diff options
Diffstat (limited to 'vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go')
| -rw-r--r-- | vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go | 44 |
1 files changed, 42 insertions, 2 deletions
diff --git a/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go b/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go index 79a38a0..a968b80 100644 --- a/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go +++ b/vendor/golang.org/x/sys/cpu/cpu_linux_arm64.go @@ -4,6 +4,11 @@ package cpu +import ( + "strings" + "syscall" +) + // HWCAP/HWCAP2 bits. These are exposed by Linux. const ( hwcap_FP = 1 << 0 @@ -32,10 +37,45 @@ const ( hwcap_ASIMDFHM = 1 << 23 ) +// linuxKernelCanEmulateCPUID reports whether we're running +// on Linux 4.11+. Ideally we'd like to ask the question about +// whether the current kernel contains +// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77c97b4ee21290f5f083173d957843b615abbff2 +// but the version number will have to do. +func linuxKernelCanEmulateCPUID() bool { + var un syscall.Utsname + syscall.Uname(&un) + var sb strings.Builder + for _, b := range un.Release[:] { + if b == 0 { + break + } + sb.WriteByte(byte(b)) + } + major, minor, _, ok := parseRelease(sb.String()) + return ok && (major > 4 || major == 4 && minor >= 11) +} + func doinit() { if err := readHWCAP(); err != nil { - // failed to read /proc/self/auxv, try reading registers directly - readARM64Registers() + // We failed to read /proc/self/auxv. This can happen if the binary has + // been given extra capabilities(7) with /bin/setcap. + // + // When this happens, we have two options. If the Linux kernel is new + // enough (4.11+), we can read the arm64 registers directly which'll + // trap into the kernel and then return back to userspace. + // + // But on older kernels, such as Linux 4.4.180 as used on many Synology + // devices, calling readARM64Registers (specifically getisar0) will + // cause a SIGILL and we'll die. So for older kernels, parse /proc/cpuinfo + // instead. + // + // See golang/go#57336. + if linuxKernelCanEmulateCPUID() { + readARM64Registers() + } else { + readLinuxProcCPUInfo() + } return } |