/* * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Licensed under the GPL */ #include <linux/mm.h>#include <linux/sched/signal.h>#include <linux/hardirq.h>#include <linux/module.h>#include <linux/uaccess.h>#include <linux/sched/debug.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> /* * 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; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; *code_out = SEGV_MAPERR; /* * If the fault was with pagefaults disabled, don't take the fault, just * fail. */ if (faulthandler_disabled()) goto out_nosemaphore; if (is_user) flags |= FAULT_FLAG_USER;retry: 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) { if (!(vma->vm_flags & VM_WRITE)) goto out; flags |= FAULT_FLAG_WRITE; } else { /* Don't require VM_READ|VM_EXEC for write faults! */ if (!(vma->vm_flags & (VM_READ | VM_EXEC))) goto out; } do { int fault; fault = handle_mm_fault(vma, address, flags); if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) goto out_nosemaphore; if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) { goto out_of_memory; } else if (fault & VM_FAULT_SIGSEGV) { goto out; } else if (fault & VM_FAULT_SIGBUS) { err = -EACCES; goto out; } BUG(); } if (flags & FAULT_FLAG_ALLOW_RETRY) { if (fault & VM_FAULT_MAJOR) current->maj_flt++; else current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; flags |= FAULT_FLAG_TRIED; goto retry; } } 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); if (!is_user) goto out_nosemaphore; pagefault_out_of_memory(); return 0;}EXPORT_SYMBOL(handle_page_fault); 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(¤t->thread.regs); /* * 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();} /** * segv_handler() - the SIGSEGV handler * @sig: the signal number * @unused_si: the signal info struct; unused in this handler * @regs: the ptrace register information * * The handler first extracts the faultinfo from the UML ptrace regs struct. * If the userfault did not happen in an UML userspace process, bad_segv is called. * Otherwise the signal did happen in a cloned userspace process, handle it. */void segv_handler(int sig, struct siginfo *unused_si, 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 && regs) current->thread.segv_regs = container_of(regs, struct pt_regs, regs); if (!is_user && (address >= start_vm) && (address < end_vm)) { flush_tlb_kernel_vm(); goto out; } else if (current->mm == NULL) { show_regs(container_of(regs, struct pt_regs, regs)); panic("Segfault with no mm"); } else if (!is_user && address > PAGE_SIZE && address < TASK_SIZE) { show_regs(container_of(regs, struct pt_regs, regs)); panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx", address, ip); } if (SEGV_IS_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) goto out; 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)) goto out; 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); } out: if (regs) current->thread.segv_regs = NULL; return 0;} void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs){ struct faultinfo *fi; struct siginfo clean_si; 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); memset(&clean_si, 0, sizeof(clean_si)); clean_si.si_signo = si->si_signo; clean_si.si_errno = si->si_errno; clean_si.si_code = si->si_code; switch (sig) { case SIGILL: case SIGFPE: case SIGSEGV: case SIGBUS: case SIGTRAP: fi = UPT_FAULTINFO(regs); clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi); current->thread.arch.faultinfo = *fi;#ifdef __ARCH_SI_TRAPNO clean_si.si_trapno = si->si_trapno;#endif break; default: printk(KERN_ERR "Attempted to relay unknown signal %d (si_code = %d)\n", sig, si->si_code); } force_sig_info(sig, &clean_si, current);} void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs){ if (current->thread.fault_catcher != NULL) UML_LONGJMP(current->thread.fault_catcher, 1); else relay_signal(sig, si, regs);} void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs){ do_IRQ(WINCH_IRQ, regs);} void trap_init(void){}
/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/hardirq.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/sched/debug.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>
/*
* 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;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
*code_out = SEGV_MAPERR;
/*
* If the fault was with pagefaults disabled, don't take the fault, just
* fail.
*/
if (faulthandler_disabled())
goto out_nosemaphore;
if (is_user)
flags |= FAULT_FLAG_USER;
retry:
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) {
if (!(vma->vm_flags & VM_WRITE))
goto out;
flags |= FAULT_FLAG_WRITE;
} else {
/* Don't require VM_READ|VM_EXEC for write faults! */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto out;
}
do {
int fault;
fault = handle_mm_fault(vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
goto out_nosemaphore;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
} else if (fault & VM_FAULT_SIGSEGV) {
goto out;
} else if (fault & VM_FAULT_SIGBUS) {
err = -EACCES;
goto out;
}
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
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);
if (!is_user)
goto out_nosemaphore;
pagefault_out_of_memory();
return 0;
}
EXPORT_SYMBOL(handle_page_fault);
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(¤t->thread.regs);
/*
* 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();
}
/**
* segv_handler() - the SIGSEGV handler
* @sig: the signal number
* @unused_si: the signal info struct; unused in this handler
* @regs: the ptrace register information
*
* The handler first extracts the faultinfo from the UML ptrace regs struct.
* If the userfault did not happen in an UML userspace process, bad_segv is called.
* Otherwise the signal did happen in a cloned userspace process, handle it.
*/
void segv_handler(int sig, struct siginfo *unused_si, 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 && regs)
current->thread.segv_regs = container_of(regs, struct pt_regs, regs);
if (!is_user && (address >= start_vm) && (address < end_vm)) {
flush_tlb_kernel_vm();
goto out;
}
else if (current->mm == NULL) {
show_regs(container_of(regs, struct pt_regs, regs));
panic("Segfault with no mm");
}
else if (!is_user && address > PAGE_SIZE && address < TASK_SIZE) {
show_regs(container_of(regs, struct pt_regs, regs));
panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx",
address, ip);
}
if (SEGV_IS_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)
goto out;
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))
goto out;
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);
}
out:
if (regs)
current->thread.segv_regs = NULL;
return 0;
}
void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs)
{
struct faultinfo *fi;
struct siginfo clean_si;
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);
memset(&clean_si, 0, sizeof(clean_si));
clean_si.si_signo = si->si_signo;
clean_si.si_errno = si->si_errno;
clean_si.si_code = si->si_code;
switch (sig) {
case SIGILL:
case SIGFPE:
case SIGSEGV:
case SIGBUS:
case SIGTRAP:
fi = UPT_FAULTINFO(regs);
clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi);
current->thread.arch.faultinfo = *fi;
#ifdef __ARCH_SI_TRAPNO
clean_si.si_trapno = si->si_trapno;
#endif
break;
default:
printk(KERN_ERR "Attempted to relay unknown signal %d (si_code = %d)\n",
sig, si->si_code);
}
force_sig_info(sig, &clean_si, current);
}
void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs)
{
if (current->thread.fault_catcher != NULL)
UML_LONGJMP(current->thread.fault_catcher, 1);
else
relay_signal(sig, si, regs);
}
void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
{
do_IRQ(WINCH_IRQ, regs);
}
void trap_init(void)
{
}