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selftests/x86: In syscall_nt, test NT|TF as well 

Setting TF prevents fastpath returns in most cases, which causes the
test to fail on 32-bit kernels because 32-bit kernels do not, in
fact, handle NT correctly on SYSENTER entries.

The next patch will fix 32-bit kernels.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
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: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/bd4bb48af6b10c0dc84aec6dbcf487ed25683495.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2016-03-09 19:00:24 -08:00 committed by Ingo Molnar
parent 0dd0036f6e
commit a318beea22
1 changed files with 49 additions and 8 deletions
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57
tools/testing/selftests/x86/syscall_nt.c
View File

@ -17,6 +17,9 @@
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <err.h>
#include <sys/syscall.h>
#include <asm/processor-flags.h>
@ -26,6 +29,8 @@
# define WIDTH "l"
#endif
static unsigned int nerrs;
static unsigned long get_eflags(void)
{
unsigned long eflags;
@ -39,16 +44,52 @@ static void set_eflags(unsigned long eflags)
: : "rm" (eflags) : "flags");
}
int main()
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
int flags)
{
printf("[RUN]\tSet NT and issue a syscall\n");
set_eflags(get_eflags() | X86_EFLAGS_NT);
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = handler;
sa.sa_flags = SA_SIGINFO | flags;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, 0))
err(1, "sigaction");
}
static void sigtrap(int sig, siginfo_t *si, void *ctx_void)
{
}
static void do_it(unsigned long extraflags)
{
unsigned long flags;
set_eflags(get_eflags() | extraflags);
syscall(SYS_getpid);
if (get_eflags() & X86_EFLAGS_NT) {
printf("[OK]\tThe syscall worked and NT is still set\n");
return 0;
flags = get_eflags();
if ((flags & extraflags) == extraflags) {
printf("[OK]\tThe syscall worked and flags are still set\n");
} else {
printf("[FAIL]\tThe syscall worked but NT was cleared\n");
return 1;
printf("[FAIL]\tThe syscall worked but flags were cleared (flags = 0x%lx but expected 0x%lx set)\n",
flags, extraflags);
nerrs++;
}
}
int main(void)
{
printf("[RUN]\tSet NT and issue a syscall\n");
do_it(X86_EFLAGS_NT);
/*
* Now try it again with TF set -- TF forces returns via IRET in all
* cases except non-ptregs-using 64-bit full fast path syscalls.
*/
sethandler(SIGTRAP, sigtrap, 0);
printf("[RUN]\tSet NT|TF and issue a syscall\n");
do_it(X86_EFLAGS_NT | X86_EFLAGS_TF);
return nerrs == 0 ? 0 : 1;
}