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

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>

diff --git a/tools/testing/selftests/x86/iopl.c b/tools/testing/selftests/x86/iopl.c
index 6aa27f34644c495ecb81b379521b0b795372eb0d..bab2f6e06b63d06a01fa03d32623bebd3bc9755b 100644 (file)
--- a/tools/testing/selftests/x86/iopl.c
+++ b/tools/testing/selftests/x86/iopl.c
@@ -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;
 }
-