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authorLinus Torvalds <torvalds@linux-foundation.org>2016-03-15 09:32:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-15 09:32:27 -0700
commitba33ea811e1ff6726abb7f8f96df38c2d7b50304 (patch)
tree29134e5cc7c19c8e520cb9336b476144d3d1252f /tools
parente23604edac2a7be6a8808a5d13fac6b9df4eb9a8 (diff)
parentd05004944206cbbf1c453e179768163731c7c6f1 (diff)
downloadlinux-sh-ba33ea811e1ff6726abb7f8f96df38c2d7b50304.tar.gz
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar: "This is another big update. Main changes are: - lots of x86 system call (and other traps/exceptions) entry code enhancements. In particular the complex parts of the 64-bit entry code have been migrated to C code as well, and a number of dusty corners have been refreshed. (Andy Lutomirski) - vDSO special mapping robustification and general cleanups (Andy Lutomirski) - cpufeature refactoring, cleanups and speedups (Borislav Petkov) - lots of other changes ..." * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) x86/cpufeature: Enable new AVX-512 features x86/entry/traps: Show unhandled signal for i386 in do_trap() x86/entry: Call enter_from_user_mode() with IRQs off x86/entry/32: Change INT80 to be an interrupt gate x86/entry: Improve system call entry comments x86/entry: Remove TIF_SINGLESTEP entry work x86/entry/32: Add and check a stack canary for the SYSENTER stack x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed x86/entry: Vastly simplify SYSENTER TF (single-step) handling x86/entry/traps: Clear DR6 early in do_debug() and improve the comment x86/entry/traps: Clear TIF_BLOCKSTEP on all debug exceptions x86/entry/32: Restore FLAGS on SYSEXIT x86/entry/32: Filter NT and speed up AC filtering in SYSENTER x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test selftests/x86: In syscall_nt, test NT|TF as well x86/asm-offsets: Remove PARAVIRT_enabled x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled uprobes: __create_xol_area() must nullify xol_mapping.fault x86/cpufeature: Create a new synthetic cpu capability for machine check recovery ...
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/x86/Makefile17
-rw-r--r--tools/testing/selftests/x86/check_initial_reg_state.c109
-rw-r--r--tools/testing/selftests/x86/ptrace_syscall.c132
-rw-r--r--tools/testing/selftests/x86/sigreturn.c230
-rw-r--r--tools/testing/selftests/x86/syscall_nt.c57
5 files changed, 501 insertions, 44 deletions
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index d0c473f65850..d5ce7d7aae3e 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -4,15 +4,16 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
-TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall
-TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn test_syscall_vdso unwind_vdso \
+TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall \
+ check_initial_reg_state sigreturn ldt_gdt
+TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
- ldt_gdt \
vdso_restorer
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
+TARGETS_C_64BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_64BIT_ONLY)
BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)
-BINARIES_64 := $(TARGETS_C_BOTHBITS:%=%_64)
+BINARIES_64 := $(TARGETS_C_64BIT_ALL:%=%_64)
CFLAGS := -O2 -g -std=gnu99 -pthread -Wall
@@ -40,7 +41,7 @@ clean:
$(TARGETS_C_32BIT_ALL:%=%_32): %_32: %.c
$(CC) -m32 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl -lm
-$(TARGETS_C_BOTHBITS:%=%_64): %_64: %.c
+$(TARGETS_C_64BIT_ALL:%=%_64): %_64: %.c
$(CC) -m64 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl
# x86_64 users should be encouraged to install 32-bit libraries
@@ -65,3 +66,9 @@ endif
sysret_ss_attrs_64: thunks.S
ptrace_syscall_32: raw_syscall_helper_32.S
test_syscall_vdso_32: thunks_32.S
+
+# check_initial_reg_state is special: it needs a custom entry, and it
+# needs to be static so that its interpreter doesn't destroy its initial
+# state.
+check_initial_reg_state_32: CFLAGS += -Wl,-ereal_start -static
+check_initial_reg_state_64: CFLAGS += -Wl,-ereal_start -static
diff --git a/tools/testing/selftests/x86/check_initial_reg_state.c b/tools/testing/selftests/x86/check_initial_reg_state.c
new file mode 100644
index 000000000000..6aaed9b85baf
--- /dev/null
+++ b/tools/testing/selftests/x86/check_initial_reg_state.c
@@ -0,0 +1,109 @@
+/*
+ * check_initial_reg_state.c - check that execve sets the correct state
+ * Copyright (c) 2014-2016 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+
+unsigned long ax, bx, cx, dx, si, di, bp, sp, flags;
+unsigned long r8, r9, r10, r11, r12, r13, r14, r15;
+
+asm (
+ ".pushsection .text\n\t"
+ ".type real_start, @function\n\t"
+ ".global real_start\n\t"
+ "real_start:\n\t"
+#ifdef __x86_64__
+ "mov %rax, ax\n\t"
+ "mov %rbx, bx\n\t"
+ "mov %rcx, cx\n\t"
+ "mov %rdx, dx\n\t"
+ "mov %rsi, si\n\t"
+ "mov %rdi, di\n\t"
+ "mov %rbp, bp\n\t"
+ "mov %rsp, sp\n\t"
+ "mov %r8, r8\n\t"
+ "mov %r9, r9\n\t"
+ "mov %r10, r10\n\t"
+ "mov %r11, r11\n\t"
+ "mov %r12, r12\n\t"
+ "mov %r13, r13\n\t"
+ "mov %r14, r14\n\t"
+ "mov %r15, r15\n\t"
+ "pushfq\n\t"
+ "popq flags\n\t"
+#else
+ "mov %eax, ax\n\t"
+ "mov %ebx, bx\n\t"
+ "mov %ecx, cx\n\t"
+ "mov %edx, dx\n\t"
+ "mov %esi, si\n\t"
+ "mov %edi, di\n\t"
+ "mov %ebp, bp\n\t"
+ "mov %esp, sp\n\t"
+ "pushfl\n\t"
+ "popl flags\n\t"
+#endif
+ "jmp _start\n\t"
+ ".size real_start, . - real_start\n\t"
+ ".popsection");
+
+int main()
+{
+ int nerrs = 0;
+
+ if (sp == 0) {
+ printf("[FAIL]\tTest was built incorrectly\n");
+ return 1;
+ }
+
+ if (ax || bx || cx || dx || si || di || bp
+#ifdef __x86_64__
+ || r8 || r9 || r10 || r11 || r12 || r13 || r14 || r15
+#endif
+ ) {
+ printf("[FAIL]\tAll GPRs except SP should be 0\n");
+#define SHOW(x) printf("\t" #x " = 0x%lx\n", x);
+ SHOW(ax);
+ SHOW(bx);
+ SHOW(cx);
+ SHOW(dx);
+ SHOW(si);
+ SHOW(di);
+ SHOW(bp);
+ SHOW(sp);
+#ifdef __x86_64__
+ SHOW(r8);
+ SHOW(r9);
+ SHOW(r10);
+ SHOW(r11);
+ SHOW(r12);
+ SHOW(r13);
+ SHOW(r14);
+ SHOW(r15);
+#endif
+ nerrs++;
+ } else {
+ printf("[OK]\tAll GPRs except SP are 0\n");
+ }
+
+ if (flags != 0x202) {
+ printf("[FAIL]\tFLAGS is 0x%lx, but it should be 0x202\n", flags);
+ nerrs++;
+ } else {
+ printf("[OK]\tFLAGS is 0x202\n");
+ }
+
+ return nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index 5105b49cd8aa..421456784bc6 100644
--- a/tools/testing/selftests/x86/ptrace_syscall.c
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -103,6 +103,17 @@ static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
err(1, "sigaction");
}
+static void setsigign(int sig, int flags)
+{
+ struct sigaction sa;
+ memset(&sa, 0, sizeof(sa));
+ sa.sa_sigaction = (void *)SIG_IGN;
+ sa.sa_flags = flags;
+ sigemptyset(&sa.sa_mask);
+ if (sigaction(sig, &sa, 0))
+ err(1, "sigaction");
+}
+
static void clearhandler(int sig)
{
struct sigaction sa;
@@ -187,7 +198,7 @@ static void test_ptrace_syscall_restart(void)
printf("[RUN]\tSYSEMU\n");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
- err(1, "PTRACE_SYSCALL");
+ err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
@@ -218,7 +229,7 @@ static void test_ptrace_syscall_restart(void)
err(1, "PTRACE_SETREGS");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
- err(1, "PTRACE_SYSCALL");
+ err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
@@ -250,7 +261,7 @@ static void test_ptrace_syscall_restart(void)
err(1, "PTRACE_SETREGS");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
- err(1, "PTRACE_SYSCALL");
+ err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
@@ -277,6 +288,119 @@ static void test_ptrace_syscall_restart(void)
}
}
+static void test_restart_under_ptrace(void)
+{
+ printf("[RUN]\tkernel syscall restart under ptrace\n");
+ pid_t chld = fork();
+ if (chld < 0)
+ err(1, "fork");
+
+ if (chld == 0) {
+ if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
+ err(1, "PTRACE_TRACEME");
+
+ printf("\tChild will take a nap until signaled\n");
+ setsigign(SIGUSR1, SA_RESTART);
+ raise(SIGSTOP);
+
+ syscall(SYS_pause, 0, 0, 0, 0, 0, 0);
+ _exit(0);
+ }
+
+ int status;
+
+ /* Wait for SIGSTOP. */
+ if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
+ err(1, "waitpid");
+
+ struct user_regs_struct regs;
+
+ printf("[RUN]\tSYSCALL\n");
+ if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+ err(1, "PTRACE_SYSCALL");
+ wait_trap(chld);
+
+ /* We should be stopped at pause(2) entry. */
+
+ if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+ err(1, "PTRACE_GETREGS");
+
+ if (regs.user_syscall_nr != SYS_pause ||
+ regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+ regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+ regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+ printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+ nerrs++;
+ } else {
+ printf("[OK]\tInitial nr and args are correct\n");
+ }
+
+ /* Interrupt it. */
+ kill(chld, SIGUSR1);
+
+ /* Advance. We should be stopped at exit. */
+ printf("[RUN]\tSYSCALL\n");
+ if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+ err(1, "PTRACE_SYSCALL");
+ wait_trap(chld);
+
+ if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+ err(1, "PTRACE_GETREGS");
+
+ if (regs.user_syscall_nr != SYS_pause ||
+ regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+ regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+ regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+ printf("[FAIL]\tArgs after SIGUSR1 are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+ nerrs++;
+ } else {
+ printf("[OK]\tArgs after SIGUSR1 are correct (ax = %ld)\n",
+ (long)regs.user_ax);
+ }
+
+ /* Poke the regs back in. This must not break anything. */
+ if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
+ err(1, "PTRACE_SETREGS");
+
+ /* Catch the (ignored) SIGUSR1. */
+ if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
+ err(1, "PTRACE_CONT");
+ if (waitpid(chld, &status, 0) != chld)
+ err(1, "waitpid");
+ if (!WIFSTOPPED(status)) {
+ printf("[FAIL]\tChild was stopped for SIGUSR1 (status = 0x%x)\n", status);
+ nerrs++;
+ } else {
+ printf("[OK]\tChild got SIGUSR1\n");
+ }
+
+ /* The next event should be pause(2) again. */
+ printf("[RUN]\tStep again\n");
+ if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+ err(1, "PTRACE_SYSCALL");
+ wait_trap(chld);
+
+ /* We should be stopped at pause(2) entry. */
+
+ if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+ err(1, "PTRACE_GETREGS");
+
+ if (regs.user_syscall_nr != SYS_pause ||
+ regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+ regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+ regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+ printf("[FAIL]\tpause did not restart (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+ nerrs++;
+ } else {
+ printf("[OK]\tpause(2) restarted correctly\n");
+ }
+
+ /* Kill it. */
+ kill(chld, SIGKILL);
+ if (waitpid(chld, &status, 0) != chld)
+ err(1, "waitpid");
+}
+
int main()
{
printf("[RUN]\tCheck int80 return regs\n");
@@ -290,5 +414,7 @@ int main()
test_ptrace_syscall_restart();
+ test_restart_under_ptrace();
+
return 0;
}
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
index b5aa1bab7416..8a577e7070c6 100644
--- a/tools/testing/selftests/x86/sigreturn.c
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -54,6 +54,37 @@
#include <sys/ptrace.h>
#include <sys/user.h>
+/* Pull in AR_xyz defines. */
+typedef unsigned int u32;
+typedef unsigned short u16;
+#include "../../../../arch/x86/include/asm/desc_defs.h"
+
+/*
+ * Copied from asm/ucontext.h, as asm/ucontext.h conflicts badly with the glibc
+ * headers.
+ */
+#ifdef __x86_64__
+/*
+ * UC_SIGCONTEXT_SS will be set when delivering 64-bit or x32 signals on
+ * kernels that save SS in the sigcontext. All kernels that set
+ * UC_SIGCONTEXT_SS will correctly restore at least the low 32 bits of esp
+ * regardless of SS (i.e. they implement espfix).
+ *
+ * Kernels that set UC_SIGCONTEXT_SS will also set UC_STRICT_RESTORE_SS
+ * when delivering a signal that came from 64-bit code.
+ *
+ * Sigreturn restores SS as follows:
+ *
+ * if (saved SS is valid || UC_STRICT_RESTORE_SS is set ||
+ * saved CS is not 64-bit)
+ * new SS = saved SS (will fail IRET and signal if invalid)
+ * else
+ * new SS = a flat 32-bit data segment
+ */
+#define UC_SIGCONTEXT_SS 0x2
+#define UC_STRICT_RESTORE_SS 0x4
+#endif
+
/*
* In principle, this test can run on Linux emulation layers (e.g.
* Illumos "LX branded zones"). Solaris-based kernels reserve LDT
@@ -267,6 +298,9 @@ static gregset_t initial_regs, requested_regs, resulting_regs;
/* Instructions for the SIGUSR1 handler. */
static volatile unsigned short sig_cs, sig_ss;
static volatile sig_atomic_t sig_trapped, sig_err, sig_trapno;
+#ifdef __x86_64__
+static volatile sig_atomic_t sig_corrupt_final_ss;
+#endif
/* Abstractions for some 32-bit vs 64-bit differences. */
#ifdef __x86_64__
@@ -305,9 +339,105 @@ static greg_t *csptr(ucontext_t *ctx)
}
#endif
+/*
+ * Checks a given selector for its code bitness or returns -1 if it's not
+ * a usable code segment selector.
+ */
+int cs_bitness(unsigned short cs)
+{
+ uint32_t valid = 0, ar;
+ asm ("lar %[cs], %[ar]\n\t"
+ "jnz 1f\n\t"
+ "mov $1, %[valid]\n\t"
+ "1:"
+ : [ar] "=r" (ar), [valid] "+rm" (valid)
+ : [cs] "r" (cs));
+
+ if (!valid)
+ return -1;
+
+ bool db = (ar & (1 << 22));
+ bool l = (ar & (1 << 21));
+
+ if (!(ar & (1<<11)))
+ return -1; /* Not code. */
+
+ if (l && !db)
+ return 64;
+ else if (!l && db)
+ return 32;
+ else if (!l && !db)
+ return 16;
+ else
+ return -1; /* Unknown bitness. */
+}
+
+/*
+ * Checks a given selector for its code bitness or returns -1 if it's not
+ * a usable code segment selector.
+ */
+bool is_valid_ss(unsigned short cs)
+{
+ uint32_t valid = 0, ar;
+ asm ("lar %[cs], %[ar]\n\t"
+ "jnz 1f\n\t"
+ "mov $1, %[valid]\n\t"
+ "1:"
+ : [ar] "=r" (ar), [valid] "+rm" (valid)
+ : [cs] "r" (cs));
+
+ if (!valid)
+ return false;
+
+ if ((ar & AR_TYPE_MASK) != AR_TYPE_RWDATA &&
+ (ar & AR_TYPE_MASK) != AR_TYPE_RWDATA_EXPDOWN)
+ return false;
+
+ return (ar & AR_P);
+}
+
/* Number of errors in the current test case. */
static volatile sig_atomic_t nerrs;
+static void validate_signal_ss(int sig, ucontext_t *ctx)
+{
+#ifdef __x86_64__
+ bool was_64bit = (cs_bitness(*csptr(ctx)) == 64);
+
+ if (!(ctx->uc_flags & UC_SIGCONTEXT_SS)) {
+ printf("[FAIL]\tUC_SIGCONTEXT_SS was not set\n");
+ nerrs++;
+
+ /*
+ * This happens on Linux 4.1. The rest will fail, too, so
+ * return now to reduce the noise.
+ */
+ return;
+ }
+
+ /* UC_STRICT_RESTORE_SS is set iff we came from 64-bit mode. */
+ if (!!(ctx->uc_flags & UC_STRICT_RESTORE_SS) != was_64bit) {
+ printf("[FAIL]\tUC_STRICT_RESTORE_SS was wrong in signal %d\n",
+ sig);
+ nerrs++;
+ }
+
+ if (is_valid_ss(*ssptr(ctx))) {
+ /*
+ * DOSEMU was written before 64-bit sigcontext had SS, and
+ * it tries to figure out the signal source SS by looking at
+ * the physical register. Make sure that keeps working.
+ */
+ unsigned short hw_ss;
+ asm ("mov %%ss, %0" : "=rm" (hw_ss));
+ if (hw_ss != *ssptr(ctx)) {
+ printf("[FAIL]\tHW SS didn't match saved SS\n");
+ nerrs++;
+ }
+ }
+#endif
+}
+
/*
* SIGUSR1 handler. Sets CS and SS as requested and points IP to the
* int3 trampoline. Sets SP to a large known value so that we can see
@@ -317,6 +447,8 @@ static void sigusr1(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t*)ctx_void;
+ validate_signal_ss(sig, ctx);
+
memcpy(&initial_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
*csptr(ctx) = sig_cs;
@@ -334,13 +466,16 @@ static void sigusr1(int sig, siginfo_t *info, void *ctx_void)
}
/*
- * Called after a successful sigreturn. Restores our state so that
- * the original raise(SIGUSR1) returns.
+ * Called after a successful sigreturn (via int3) or from a failed
+ * sigreturn (directly by kernel). Restores our state so that the
+ * original raise(SIGUSR1) returns.
*/
static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t*)ctx_void;
+ validate_signal_ss(sig, ctx);
+
sig_err = ctx->uc_mcontext.gregs[REG_ERR];
sig_trapno = ctx->uc_mcontext.gregs[REG_TRAPNO];
@@ -358,41 +493,62 @@ static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
memcpy(&resulting_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
memcpy(&ctx->uc_mcontext.gregs, &initial_regs, sizeof(gregset_t));
+#ifdef __x86_64__
+ if (sig_corrupt_final_ss) {
+ if (ctx->uc_flags & UC_STRICT_RESTORE_SS) {
+ printf("[FAIL]\tUC_STRICT_RESTORE_SS was set inappropriately\n");
+ nerrs++;
+ } else {
+ /*
+ * DOSEMU transitions from 32-bit to 64-bit mode by
+ * adjusting sigcontext, and it requires that this work
+ * even if the saved SS is bogus.
+ */
+ printf("\tCorrupting SS on return to 64-bit mode\n");
+ *ssptr(ctx) = 0;
+ }
+ }
+#endif
+
sig_trapped = sig;
}
-/*
- * Checks a given selector for its code bitness or returns -1 if it's not
- * a usable code segment selector.
- */
-int cs_bitness(unsigned short cs)
+#ifdef __x86_64__
+/* Tests recovery if !UC_STRICT_RESTORE_SS */
+static void sigusr2(int sig, siginfo_t *info, void *ctx_void)
{
- uint32_t valid = 0, ar;
- asm ("lar %[cs], %[ar]\n\t"
- "jnz 1f\n\t"
- "mov $1, %[valid]\n\t"
- "1:"
- : [ar] "=r" (ar), [valid] "+rm" (valid)
- : [cs] "r" (cs));
+ ucontext_t *ctx = (ucontext_t*)ctx_void;
- if (!valid)
- return -1;
+ if (!(ctx->uc_flags & UC_STRICT_RESTORE_SS)) {
+ printf("[FAIL]\traise(2) didn't set UC_STRICT_RESTORE_SS\n");
+ nerrs++;
+ return; /* We can't do the rest. */
+ }
- bool db = (ar & (1 << 22));
- bool l = (ar & (1 << 21));
+ ctx->uc_flags &= ~UC_STRICT_RESTORE_SS;
+ *ssptr(ctx) = 0;
- if (!(ar & (1<<11)))
- return -1; /* Not code. */
+ /* Return. The kernel should recover without sending another signal. */
+}
- if (l && !db)
- return 64;
- else if (!l && db)
- return 32;
- else if (!l && !db)
- return 16;
- else
- return -1; /* Unknown bitness. */
+static int test_nonstrict_ss(void)
+{
+ clearhandler(SIGUSR1);
+ clearhandler(SIGTRAP);
+ clearhandler(SIGSEGV);
+ clearhandler(SIGILL);
+ sethandler(SIGUSR2, sigusr2, 0);
+
+ nerrs = 0;
+
+ printf("[RUN]\tClear UC_STRICT_RESTORE_SS and corrupt SS\n");
+ raise(SIGUSR2);
+ if (!nerrs)
+ printf("[OK]\tIt worked\n");
+
+ return nerrs;
}
+#endif
/* Finds a usable code segment of the requested bitness. */
int find_cs(int bitness)
@@ -576,6 +732,12 @@ static int test_bad_iret(int cs_bits, unsigned short ss, int force_cs)
errdesc, strsignal(sig_trapped));
return 0;
} else {
+ /*
+ * This also implicitly tests UC_STRICT_RESTORE_SS:
+ * We check that these signals set UC_STRICT_RESTORE_SS and,
+ * if UC_STRICT_RESTORE_SS doesn't cause strict behavior,
+ * then we won't get SIGSEGV.
+ */
printf("[FAIL]\tDid not get SIGSEGV\n");
return 1;
}
@@ -632,6 +794,14 @@ int main()
GDT3(gdt_data16_idx));
}
+#ifdef __x86_64__
+ /* Nasty ABI case: check SS corruption handling. */
+ sig_corrupt_final_ss = 1;
+ total_nerrs += test_valid_sigreturn(32, false, -1);
+ total_nerrs += test_valid_sigreturn(32, true, -1);
+ sig_corrupt_final_ss = 0;
+#endif
+
/*
* We're done testing valid sigreturn cases. Now we test states
* for which sigreturn itself will succeed but the subsequent
@@ -680,5 +850,9 @@ int main()
if (gdt_npdata32_idx)
test_bad_iret(32, GDT3(gdt_npdata32_idx), -1);
+#ifdef __x86_64__
+ total_nerrs += test_nonstrict_ss();
+#endif
+
return total_nerrs ? 1 : 0;
}
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 <stdio.h>
#include <unistd.h>
+#include <string.h>
+#include <signal.h>
+#include <err.h>
#include <sys/syscall.h>
#include <asm/processor-flags.h>
@@ -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;
+}