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selftests/x86/iopl: Extend test to cover IOPL emulation

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Add tests that the now emulated iopl() functionality:

    - does not longer allow user space to disable interrupts.

    - does restore a I/O bitmap when IOPL is dropped

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2019-11-11 23:03:30 +01:00
parent 111e7b15cf
commit e638ad0080
1 changed files with 118 additions and 11 deletions
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129
tools/testing/selftests/x86/iopl.c
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@ -35,6 +35,16 @@ static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
}
static void clearhandler(int sig)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_DFL;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, 0))
err(1, "sigaction");
}
static jmp_buf jmpbuf;
static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
@ -42,25 +52,128 @@ static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
siglongjmp(jmpbuf, 1);
}
static bool try_outb(unsigned short port)
{
sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
if (sigsetjmp(jmpbuf, 1) != 0) {
return false;
} else {
asm volatile ("outb %%al, %w[port]"
: : [port] "Nd" (port), "a" (0));
return true;
}
clearhandler(SIGSEGV);
}
static void expect_ok_outb(unsigned short port)
{
if (!try_outb(port)) {
printf("[FAIL]\toutb to 0x%02hx failed\n", port);
exit(1);
}
printf("[OK]\toutb to 0x%02hx worked\n", port);
}
static void expect_gp_outb(unsigned short port)
{
if (try_outb(port)) {
printf("[FAIL]\toutb to 0x%02hx worked\n", port);
nerrs++;
}
printf("[OK]\toutb to 0x%02hx failed\n", port);
}
static bool try_cli(void)
{
sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
if (sigsetjmp(jmpbuf, 1) != 0) {
return false;
} else {
asm volatile ("cli");
return true;
}
clearhandler(SIGSEGV);
}
static bool try_sti(void)
{
sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
if (sigsetjmp(jmpbuf, 1) != 0) {
return false;
} else {
asm volatile ("sti");
return true;
}
clearhandler(SIGSEGV);
}
static void expect_gp_sti(void)
{
if (try_sti()) {
printf("[FAIL]\tSTI worked\n");
nerrs++;
} else {
printf("[OK]\tSTI faulted\n");
}
}
static void expect_gp_cli(void)
{
if (try_cli()) {
printf("[FAIL]\tCLI worked\n");
nerrs++;
} else {
printf("[OK]\tCLI faulted\n");
}
}
int main(void)
{
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(0, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
err(1, "sched_setaffinity to CPU 0");
/* Probe for iopl support. Note that iopl(0) works even as nonroot. */
if (iopl(3) != 0) {
switch(iopl(3)) {
case 0:
break;
case -ENOSYS:
printf("[OK]\tiopl() nor supported\n");
return 0;
default:
printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
errno);
return 0;
}
/* Restore our original state prior to starting the test. */
/* Make sure that CLI/STI are blocked even with IOPL level 3 */
expect_gp_cli();
expect_gp_sti();
expect_ok_outb(0x80);
/* Establish an I/O bitmap to test the restore */
if (ioperm(0x80, 1, 1) != 0)
err(1, "ioperm(0x80, 1, 1) failed\n");
/* Restore our original state prior to starting the fork test. */
if (iopl(0) != 0)
err(1, "iopl(0)");
/*
* Verify that IOPL emulation is disabled and the I/O bitmap still
* works.
*/
expect_ok_outb(0x80);
expect_gp_outb(0xed);
/* Drop the I/O bitmap */
if (ioperm(0x80, 1, 0) != 0)
err(1, "ioperm(0x80, 1, 0) failed\n");
pid_t child = fork();
if (child == -1)
err(1, "fork");
@ -90,14 +203,9 @@ int main(void)
printf("[RUN]\tparent: write to 0x80 (should fail)\n");
sethandler(SIGSEGV, sigsegv, 0);
if (sigsetjmp(jmpbuf, 1) != 0) {
printf("[OK]\twrite was denied\n");
} else {
asm volatile ("outb %%al, $0x80" : : "a" (0));
printf("[FAIL]\twrite was allowed\n");
nerrs++;
}
expect_gp_outb(0x80);
expect_gp_cli();
expect_gp_sti();
/* Test the capability checks. */
printf("\tiopl(3)\n");
@ -133,4 +241,3 @@ int main(void)
done:
return nerrs ? 1 : 0;
}