diff options
Diffstat (limited to 'vdso')
| -rw-r--r-- | vdso/BUILD | 92 | ||||
| -rw-r--r-- | vdso/barrier.h | 49 | ||||
| -rw-r--r-- | vdso/check_vdso.py | 204 | ||||
| -rw-r--r-- | vdso/compiler.h | 29 | ||||
| -rw-r--r-- | vdso/cycle_clock.h | 51 | ||||
| -rw-r--r-- | vdso/seqlock.h | 39 | ||||
| -rw-r--r-- | vdso/syscalls.h | 99 | ||||
| -rw-r--r-- | vdso/vdso.cc | 151 | ||||
| -rw-r--r-- | vdso/vdso_amd64.lds | 101 | ||||
| -rw-r--r-- | vdso/vdso_arm64.lds | 99 | ||||
| -rw-r--r-- | vdso/vdso_time.cc | 159 | ||||
| -rw-r--r-- | vdso/vdso_time.h | 27 |
12 files changed, 0 insertions, 1100 deletions
diff --git a/vdso/BUILD b/vdso/BUILD deleted file mode 100644 index 7ceed349e..000000000 --- a/vdso/BUILD +++ /dev/null @@ -1,92 +0,0 @@ -# Description: -# This VDSO is a shared library that provides the same interfaces as the -# normal system VDSO (time, gettimeofday, clock_gettimeofday) but which uses -# timekeeping parameters managed by the sandbox kernel. - -load("@bazel_tools//tools/cpp:cc_flags_supplier.bzl", "cc_flags_supplier") - -package(licenses = ["notice"]) - -config_setting( - name = "x86_64", - constraint_values = ["@bazel_tools//platforms:x86_64"], -) - -config_setting( - name = "aarch64", - constraint_values = ["@bazel_tools//platforms:aarch64"], -) - -genrule( - name = "vdso", - srcs = [ - "barrier.h", - "compiler.h", - "cycle_clock.h", - "seqlock.h", - "syscalls.h", - "vdso.cc", - "vdso_amd64.lds", - "vdso_arm64.lds", - "vdso_time.h", - "vdso_time.cc", - ], - outs = [ - "vdso.so", - ], - cmd = "$(CC) $(CC_FLAGS) " + - "-I. " + - "-O2 " + - "-std=c++11 " + - "-fPIC " + - # Some toolchains enable stack protector by default. Disable it, the - # VDSO has no hooks to handle failures. - "-fno-stack-protector " + - "-fuse-ld=gold " + - select({ - ":x86_64": "-m64 ", - "//conditions:default": "", - }) + - "-shared " + - "-nostdlib " + - "-Wl,-soname=linux-vdso.so.1 " + - "-Wl,--hash-style=sysv " + - "-Wl,--no-undefined " + - "-Wl,-Bsymbolic " + - "-Wl,-z,max-page-size=4096 " + - "-Wl,-z,common-page-size=4096 " + - select( - { - ":x86_64": "-Wl,-T$(location vdso_amd64.lds) ", - ":aarch64": "-Wl,-T$(location vdso_arm64.lds) ", - }, - no_match_error = "Unsupported architecture", - ) + - "-o $(location vdso.so) " + - "$(location vdso.cc) " + - "$(location vdso_time.cc) " + - "&& $(location :check_vdso) " + - "--check-data " + - "--vdso $(location vdso.so) ", - features = ["-pie"], - toolchains = [ - "@bazel_tools//tools/cpp:current_cc_toolchain", - ":no_pie_cc_flags", - ], - tools = [ - ":check_vdso", - ], - visibility = ["//:sandbox"], -) - -cc_flags_supplier( - name = "no_pie_cc_flags", - features = ["-pie"], -) - -py_binary( - name = "check_vdso", - srcs = ["check_vdso.py"], - python_version = "PY2", - visibility = ["//:sandbox"], -) diff --git a/vdso/barrier.h b/vdso/barrier.h deleted file mode 100644 index edba4afb5..000000000 --- a/vdso/barrier.h +++ /dev/null @@ -1,49 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#ifndef VDSO_BARRIER_H_ -#define VDSO_BARRIER_H_ - -namespace vdso { - -// Compiler Optimization barrier. -inline void barrier(void) { __asm__ __volatile__("" ::: "memory"); } - -#if __x86_64__ - -inline void memory_barrier(void) { - __asm__ __volatile__("mfence" ::: "memory"); -} -inline void read_barrier(void) { barrier(); } -inline void write_barrier(void) { barrier(); } - -#elif __aarch64__ - -inline void memory_barrier(void) { - __asm__ __volatile__("dmb ish" ::: "memory"); -} -inline void read_barrier(void) { - __asm__ __volatile__("dmb ishld" ::: "memory"); -} -inline void write_barrier(void) { - __asm__ __volatile__("dmb ishst" ::: "memory"); -} - -#else -#error "unsupported architecture" -#endif - -} // namespace vdso - -#endif // VDSO_BARRIER_H_ diff --git a/vdso/check_vdso.py b/vdso/check_vdso.py deleted file mode 100644 index b3ee574f3..000000000 --- a/vdso/check_vdso.py +++ /dev/null @@ -1,204 +0,0 @@ -# Copyright 2018 The gVisor Authors. -# -# Licensed under the Apache License, Version 2.0 (the "License"); -# you may not use this file except in compliance with the License. -# You may obtain a copy of the License at -# -# http://www.apache.org/licenses/LICENSE-2.0 -# -# Unless required by applicable law or agreed to in writing, software -# distributed under the License is distributed on an "AS IS" BASIS, -# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -# See the License for the specific language governing permissions and -# limitations under the License. - -"""Verify VDSO ELF does not contain any relocations and is directly mmappable. -""" - -import argparse -import logging -import re -import subprocess - -PAGE_SIZE = 4096 - - -def PageRoundDown(addr): - """Rounds down to the nearest page. - - Args: - addr: An address. - - Returns: - The address rounded down to the nearest page. - """ - return addr & ~(PAGE_SIZE - 1) - - -def Fatal(*args, **kwargs): - """Logs a critical message and exits with code 1. - - Args: - *args: Args to pass to logging.critical. - **kwargs: Keyword args to pass to logging.critical. - """ - logging.critical(*args, **kwargs) - exit(1) - - -def CheckSegments(vdso_path): - """Verifies layout of PT_LOAD segments. - - PT_LOAD segments must be laid out such that the ELF is directly mmappable. - - Specifically, check that: - * PT_LOAD file offsets are equivalent to the memory offset from the first - segment. - * No extra zeroed space (memsz) is required. - * PT_LOAD segments are in order (required for any ELF). - * No two PT_LOAD segments share part of the same page. - - The readelf line format looks like: - Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align - LOAD 0x000000 0xffffffffff700000 0xffffffffff700000 0x000e68 0x000e68 R E 0x1000 - - Args: - vdso_path: Path to VDSO binary. - """ - output = subprocess.check_output(["readelf", "-lW", vdso_path]).decode() - lines = output.split("\n") - - segments = [] - for line in lines: - if not line.startswith(" LOAD"): - continue - - components = line.split() - - segments.append({ - "offset": int(components[1], 16), - "addr": int(components[2], 16), - "filesz": int(components[4], 16), - "memsz": int(components[5], 16), - }) - - if not segments: - Fatal("No PT_LOAD segments in VDSO") - - first = segments[0] - if first["offset"] != 0: - Fatal("First PT_LOAD segment has non-zero file offset: %s", first) - - for i, segment in enumerate(segments): - memoff = segment["addr"] - first["addr"] - if memoff != segment["offset"]: - Fatal("PT_LOAD segment has different memory and file offsets: %s", - segments) - - if segment["memsz"] != segment["filesz"]: - Fatal("PT_LOAD segment memsz != filesz: %s", segment) - - if i > 0: - last_end = segments[i-1]["addr"] + segments[i-1]["memsz"] - if segment["addr"] < last_end: - Fatal("PT_LOAD segments out of order") - - last_page = PageRoundDown(last_end) - start_page = PageRoundDown(segment["addr"]) - if last_page >= start_page: - Fatal("PT_LOAD segments share a page: %s and %s", segment, - segments[i - 1]) - - -# Matches the section name in readelf -SW output. -_SECTION_NAME_RE = re.compile(r"""^\s+\[\ ?\d+\]\s+ - (?P<name>\.\S+)\s+ - (?P<type>\S+)\s+ - (?P<addr>[0-9a-f]+)\s+ - (?P<off>[0-9a-f]+)\s+ - (?P<size>[0-9a-f]+)""", re.VERBOSE) - - -def CheckData(vdso_path): - """Verifies the VDSO contains no .data or .bss sections. - - The readelf line format looks like: - - There are 15 section headers, starting at offset 0x15f0: - - Section Headers: - [Nr] Name Type Address Off Size ES Flg Lk Inf Al - [ 0] NULL 0000000000000000 000000 000000 00 0 0 0 - [ 1] .hash HASH ffffffffff700120 000120 000040 04 A 2 0 8 - [ 2] .dynsym DYNSYM ffffffffff700160 000160 000108 18 A 3 1 8 - ... - [13] .strtab STRTAB 0000000000000000 001448 000123 00 0 0 1 - [14] .shstrtab STRTAB 0000000000000000 00156b 000083 00 0 0 1 - Key to Flags: - W (write), A (alloc), X (execute), M (merge), S (strings), I (info), - L (link order), O (extra OS processing required), G (group), T (TLS), - C (compressed), x (unknown), o (OS specific), E (exclude), - l (large), p (processor specific) - - Args: - vdso_path: Path to VDSO binary. - """ - output = subprocess.check_output(["readelf", "-SW", vdso_path]).decode() - lines = output.split("\n") - - found_text = False - for line in lines: - m = re.search(_SECTION_NAME_RE, line) - if not m: - continue - - if not line.startswith(" ["): - continue - - name = m.group("name") - size = int(m.group("size"), 16) - - if name == ".text" and size != 0: - found_text = True - - # Clang will typically omit these sections entirely; gcc will include them - # but with size 0. - if name.startswith(".data") and size != 0: - Fatal("VDSO contains non-empty .data section:\n%s" % output) - - if name.startswith(".bss") and size != 0: - Fatal("VDSO contains non-empty .bss section:\n%s" % output) - - if not found_text: - Fatal("VDSO contains no/empty .text section? Bad parsing?:\n%s" % output) - - -def CheckRelocs(vdso_path): - """Verifies that the VDSO includes no relocations. - - Args: - vdso_path: Path to VDSO binary. - """ - output = subprocess.check_output(["readelf", "-r", vdso_path]).decode() - if output.strip() != "There are no relocations in this file.": - Fatal("VDSO contains relocations: %s", output) - - -def main(): - parser = argparse.ArgumentParser(description="Verify VDSO ELF.") - parser.add_argument("--vdso", required=True, help="Path to VDSO ELF") - parser.add_argument( - "--check-data", - action="store_true", - help="Check that the ELF contains no .data or .bss sections") - args = parser.parse_args() - - CheckSegments(args.vdso) - CheckRelocs(args.vdso) - - if args.check_data: - CheckData(args.vdso) - - -if __name__ == "__main__": - main() diff --git a/vdso/compiler.h b/vdso/compiler.h deleted file mode 100644 index 54a510000..000000000 --- a/vdso/compiler.h +++ /dev/null @@ -1,29 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#ifndef VDSO_COMPILER_H_ -#define VDSO_COMPILER_H_ - -#define likely(x) __builtin_expect(!!(x), 1) -#define unlikely(x) __builtin_expect(!!(x), 0) - -#ifndef __section -#define __section(S) __attribute__((__section__(#S))) -#endif - -#ifndef __aligned -#define __aligned(N) __attribute__((__aligned__(N))) -#endif - -#endif // VDSO_COMPILER_H_ diff --git a/vdso/cycle_clock.h b/vdso/cycle_clock.h deleted file mode 100644 index 5d3fbb257..000000000 --- a/vdso/cycle_clock.h +++ /dev/null @@ -1,51 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#ifndef VDSO_CYCLE_CLOCK_H_ -#define VDSO_CYCLE_CLOCK_H_ - -#include <stdint.h> - -#include "vdso/barrier.h" - -namespace vdso { - -#if __x86_64__ - -// TODO(b/74613497): The appropriate barrier instruction to use with rdtsc on -// x86_64 depends on the vendor. Intel processors can use lfence but AMD may -// need mfence, depending on MSR_F10H_DECFG_LFENCE_SERIALIZE_BIT. - -static inline uint64_t cycle_clock(void) { - uint32_t lo, hi; - asm volatile("lfence" : : : "memory"); - asm volatile("rdtsc" : "=a"(lo), "=d"(hi)); - return ((uint64_t)hi << 32) | lo; -} - -#elif __aarch64__ - -static inline uint64_t cycle_clock(void) { - uint64_t val; - asm volatile("mrs %0, CNTVCT_EL0" : "=r"(val)::"memory"); - return val; -} - -#else -#error "unsupported architecture" -#endif - -} // namespace vdso - -#endif // VDSO_CYCLE_CLOCK_H_ diff --git a/vdso/seqlock.h b/vdso/seqlock.h deleted file mode 100644 index 7a173174b..000000000 --- a/vdso/seqlock.h +++ /dev/null @@ -1,39 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Low level raw interfaces to the sequence counter used by the VDSO. -#ifndef VDSO_SEQLOCK_H_ -#define VDSO_SEQLOCK_H_ - -#include <stdint.h> - -#include "vdso/barrier.h" -#include "vdso/compiler.h" - -namespace vdso { - -inline int32_t read_seqcount_begin(const uint64_t* s) { - uint64_t seq = *s; - read_barrier(); - return seq & ~1; -} - -inline int read_seqcount_retry(const uint64_t* s, uint64_t seq) { - read_barrier(); - return unlikely(*s != seq); -} - -} // namespace vdso - -#endif // VDSO_SEQLOCK_H_ diff --git a/vdso/syscalls.h b/vdso/syscalls.h deleted file mode 100644 index f5865bb72..000000000 --- a/vdso/syscalls.h +++ /dev/null @@ -1,99 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// System call support for the VDSO. -// -// Provides fallback system call interfaces for getcpu() -// and clock_gettime(). - -#ifndef VDSO_SYSCALLS_H_ -#define VDSO_SYSCALLS_H_ - -#include <asm/unistd.h> -#include <errno.h> -#include <fcntl.h> -#include <stddef.h> -#include <sys/types.h> - -namespace vdso { - -#if __x86_64__ - -struct getcpu_cache; - -static inline int sys_clock_gettime(clockid_t clock, struct timespec* ts) { - int num = __NR_clock_gettime; - asm volatile("syscall\n" - : "+a"(num) - : "D"(clock), "S"(ts) - : "rcx", "r11", "memory"); - return num; -} - -static inline int sys_getcpu(unsigned* cpu, unsigned* node, - struct getcpu_cache* cache) { - int num = __NR_getcpu; - asm volatile("syscall\n" - : "+a"(num) - : "D"(cpu), "S"(node), "d"(cache) - : "rcx", "r11", "memory"); - return num; -} - -#elif __aarch64__ - -static inline int sys_rt_sigreturn(void) { - int num = __NR_rt_sigreturn; - - asm volatile( - "mov x8, %0\n" - "svc #0 \n" - : "+r"(num) - : - :); - return num; -} - -static inline int sys_clock_gettime(clockid_t _clkid, struct timespec *_ts) { - register struct timespec *ts asm("x1") = _ts; - register clockid_t clkid asm("x0") = _clkid; - register long ret asm("x0"); - register long nr asm("x8") = __NR_clock_gettime; - - asm volatile("svc #0\n" - : "=r"(ret) - : "r"(clkid), "r"(ts), "r"(nr) - : "memory"); - return ret; -} - -static inline int sys_clock_getres(clockid_t _clkid, struct timespec *_ts) { - register struct timespec *ts asm("x1") = _ts; - register clockid_t clkid asm("x0") = _clkid; - register long ret asm("x0"); - register long nr asm("x8") = __NR_clock_getres; - - asm volatile("svc #0\n" - : "=r"(ret) - : "r"(clkid), "r"(ts), "r"(nr) - : "memory"); - return ret; -} - -#else -#error "unsupported architecture" -#endif -} // namespace vdso - -#endif // VDSO_SYSCALLS_H_ diff --git a/vdso/vdso.cc b/vdso/vdso.cc deleted file mode 100644 index 8bb80a7a4..000000000 --- a/vdso/vdso.cc +++ /dev/null @@ -1,151 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// This is the VDSO for sandboxed binaries. This file just contains the entry -// points to the VDSO. All of the real work is done in vdso_time.cc - -#define _DEFAULT_SOURCE // ensure glibc provides struct timezone. -#include <sys/time.h> -#include <time.h> - -#include "vdso/syscalls.h" -#include "vdso/vdso_time.h" - -namespace vdso { -namespace { - -int __common_clock_gettime(clockid_t clock, struct timespec* ts) { - int ret; - - switch (clock) { - case CLOCK_REALTIME: - ret = ClockRealtime(ts); - break; - - case CLOCK_BOOTTIME: - // Fallthrough, CLOCK_BOOTTIME is an alias for CLOCK_MONOTONIC - case CLOCK_MONOTONIC: - ret = ClockMonotonic(ts); - break; - - default: - ret = sys_clock_gettime(clock, ts); - break; - } - - return ret; -} - -int __common_gettimeofday(struct timeval* tv, struct timezone* tz) { - if (tv) { - struct timespec ts; - int ret = ClockRealtime(&ts); - if (ret) { - return ret; - } - tv->tv_sec = ts.tv_sec; - tv->tv_usec = ts.tv_nsec / 1000; - } - - // Nobody should be calling gettimeofday() with a non-NULL - // timezone pointer. If they do then they will get zeros. - if (tz) { - tz->tz_minuteswest = 0; - tz->tz_dsttime = 0; - } - - return 0; -} -} // namespace - -#if __x86_64__ - -// __vdso_clock_gettime() implements clock_gettime() -extern "C" int __vdso_clock_gettime(clockid_t clock, struct timespec* ts) { - return __common_clock_gettime(clock, ts); -} -extern "C" int clock_gettime(clockid_t clock, struct timespec* ts) - __attribute__((weak, alias("__vdso_clock_gettime"))); - -// __vdso_gettimeofday() implements gettimeofday() -extern "C" int __vdso_gettimeofday(struct timeval* tv, struct timezone* tz) { - return __common_gettimeofday(tv, tz); -} -extern "C" int gettimeofday(struct timeval* tv, struct timezone* tz) - __attribute__((weak, alias("__vdso_gettimeofday"))); - -// __vdso_time() implements time() -extern "C" time_t __vdso_time(time_t* t) { - struct timespec ts; - ClockRealtime(&ts); - if (t) { - *t = ts.tv_sec; - } - return ts.tv_sec; -} -extern "C" time_t time(time_t* t) __attribute__((weak, alias("__vdso_time"))); - -// __vdso_getcpu() implements getcpu() -extern "C" long __vdso_getcpu(unsigned* cpu, unsigned* node, - struct getcpu_cache* cache) { - // No optimizations yet, just make the real system call. - return sys_getcpu(cpu, node, cache); -} -extern "C" long getcpu(unsigned* cpu, unsigned* node, - struct getcpu_cache* cache) - __attribute__((weak, alias("__vdso_getcpu"))); - -#elif __aarch64__ - -// __kernel_clock_gettime() implements clock_gettime() -extern "C" int __kernel_clock_gettime(clockid_t clock, struct timespec* ts) { - return __common_clock_gettime(clock, ts); -} - -// __kernel_gettimeofday() implements gettimeofday() -extern "C" int __kernel_gettimeofday(struct timeval* tv, struct timezone* tz) { - return __common_gettimeofday(tv, tz); -} - -// __kernel_clock_getres() implements clock_getres() -extern "C" int __kernel_clock_getres(clockid_t clock, struct timespec* res) { - int ret = 0; - - switch (clock) { - case CLOCK_REALTIME: - case CLOCK_MONOTONIC: - case CLOCK_BOOTTIME: { - res->tv_sec = 0; - res->tv_nsec = 1; - break; - } - - default: - ret = sys_clock_getres(clock, res); - break; - } - - return ret; -} - -// __kernel_rt_sigreturn() implements gettimeofday() -extern "C" int __kernel_rt_sigreturn(unsigned long unused) { - // No optimizations yet, just make the real system call. - return sys_rt_sigreturn(); -} - -#else -#error "unsupported architecture" -#endif -} // namespace vdso diff --git a/vdso/vdso_amd64.lds b/vdso/vdso_amd64.lds deleted file mode 100644 index e2615ae9e..000000000 --- a/vdso/vdso_amd64.lds +++ /dev/null @@ -1,101 +0,0 @@ -/* - * Linker script for the VDSO. - * - * The VDSO is essentially a normal ELF shared library that is mapped into the - * address space of the process that is going to use it. The address of the - * VDSO is passed to the runtime linker in the AT_SYSINFO_EHDR entry of the aux - * vector. - * - * There are, however, three ways in which the VDSO differs from a normal - * shared library: - * - * - The runtime linker does not attempt to process any relocations for the - * VDSO so it is the responsibility of whoever loads the VDSO into the - * address space to do this if necessary. Because of this restriction we are - * careful to ensure that the VDSO does not need to have any relocations - * applied to it. - * - * - Although the VDSO is position independent and would normally be linked at - * virtual address 0, the Linux kernel VDSO is actually linked at a non zero - * virtual address and the code in the system runtime linker that handles the - * VDSO expects this to be the case so we have to explicitly link this VDSO - * at a non zero address. The actual address is arbitrary, but we use the - * same one as the Linux kernel VDSO. - * - * - The VDSO will be directly mmapped by the sentry, rather than going through - * a normal ELF loading process. The VDSO must be carefully constructed such - * that the layout in the ELF file is identical to the layout in memory. - */ - -VDSO_PRELINK = 0xffffffffff700000; - -SECTIONS { - /* The parameter page is mapped just before the VDSO. */ - _params = VDSO_PRELINK - 0x1000; - - . = VDSO_PRELINK + SIZEOF_HEADERS; - - .hash : { *(.hash) } :text - .gnu.hash : { *(.gnu.hash) } - .dynsym : { *(.dynsym) } - .dynstr : { *(.dynstr) } - .gnu.version : { *(.gnu.version) } - .gnu.version_d : { *(.gnu.version_d) } - .gnu.version_r : { *(.gnu.version_r) } - - .note : { *(.note.*) } :text :note - - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr - .eh_frame : { KEEP (*(.eh_frame)) } :text - - .dynamic : { *(.dynamic) } :text :dynamic - - .rodata : { *(.rodata*) } :text - - .altinstructions : { *(.altinstructions) } - .altinstr_replacement : { *(.altinstr_replacement) } - - /* - * TODO(gvisor.dev/issue/157): Remove this alignment? Then the VDSO would fit - * in a single page. - */ - . = ALIGN(0x1000); - .text : { *(.text*) } :text =0x90909090 - - /* - * N.B. There is no data/bss section. This VDSO neither needs nor uses a data - * section. We omit it entirely because some gcc/clang and gold/bfd version - * combinations struggle to handle an empty data PHDR segment (internal - * linker assertion failures result). - * - * If the VDSO does incorrectly include a data section, the linker will - * include it in the text segment. check_vdso.py looks for this degenerate - * case. - */ -} - -PHDRS { - text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R | PF_X */ - dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ - note PT_NOTE FLAGS(4); /* PF_R */ - eh_frame_hdr PT_GNU_EH_FRAME; -} - -/* - * Define the symbols that are to be exported. - */ -VERSION { - LINUX_2.6 { - global: - clock_gettime; - __vdso_clock_gettime; - gettimeofday; - __vdso_gettimeofday; - getcpu; - __vdso_getcpu; - time; - __vdso_time; - - local: *; - }; -} diff --git a/vdso/vdso_arm64.lds b/vdso/vdso_arm64.lds deleted file mode 100644 index 469185468..000000000 --- a/vdso/vdso_arm64.lds +++ /dev/null @@ -1,99 +0,0 @@ -/* - * Linker script for the VDSO. - * - * The VDSO is essentially a normal ELF shared library that is mapped into the - * address space of the process that is going to use it. The address of the - * VDSO is passed to the runtime linker in the AT_SYSINFO_EHDR entry of the aux - * vector. - * - * There are, however, three ways in which the VDSO differs from a normal - * shared library: - * - * - The runtime linker does not attempt to process any relocations for the - * VDSO so it is the responsibility of whoever loads the VDSO into the - * address space to do this if necessary. Because of this restriction we are - * careful to ensure that the VDSO does not need to have any relocations - * applied to it. - * - * - Although the VDSO is position independent and would normally be linked at - * virtual address 0, the Linux kernel VDSO is actually linked at a non zero - * virtual address and the code in the system runtime linker that handles the - * VDSO expects this to be the case so we have to explicitly link this VDSO - * at a non zero address. The actual address is arbitrary, but we use the - * same one as the Linux kernel VDSO. - * - * - The VDSO will be directly mmapped by the sentry, rather than going through - * a normal ELF loading process. The VDSO must be carefully constructed such - * that the layout in the ELF file is identical to the layout in memory. - */ - -VDSO_PRELINK = 0xffffffffff700000; - -OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64") -OUTPUT_ARCH(aarch64) - -SECTIONS { - /* The parameter page is mapped just before the VDSO. */ - _params = VDSO_PRELINK - 0x1000; - - . = VDSO_PRELINK + SIZEOF_HEADERS; - - .hash : { *(.hash) } :text - .gnu.hash : { *(.gnu.hash) } - .dynsym : { *(.dynsym) } - .dynstr : { *(.dynstr) } - .gnu.version : { *(.gnu.version) } - .gnu.version_d : { *(.gnu.version_d) } - .gnu.version_r : { *(.gnu.version_r) } - - .note : { *(.note.*) } :text :note - - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr - .eh_frame : { KEEP (*(.eh_frame)) } :text - - .dynamic : { *(.dynamic) } :text :dynamic - - .rodata : { *(.rodata*) } :text - - .altinstructions : { *(.altinstructions) } - .altinstr_replacement : { *(.altinstr_replacement) } - - /* - * TODO(gvisor.dev/issue/157): Remove this alignment? Then the VDSO would fit - * in a single page. - */ - . = ALIGN(0x1000); - .text : { *(.text*) } :text =0xd503201f - - /* - * N.B. There is no data/bss section. This VDSO neither needs nor uses a data - * section. We omit it entirely because some gcc/clang and gold/bfd version - * combinations struggle to handle an empty data PHDR segment (internal - * linker assertion failures result). - * - * If the VDSO does incorrectly include a data section, the linker will - * include it in the text segment. check_vdso.py looks for this degenerate - * case. - */ -} - -PHDRS { - text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R | PF_X */ - dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ - note PT_NOTE FLAGS(4); /* PF_R */ - eh_frame_hdr PT_GNU_EH_FRAME; -} - -/* - * Define the symbols that are to be exported. - */ -VERSION { - LINUX_2.6.39 { - global: - __kernel_clock_getres; - __kernel_clock_gettime; - __kernel_gettimeofday; - __kernel_rt_sigreturn; - local: *; - }; -} diff --git a/vdso/vdso_time.cc b/vdso/vdso_time.cc deleted file mode 100644 index 1bb4bb86b..000000000 --- a/vdso/vdso_time.cc +++ /dev/null @@ -1,159 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#include "vdso/vdso_time.h" - -#include <stdint.h> -#include <sys/time.h> -#include <time.h> - -#include "vdso/cycle_clock.h" -#include "vdso/seqlock.h" -#include "vdso/syscalls.h" - -// struct params defines the layout of the parameter page maintained by the -// kernel (i.e., sentry). -// -// This is similar to the VVAR page maintained by the normal Linux kernel for -// its VDSO, but it has a different layout. -// -// It must be kept in sync with VDSOParamPage in pkg/sentry/kernel/vdso.go. -struct params { - uint64_t seq_count; - - uint64_t monotonic_ready; - int64_t monotonic_base_cycles; - int64_t monotonic_base_ref; - uint64_t monotonic_frequency; - - uint64_t realtime_ready; - int64_t realtime_base_cycles; - int64_t realtime_base_ref; - uint64_t realtime_frequency; -}; - -// Returns a pointer to the global parameter page. -// -// This page lives in the page just before the VDSO binary itself. The linker -// defines _params as the page before the VDSO. -// -// Ideally, we'd simply declare _params as an extern struct params. -// Unfortunately various combinations of old/new versions of gcc/clang and -// gold/bfd struggle to generate references to such a global without generating -// relocations. -// -// So instead, we use inline assembly with a construct that seems to have wide -// compatibility across many toolchains. -#if __x86_64__ - -inline struct params* get_params() { - struct params* p = nullptr; - asm("leaq _params(%%rip), %0" : "=r"(p) : :); - return p; -} - -#elif __aarch64__ - -inline struct params* get_params() { - struct params* p = nullptr; - asm("adr %0, _params" : "=r"(p) : :); - return p; -} - -#else -#error "unsupported architecture" -#endif - -namespace vdso { - -const uint64_t kNsecsPerSec = 1000000000UL; - -inline struct timespec ns_to_timespec(uint64_t ns) { - struct timespec ts; - ts.tv_sec = ns / kNsecsPerSec; - ts.tv_nsec = ns % kNsecsPerSec; - return ts; -} - -inline uint64_t cycles_to_ns(uint64_t frequency, uint64_t cycles) { - uint64_t mult = (kNsecsPerSec << 32) / frequency; - return ((unsigned __int128)cycles * mult) >> 32; -} - -// ClockRealtime() is the VDSO implementation of clock_gettime(CLOCK_REALTIME). -int ClockRealtime(struct timespec* ts) { - struct params* params = get_params(); - uint64_t seq; - uint64_t ready; - int64_t base_ref; - int64_t base_cycles; - uint64_t frequency; - int64_t now_cycles; - - do { - seq = read_seqcount_begin(¶ms->seq_count); - ready = params->realtime_ready; - base_ref = params->realtime_base_ref; - base_cycles = params->realtime_base_cycles; - frequency = params->realtime_frequency; - now_cycles = cycle_clock(); - } while (read_seqcount_retry(¶ms->seq_count, seq)); - - if (!ready) { - // The sandbox kernel ensures that we won't compute a time later than this - // once the params are ready. - return sys_clock_gettime(CLOCK_REALTIME, ts); - } - - int64_t delta_cycles = - (now_cycles < base_cycles) ? 0 : now_cycles - base_cycles; - int64_t now_ns = base_ref + cycles_to_ns(frequency, delta_cycles); - *ts = ns_to_timespec(now_ns); - return 0; -} - -// ClockMonotonic() is the VDSO implementation of -// clock_gettime(CLOCK_MONOTONIC). -int ClockMonotonic(struct timespec* ts) { - struct params* params = get_params(); - uint64_t seq; - uint64_t ready; - int64_t base_ref; - int64_t base_cycles; - uint64_t frequency; - int64_t now_cycles; - - do { - seq = read_seqcount_begin(¶ms->seq_count); - ready = params->monotonic_ready; - base_ref = params->monotonic_base_ref; - base_cycles = params->monotonic_base_cycles; - frequency = params->monotonic_frequency; - now_cycles = cycle_clock(); - } while (read_seqcount_retry(¶ms->seq_count, seq)); - - if (!ready) { - // The sandbox kernel ensures that we won't compute a time later than this - // once the params are ready. - return sys_clock_gettime(CLOCK_MONOTONIC, ts); - } - - int64_t delta_cycles = - (now_cycles < base_cycles) ? 0 : now_cycles - base_cycles; - int64_t now_ns = base_ref + cycles_to_ns(frequency, delta_cycles); - *ts = ns_to_timespec(now_ns); - return 0; -} - -} // namespace vdso diff --git a/vdso/vdso_time.h b/vdso/vdso_time.h deleted file mode 100644 index 70d079efc..000000000 --- a/vdso/vdso_time.h +++ /dev/null @@ -1,27 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#ifndef VDSO_VDSO_TIME_H_ -#define VDSO_VDSO_TIME_H_ - -#include <time.h> - -namespace vdso { - -int ClockRealtime(struct timespec* ts); -int ClockMonotonic(struct timespec* ts); - -} // namespace vdso - -#endif // VDSO_VDSO_TIME_H_ |