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linux-next/arch/um/kernel/trap.c
Jeff Dike fab95c55e3 uml: get rid of do_longjmp
do_longjmp used to be needed when UML didn't have its own implementation of
setjmp and longjmp.  They came from libc, and couldn't be called directly from
kernel code, as the libc jmp_buf couldn't be imported there.  do_longjmp was a
userspace function which served to provide longjmp access to kernel code.

This is gone, and a number of void * pointers can now be jmp_buf *.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:43:05 -07:00

257 lines
6.1 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 "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;
survive:
fault = handle_mm_fault(mm, vma, address, is_write);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM) {
err = -ENOMEM;
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;
/*
* 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:
if (is_init(current)) {
up_read(&mm->mmap_sem);
yield();
down_read(&mm->mmap_sem);
goto survive;
}
goto out;
}
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);
}
static 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)) {
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);
}
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 if (err == -ENOMEM) {
printk(KERN_INFO "VM: killing process %s\n", current->comm);
do_exit(SIGKILL);
} 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 (arch_handle_signal(sig, regs))
return;
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);
}
current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
force_sig(sig, current);
}
static 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);
}
static void winch(int sig, struct uml_pt_regs *regs)
{
do_IRQ(WINCH_IRQ, regs);
}
const struct kern_handlers handlinfo_kern = {
.relay_signal = relay_signal,
.winch = winch,
.bus_handler = bus_handler,
.page_fault = segv_handler,
.sigio_handler = sigio_handler,
.timer_handler = timer_handler
};
void trap_init(void)
{
}