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 00000000000..ac70fa5a2e2
--- /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)
+{
+}