Buildmach: Add Linux rseq support detection utility
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@@ -1,6 +1,8 @@
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option(COMPILE_CL_CHECKS "Compile CL checks" OFF)
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option(COMPILE_PCL_TOOLS "Compile PCL-based validation tools" ON)
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add_executable(rseqsliceprobe rseqsliceprobe.cpp)
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if(COMPILE_CL_CHECKS)
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# Find OpenCL: try find_package first, fall back to pkg-config
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find_package(OpenCL QUIET)
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@@ -0,0 +1,302 @@
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#include <asm/prctl.h>
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#include <cerrno>
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#include <cinttypes>
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#include <cstddef>
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#include <cstdint>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <linux/auxvec.h>
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#include <linux/rseq.h>
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#include <sys/auxv.h>
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#include <sys/prctl.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#ifndef PR_RSEQ_SLICE_EXTENSION
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#define PR_RSEQ_SLICE_EXTENSION 79
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#define PR_RSEQ_SLICE_EXTENSION_GET 1
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#define PR_RSEQ_SLICE_EXTENSION_SET 2
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#define PR_RSEQ_SLICE_EXT_ENABLE 0x01
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#endif
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#ifndef RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE
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#define RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE (1U << 4)
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#define RSEQ_CS_FLAG_SLICE_EXT_ENABLED (1U << 5)
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#endif
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#ifndef RSEQ_SIG
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#if defined(__x86_64__) || defined(__i386__)
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#define RSEQ_SIG 0x53053053
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#elif defined(__aarch64__)
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#define RSEQ_SIG 0x00bc28d4
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#else
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#error "Add RSEQ_SIG for this architecture"
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#endif
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#endif
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#ifndef SYS_rseq
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#ifdef __NR_rseq
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#define SYS_rseq __NR_rseq
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#endif
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#endif
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#ifndef SYS_getcpu
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#ifdef __NR_getcpu
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#define SYS_getcpu __NR_getcpu
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#endif
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#endif
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extern "C" {
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extern __attribute__((weak)) ptrdiff_t __rseq_offset;
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extern __attribute__((weak)) unsigned int __rseq_size;
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extern __attribute__((weak)) unsigned int __rseq_flags;
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}
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struct rseq_slice_ctrl_compat {
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union {
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uint32_t all;
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struct {
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uint8_t request;
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uint8_t granted;
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uint16_t reserved;
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};
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};
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};
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struct rseq_compat {
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uint32_t cpu_id_start;
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int32_t cpu_id;
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uint64_t rseq_cs;
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uint32_t flags;
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uint32_t node_id;
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uint32_t mm_cid;
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struct rseq_slice_ctrl_compat slice_ctrl;
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uint8_t reserved;
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char end[];
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} __attribute__((aligned(32)));
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alignas(32) static thread_local unsigned char local_rseq_storage[512];
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static unsigned int g_rseq_feature_size;
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static unsigned int g_rseq_alloc_size;
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static unsigned int g_rseq_align;
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static struct rseq *g_registered_rseq;
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static struct rseq_compat *g_registered_rseq_compat;
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static bool g_own_registration;
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static int get_thread_pointer(uintptr_t *tp_out)
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{
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#if defined(__x86_64__)
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unsigned long fsbase = 0;
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if (syscall(SYS_arch_prctl, ARCH_GET_FS, &fsbase) != 0)
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return -1;
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*tp_out = fsbase;
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return 0;
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#else
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(void) tp_out;
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errno = ENOTSUP;
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return -1;
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#endif
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}
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static int sys_rseq(struct rseq *rseq, uint32_t len, int flags, uint32_t sig)
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{
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#ifdef SYS_rseq
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return static_cast<int>(syscall(SYS_rseq, rseq, len, flags, sig));
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#else
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(void) rseq;
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(void) len;
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(void) flags;
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(void) sig;
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errno = ENOSYS;
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return -1;
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#endif
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}
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static int sys_getcpu(unsigned int *cpu, unsigned int *node)
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{
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#ifdef SYS_getcpu
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return static_cast<int>(syscall(SYS_getcpu, cpu, node, nullptr));
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#else
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(void) cpu;
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(void) node;
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errno = ENOSYS;
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return -1;
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#endif
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}
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static const char *errno_name(int err)
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{
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switch (err) {
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case 0: return "0";
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case EINVAL: return "EINVAL";
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case ENOSYS: return "ENOSYS";
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case ENOTSUP: return "ENOTSUP";
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case ENXIO: return "ENXIO";
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case EPERM: return "EPERM";
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case EBUSY: return "EBUSY";
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default: return "UNKNOWN";
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}
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}
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static unsigned int max_u32(unsigned int a, unsigned int b)
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{
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return a > b ? a : b;
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}
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static bool feature_present(size_t end_offset)
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{
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return g_rseq_feature_size >= end_offset;
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}
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static void print_registration_source(void)
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{
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if (g_own_registration)
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std::printf("rseq registration: local syscall registration\n");
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else
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std::printf("rseq registration: existing libc-owned registration\n");
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}
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static int setup_rseq(void)
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{
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unsigned long aux_feature_size = getauxval(AT_RSEQ_FEATURE_SIZE);
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unsigned long aux_align = getauxval(AT_RSEQ_ALIGN);
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g_rseq_feature_size = aux_feature_size ? static_cast<unsigned int>(aux_feature_size) : 20U;
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g_rseq_align = aux_align ? static_cast<unsigned int>(aux_align) : 32U;
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g_rseq_alloc_size = max_u32(g_rseq_feature_size, 32U);
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if (&__rseq_size != nullptr && __rseq_size != 0) {
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uintptr_t tp = 0;
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if (get_thread_pointer(&tp) != 0) {
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std::perror("get_thread_pointer");
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return -1;
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}
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g_registered_rseq = reinterpret_cast<struct rseq *>(tp + __rseq_offset);
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g_registered_rseq_compat = reinterpret_cast<struct rseq_compat *>(tp + __rseq_offset);
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if (__rseq_size < g_rseq_feature_size)
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g_rseq_feature_size = __rseq_size;
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if (__rseq_size > g_rseq_alloc_size)
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g_rseq_alloc_size = __rseq_size;
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return 0;
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}
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if (g_rseq_alloc_size > sizeof(local_rseq_storage)) {
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std::fprintf(stderr,
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"local rseq area too small: need %u bytes, have %zu\n",
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g_rseq_alloc_size, sizeof(local_rseq_storage));
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errno = EOVERFLOW;
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return -1;
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}
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if ((reinterpret_cast<uintptr_t>(local_rseq_storage) % g_rseq_align) != 0) {
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std::fprintf(stderr, "local rseq area alignment mismatch: need %u\n",
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g_rseq_align);
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errno = EINVAL;
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return -1;
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}
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auto *local_rseq = reinterpret_cast<struct rseq *>(local_rseq_storage);
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auto *local_rseq_compat = reinterpret_cast<struct rseq_compat *>(local_rseq_storage);
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std::memset(local_rseq_storage, 0, sizeof(local_rseq_storage));
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local_rseq_compat->cpu_id = RSEQ_CPU_ID_UNINITIALIZED;
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if (sys_rseq(local_rseq, g_rseq_alloc_size, 0, RSEQ_SIG) != 0) {
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std::perror("rseq register");
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return -1;
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}
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g_registered_rseq = local_rseq;
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g_registered_rseq_compat = local_rseq_compat;
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g_own_registration = true;
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return 0;
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}
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static void teardown_rseq(void)
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{
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if (!g_own_registration)
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return;
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auto *local_rseq = reinterpret_cast<struct rseq *>(local_rseq_storage);
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if (sys_rseq(local_rseq, g_rseq_alloc_size, RSEQ_FLAG_UNREGISTER, RSEQ_SIG) != 0)
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std::perror("rseq unregister");
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}
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static void probe_slice_extension(void)
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{
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bool has_slice_ctrl = feature_present(offsetof(struct rseq_compat, slice_ctrl) +
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sizeof(g_registered_rseq_compat->slice_ctrl));
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bool flags_available = feature_present(offsetof(struct rseq_compat, flags) +
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sizeof(g_registered_rseq_compat->flags));
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unsigned int cpu = 0;
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unsigned int node = 0;
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std::printf("AT_RSEQ_FEATURE_SIZE: %u\n", g_rseq_feature_size);
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std::printf("AT_RSEQ_ALIGN: %u\n", g_rseq_align);
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std::printf("registered rseq size: %u\n", g_rseq_alloc_size);
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print_registration_source();
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std::printf("registered rseq addr: %p\n", static_cast<void *>(g_registered_rseq));
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std::printf("struct rseq has slice_ctrl field available: %s\n",
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has_slice_ctrl ? "yes" : "no");
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if (sys_getcpu(&cpu, &node) == 0)
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std::printf("getcpu(): cpu=%u node=%u\n", cpu, node);
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std::printf("rseq cpu_id_start=%u cpu_id=%d\n",
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g_registered_rseq->cpu_id_start,
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static_cast<int32_t>(g_registered_rseq->cpu_id));
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if (feature_present(offsetof(struct rseq_compat, node_id) +
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sizeof(g_registered_rseq_compat->node_id))) {
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std::printf("rseq node_id=%u\n", g_registered_rseq_compat->node_id);
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}
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if (feature_present(offsetof(struct rseq_compat, mm_cid) +
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sizeof(g_registered_rseq_compat->mm_cid))) {
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std::printf("rseq mm_cid=%u\n", g_registered_rseq_compat->mm_cid);
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}
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if (flags_available) {
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std::printf("rseq flags=0x%x\n", g_registered_rseq_compat->flags);
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std::printf("slice ext available bit: %s\n",
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(g_registered_rseq_compat->flags & RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE) ? "set" : "clear");
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std::printf("slice ext enabled bit: %s\n",
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(g_registered_rseq_compat->flags & RSEQ_CS_FLAG_SLICE_EXT_ENABLED) ? "set" : "clear");
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}
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if (has_slice_ctrl) {
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std::printf("slice_ctrl.request=%u granted=%u raw=0x%x\n",
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g_registered_rseq_compat->slice_ctrl.request,
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g_registered_rseq_compat->slice_ctrl.granted,
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g_registered_rseq_compat->slice_ctrl.all);
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}
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errno = 0;
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int rc = prctl(PR_RSEQ_SLICE_EXTENSION, PR_RSEQ_SLICE_EXTENSION_GET, 0UL, 0UL, 0UL);
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int saved_errno = errno;
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if (rc >= 0) {
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std::printf("prctl(GET) result=%d\n", rc);
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std::printf("slice extension runtime availability: yes\n");
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std::printf("slice extension enabled for this thread: %s\n",
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(rc & PR_RSEQ_SLICE_EXT_ENABLE) ? "yes" : "no");
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return;
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}
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std::printf("prctl(GET) failed: errno=%d (%s)\n",
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saved_errno, errno_name(saved_errno));
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std::printf("slice extension runtime availability: %s\n",
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saved_errno == EINVAL ? "no" : "unknown");
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}
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int main()
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{
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if (setup_rseq() != 0)
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return 1;
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probe_slice_extension();
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teardown_rseq();
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return 0;
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}
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