122 lines
3.6 KiB
C
122 lines
3.6 KiB
C
/*
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* Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/** @file
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*
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* Real mode transition self-tests
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*
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* This file allows for easy measurement of the time taken to perform
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* real mode transitions, which may have a substantial overhead when
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* running under a hypervisor.
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*
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*/
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/* Forcibly enable assertions */
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#undef NDEBUG
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#include <ipxe/test.h>
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#include <ipxe/profile.h>
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#include <realmode.h>
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/** Number of sample iterations for profiling */
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#define PROFILE_COUNT 4096
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/** Protected-to-real mode transition profiler */
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static struct profiler p2r_profiler __profiler = { .name = "p2r" };
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/** Real-to-protected mode transition profiler */
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static struct profiler r2p_profiler __profiler = { .name = "r2p" };
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/** Real-mode call profiler */
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static struct profiler real_call_profiler __profiler = { .name = "real_call" };
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/** Protected-mode call profiler */
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static struct profiler prot_call_profiler __profiler = { .name = "prot_call" };
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/**
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* Dummy protected-mode function
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*/
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static void librm_test_prot_call ( void ) {
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/* Do nothing */
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}
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/**
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* Perform real mode transition self-tests
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*
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*/
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static void librm_test_exec ( void ) {
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unsigned int i;
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unsigned long timestamp;
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unsigned long started;
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unsigned long stopped;
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unsigned int discard_d;
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/* Profile mode transitions. We want to profile each
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* direction of the transition separately, so perform an RDTSC
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* while in real mode and tweak the profilers' start/stop
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* times appropriately.
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*/
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for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
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profile_start ( &p2r_profiler );
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__asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t" )
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: "=a" ( timestamp ), "=d" ( discard_d )
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: );
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profile_start_at ( &r2p_profiler, timestamp );
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profile_stop ( &r2p_profiler );
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profile_stop_at ( &p2r_profiler, timestamp );
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}
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/* Profile complete real-mode call cycle */
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for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
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profile_start ( &real_call_profiler );
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__asm__ __volatile__ ( REAL_CODE ( "" ) : : );
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profile_stop ( &real_call_profiler );
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}
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/* Profile complete protected-mode call cycle */
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for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
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__asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t"
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"movl %0, %2\n\t"
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"pushl %3\n\t"
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"pushw %%cs\n\t"
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"call prot_call\n\t"
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"addw $4, %%sp\n\t"
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"rdtsc\n\t" )
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: "=a" ( stopped ), "=d" ( discard_d ),
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"=r" ( started )
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: "i" ( librm_test_prot_call ) );
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profile_start_at ( &prot_call_profiler, started );
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profile_stop_at ( &prot_call_profiler, stopped );
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}
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}
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/** Real mode transition self-test */
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struct self_test librm_test __self_test = {
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.name = "librm",
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.exec = librm_test_exec,
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};
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REQUIRE_OBJECT ( test );
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