syscall_exit_regs: Test more things

This fails on current kernels.  Oops.

1 files changed, 150 insertions, 12 deletions

diff --git a/syscall_exit_regs.c b/syscall_exit_regs.c
index 337dbf5..a794981 100644
--- a/syscall_exit_regs.c
+++ b/syscall_exit_regs.c
@@ -1,29 +1,167 @@
+#define _GNU_SOURCE
+
 #include <stdio.h>
+#include <sys/prctl.h>
 #include <asm/prctl.h>
+#include <sys/ucontext.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <err.h>
 
-int main()
+static volatile sig_atomic_t got_sigill = 0;
+
+extern int arch_prctl(int, unsigned long);
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	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");
+}
+
+#ifdef __x86_64__
+# define REG_IP REG_RIP
+#else
+# define REG_IP REG_EIP
+#endif
+
+static void sigill(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	got_sigill = 1;
+	ctx->uc_mcontext.gregs[REG_IP] += 2;
+}
+
+static int nerrs = 0;
+
+static void test_syscall(long nr)
 {
 	extern const char syscall_rip[];
 	unsigned long rcx = 1;
 	unsigned long orig_rcx = rcx;
 	unsigned short orig_ss, ss;
+	long ret;
+	int local_nerrs = 0;
 
 #ifdef __x86_64__
 	arch_prctl(ARCH_SET_GS, 500);  // Enable segment 13
 	asm volatile ("mov %0,%%ss" : : "r" ((13 << 3) | 3));
 #endif
 
-	asm ("mov %%ss,%[orig_ss]\n\t"
-	     "mov $0x80000000, %%eax\n\t"
-	     "syscall\n\t"
-	     "syscall_rip:"
-	     "mov %%ss,%[ss]\n\t"
-	     : "+c" (rcx), [orig_ss] "=rm" (orig_ss), [ss] "=rm" (ss) : :
+	got_sigill = 0;
+
+	asm volatile ("mov %%ss,%[orig_ss]\n\t"
+		      "syscall\n\t"
+		      "syscall_rip:"
+		      "mov %%ss,%[ss]\n\t"
+		      : "+c" (rcx), [orig_ss] "=rm" (orig_ss), [ss] "=rm" (ss),
+			"=a" (ret)
+		      : "a" (nr) :
 #ifdef __x86_64__
-	       "r11"
+			"r11"
 #endif
-	     );
-	printf("syscall: RCX = %lX  RIP = %lX  orig RCX = %lx  ss = %hx  orig_ss = %hx\n",
-	       rcx, (unsigned long)syscall_rip, orig_rcx, ss, orig_ss);
-	return 0;
+		);
+
+	if (got_sigill) {
+		printf("[OK]\tsyscall %lx: SIGILL\n", nr);
+	} else {
+		const char *outcome;
+		if (rcx != (unsigned long)syscall_rip) {
+			local_nerrs++;
+			outcome = "[FAIL]";
+		} else {
+			outcome = "[OK]";
+		}
+		printf("%s\tsyscall %lx: RCX = %lX  RIP = %lX\n",
+		       outcome, nr, rcx, (unsigned long)syscall_rip);
+
+		if (ret != (long)-ENOSYS) {
+			local_nerrs++;
+			outcome = "[FAIL]";
+		} else {
+			outcome = "[OK]";
+		}
+		printf("%s\tsyscall %lx: AX = %lx\n",
+		       outcome, nr, ret);
+
+		printf("[NOTE]\tsyscall %lx: orig RCX = %lx  ss = %hx  orig_ss = %hx\n",
+		       nr, orig_rcx, ss, orig_ss);
+	}
+
+	nerrs += local_nerrs;
+}
+
+static void test_int80(long nr)
+{
+	long ret;
+	int local_nerrs = 0;
+
+	got_sigill = 0;
+
+	asm volatile ("int $0x80"
+		      : "=a" (ret)
+		      : "a" (nr)
+		      :
+		);
+
+	if (got_sigill) {
+		printf("[OK]\tint80 %lx: SIGILL\n", nr);
+	} else {
+		const char *outcome;
+
+		if (ret != (long)-ENOSYS) {
+			local_nerrs++;
+			outcome = "[FAIL]";
+		} else {
+			outcome = "[OK]";
+		}
+		printf("%s\tint80 %lx: AX = %lx\n",
+		       outcome, nr, ret);
+	}
+
+	nerrs += local_nerrs;
+}
+
+static void test_syscallfn(long nr)
+{
+	long ret;
+	int local_nerrs = 0;
+
+	ret = syscall(nr);
+
+	const char *outcome;
+
+	if (ret != -1 || errno != ENOSYS) {
+		local_nerrs++;
+		outcome = "[FAIL]";
+	} else {
+		outcome = "[OK]";
+	}
+	printf("%s\tsyscall(%lx): ret = %ld, errno = %d\n",
+	       outcome, nr, ret, errno);
+
+	nerrs += local_nerrs;
+}
+
+int main()
+{
+	sethandler(SIGILL, sigill, 0);
+
+	test_int80(0xFFFF);
+	test_int80(0x40000000);
+
+	test_syscall(0xFFFF);
+	test_syscall(0x40000000);
+
+	test_syscallfn(0xFFFF);
+
+	return nerrs ? 1 : 0;
 }