From a318beea224d255c38652f88a7ae0d30ac4c23c3 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 9 Mar 2016 19:00:24 -0800 Subject: [PATCH] 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 Cc: Andrew Cooper Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/bd4bb48af6b10c0dc84aec6dbcf487ed25683495.1457578375.git.luto@kernel.org Signed-off-by: Ingo Molnar --- tools/testing/selftests/x86/syscall_nt.c | 57 ++++++++++++++++++++---- 1 file changed, 49 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/x86/syscall_nt.c b/tools/testing/selftests/x86/syscall_nt.c index 60c06af4646a..43fcab367fb0 100644 --- a/tools/testing/selftests/x86/syscall_nt.c +++ b/tools/testing/selftests/x86/syscall_nt.c @@ -17,6 +17,9 @@ #include #include +#include +#include +#include #include #include @@ -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; +}