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-rw-r--r--tools/objtool/check.c69
-rw-r--r--tools/objtool/check.h2
-rw-r--r--tools/testing/selftests/x86/Makefile2
-rw-r--r--tools/testing/selftests/x86/test_vsyscall.c500
4 files changed, 565 insertions, 8 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9b341584eb1b..f40d46e24bcc 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -428,6 +428,40 @@ static void add_ignores(struct objtool_file *file)
}
/*
+ * FIXME: For now, just ignore any alternatives which add retpolines. This is
+ * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
+ * But it at least allows objtool to understand the control flow *around* the
+ * retpoline.
+ */
+static int add_nospec_ignores(struct objtool_file *file)
+{
+ struct section *sec;
+ struct rela *rela;
+ struct instruction *insn;
+
+ sec = find_section_by_name(file->elf, ".rela.discard.nospec");
+ if (!sec)
+ return 0;
+
+ list_for_each_entry(rela, &sec->rela_list, list) {
+ if (rela->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", sec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, rela->sym->sec, rela->addend);
+ if (!insn) {
+ WARN("bad .discard.nospec entry");
+ return -1;
+ }
+
+ insn->ignore_alts = true;
+ }
+
+ return 0;
+}
+
+/*
* Find the destination instructions for all jumps.
*/
static int add_jump_destinations(struct objtool_file *file)
@@ -456,6 +490,13 @@ static int add_jump_destinations(struct objtool_file *file)
} else if (rela->sym->sec->idx) {
dest_sec = rela->sym->sec;
dest_off = rela->sym->sym.st_value + rela->addend + 4;
+ } else if (strstr(rela->sym->name, "_indirect_thunk_")) {
+ /*
+ * Retpoline jumps are really dynamic jumps in
+ * disguise, so convert them accordingly.
+ */
+ insn->type = INSN_JUMP_DYNAMIC;
+ continue;
} else {
/* sibling call */
insn->jump_dest = 0;
@@ -502,11 +543,18 @@ static int add_call_destinations(struct objtool_file *file)
dest_off = insn->offset + insn->len + insn->immediate;
insn->call_dest = find_symbol_by_offset(insn->sec,
dest_off);
+ /*
+ * FIXME: Thanks to retpolines, it's now considered
+ * normal for a function to call within itself. So
+ * disable this warning for now.
+ */
+#if 0
if (!insn->call_dest) {
WARN_FUNC("can't find call dest symbol at offset 0x%lx",
insn->sec, insn->offset, dest_off);
return -1;
}
+#endif
} else if (rela->sym->type == STT_SECTION) {
insn->call_dest = find_symbol_by_offset(rela->sym->sec,
rela->addend+4);
@@ -671,12 +719,6 @@ static int add_special_section_alts(struct objtool_file *file)
return ret;
list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
- alt = malloc(sizeof(*alt));
- if (!alt) {
- WARN("malloc failed");
- ret = -1;
- goto out;
- }
orig_insn = find_insn(file, special_alt->orig_sec,
special_alt->orig_off);
@@ -687,6 +729,10 @@ static int add_special_section_alts(struct objtool_file *file)
goto out;
}
+ /* Ignore retpoline alternatives. */
+ if (orig_insn->ignore_alts)
+ continue;
+
new_insn = NULL;
if (!special_alt->group || special_alt->new_len) {
new_insn = find_insn(file, special_alt->new_sec,
@@ -712,6 +758,13 @@ static int add_special_section_alts(struct objtool_file *file)
goto out;
}
+ alt = malloc(sizeof(*alt));
+ if (!alt) {
+ WARN("malloc failed");
+ ret = -1;
+ goto out;
+ }
+
alt->insn = new_insn;
list_add_tail(&alt->list, &orig_insn->alts);
@@ -1028,6 +1081,10 @@ static int decode_sections(struct objtool_file *file)
add_ignores(file);
+ ret = add_nospec_ignores(file);
+ if (ret)
+ return ret;
+
ret = add_jump_destinations(file);
if (ret)
return ret;
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 47d9ea70a83d..dbadb304a410 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -44,7 +44,7 @@ struct instruction {
unsigned int len;
unsigned char type;
unsigned long immediate;
- bool alt_group, visited, dead_end, ignore, hint, save, restore;
+ bool alt_group, visited, dead_end, ignore, hint, save, restore, ignore_alts;
struct symbol *call_dest;
struct instruction *jump_dest;
struct list_head alts;
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 939a337128db..5d4f10ac2af2 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -7,7 +7,7 @@ include ../lib.mk
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall test_mremap_vdso \
check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test ioperm \
- protection_keys test_vdso
+ protection_keys test_vdso test_vsyscall
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
new file mode 100644
index 000000000000..7a744fa7b786
--- /dev/null
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -0,0 +1,500 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <sys/ucontext.h>
+#include <errno.h>
+#include <err.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <setjmp.h>
+
+#ifdef __x86_64__
+# define VSYS(x) (x)
+#else
+# define VSYS(x) 0
+#endif
+
+#ifndef SYS_getcpu
+# ifdef __x86_64__
+# define SYS_getcpu 309
+# else
+# define SYS_getcpu 318
+# endif
+#endif
+
+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");
+}
+
+/* vsyscalls and vDSO */
+bool should_read_vsyscall = false;
+
+typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
+gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
+gtod_t vdso_gtod;
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+vgettime_t vdso_gettime;
+
+typedef long (*time_func_t)(time_t *t);
+time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
+time_func_t vdso_time;
+
+typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
+getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
+getcpu_t vdso_getcpu;
+
+static void init_vdso(void)
+{
+ void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso)
+ vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso) {
+ printf("[WARN]\tfailed to find vDSO\n");
+ return;
+ }
+
+ vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");
+ if (!vdso_gtod)
+ printf("[WARN]\tfailed to find gettimeofday in vDSO\n");
+
+ vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+ if (!vdso_gettime)
+ printf("[WARN]\tfailed to find clock_gettime in vDSO\n");
+
+ vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");
+ if (!vdso_time)
+ printf("[WARN]\tfailed to find time in vDSO\n");
+
+ vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
+ if (!vdso_getcpu) {
+ /* getcpu() was never wired up in the 32-bit vDSO. */
+ printf("[%s]\tfailed to find getcpu in vDSO\n",
+ sizeof(long) == 8 ? "WARN" : "NOTE");
+ }
+}
+
+static int init_vsys(void)
+{
+#ifdef __x86_64__
+ int nerrs = 0;
+ FILE *maps;
+ char line[128];
+ bool found = false;
+
+ maps = fopen("/proc/self/maps", "r");
+ if (!maps) {
+ printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n");
+ should_read_vsyscall = true;
+ return 0;
+ }
+
+ while (fgets(line, sizeof(line), maps)) {
+ char r, x;
+ void *start, *end;
+ char name[128];
+ if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
+ &start, &end, &r, &x, name) != 5)
+ continue;
+
+ if (strcmp(name, "[vsyscall]"))
+ continue;
+
+ printf("\tvsyscall map: %s", line);
+
+ if (start != (void *)0xffffffffff600000 ||
+ end != (void *)0xffffffffff601000) {
+ printf("[FAIL]\taddress range is nonsense\n");
+ nerrs++;
+ }
+
+ printf("\tvsyscall permissions are %c-%c\n", r, x);
+ should_read_vsyscall = (r == 'r');
+ if (x != 'x') {
+ vgtod = NULL;
+ vtime = NULL;
+ vgetcpu = NULL;
+ }
+
+ found = true;
+ break;
+ }
+
+ fclose(maps);
+
+ if (!found) {
+ printf("\tno vsyscall map in /proc/self/maps\n");
+ should_read_vsyscall = false;
+ vgtod = NULL;
+ vtime = NULL;
+ vgetcpu = NULL;
+ }
+
+ return nerrs;
+#else
+ return 0;
+#endif
+}
+
+/* syscalls */
+static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
+{
+ return syscall(SYS_gettimeofday, tv, tz);
+}
+
+static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
+{
+ return syscall(SYS_clock_gettime, id, ts);
+}
+
+static inline long sys_time(time_t *t)
+{
+ return syscall(SYS_time, t);
+}
+
+static inline long sys_getcpu(unsigned * cpu, unsigned * node,
+ void* cache)
+{
+ return syscall(SYS_getcpu, cpu, node, cache);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+ siglongjmp(jmpbuf, 1);
+}
+
+static double tv_diff(const struct timeval *a, const struct timeval *b)
+{
+ return (double)(a->tv_sec - b->tv_sec) +
+ (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6;
+}
+
+static int check_gtod(const struct timeval *tv_sys1,
+ const struct timeval *tv_sys2,
+ const struct timezone *tz_sys,
+ const char *which,
+ const struct timeval *tv_other,
+ const struct timezone *tz_other)
+{
+ int nerrs = 0;
+ double d1, d2;
+
+ if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) {
+ printf("[FAIL] %s tz mismatch\n", which);
+ nerrs++;
+ }
+
+ d1 = tv_diff(tv_other, tv_sys1);
+ d2 = tv_diff(tv_sys2, tv_other);
+ printf("\t%s time offsets: %lf %lf\n", which, d1, d2);
+
+ if (d1 < 0 || d2 < 0) {
+ printf("[FAIL]\t%s time was inconsistent with the syscall\n", which);
+ nerrs++;
+ } else {
+ printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which);
+ }
+
+ return nerrs;
+}
+
+static int test_gtod(void)
+{
+ struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys;
+ struct timezone tz_sys, tz_vdso, tz_vsys;
+ long ret_vdso = -1;
+ long ret_vsys = -1;
+ int nerrs = 0;
+
+ printf("[RUN]\ttest gettimeofday()\n");
+
+ if (sys_gtod(&tv_sys1, &tz_sys) != 0)
+ err(1, "syscall gettimeofday");
+ if (vdso_gtod)
+ ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
+ if (vgtod)
+ ret_vsys = vgtod(&tv_vsys, &tz_vsys);
+ if (sys_gtod(&tv_sys2, &tz_sys) != 0)
+ err(1, "syscall gettimeofday");
+
+ if (vdso_gtod) {
+ if (ret_vdso == 0) {
+ nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);
+ } else {
+ printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso);
+ nerrs++;
+ }
+ }
+
+ if (vgtod) {
+ if (ret_vsys == 0) {
+ nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
+ } else {
+ printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys);
+ nerrs++;
+ }
+ }
+
+ return nerrs;
+}
+
+static int test_time(void) {
+ int nerrs = 0;
+
+ printf("[RUN]\ttest time()\n");
+ long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;
+ long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;
+ t_sys1 = sys_time(&t2_sys1);
+ if (vdso_time)
+ t_vdso = vdso_time(&t2_vdso);
+ if (vtime)
+ t_vsys = vtime(&t2_vsys);
+ t_sys2 = sys_time(&t2_sys2);
+ if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {
+ printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2);
+ nerrs++;
+ return nerrs;
+ }
+
+ if (vdso_time) {
+ if (t_vdso < 0 || t_vdso != t2_vdso) {
+ printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso);
+ nerrs++;
+ } else if (t_vdso < t_sys1 || t_vdso > t_sys2) {
+ printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2);
+ nerrs++;
+ } else {
+ printf("[OK]\tvDSO time() is okay\n");
+ }
+ }
+
+ if (vtime) {
+ if (t_vsys < 0 || t_vsys != t2_vsys) {
+ printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys);
+ nerrs++;
+ } else if (t_vsys < t_sys1 || t_vsys > t_sys2) {
+ printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2);
+ nerrs++;
+ } else {
+ printf("[OK]\tvsyscall time() is okay\n");
+ }
+ }
+
+ return nerrs;
+}
+
+static int test_getcpu(int cpu)
+{
+ int nerrs = 0;
+ long ret_sys, ret_vdso = -1, ret_vsys = -1;
+
+ printf("[RUN]\tgetcpu() on CPU %d\n", cpu);
+
+ cpu_set_t cpuset;
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu, &cpuset);
+ if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+ printf("[SKIP]\tfailed to force CPU %d\n", cpu);
+ return nerrs;
+ }
+
+ unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;
+ unsigned node = 0;
+ bool have_node = false;
+ ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
+ if (vdso_getcpu)
+ ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
+ if (vgetcpu)
+ ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
+
+ if (ret_sys == 0) {
+ if (cpu_sys != cpu) {
+ printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu);
+ nerrs++;
+ }
+
+ have_node = true;
+ node = node_sys;
+ }
+
+ if (vdso_getcpu) {
+ if (ret_vdso) {
+ printf("[FAIL]\tvDSO getcpu() failed\n");
+ nerrs++;
+ } else {
+ if (!have_node) {
+ have_node = true;
+ node = node_vdso;
+ }
+
+ if (cpu_vdso != cpu) {
+ printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu);
+ nerrs++;
+ } else {
+ printf("[OK]\tvDSO reported correct CPU\n");
+ }
+
+ if (node_vdso != node) {
+ printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node);
+ nerrs++;
+ } else {
+ printf("[OK]\tvDSO reported correct node\n");
+ }
+ }
+ }
+
+ if (vgetcpu) {
+ if (ret_vsys) {
+ printf("[FAIL]\tvsyscall getcpu() failed\n");
+ nerrs++;
+ } else {
+ if (!have_node) {
+ have_node = true;
+ node = node_vsys;
+ }
+
+ if (cpu_vsys != cpu) {
+ printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu);
+ nerrs++;
+ } else {
+ printf("[OK]\tvsyscall reported correct CPU\n");
+ }
+
+ if (node_vsys != node) {
+ printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node);
+ nerrs++;
+ } else {
+ printf("[OK]\tvsyscall reported correct node\n");
+ }
+ }
+ }
+
+ return nerrs;
+}
+
+static int test_vsys_r(void)
+{
+#ifdef __x86_64__
+ printf("[RUN]\tChecking read access to the vsyscall page\n");
+ bool can_read;
+ if (sigsetjmp(jmpbuf, 1) == 0) {
+ *(volatile int *)0xffffffffff600000;
+ can_read = true;
+ } else {
+ can_read = false;
+ }
+
+ if (can_read && !should_read_vsyscall) {
+ printf("[FAIL]\tWe have read access, but we shouldn't\n");
+ return 1;
+ } else if (!can_read && should_read_vsyscall) {
+ printf("[FAIL]\tWe don't have read access, but we should\n");
+ return 1;
+ } else {
+ printf("[OK]\tgot expected result\n");
+ }
+#endif
+
+ return 0;
+}
+
+
+#ifdef __x86_64__
+#define X86_EFLAGS_TF (1UL << 8)
+static volatile sig_atomic_t num_vsyscall_traps;
+
+static unsigned long get_eflags(void)
+{
+ unsigned long eflags;
+ asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags));
+ return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+ asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags");
+}
+
+static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
+{
+ ucontext_t *ctx = (ucontext_t *)ctx_void;
+ unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP];
+
+ if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0)
+ num_vsyscall_traps++;
+}
+
+static int test_native_vsyscall(void)
+{
+ time_t tmp;
+ bool is_native;
+
+ if (!vtime)
+ return 0;
+
+ printf("[RUN]\tchecking for native vsyscall\n");
+ sethandler(SIGTRAP, sigtrap, 0);
+ set_eflags(get_eflags() | X86_EFLAGS_TF);
+ vtime(&tmp);
+ set_eflags(get_eflags() & ~X86_EFLAGS_TF);
+
+ /*
+ * If vsyscalls are emulated, we expect a single trap in the
+ * vsyscall page -- the call instruction will trap with RIP
+ * pointing to the entry point before emulation takes over.
+ * In native mode, we expect two traps, since whatever code
+ * the vsyscall page contains will be more than just a ret
+ * instruction.
+ */
+ is_native = (num_vsyscall_traps > 1);
+
+ printf("\tvsyscalls are %s (%d instructions in vsyscall page)\n",
+ (is_native ? "native" : "emulated"),
+ (int)num_vsyscall_traps);
+
+ return 0;
+}
+#endif
+
+int main(int argc, char **argv)
+{
+ int nerrs = 0;
+
+ init_vdso();
+ nerrs += init_vsys();
+
+ nerrs += test_gtod();
+ nerrs += test_time();
+ nerrs += test_getcpu(0);
+ nerrs += test_getcpu(1);
+
+ sethandler(SIGSEGV, sigsegv, 0);
+ nerrs += test_vsys_r();
+
+#ifdef __x86_64__
+ nerrs += test_native_vsyscall();
+#endif
+
+ return nerrs ? 1 : 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 09:59:01 +0000