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git.proxmox.com Git - mirror_ubuntu-jammy-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/signal.h>
8 #include <linux/hardirq.h>
9 #include <linux/module.h>
10 #include <linux/uaccess.h>
11 #include <linux/sched/debug.h>
12 #include <asm/current.h>
13 #include <asm/pgtable.h>
14 #include <asm/tlbflush.h>
16 #include <as-layout.h>
17 #include <kern_util.h>
22 * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
25 int handle_page_fault(unsigned long address
, unsigned long ip
,
26 int is_write
, int is_user
, int *code_out
)
28 struct mm_struct
*mm
= current
->mm
;
29 struct vm_area_struct
*vma
;
35 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
37 *code_out
= SEGV_MAPERR
;
40 * If the fault was with pagefaults disabled, don't take the fault, just
43 if (faulthandler_disabled())
47 flags
|= FAULT_FLAG_USER
;
49 down_read(&mm
->mmap_sem
);
50 vma
= find_vma(mm
, address
);
53 else if (vma
->vm_start
<= address
)
55 else if (!(vma
->vm_flags
& VM_GROWSDOWN
))
57 else if (is_user
&& !ARCH_IS_STACKGROW(address
))
59 else if (expand_stack(vma
, address
))
63 *code_out
= SEGV_ACCERR
;
65 if (!(vma
->vm_flags
& VM_WRITE
))
67 flags
|= FAULT_FLAG_WRITE
;
69 /* Don't require VM_READ|VM_EXEC for write faults! */
70 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
77 fault
= handle_mm_fault(vma
, address
, flags
);
79 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
82 if (unlikely(fault
& VM_FAULT_ERROR
)) {
83 if (fault
& VM_FAULT_OOM
) {
85 } else if (fault
& VM_FAULT_SIGSEGV
) {
87 } else if (fault
& VM_FAULT_SIGBUS
) {
93 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
94 if (fault
& VM_FAULT_MAJOR
)
98 if (fault
& VM_FAULT_RETRY
) {
99 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
100 flags
|= FAULT_FLAG_TRIED
;
106 pgd
= pgd_offset(mm
, address
);
107 pud
= pud_offset(pgd
, address
);
108 pmd
= pmd_offset(pud
, address
);
109 pte
= pte_offset_kernel(pmd
, address
);
110 } while (!pte_present(*pte
));
113 * The below warning was added in place of
114 * pte_mkyoung(); if (is_write) pte_mkdirty();
115 * If it's triggered, we'd see normally a hang here (a clean pte is
116 * marked read-only to emulate the dirty bit).
117 * However, the generic code can mark a PTE writable but clean on a
118 * concurrent read fault, triggering this harmlessly. So comment it out.
121 WARN_ON(!pte_young(*pte
) || (is_write
&& !pte_dirty(*pte
)));
123 flush_tlb_page(vma
, address
);
125 up_read(&mm
->mmap_sem
);
131 * We ran out of memory, call the OOM killer, and return the userspace
132 * (which will retry the fault, or kill us if we got oom-killed).
134 up_read(&mm
->mmap_sem
);
136 goto out_nosemaphore
;
137 pagefault_out_of_memory();
140 EXPORT_SYMBOL(handle_page_fault
);
142 static void show_segv_info(struct uml_pt_regs
*regs
)
144 struct task_struct
*tsk
= current
;
145 struct faultinfo
*fi
= UPT_FAULTINFO(regs
);
147 if (!unhandled_signal(tsk
, SIGSEGV
))
150 if (!printk_ratelimit())
153 printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
154 task_pid_nr(tsk
) > 1 ? KERN_INFO
: KERN_EMERG
,
155 tsk
->comm
, task_pid_nr(tsk
), FAULT_ADDRESS(*fi
),
156 (void *)UPT_IP(regs
), (void *)UPT_SP(regs
),
159 print_vma_addr(KERN_CONT
" in ", UPT_IP(regs
));
160 printk(KERN_CONT
"\n");
163 static void bad_segv(struct faultinfo fi
, unsigned long ip
)
167 si
.si_signo
= SIGSEGV
;
168 si
.si_code
= SEGV_ACCERR
;
169 si
.si_addr
= (void __user
*) FAULT_ADDRESS(fi
);
170 current
->thread
.arch
.faultinfo
= fi
;
171 force_sig_info(SIGSEGV
, &si
, current
);
174 void fatal_sigsegv(void)
176 force_sigsegv(SIGSEGV
, current
);
177 do_signal(¤t
->thread
.regs
);
179 * This is to tell gcc that we're not returning - do_signal
180 * can, in general, return, but in this case, it's not, since
181 * we just got a fatal SIGSEGV queued.
187 * segv_handler() - the SIGSEGV handler
188 * @sig: the signal number
189 * @unused_si: the signal info struct; unused in this handler
190 * @regs: the ptrace register information
192 * The handler first extracts the faultinfo from the UML ptrace regs struct.
193 * If the userfault did not happen in an UML userspace process, bad_segv is called.
194 * Otherwise the signal did happen in a cloned userspace process, handle it.
196 void segv_handler(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
198 struct faultinfo
* fi
= UPT_FAULTINFO(regs
);
200 if (UPT_IS_USER(regs
) && !SEGV_IS_FIXABLE(fi
)) {
201 show_segv_info(regs
);
202 bad_segv(*fi
, UPT_IP(regs
));
205 segv(*fi
, UPT_IP(regs
), UPT_IS_USER(regs
), regs
);
209 * We give a *copy* of the faultinfo in the regs to segv.
210 * This must be done, since nesting SEGVs could overwrite
211 * the info in the regs. A pointer to the info then would
214 unsigned long segv(struct faultinfo fi
, unsigned long ip
, int is_user
,
215 struct uml_pt_regs
*regs
)
220 int is_write
= FAULT_WRITE(fi
);
221 unsigned long address
= FAULT_ADDRESS(fi
);
223 if (!is_user
&& regs
)
224 current
->thread
.segv_regs
= container_of(regs
, struct pt_regs
, regs
);
226 if (!is_user
&& (address
>= start_vm
) && (address
< end_vm
)) {
227 flush_tlb_kernel_vm();
230 else if (current
->mm
== NULL
) {
231 show_regs(container_of(regs
, struct pt_regs
, regs
));
232 panic("Segfault with no mm");
234 else if (!is_user
&& address
> PAGE_SIZE
&& address
< TASK_SIZE
) {
235 show_regs(container_of(regs
, struct pt_regs
, regs
));
236 panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx",
240 if (SEGV_IS_FIXABLE(&fi
))
241 err
= handle_page_fault(address
, ip
, is_write
, is_user
,
246 * A thread accessed NULL, we get a fault, but CR2 is invalid.
247 * This code is used in __do_copy_from_user() of TT mode.
248 * XXX tt mode is gone, so maybe this isn't needed any more
253 catcher
= current
->thread
.fault_catcher
;
256 else if (catcher
!= NULL
) {
257 current
->thread
.fault_addr
= (void *) address
;
258 UML_LONGJMP(catcher
, 1);
260 else if (current
->thread
.fault_addr
!= NULL
)
261 panic("fault_addr set but no fault catcher");
262 else if (!is_user
&& arch_fixup(ip
, regs
))
266 show_regs(container_of(regs
, struct pt_regs
, regs
));
267 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
271 show_segv_info(regs
);
273 if (err
== -EACCES
) {
274 si
.si_signo
= SIGBUS
;
276 si
.si_code
= BUS_ADRERR
;
277 si
.si_addr
= (void __user
*)address
;
278 current
->thread
.arch
.faultinfo
= fi
;
279 force_sig_info(SIGBUS
, &si
, current
);
281 BUG_ON(err
!= -EFAULT
);
282 si
.si_signo
= SIGSEGV
;
283 si
.si_addr
= (void __user
*) address
;
284 current
->thread
.arch
.faultinfo
= fi
;
285 force_sig_info(SIGSEGV
, &si
, current
);
290 current
->thread
.segv_regs
= NULL
;
295 void relay_signal(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
297 struct faultinfo
*fi
;
298 struct siginfo clean_si
;
300 if (!UPT_IS_USER(regs
)) {
302 printk(KERN_ERR
"Bus error - the host /dev/shm or /tmp "
303 "mount likely just ran out of space\n");
304 panic("Kernel mode signal %d", sig
);
307 arch_examine_signal(sig
, regs
);
309 memset(&clean_si
, 0, sizeof(clean_si
));
310 clean_si
.si_signo
= si
->si_signo
;
311 clean_si
.si_errno
= si
->si_errno
;
312 clean_si
.si_code
= si
->si_code
;
319 fi
= UPT_FAULTINFO(regs
);
320 clean_si
.si_addr
= (void __user
*) FAULT_ADDRESS(*fi
);
321 current
->thread
.arch
.faultinfo
= *fi
;
322 #ifdef __ARCH_SI_TRAPNO
323 clean_si
.si_trapno
= si
->si_trapno
;
327 printk(KERN_ERR
"Attempted to relay unknown signal %d (si_code = %d)\n",
331 force_sig_info(sig
, &clean_si
, current
);
334 void bus_handler(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
336 if (current
->thread
.fault_catcher
!= NULL
)
337 UML_LONGJMP(current
->thread
.fault_catcher
, 1);
339 relay_signal(sig
, si
, regs
);
342 void winch(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
344 do_IRQ(WINCH_IRQ
, regs
);