Merge branch 'torvalds/master'

[firefly-linux-kernel-4.4.55.git] / arch / um / kernel / trap.c

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 089f3987e273a2c3f9576ef923dbd8ba8648cca5..98783dd0fa2ea697a50cb65afb661aa7f7bf0322 100644 (file)
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -7,6 +7,7 @@
 #include <linux/sched.h>
 #include <linux/hardirq.h>
 #include <linux/module.h>
+#include <linux/uaccess.h>
 #include <asm/current.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
@@ -30,18 +31,19 @@ int handle_page_fault(unsigned long address, unsigned long ip,
        pmd_t *pmd;
        pte_t *pte;
        int err = -EFAULT;
-       unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-                                (is_write ? FAULT_FLAG_WRITE : 0);
+       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
+        * If the fault was with pagefaults disabled, don't take the fault, just
         * fail.
         */
-       if (in_atomic())
+       if (faulthandler_disabled())
                goto out_nosemaphore;
 
+       if (is_user)
+               flags |= FAULT_FLAG_USER;
 retry:
        down_read(&mm->mmap_sem);
        vma = find_vma(mm, address);
@@ -58,12 +60,15 @@ retry:
 
 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;
+       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;
@@ -76,6 +81,8 @@ good_area:
                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;
@@ -124,6 +131,8 @@ out_of_memory:
         * (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;
 }
@@ -164,7 +173,7 @@ static void bad_segv(struct faultinfo fi, unsigned long ip)
 void fatal_sigsegv(void)
 {
        force_sigsegv(SIGSEGV, current);
-       do_signal();
+       do_signal(&current->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
@@ -200,16 +209,24 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
        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();
-               return 0;
+               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) || SEGV_MAYBE_FIXABLE(&fi))
+       if (SEGV_IS_FIXABLE(&fi))
                err = handle_page_fault(address, ip, is_write, is_user,
                                        &si.si_code);
        else {
@@ -224,7 +241,7 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
 
        catcher = current->thread.fault_catcher;
        if (!err)
-               return 0;
+               goto out;
        else if (catcher != NULL) {
                current->thread.fault_addr = (void *) address;
                UML_LONGJMP(catcher, 1);
@@ -232,7 +249,7 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
        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;
+               goto out;
 
        if (!is_user) {
                show_regs(container_of(regs, struct pt_regs, regs));
@@ -256,6 +273,11 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
                current->thread.arch.faultinfo = fi;
                force_sig_info(SIGSEGV, &si, current);
        }
+
+out:
+       if (regs)
+               current->thread.segv_regs = NULL;
+
        return 0;
 }