2 * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
28 * Real mode transition self-tests
30 * This file allows for easy measurement of the time taken to perform
31 * real mode transitions, which may have a substantial overhead when
32 * running under a hypervisor.
36 /* Forcibly enable assertions */
39 #include <ipxe/test.h>
40 #include <ipxe/profile.h>
43 /** Number of sample iterations for profiling */
44 #define PROFILE_COUNT 4096
46 /** Protected-to-real mode transition profiler */
47 static struct profiler p2r_profiler __profiler = { .name = "p2r" };
49 /** Real-to-protected mode transition profiler */
50 static struct profiler r2p_profiler __profiler = { .name = "r2p" };
52 /** Real-mode call profiler */
53 static struct profiler real_call_profiler __profiler = { .name = "real_call" };
55 /** Protected-mode call profiler */
56 static struct profiler prot_call_profiler __profiler = { .name = "prot_call" };
59 * Dummy protected-mode function
61 static void librm_test_prot_call ( void ) {
66 * Perform real mode transition self-tests
69 static void librm_test_exec ( void ) {
71 unsigned long timestamp;
72 unsigned long started;
73 unsigned long stopped;
74 unsigned int discard_d;
76 /* Profile mode transitions. We want to profile each
77 * direction of the transition separately, so perform an RDTSC
78 * while in real mode and tweak the profilers' start/stop
79 * times appropriately.
81 for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
82 profile_start ( &p2r_profiler );
83 __asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t" )
84 : "=a" ( timestamp ), "=d" ( discard_d )
86 profile_start_at ( &r2p_profiler, timestamp );
87 profile_stop ( &r2p_profiler );
88 profile_stop_at ( &p2r_profiler, timestamp );
91 /* Profile complete real-mode call cycle */
92 for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
93 profile_start ( &real_call_profiler );
94 __asm__ __volatile__ ( REAL_CODE ( "" ) : : );
95 profile_stop ( &real_call_profiler );
98 /* Profile complete protected-mode call cycle */
99 for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
100 __asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t"
107 : "=a" ( stopped ), "=d" ( discard_d ),
109 : "i" ( librm_test_prot_call ) );
110 profile_start_at ( &prot_call_profiler, started );
111 profile_stop_at ( &prot_call_profiler, stopped );
115 /** Real mode transition self-test */
116 struct self_test librm_test __self_test = {
118 .exec = librm_test_exec,
121 REQUIRING_SYMBOL ( librm_test );
122 REQUIRE_OBJECT ( test );