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Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull x86 asm changes from Ingo Molnar:
 "The biggest changes in this cycle were:

   - Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC)
     primitives.  (Andy Lutomirski)

   - Add new, comprehensible entry and exit handlers written in C.
     (Andy Lutomirski)

   - vm86 mode cleanups and fixes.  (Brian Gerst)

   - 32-bit compat code cleanups.  (Brian Gerst)

  The amount of simplification in low level assembly code is already
  palpable:

     arch/x86/entry/entry_32.S                          | 130 +----
     arch/x86/entry/entry_64.S                          | 197 ++-----

  but more simplifications are planned.

  There's also the usual laudry mix of low level changes - see the
  changelog for details"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits)
  x86/asm: Drop repeated macro of X86_EFLAGS_AC definition
  x86/asm/msr: Make wrmsrl() a function
  x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer
  x86/asm: Add MONITORX/MWAITX instruction support
  x86/traps: Weaken context tracking entry assertions
  x86/asm/tsc: Add rdtscll() merge helper
  selftests/x86: Add syscall_nt selftest
  selftests/x86: Disable sigreturn_64
  x86/vdso: Emit a GNU hash
  x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
  x86/entry/32: Migrate to C exit path
  x86/entry/32: Remove 32-bit syscall audit optimizations
  x86/vm86: Rename vm86->v86flags and v86mask
  x86/vm86: Rename vm86->vm86_info to user_vm86
  x86/vm86: Clean up vm86.h includes
  x86/vm86: Move the vm86 IRQ definitions to vm86.h
  x86/vm86: Use the normal pt_regs area for vm86
  x86/vm86: Eliminate 'struct kernel_vm86_struct'
  x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
  x86/vm86: Move vm86 fields out of 'thread_struct'
  ...
This commit is contained in:
Linus Torvalds
2015-09-01 08:40:25 -07:00
parent 65a99597f0 7e01ebffff
commit 5778077d03
100 changed files with 2196 additions and 1383 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
tools/testing/selftests/x86/Makefile
View File

@@ -4,8 +4,8 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
TARGETS_C_BOTHBITS := sigreturn single_step_syscall sysret_ss_attrs
TARGETS_C_32BIT_ONLY := entry_from_vm86
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)

137
tools/testing/selftests/x86/entry_from_vm86.c
View File

@@ -28,6 +28,55 @@
static unsigned long load_addr = 0x10000;
static int nerrs = 0;
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");
}
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 sig_atomic_t got_signal;
static void sighandler(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t*)ctx_void;
if (ctx->uc_mcontext.gregs[REG_EFL] & X86_EFLAGS_VM ||
(ctx->uc_mcontext.gregs[REG_CS] & 3) != 3) {
printf("[FAIL]\tSignal frame should not reflect vm86 mode\n");
nerrs++;
}
const char *signame;
if (sig == SIGSEGV)
signame = "SIGSEGV";
else if (sig == SIGILL)
signame = "SIGILL";
else
signame = "unexpected signal";
printf("[INFO]\t%s: FLAGS = 0x%lx, CS = 0x%hx\n", signame,
(unsigned long)ctx->uc_mcontext.gregs[REG_EFL],
(unsigned short)ctx->uc_mcontext.gregs[REG_CS]);
got_signal = 1;
}
asm (
".pushsection .rodata\n\t"
".type vmcode_bound, @object\n\t"
@@ -38,6 +87,14 @@ asm (
"int3\n\t"
"vmcode_sysenter:\n\t"
"sysenter\n\t"
"vmcode_syscall:\n\t"
"syscall\n\t"
"vmcode_sti:\n\t"
"sti\n\t"
"vmcode_int3:\n\t"
"int3\n\t"
"vmcode_int80:\n\t"
"int $0x80\n\t"
".size vmcode, . - vmcode\n\t"
"end_vmcode:\n\t"
".code32\n\t"
@@ -45,9 +102,12 @@ asm (
);
extern unsigned char vmcode[], end_vmcode[];
extern unsigned char vmcode_bound[], vmcode_sysenter[];
extern unsigned char vmcode_bound[], vmcode_sysenter[], vmcode_syscall[],
vmcode_sti[], vmcode_int3[], vmcode_int80[];
static void do_test(struct vm86plus_struct *v86, unsigned long eip,
/* Returns false if the test was skipped. */
static bool do_test(struct vm86plus_struct *v86, unsigned long eip,
unsigned int rettype, unsigned int retarg,
const char *text)
{
long ret;
@@ -58,7 +118,7 @@ static void do_test(struct vm86plus_struct *v86, unsigned long eip,
if (ret == -1 && errno == ENOSYS) {
printf("[SKIP]\tvm86 not supported\n");
return;
return false;
}
if (VM86_TYPE(ret) == VM86_INTx) {
@@ -73,13 +133,30 @@ static void do_test(struct vm86plus_struct *v86, unsigned long eip,
else
sprintf(trapname, "%d", trapno);
printf("[OK]\tExited vm86 mode due to #%s\n", trapname);
printf("[INFO]\tExited vm86 mode due to #%s\n", trapname);
} else if (VM86_TYPE(ret) == VM86_UNKNOWN) {
printf("[OK]\tExited vm86 mode due to unhandled GP fault\n");
printf("[INFO]\tExited vm86 mode due to unhandled GP fault\n");
} else if (VM86_TYPE(ret) == VM86_TRAP) {
printf("[INFO]\tExited vm86 mode due to a trap (arg=%ld)\n",
VM86_ARG(ret));
} else if (VM86_TYPE(ret) == VM86_SIGNAL) {
printf("[INFO]\tExited vm86 mode due to a signal\n");
} else if (VM86_TYPE(ret) == VM86_STI) {
printf("[INFO]\tExited vm86 mode due to STI\n");
} else {
printf("[OK]\tExited vm86 mode due to type %ld, arg %ld\n",
printf("[INFO]\tExited vm86 mode due to type %ld, arg %ld\n",
VM86_TYPE(ret), VM86_ARG(ret));
}
if (rettype == -1 ||
(VM86_TYPE(ret) == rettype && VM86_ARG(ret) == retarg)) {
printf("[OK]\tReturned correctly\n");
} else {
printf("[FAIL]\tIncorrect return reason\n");
nerrs++;
}
return true;
}
int main(void)
@@ -105,10 +182,52 @@ int main(void)
assert((v86.regs.cs & 3) == 0); /* Looks like RPL = 0 */
/* #BR -- should deliver SIG??? */
do_test(&v86, vmcode_bound - vmcode, "#BR");
do_test(&v86, vmcode_bound - vmcode, VM86_INTx, 5, "#BR");
/* SYSENTER -- should cause #GP or #UD depending on CPU */
do_test(&v86, vmcode_sysenter - vmcode, "SYSENTER");
/*
* SYSENTER -- should cause #GP or #UD depending on CPU.
* Expected return type -1 means that we shouldn't validate
* the vm86 return value. This will avoid problems on non-SEP
* CPUs.
*/
sethandler(SIGILL, sighandler, 0);
do_test(&v86, vmcode_sysenter - vmcode, -1, 0, "SYSENTER");
clearhandler(SIGILL);
/*
* SYSCALL would be a disaster in VM86 mode. Fortunately,
* there is no kernel that both enables SYSCALL and sets
* EFER.SCE, so it's #UD on all systems. But vm86 is
* buggy (or has a "feature"), so the SIGILL will actually
* be delivered.
*/
sethandler(SIGILL, sighandler, 0);
do_test(&v86, vmcode_syscall - vmcode, VM86_SIGNAL, 0, "SYSCALL");
clearhandler(SIGILL);
/* STI with VIP set */
v86.regs.eflags |= X86_EFLAGS_VIP;
v86.regs.eflags &= ~X86_EFLAGS_IF;
do_test(&v86, vmcode_sti - vmcode, VM86_STI, 0, "STI with VIP set");
/* INT3 -- should cause #BP */
do_test(&v86, vmcode_int3 - vmcode, VM86_TRAP, 3, "INT3");
/* INT80 -- should exit with "INTx 0x80" */
v86.regs.eax = (unsigned int)-1;
do_test(&v86, vmcode_int80 - vmcode, VM86_INTx, 0x80, "int80");
/* Execute a null pointer */
v86.regs.cs = 0;
v86.regs.ss = 0;
sethandler(SIGSEGV, sighandler, 0);
got_signal = 0;
if (do_test(&v86, 0, VM86_SIGNAL, 0, "Execute null pointer") &&
!got_signal) {
printf("[FAIL]\tDid not receive SIGSEGV\n");
nerrs++;
}
clearhandler(SIGSEGV);
return (nerrs == 0 ? 0 : 1);
}

576
tools/testing/selftests/x86/ldt_gdt.c Normal file
View File

@@ -0,0 +1,576 @@
/*
* ldt_gdt.c - Test cases for LDT and GDT access
* Copyright (c) 2015 Andrew Lutomirski
*/
#define _GNU_SOURCE
#include <err.h>
#include <stdio.h>
#include <stdint.h>
#include <signal.h>
#include <setjmp.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/ldt.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdbool.h>
#include <pthread.h>
#include <sched.h>
#include <linux/futex.h>
#define AR_ACCESSED (1<<8)
#define AR_TYPE_RODATA (0 * (1<<9))
#define AR_TYPE_RWDATA (1 * (1<<9))
#define AR_TYPE_RODATA_EXPDOWN (2 * (1<<9))
#define AR_TYPE_RWDATA_EXPDOWN (3 * (1<<9))
#define AR_TYPE_XOCODE (4 * (1<<9))
#define AR_TYPE_XRCODE (5 * (1<<9))
#define AR_TYPE_XOCODE_CONF (6 * (1<<9))
#define AR_TYPE_XRCODE_CONF (7 * (1<<9))
#define AR_DPL3 (3 * (1<<13))
#define AR_S (1 << 12)
#define AR_P (1 << 15)
#define AR_AVL (1 << 20)
#define AR_L (1 << 21)
#define AR_DB (1 << 22)
#define AR_G (1 << 23)
static int nerrs;
static void check_invalid_segment(uint16_t index, int ldt)
{
uint32_t has_limit = 0, has_ar = 0, limit, ar;
uint32_t selector = (index << 3) | (ldt << 2) | 3;
asm ("lsl %[selector], %[limit]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_limit]\n\t"
"1:"
: [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
: [selector] "r" (selector));
asm ("larl %[selector], %[ar]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_ar]\n\t"
"1:"
: [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
: [selector] "r" (selector));
if (has_limit || has_ar) {
printf("[FAIL]\t%s entry %hu is valid but should be invalid\n",
(ldt ? "LDT" : "GDT"), index);
nerrs++;
} else {
printf("[OK]\t%s entry %hu is invalid\n",
(ldt ? "LDT" : "GDT"), index);
}
}
static void check_valid_segment(uint16_t index, int ldt,
uint32_t expected_ar, uint32_t expected_limit,
bool verbose)
{
uint32_t has_limit = 0, has_ar = 0, limit, ar;
uint32_t selector = (index << 3) | (ldt << 2) | 3;
asm ("lsl %[selector], %[limit]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_limit]\n\t"
"1:"
: [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
: [selector] "r" (selector));
asm ("larl %[selector], %[ar]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_ar]\n\t"
"1:"
: [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
: [selector] "r" (selector));
if (!has_limit || !has_ar) {
printf("[FAIL]\t%s entry %hu is invalid but should be valid\n",
(ldt ? "LDT" : "GDT"), index);
nerrs++;
return;
}
if (ar != expected_ar) {
printf("[FAIL]\t%s entry %hu has AR 0x%08X but expected 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, ar, expected_ar);
nerrs++;
} else if (limit != expected_limit) {
printf("[FAIL]\t%s entry %hu has limit 0x%08X but expected 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, limit, expected_limit);
nerrs++;
} else if (verbose) {
printf("[OK]\t%s entry %hu has AR 0x%08X and limit 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, ar, limit);
}
}
static bool install_valid_mode(const struct user_desc *desc, uint32_t ar,
bool oldmode)
{
int ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
desc, sizeof(*desc));
if (ret < -1)
errno = -ret;
if (ret == 0) {
uint32_t limit = desc->limit;
if (desc->limit_in_pages)
limit = (limit << 12) + 4095;
check_valid_segment(desc->entry_number, 1, ar, limit, true);
return true;
} else if (errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
return false;
} else {
if (desc->seg_32bit) {
printf("[FAIL]\tUnexpected modify_ldt failure %d\n",
errno);
nerrs++;
return false;
} else {
printf("[OK]\tmodify_ldt rejected 16 bit segment\n");
return false;
}
}
}
static bool install_valid(const struct user_desc *desc, uint32_t ar)
{
return install_valid_mode(desc, ar, false);
}
static void install_invalid(const struct user_desc *desc, bool oldmode)
{
int ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
desc, sizeof(*desc));
if (ret < -1)
errno = -ret;
if (ret == 0) {
check_invalid_segment(desc->entry_number, 1);
} else if (errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
} else {
if (desc->seg_32bit) {
printf("[FAIL]\tUnexpected modify_ldt failure %d\n",
errno);
nerrs++;
} else {
printf("[OK]\tmodify_ldt rejected 16 bit segment\n");
}
}
}
static int safe_modify_ldt(int func, struct user_desc *ptr,
unsigned long bytecount)
{
int ret = syscall(SYS_modify_ldt, 0x11, ptr, bytecount);
if (ret < -1)
errno = -ret;
return ret;
}
static void fail_install(struct user_desc *desc)
{
if (safe_modify_ldt(0x11, desc, sizeof(*desc)) == 0) {
printf("[FAIL]\tmodify_ldt accepted a bad descriptor\n");
nerrs++;
} else if (errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
} else {
printf("[OK]\tmodify_ldt failure %d\n", errno);
}
}
static void do_simple_tests(void)
{
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 10,
.seg_32bit = 1,
.contents = 2, /* Code, not conforming */
.read_exec_only = 0,
.limit_in_pages = 0,
.seg_not_present = 0,
.useable = 0
};
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
desc.limit_in_pages = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
check_invalid_segment(1, 1);
desc.entry_number = 2;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
check_invalid_segment(1, 1);
desc.base_addr = 0xf0000000;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
desc.useable = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G | AR_AVL);
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_DB | AR_G | AR_AVL);
desc.seg_32bit = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_G | AR_AVL);
desc.seg_32bit = 1;
desc.contents = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA |
AR_S | AR_DB | AR_G | AR_AVL);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA |
AR_S | AR_DB | AR_G | AR_AVL);
desc.contents = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN |
AR_S | AR_DB | AR_G | AR_AVL);
desc.read_exec_only = 0;
desc.limit_in_pages = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN |
AR_S | AR_DB | AR_AVL);
desc.contents = 3;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE_CONF |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE_CONF |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 0;
desc.contents = 2;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 1;
#ifdef __x86_64__
desc.lm = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL);
desc.lm = 0;
#endif
bool entry1_okay = install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL);
if (entry1_okay) {
printf("[RUN]\tTest fork\n");
pid_t child = fork();
if (child == 0) {
nerrs = 0;
check_valid_segment(desc.entry_number, 1,
AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL, desc.limit,
true);
check_invalid_segment(1, 1);
exit(nerrs ? 1 : 0);
} else {
int status;
if (waitpid(child, &status, 0) != child ||
!WIFEXITED(status)) {
printf("[FAIL]\tChild died\n");
nerrs++;
} else if (WEXITSTATUS(status) != 0) {
printf("[FAIL]\tChild failed\n");
nerrs++;
} else {
printf("[OK]\tChild succeeded\n");
}
}
printf("[RUN]\tTest size\n");
int i;
for (i = 0; i < 8192; i++) {
desc.entry_number = i;
desc.limit = i;
if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
printf("[FAIL]\tFailed to install entry %d\n", i);
nerrs++;
break;
}
}
for (int j = 0; j < i; j++) {
check_valid_segment(j, 1, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL, j, false);
}
printf("[DONE]\tSize test\n");
} else {
printf("[SKIP]\tSkipping fork and size tests because we have no LDT\n");
}
/* Test entry_number too high. */
desc.entry_number = 8192;
fail_install(&desc);
/* Test deletion and actions mistakeable for deletion. */
memset(&desc, 0, sizeof(desc));
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P);
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
desc.seg_not_present = 0;
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P);
desc.read_exec_only = 0;
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
desc.read_exec_only = 1;
desc.limit = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
desc.limit = 0;
desc.base_addr = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
desc.base_addr = 0;
install_invalid(&desc, false);
desc.seg_not_present = 0;
desc.read_exec_only = 0;
desc.seg_32bit = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB);
install_invalid(&desc, true);
}
/*
* 0: thread is idle
* 1: thread armed
* 2: thread should clear LDT entry 0
* 3: thread should exit
*/
static volatile unsigned int ftx;
static void *threadproc(void *ctx)
{
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(1, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
err(1, "sched_setaffinity to CPU 1"); /* should never fail */
while (1) {
syscall(SYS_futex, &ftx, FUTEX_WAIT, 0, NULL, NULL, 0);
while (ftx != 2) {
if (ftx >= 3)
return NULL;
}
/* clear LDT entry 0 */
const struct user_desc desc = {};
if (syscall(SYS_modify_ldt, 1, &desc, sizeof(desc)) != 0)
err(1, "modify_ldt");
/* If ftx == 2, set it to zero. If ftx == 100, quit. */
unsigned int x = -2;
asm volatile ("lock xaddl %[x], %[ftx]" :
[x] "+r" (x), [ftx] "+m" (ftx));
if (x != 2)
return NULL;
}
}
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");
}
static jmp_buf jmpbuf;
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
siglongjmp(jmpbuf, 1);
}
static void do_multicpu_tests(void)
{
cpu_set_t cpuset;
pthread_t thread;
int failures = 0, iters = 5, i;
unsigned short orig_ss;
CPU_ZERO(&cpuset);
CPU_SET(1, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
printf("[SKIP]\tCannot set affinity to CPU 1\n");
return;
}
CPU_ZERO(&cpuset);
CPU_SET(0, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
printf("[SKIP]\tCannot set affinity to CPU 0\n");
return;
}
sethandler(SIGSEGV, sigsegv, 0);
#ifdef __i386__
/* True 32-bit kernels send SIGILL instead of SIGSEGV on IRET faults. */
sethandler(SIGILL, sigsegv, 0);
#endif
printf("[RUN]\tCross-CPU LDT invalidation\n");
if (pthread_create(&thread, 0, threadproc, 0) != 0)
err(1, "pthread_create");
asm volatile ("mov %%ss, %0" : "=rm" (orig_ss));
for (i = 0; i < 5; i++) {
if (sigsetjmp(jmpbuf, 1) != 0)
continue;
/* Make sure the thread is ready after the last test. */
while (ftx != 0)
;
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 0xfffff,
.seg_32bit = 1,
.contents = 0, /* Data */
.read_exec_only = 0,
.limit_in_pages = 1,
.seg_not_present = 0,
.useable = 0
};
if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
if (errno != ENOSYS)
err(1, "modify_ldt");
printf("[SKIP]\tmodify_ldt unavailable\n");
break;
}
/* Arm the thread. */
ftx = 1;
syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
asm volatile ("mov %0, %%ss" : : "r" (0x7));
/* Go! */
ftx = 2;
while (ftx != 0)
;
/*
* On success, modify_ldt will segfault us synchronously,
* and we'll escape via siglongjmp.
*/
failures++;
asm volatile ("mov %0, %%ss" : : "rm" (orig_ss));
};
ftx = 100; /* Kill the thread. */
syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
if (pthread_join(thread, NULL) != 0)
err(1, "pthread_join");
if (failures) {
printf("[FAIL]\t%d of %d iterations failed\n", failures, iters);
nerrs++;
} else {
printf("[OK]\tAll %d iterations succeeded\n", iters);
}
}
static int finish_exec_test(void)
{
/*
* In a sensible world, this would be check_invalid_segment(0, 1);
* For better or for worse, though, the LDT is inherited across exec.
* We can probably change this safely, but for now we test it.
*/
check_valid_segment(0, 1,
AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB,
42, true);
return nerrs ? 1 : 0;
}
static void do_exec_test(void)
{
printf("[RUN]\tTest exec\n");
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 42,
.seg_32bit = 1,
.contents = 2, /* Code, not conforming */
.read_exec_only = 0,
.limit_in_pages = 0,
.seg_not_present = 0,
.useable = 0
};
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
pid_t child = fork();
if (child == 0) {
execl("/proc/self/exe", "ldt_gdt_test_exec", NULL);
printf("[FAIL]\tCould not exec self\n");
exit(1); /* exec failed */
} else {
int status;
if (waitpid(child, &status, 0) != child ||
!WIFEXITED(status)) {
printf("[FAIL]\tChild died\n");
nerrs++;
} else if (WEXITSTATUS(status) != 0) {
printf("[FAIL]\tChild failed\n");
nerrs++;
} else {
printf("[OK]\tChild succeeded\n");
}
}
}
int main(int argc, char **argv)
{
if (argc == 1 && !strcmp(argv[0], "ldt_gdt_test_exec"))
return finish_exec_test();
do_simple_tests();
do_multicpu_tests();
do_exec_test();
return nerrs ? 1 : 0;
}

130
tools/testing/selftests/x86/syscall_arg_fault.c Normal file
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/*
* syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
* Copyright (c) 2015 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 <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/signal.h>
#include <sys/ucontext.h>
#include <err.h>
#include <setjmp.h>
#include <errno.h>
/* Our sigaltstack scratch space. */
static unsigned char altstack_data[SIGSTKSZ];
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");
}
static volatile sig_atomic_t sig_traps;
static sigjmp_buf jmpbuf;
static volatile sig_atomic_t n_errs;
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t*)ctx_void;
if (ctx->uc_mcontext.gregs[REG_EAX] != -EFAULT) {
printf("[FAIL]\tAX had the wrong value: 0x%x\n",
ctx->uc_mcontext.gregs[REG_EAX]);
n_errs++;
} else {
printf("[OK]\tSeems okay\n");
}
siglongjmp(jmpbuf, 1);
}
static void sigill(int sig, siginfo_t *info, void *ctx_void)
{
printf("[SKIP]\tIllegal instruction\n");
siglongjmp(jmpbuf, 1);
}
int main()
{
stack_t stack = {
.ss_sp = altstack_data,
.ss_size = SIGSTKSZ,
};
if (sigaltstack(&stack, NULL) != 0)
err(1, "sigaltstack");
sethandler(SIGSEGV, sigsegv, SA_ONSTACK);
sethandler(SIGILL, sigill, SA_ONSTACK);
/*
* Exercise another nasty special case. The 32-bit SYSCALL
* and SYSENTER instructions (even in compat mode) each
* clobber one register. A Linux system call has a syscall
* number and six arguments, and the user stack pointer
* needs to live in some register on return. That means
* that we need eight registers, but SYSCALL and SYSENTER
* only preserve seven registers. As a result, one argument
* ends up on the stack. The stack is user memory, which
* means that the kernel can fail to read it.
*
* The 32-bit fast system calls don't have a defined ABI:
* we're supposed to invoke them through the vDSO. So we'll
* fudge it: we set all regs to invalid pointer values and
* invoke the entry instruction. The return will fail no
* matter what, and we completely lose our program state,
* but we can fix it up with a signal handler.
*/
printf("[RUN]\tSYSENTER with invalid state\n");
if (sigsetjmp(jmpbuf, 1) == 0) {
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");
}
printf("[RUN]\tSYSCALL with invalid state\n");
if (sigsetjmp(jmpbuf, 1) == 0) {
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"
"pushl $0" /* make sure we segfault cleanly */
: : : "memory", "flags");
}
return 0;
}

54
tools/testing/selftests/x86/syscall_nt.c Normal file
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/*
* syscall_nt.c - checks syscalls with NT set
* Copyright (c) 2014-2015 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.
*
* Some obscure user-space code requires the ability to make system calls
* with FLAGS.NT set. Make sure it works.
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/processor-flags.h>
#ifdef __x86_64__
# define WIDTH "q"
#else
# define WIDTH "l"
#endif
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");
}
int main()
{
printf("[RUN]\tSet NT and issue a syscall\n");
set_eflags(get_eflags() | X86_EFLAGS_NT);
syscall(SYS_getpid);
if (get_eflags() & X86_EFLAGS_NT) {
printf("[OK]\tThe syscall worked and NT is still set\n");
return 0;
} else {
printf("[FAIL]\tThe syscall worked but NT was cleared\n");
return 1;
}
}