litmus-rt.git - The LITMUS^RT kernel.

	Commit message (Expand)	Author	Age
*	irq_work: Add generic hardirq context callbacks	Peter Zijlstra	2010-10-18

/* * 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 "skas.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; fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) { 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; 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); pagefault_out_of_memory(); return 0; } 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 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 { 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 (!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); current->thread.arch.faultinfo = *UPT_FAULTINFO(regs); force_sig(sig, current); } 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); } void winch(int sig, struct uml_pt_regs *regs) { do_IRQ(WINCH_IRQ, regs); } void trap_init(void) { }