x86/ioemul: Misc improvements to ioport_emulate.c

Put the opcode into an array and use memcpy. This allows the compiled code to be written with two movs, rather than 10 mov $imm8's. Also, drop trailing whitespace in the file. Signed-off-by: Andrew Cooper <[email protected]> Reviewed-by: Jan Beulich <[email protected]>
MultipleCrashes · Feb 1, 2018 · f2f6843 · f2f6843
1 parent 98dc960
commit f2f6843
Showing 1 changed file with 13 additions and 21 deletions.
diff --git a/xen/arch/x86/ioport_emulate.c b/xen/arch/x86/ioport_emulate.c
@@ -1,6 +1,6 @@
 /******************************************************************************
  * ioport_emulate.c
- * 
+ *
  * Handle I/O port access quirks of various platforms.
  */
 
@@ -11,32 +11,24 @@
 static bool ioemul_handle_proliant_quirk(
     u8 opcode, char *io_emul_stub, struct cpu_user_regs *regs)
 {
+    static const char stub[] = {
+        0x9c,       /*    pushf           */
+        0xfa,       /*    cli             */
+        0xee,       /*    out %al, %dx    */
+        0xec,       /* 1: in %dx, %al     */
+        0xa8, 0x80, /*    test $0x80, %al */
+        0x75, 0xfb, /*    jnz 1b          */
+        0x9d,       /*    popf            */
+        0xc3,       /*    ret             */
+    };
     uint16_t port = regs->dx;
     uint8_t value = regs->al;
 
     if ( (opcode != 0xee) || (port != 0xcd4) || !(value & 0x80) )
         return false;
 
-    /*    pushf */
-    io_emul_stub[0] = 0x9c;
-    /*    cli */
-    io_emul_stub[1] = 0xfa;
-    /*    out %al,%dx */
-    io_emul_stub[2] = 0xee;
-    /* 1: in %dx,%al */
-    io_emul_stub[3] = 0xec;
-    /*    test $0x80,%al */
-    io_emul_stub[4] = 0xa8;
-    io_emul_stub[5] = 0x80;
-    /*    jnz 1b */
-    io_emul_stub[6] = 0x75;
-    io_emul_stub[7] = 0xfb;
-    /*    popf */
-    io_emul_stub[8] = 0x9d;
-    /*    ret */
-    io_emul_stub[9] = 0xc3;
-
-    BUILD_BUG_ON(IOEMUL_QUIRK_STUB_BYTES < 10);
+    memcpy(io_emul_stub, stub, sizeof(stub));
+    BUILD_BUG_ON(IOEMUL_QUIRK_STUB_BYTES < sizeof(stub));
 
     return true;
 }