1 files changed, 251 insertions, 0 deletions

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
new file mode 100644
index 000000000000..ac70fa5a2e2a
--- /dev/null
+++ b/arch/um/kernel/trap.c
@@ -0,0 +1,251 @@
+/*
+ * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include "linux/kernel.h"
+#include "asm/errno.h"
+#include "linux/sched.h"
+#include "linux/mm.h"
+#include "linux/spinlock.h"
+#include "linux/config.h"
+#include "linux/init.h"
+#include "linux/ptrace.h"
+#include "asm/semaphore.h"
+#include "asm/pgtable.h"
+#include "asm/pgalloc.h"
+#include "asm/tlbflush.h"
+#include "asm/a.out.h"
+#include "asm/current.h"
+#include "asm/irq.h"
+#include "sysdep/sigcontext.h"
+#include "user_util.h"
+#include "kern_util.h"
+#include "kern.h"
+#include "chan_kern.h"
+#include "mconsole_kern.h"
+#include "mem.h"
+#include "mem_kern.h"
+#include "sysdep/sigcontext.h"
+#include "sysdep/ptrace.h"
+#include "os.h"
+#ifdef CONFIG_MODE_SKAS
+#include "skas.h"
+#endif
+#include "os.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 {
+survive:
+                switch (handle_mm_fault(mm, vma, address, is_write)){
+                case VM_FAULT_MINOR:
+                        current->min_flt++;
+                        break;
+                case VM_FAULT_MAJOR:
+                        current->maj_flt++;
+                        break;
+                case VM_FAULT_SIGBUS:
+                        err = -EACCES;
+                        goto out;
+                case VM_FAULT_OOM:
+                        err = -ENOMEM;
+                        goto out_of_memory;
+                default:
+                        BUG();
+                }
+                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);
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+out_of_memory:
+        if (current->pid == 1) {
+                up_read(&mm->mmap_sem);
+                yield();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        goto out;
+}
+
+void segv_handler(int sig, union 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);
+}
+
+struct kern_handlers handlinfo_kern = {
+        .relay_signal = relay_signal,
+        .winch = winch,
+        .bus_handler = relay_signal,
+        .page_fault = segv_handler,
+        .sigio_handler = sigio_handler,
+        .timer_handler = timer_handler
+};
+/*
+ * 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, void *sc)
+{
+        struct siginfo si;
+        void *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)
+                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. */
+                address = 0;
+        }
+
+        catcher = current->thread.fault_catcher;
+        if(!err)
+                return(0);
+        else if(catcher != NULL){
+                current->thread.fault_addr = (void *) address;
+                do_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, sc))
+                return(0);
+
+        if(!is_user)
+                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 if (err == -ENOMEM) {
+                printk("VM: killing process %s\n", current->comm);
+                do_exit(SIGKILL);
+        } 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 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 relay_signal(int sig, union uml_pt_regs *regs)
+{
+        if(arch_handle_signal(sig, regs)) return;
+        if(!UPT_IS_USER(regs))
+                panic("Kernel mode signal %d", sig);
+        current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
+        force_sig(sig, current);
+}
+
+void bus_handler(int sig, union uml_pt_regs *regs)
+{
+        if(current->thread.fault_catcher != NULL)
+                do_longjmp(current->thread.fault_catcher, 1);
+        else relay_signal(sig, regs);
+}
+
+void winch(int sig, union uml_pt_regs *regs)
+{
+        do_IRQ(WINCH_IRQ, regs);
+}
+
+void trap_init(void)
+{
+}