[PATCH] x86/oprofile: remove compat accessors usage from backtrace

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Remove the unneeded usage of the compat layer to copy frame pointers
from guest address space. Instead just use raw_copy_from_guest.

Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Just build tested. Note sure I'm missing something, since using the
compat layer here was IMO much more complicated than just using the
raw accessors.
---
 xen/arch/x86/oprofile/backtrace.c | 26 +++-----------------------
 1 file changed, 3 insertions(+), 23 deletions(-)

diff --git a/xen/arch/x86/oprofile/backtrace.c 
b/xen/arch/x86/oprofile/backtrace.c
index bd5d1b0f6ce..45f7fb65fa2 100644
--- a/xen/arch/x86/oprofile/backtrace.c
+++ b/xen/arch/x86/oprofile/backtrace.c
@@ -20,7 +20,6 @@ struct __packed frame_head {
     unsigned long ret;
 };
 typedef struct frame_head frame_head_t;
-DEFINE_XEN_GUEST_HANDLE(frame_head_t);
 
 struct __packed frame_head_32bit {
     uint32_t ebp;
@@ -43,7 +42,6 @@ dump_hypervisor_backtrace(struct vcpu *vcpu, const struct 
frame_head *head,
     return head->ebp;
 }
 
-#ifdef CONFIG_COMPAT
 static inline int is_32bit_vcpu(struct vcpu *vcpu)
 {
     if (is_hvm_vcpu(vcpu))
@@ -51,7 +49,6 @@ static inline int is_32bit_vcpu(struct vcpu *vcpu)
     else
         return is_pv_32bit_vcpu(vcpu);
 }
-#endif
 
 static struct frame_head *
 dump_guest_backtrace(struct vcpu *vcpu, const struct frame_head *head,
@@ -59,34 +56,17 @@ dump_guest_backtrace(struct vcpu *vcpu, const struct 
frame_head *head,
 {
     frame_head_t bufhead;
 
-#ifdef CONFIG_COMPAT
     if ( is_32bit_vcpu(vcpu) )
     {
-        DEFINE_COMPAT_HANDLE(frame_head32_t);
-        __compat_handle_const_frame_head32_t guest_head =
-            { .c = (unsigned long)head };
         frame_head32_t bufhead32;
 
-        /* Also check accessibility of one struct frame_head beyond */
-        if (!compat_handle_okay(guest_head, 2))
-            return 0;
-        if (__copy_from_compat(&bufhead32, guest_head, 1))
+        if (raw_copy_from_guest(&bufhead32, head, sizeof(bufhead32)))
             return 0;
         bufhead.ebp = (struct frame_head *)(unsigned long)bufhead32.ebp;
         bufhead.ret = bufhead32.ret;
     }
-    else
-#endif
-    {
-        XEN_GUEST_HANDLE_PARAM(const_frame_head_t) guest_head =
-            const_guest_handle_from_ptr(head, frame_head_t);
-
-        /* Also check accessibility of one struct frame_head beyond */
-        if (!guest_handle_okay(guest_head, 2))
-            return 0;
-        if (__copy_from_guest(&bufhead, guest_head, 1))
-            return 0;
-    }
+    else if (raw_copy_from_guest(&bufhead, head, sizeof(bufhead)))
+        return 0;
     
     if (!xenoprof_add_trace(vcpu, bufhead.ret, mode))
         return 0;
-- 
2.30.1