|
|
*/
|
|
unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
|
|
struct uml_pt_regs *regs)
|
|
{
|
|
struct siginfo si;
|
|
jmp_buf *catcher;
|
|
int err;
|
|
int is_write = FAULT_WRITE(fi);
|
|
unsigned long address = FAULT_ADDRESS(fi);
|
|
|
|
if (!is_user && (address >= start_vm) && (address < end_vm)) {
|
|
flush_tlb_kernel_vm();
|
|
return 0;
|
|
}
|
|
else if (current->mm == NULL) {
|
|
show_regs(container_of(regs, struct pt_regs, regs));
|
|
panic("Segfault with no mm");
|
|
}
|
|
|
|
if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
|
|
err = handle_page_fault(address, ip, is_write, is_user,
|
|
&si.si_code);
|
|
else {
|
|
err = -EFAULT;
|
|
/*
|
|
* A thread accessed NULL, we get a fault, but CR2 is invalid.
|
|
* This code is used in __do_copy_from_user() of TT mode.
|
|
* XXX tt mode is gone, so maybe this isn't needed any more
|
|
*/
|
|
address = 0;
|
|
}
|
|
|
|
catcher = current->thread.fault_catcher;
|
|
if (!err)
|
|
return 0;
|
|
else if (catcher != NULL) {
|
|
current->thread.fault_addr = (void *) address;
|
|
UML_LONGJMP(catcher, 1);
|
|
}
|
|
else if (current->thread.fault_addr != NULL)
|
|
panic("fault_addr set but no fault catcher");
|
|
else if (!is_user && arch_fixup(ip, regs))
|
|
return 0;
|
|
|
|
if (!is_user) {
|
|
show_regs(container_of(regs, struct pt_regs, regs));
|
|
panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
|
|
address, ip);
|
|
}
|
|
|
|
show_segv_info(regs);
|
|
|
|
if (err == -EACCES) {
|
|
si.si_signo = SIGBUS;
|
|
si.si_errno = 0;
|
|
si.si_code = BUS_ADRERR;
|
|
si.si_addr = (void __user *)address;
|
|
current->thread.arch.faultinfo = fi;
|
|
force_sig_info(SIGBUS, &si, current);
|
|
} else {
|
|
BUG_ON(err != -EFAULT);
|
|
si.si_signo = SIGSEGV;
|
|
si.si_addr = (void __user *) address;
|
|
current->thread.arch.faultinfo = fi;
|
|
force_sig_info(SIGSEGV, &si, current);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void relay_signal(int sig, struct uml_pt_regs *regs)
|
|
{
|
|
if (!UPT_IS_USER(regs)) {
|
|
if (sig == SIGBUS)
|
|
printk(KERN_ERR "Bus error - the host /dev/shm or /tmp "
|
|
"mount likely just ran out of space\n");
|
|
panic("Kernel mode signal %d", sig);
|
|
}
|
|
|
|
arch_examine_signal(sig, regs);
|
|
|
|
current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
|
|
force_sig(sig, current);
|
|
}
|
|
|
|
void bus_handler(int sig, struct uml_pt_regs *regs)
|
|
{
|
|
if (current->thread.fault_catcher != NULL)
|
|
UML_LONGJMP(current->thread.fault_catcher, 1);
|
|
else relay_signal(sig, regs);
|
|
}
|
|
|
|
void winch(int sig, struct uml_pt_regs *regs)
|
|
{
|
|
do_IRQ(WINCH_IRQ, regs);
|
|
}
|
|
|
|
void trap_init(void)
|
|
{
|
|
}
|