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selftests/x86: Add syscall_nt selftest

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I've had this sitting around for a while.  Add it to the
selftests tree.  Far Cry running under Wine depends on this
behavior.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ee4d63799a9e5294b70930618b71d04d2770eb2d.1439838962.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-08-17 12:22:52 -07:00 committed by Ingo Molnar
parent 33f3df41d0
commit a9c909ce8c
2 changed files with 55 additions and 1 deletions
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2
tools/testing/selftests/x86/Makefile
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@ -4,7 +4,7 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)

54
tools/testing/selftests/x86/syscall_nt.c Normal file
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@ -0,0 +1,54 @@
/*
* syscall_nt.c - checks syscalls with NT set
* Copyright (c) 2014-2015 Andrew Lutomirski
*
* This program is free software; you can redistribute it and/or modify
* it under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* Some obscure user-space code requires the ability to make system calls
* with FLAGS.NT set. Make sure it works.
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/processor-flags.h>
#ifdef __x86_64__
# define WIDTH "q"
#else
# define WIDTH "l"
#endif
static unsigned long get_eflags(void)
{
unsigned long eflags;
asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags));
return eflags;
}
static void set_eflags(unsigned long eflags)
{
asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH
: : "rm" (eflags) : "flags");
}
int main()
{
printf("[RUN]\tSet NT and issue a syscall\n");
set_eflags(get_eflags() | X86_EFLAGS_NT);
syscall(SYS_getpid);
if (get_eflags() & X86_EFLAGS_NT) {
printf("[OK]\tThe syscall worked and NT is still set\n");
return 0;
} else {
printf("[FAIL]\tThe syscall worked but NT was cleared\n");
return 1;
}
}