xen: arm: correct return value of raw_copy_{to/from}_guest_*, raw_clear_guest

This is a generic interface which is supposed to return the number of bytes
which were not copied. Make it so.

Update the incorrect callers prepare_dtb, decode_thumb{2} and
xenmem_add_to_physmap_range.

In the xenmem_add_to_physmap_range case, observe that we are not propagating
errors from xenmem_add_to_physmap_one and do so.

In the decode_thumb case and an emacs magic block to decode.c

Make the flush_dcache parameter to the helper an int while at it.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>

xen/arch/arm/decode.c

@@ -36,12 +36,10 @@ static void update_dabt(struct hsr_dabt *dabt, int reg,
 static int decode_thumb2(register_t pc, struct hsr_dabt *dabt, uint16_t hw1)
 {
     uint16_t hw2;
-    int rc;
     uint16_t rt;
 
-    rc = raw_copy_from_guest(&hw2, (void *__user)(pc + 2), sizeof (hw2));
-    if ( rc )
-        return rc;
+    if ( raw_copy_from_guest(&hw2, (void *__user)(pc + 2), sizeof (hw2)) )
+        return -EFAULT;
 
     rt = (hw2 >> 12) & 0x7;
 
@@ -88,11 +86,9 @@ bad_thumb2:
 static int decode_thumb(register_t pc, struct hsr_dabt *dabt)
 {
     uint16_t instr;
-    int rc;
 
-    rc = raw_copy_from_guest(&instr, (void * __user)pc, sizeof (instr));
-    if ( rc )
-        return rc;
+    if ( raw_copy_from_guest(&instr, (void * __user)pc, sizeof (instr)) )
+        return -EFAULT;
 
     switch ( instr >> 12 )
     {
@@ -163,3 +159,13 @@ int decode_instruction(const struct cpu_user_regs *regs, struct hsr_dabt *dabt)
 
     return 1;
 }
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */

xen/arch/arm/domain_build.c

@@ -907,15 +907,15 @@ static int prepare_dtb(struct domain *d, struct kernel_info *kinfo)
 static void dtb_load(struct kernel_info *kinfo)
 {
     void * __user dtb_virt = (void * __user)(register_t)kinfo->dtb_paddr;
-    unsigned long rc;
+    unsigned long left;
 
     printk("Loading dom0 DTB to 0x%"PRIpaddr"-0x%"PRIpaddr"\n",
            kinfo->dtb_paddr, kinfo->dtb_paddr + fdt_totalsize(kinfo->fdt));
 
-    rc = raw_copy_to_guest_flush_dcache(dtb_virt, kinfo->fdt,
+    left = raw_copy_to_guest_flush_dcache(dtb_virt, kinfo->fdt,
                                         fdt_totalsize(kinfo->fdt));
-    if ( rc != 0 )
-        panic("Unable to copy the DTB to dom0 memory (rc = %lu)", rc);
+    if ( left != 0 )
+        panic("Unable to copy the DTB to dom0 memory (left = %lu bytes)", left);
     xfree(kinfo->fdt);
 }
 

xen/arch/arm/guestcopy.c

@@ -6,21 +6,19 @@
 #include <asm/guest_access.h>
 
 static unsigned long raw_copy_to_guest_helper(void *to, const void *from,
-                                              unsigned len, unsigned flush_dcache)
+                                              unsigned len, int flush_dcache)
 {
     /* XXX needs to handle faults */
     unsigned offset = (vaddr_t)to & ~PAGE_MASK;
 
     while ( len )
     {
-        int rc;
         paddr_t g;
         void *p;
         unsigned size = min(len, (unsigned)PAGE_SIZE - offset);
 
-        rc = gvirt_to_maddr((vaddr_t) to, &g);
-        if ( rc )
-            return rc;
+        if ( gvirt_to_maddr((vaddr_t) to, &g) )
+            return len;
 
         p = map_domain_page(g>>PAGE_SHIFT);
         p += offset;
@@ -56,14 +54,12 @@ unsigned long raw_clear_guest(void *to, unsigned len)
 
     while ( len )
     {
-        int rc;
         paddr_t g;
         void *p;
         unsigned size = min(len, (unsigned)PAGE_SIZE - offset);
 
-        rc = gvirt_to_maddr((vaddr_t) to, &g);
-        if ( rc )
-            return rc;
+        if ( gvirt_to_maddr((vaddr_t) to, &g) )
+            return len;
 
         p = map_domain_page(g>>PAGE_SHIFT);
         p += offset;
@@ -84,14 +80,12 @@ unsigned long raw_copy_from_guest(void *to, const void __user *from, unsigned le
 
     while ( len )
     {
-        int rc;
         paddr_t g;
         void *p;
         unsigned size = min(len, (unsigned)(PAGE_SIZE - offset));
 
-        rc = gvirt_to_maddr((vaddr_t) from & PAGE_MASK, &g);
-        if ( rc )
-            return rc;
+        if ( gvirt_to_maddr((vaddr_t) from & PAGE_MASK, &g) )
+            return len;
 
         p = map_domain_page(g>>PAGE_SHIFT);
         p += ((vaddr_t)from & (~PAGE_MASK));

xen/arch/arm/mm.c

@@ -1067,22 +1067,33 @@ static int xenmem_add_to_physmap_range(struct domain *d,
         xen_ulong_t idx;
         xen_pfn_t gpfn;
 
-        rc = copy_from_guest_offset(&idx, xatpr->idxs, xatpr->size-1, 1);
-        if ( rc < 0 )
+        if ( unlikely(copy_from_guest_offset(&idx, xatpr->idxs,
+                                             xatpr->size-1, 1)) )
+        {
+            rc = -EFAULT;
             goto out;
+        }
 
-        rc = copy_from_guest_offset(&gpfn, xatpr->gpfns, xatpr->size-1, 1);
-        if ( rc < 0 )
+        if ( unlikely(copy_from_guest_offset(&gpfn, xatpr->gpfns,
+                                             xatpr->size-1, 1)) )
+        {
+            rc = -EFAULT;
             goto out;
+        }
 
         rc = xenmem_add_to_physmap_one(d, xatpr->space,
                                        xatpr->foreign_domid,
                                        idx, gpfn);
-
-        rc = copy_to_guest_offset(xatpr->errs, xatpr->size-1, &rc, 1);
         if ( rc < 0 )
             goto out;
 
+        if ( unlikely(copy_to_guest_offset(xatpr->errs,
+                                           xatpr->size-1, &rc, 1)) );
+        {
+            rc = -EFAULT;
+            goto out;
+        }
+
         xatpr->size--;
 
         /* Check for continuation if it's not the last interation */