From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/um/kernel/trap.c | 332 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 332 insertions(+) create mode 100644 arch/um/kernel/trap.c (limited to 'arch/um/kernel/trap.c') diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c new file mode 100644 index 000000000..8e4daf44e --- /dev/null +++ b/arch/um/kernel/trap.c @@ -0,0 +1,332 @@ +/* + * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * 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 during atomic operation, don't take the fault, just + * fail. + */ + if (in_atomic()) + 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(mm, 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(); + /* + * 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 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"); + } + + 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) +{ +} -- cgit v1.2.3-54-g00ecf