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git.proxmox.com Git - mirror_ubuntu-focal-kernel.git/blob - arch/um/kernel/trap.c
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
7 #include <linux/sched.h>
8 #include <linux/hardirq.h>
9 #include <linux/module.h>
10 #include <asm/current.h>
11 #include <asm/pgtable.h>
12 #include <asm/tlbflush.h>
14 #include <as-layout.h>
15 #include <kern_util.h>
20 * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
23 int handle_page_fault(unsigned long address
, unsigned long ip
,
24 int is_write
, int is_user
, int *code_out
)
26 struct mm_struct
*mm
= current
->mm
;
27 struct vm_area_struct
*vma
;
33 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
35 *code_out
= SEGV_MAPERR
;
38 * If the fault was during atomic operation, don't take the fault, just
45 flags
|= FAULT_FLAG_USER
;
47 down_read(&mm
->mmap_sem
);
48 vma
= find_vma(mm
, address
);
51 else if (vma
->vm_start
<= address
)
53 else if (!(vma
->vm_flags
& VM_GROWSDOWN
))
55 else if (is_user
&& !ARCH_IS_STACKGROW(address
))
57 else if (expand_stack(vma
, address
))
61 *code_out
= SEGV_ACCERR
;
63 if (!(vma
->vm_flags
& VM_WRITE
))
65 flags
|= FAULT_FLAG_WRITE
;
67 /* Don't require VM_READ|VM_EXEC for write faults! */
68 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
75 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
77 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
80 if (unlikely(fault
& VM_FAULT_ERROR
)) {
81 if (fault
& VM_FAULT_OOM
) {
83 } else if (fault
& VM_FAULT_SIGSEGV
) {
85 } else if (fault
& VM_FAULT_SIGBUS
) {
91 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
92 if (fault
& VM_FAULT_MAJOR
)
96 if (fault
& VM_FAULT_RETRY
) {
97 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
98 flags
|= FAULT_FLAG_TRIED
;
104 pgd
= pgd_offset(mm
, address
);
105 pud
= pud_offset(pgd
, address
);
106 pmd
= pmd_offset(pud
, address
);
107 pte
= pte_offset_kernel(pmd
, address
);
108 } while (!pte_present(*pte
));
111 * The below warning was added in place of
112 * pte_mkyoung(); if (is_write) pte_mkdirty();
113 * If it's triggered, we'd see normally a hang here (a clean pte is
114 * marked read-only to emulate the dirty bit).
115 * However, the generic code can mark a PTE writable but clean on a
116 * concurrent read fault, triggering this harmlessly. So comment it out.
119 WARN_ON(!pte_young(*pte
) || (is_write
&& !pte_dirty(*pte
)));
121 flush_tlb_page(vma
, address
);
123 up_read(&mm
->mmap_sem
);
129 * We ran out of memory, call the OOM killer, and return the userspace
130 * (which will retry the fault, or kill us if we got oom-killed).
132 up_read(&mm
->mmap_sem
);
134 goto out_nosemaphore
;
135 pagefault_out_of_memory();
138 EXPORT_SYMBOL(handle_page_fault
);
140 static void show_segv_info(struct uml_pt_regs
*regs
)
142 struct task_struct
*tsk
= current
;
143 struct faultinfo
*fi
= UPT_FAULTINFO(regs
);
145 if (!unhandled_signal(tsk
, SIGSEGV
))
148 if (!printk_ratelimit())
151 printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
152 task_pid_nr(tsk
) > 1 ? KERN_INFO
: KERN_EMERG
,
153 tsk
->comm
, task_pid_nr(tsk
), FAULT_ADDRESS(*fi
),
154 (void *)UPT_IP(regs
), (void *)UPT_SP(regs
),
157 print_vma_addr(KERN_CONT
" in ", UPT_IP(regs
));
158 printk(KERN_CONT
"\n");
161 static void bad_segv(struct faultinfo fi
, unsigned long ip
)
165 si
.si_signo
= SIGSEGV
;
166 si
.si_code
= SEGV_ACCERR
;
167 si
.si_addr
= (void __user
*) FAULT_ADDRESS(fi
);
168 current
->thread
.arch
.faultinfo
= fi
;
169 force_sig_info(SIGSEGV
, &si
, current
);
172 void fatal_sigsegv(void)
174 force_sigsegv(SIGSEGV
, current
);
177 * This is to tell gcc that we're not returning - do_signal
178 * can, in general, return, but in this case, it's not, since
179 * we just got a fatal SIGSEGV queued.
184 void segv_handler(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
186 struct faultinfo
* fi
= UPT_FAULTINFO(regs
);
188 if (UPT_IS_USER(regs
) && !SEGV_IS_FIXABLE(fi
)) {
189 show_segv_info(regs
);
190 bad_segv(*fi
, UPT_IP(regs
));
193 segv(*fi
, UPT_IP(regs
), UPT_IS_USER(regs
), regs
);
197 * We give a *copy* of the faultinfo in the regs to segv.
198 * This must be done, since nesting SEGVs could overwrite
199 * the info in the regs. A pointer to the info then would
202 unsigned long segv(struct faultinfo fi
, unsigned long ip
, int is_user
,
203 struct uml_pt_regs
*regs
)
208 int is_write
= FAULT_WRITE(fi
);
209 unsigned long address
= FAULT_ADDRESS(fi
);
211 if (!is_user
&& regs
)
212 current
->thread
.segv_regs
= container_of(regs
, struct pt_regs
, regs
);
214 if (!is_user
&& (address
>= start_vm
) && (address
< end_vm
)) {
215 flush_tlb_kernel_vm();
218 else if (current
->mm
== NULL
) {
219 show_regs(container_of(regs
, struct pt_regs
, regs
));
220 panic("Segfault with no mm");
223 if (SEGV_IS_FIXABLE(&fi
))
224 err
= handle_page_fault(address
, ip
, is_write
, is_user
,
229 * A thread accessed NULL, we get a fault, but CR2 is invalid.
230 * This code is used in __do_copy_from_user() of TT mode.
231 * XXX tt mode is gone, so maybe this isn't needed any more
236 catcher
= current
->thread
.fault_catcher
;
239 else if (catcher
!= NULL
) {
240 current
->thread
.fault_addr
= (void *) address
;
241 UML_LONGJMP(catcher
, 1);
243 else if (current
->thread
.fault_addr
!= NULL
)
244 panic("fault_addr set but no fault catcher");
245 else if (!is_user
&& arch_fixup(ip
, regs
))
249 show_regs(container_of(regs
, struct pt_regs
, regs
));
250 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
254 show_segv_info(regs
);
256 if (err
== -EACCES
) {
257 si
.si_signo
= SIGBUS
;
259 si
.si_code
= BUS_ADRERR
;
260 si
.si_addr
= (void __user
*)address
;
261 current
->thread
.arch
.faultinfo
= fi
;
262 force_sig_info(SIGBUS
, &si
, current
);
264 BUG_ON(err
!= -EFAULT
);
265 si
.si_signo
= SIGSEGV
;
266 si
.si_addr
= (void __user
*) address
;
267 current
->thread
.arch
.faultinfo
= fi
;
268 force_sig_info(SIGSEGV
, &si
, current
);
273 current
->thread
.segv_regs
= NULL
;
278 void relay_signal(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
280 struct faultinfo
*fi
;
281 struct siginfo clean_si
;
283 if (!UPT_IS_USER(regs
)) {
285 printk(KERN_ERR
"Bus error - the host /dev/shm or /tmp "
286 "mount likely just ran out of space\n");
287 panic("Kernel mode signal %d", sig
);
290 arch_examine_signal(sig
, regs
);
292 memset(&clean_si
, 0, sizeof(clean_si
));
293 clean_si
.si_signo
= si
->si_signo
;
294 clean_si
.si_errno
= si
->si_errno
;
295 clean_si
.si_code
= si
->si_code
;
302 fi
= UPT_FAULTINFO(regs
);
303 clean_si
.si_addr
= (void __user
*) FAULT_ADDRESS(*fi
);
304 current
->thread
.arch
.faultinfo
= *fi
;
305 #ifdef __ARCH_SI_TRAPNO
306 clean_si
.si_trapno
= si
->si_trapno
;
310 printk(KERN_ERR
"Attempted to relay unknown signal %d (si_code = %d)\n",
314 force_sig_info(sig
, &clean_si
, current
);
317 void bus_handler(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
319 if (current
->thread
.fault_catcher
!= NULL
)
320 UML_LONGJMP(current
->thread
.fault_catcher
, 1);
322 relay_signal(sig
, si
, regs
);
325 void winch(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
327 do_IRQ(WINCH_IRQ
, regs
);