Commit-ID: 9402eaf4c11f0b892eda7b2bcb4654ab34ce34f9 Gitweb: https://git.kernel.org/tip/9402eaf4c11f0b892eda7b2bcb4654ab34ce34f9 Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Mon, 1 Jul 2019 20:43:19 -0700 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Tue, 2 Jul 2019 08:45:20 +0200
selftests/x86: Test SYSCALL and SYSENTER manually with TF set Make sure that both variants of the nasty TF-in-compat-syscall are exercised regardless of what vendor's CPU is running the tests. Also change the intentional signal after SYSCALL to use ud2, which is a lot more comprehensible. This crashes the kernel due to an FSGSBASE bug right now. This test *also* detects a bug in KVM when run on an Intel host. KVM people, feel free to use it to help debug. There's a bunch of code in this test to warn instead of going into an infinite looping when the bug gets triggered. Reported-by: Vegard Nossum <vegard.nos...@oracle.com> Signed-off-by: Andy Lutomirski <l...@kernel.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: "BaeChang Seok" <chang.seok....@intel.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: k...@vger.kernel.org Cc: "Bae, Chang Seok" <chang.seok....@intel.com> Link: https://lkml.kernel.org/r/5f5de10441ab2e3005538b4c33be9b1965d1bb63.1562035429.git.l...@kernel.org --- tools/testing/selftests/x86/Makefile | 5 +- tools/testing/selftests/x86/syscall_arg_fault.c | 112 ++++++++++++++++++++++-- 2 files changed, 110 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index 186520198de7..fa07d526fe39 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -12,8 +12,9 @@ CAN_BUILD_WITH_NOPIE := $(shell ./check_cc.sh $(CC) trivial_program.c -no-pie) TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \ check_initial_reg_state sigreturn iopl mpx-mini-test ioperm \ - protection_keys test_vdso test_vsyscall mov_ss_trap -TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \ + protection_keys test_vdso test_vsyscall mov_ss_trap \ + syscall_arg_fault +TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \ test_FCMOV test_FCOMI test_FISTTP \ vdso_restorer TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c index 4e25d38c8bbd..bc0ecc2e862e 100644 --- a/tools/testing/selftests/x86/syscall_arg_fault.c +++ b/tools/testing/selftests/x86/syscall_arg_fault.c @@ -15,9 +15,30 @@ #include <setjmp.h> #include <errno.h> +#ifdef __x86_64__ +# define WIDTH "q" +#else +# define WIDTH "l" +#endif + /* Our sigaltstack scratch space. */ static unsigned char altstack_data[SIGSTKSZ]; +static unsigned long get_eflags(void) +{ + unsigned long eflags; + asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); + return eflags; +} + +static void set_eflags(unsigned long eflags) +{ + asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH + : : "rm" (eflags) : "flags"); +} + +#define X86_EFLAGS_TF (1UL << 8) + static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { @@ -35,13 +56,22 @@ static sigjmp_buf jmpbuf; static volatile sig_atomic_t n_errs; +#ifdef __x86_64__ +#define REG_AX REG_RAX +#define REG_IP REG_RIP +#else +#define REG_AX REG_EAX +#define REG_IP REG_EIP +#endif + static void sigsegv_or_sigbus(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t*)ctx_void; + long ax = (long)ctx->uc_mcontext.gregs[REG_AX]; - if (ctx->uc_mcontext.gregs[REG_EAX] != -EFAULT) { - printf("[FAIL]\tAX had the wrong value: 0x%x\n", - ctx->uc_mcontext.gregs[REG_EAX]); + if (ax != -EFAULT && ax != -ENOSYS) { + printf("[FAIL]\tAX had the wrong value: 0x%lx\n", + (unsigned long)ax); n_errs++; } else { printf("[OK]\tSeems okay\n"); @@ -50,9 +80,42 @@ static void sigsegv_or_sigbus(int sig, siginfo_t *info, void *ctx_void) siglongjmp(jmpbuf, 1); } +static volatile sig_atomic_t sigtrap_consecutive_syscalls; + +static void sigtrap(int sig, siginfo_t *info, void *ctx_void) +{ + /* + * KVM has some bugs that can cause us to stop making progress. + * detect them and complain, but don't infinite loop or fail the + * test. + */ + + ucontext_t *ctx = (ucontext_t*)ctx_void; + unsigned short *ip = (unsigned short *)ctx->uc_mcontext.gregs[REG_IP]; + + if (*ip == 0x340f || *ip == 0x050f) { + /* The trap was on SYSCALL or SYSENTER */ + sigtrap_consecutive_syscalls++; + if (sigtrap_consecutive_syscalls > 3) { + printf("[WARN]\tGot stuck single-stepping -- you probably have a KVM bug\n"); + siglongjmp(jmpbuf, 1); + } + } else { + sigtrap_consecutive_syscalls = 0; + } +} + static void sigill(int sig, siginfo_t *info, void *ctx_void) { - printf("[SKIP]\tIllegal instruction\n"); + ucontext_t *ctx = (ucontext_t*)ctx_void; + unsigned short *ip = (unsigned short *)ctx->uc_mcontext.gregs[REG_IP]; + + if (*ip == 0x0b0f) { + /* one of the ud2 instructions faulted */ + printf("[OK]\tSYSCALL returned normally\n"); + } else { + printf("[SKIP]\tIllegal instruction\n"); + } siglongjmp(jmpbuf, 1); } @@ -120,9 +183,48 @@ int main() "movl $-1, %%ebp\n\t" "movl $-1, %%esp\n\t" "syscall\n\t" - "pushl $0" /* make sure we segfault cleanly */ + "ud2" /* make sure we recover cleanly */ + : : : "memory", "flags"); + } + + printf("[RUN]\tSYSENTER with TF and invalid state\n"); + sethandler(SIGTRAP, sigtrap, SA_ONSTACK); + + if (sigsetjmp(jmpbuf, 1) == 0) { + sigtrap_consecutive_syscalls = 0; + set_eflags(get_eflags() | X86_EFLAGS_TF); + asm volatile ( + "movl $-1, %%eax\n\t" + "movl $-1, %%ebx\n\t" + "movl $-1, %%ecx\n\t" + "movl $-1, %%edx\n\t" + "movl $-1, %%esi\n\t" + "movl $-1, %%edi\n\t" + "movl $-1, %%ebp\n\t" + "movl $-1, %%esp\n\t" + "sysenter" + : : : "memory", "flags"); + } + set_eflags(get_eflags() & ~X86_EFLAGS_TF); + + printf("[RUN]\tSYSCALL with TF and invalid state\n"); + if (sigsetjmp(jmpbuf, 1) == 0) { + sigtrap_consecutive_syscalls = 0; + set_eflags(get_eflags() | X86_EFLAGS_TF); + asm volatile ( + "movl $-1, %%eax\n\t" + "movl $-1, %%ebx\n\t" + "movl $-1, %%ecx\n\t" + "movl $-1, %%edx\n\t" + "movl $-1, %%esi\n\t" + "movl $-1, %%edi\n\t" + "movl $-1, %%ebp\n\t" + "movl $-1, %%esp\n\t" + "syscall\n\t" + "ud2" /* make sure we recover cleanly */ : : : "memory", "flags"); } + set_eflags(get_eflags() & ~X86_EFLAGS_TF); return 0; }
