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Diffstat (limited to '')
-rw-r--r-- | library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs b/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs new file mode 100644 index 000000000..29fcc8cb0 --- /dev/null +++ b/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs @@ -0,0 +1,102 @@ +//! Parses ELF auxiliary vectors. +#![cfg_attr( + any( + target_arch = "aarch64", + target_arch = "arm", + target_arch = "powerpc64", + target_arch = "riscv64" + ), + allow(dead_code) +)] + +/// Key to access the CPU Hardware capabilities bitfield. +pub(crate) const AT_HWCAP: usize = 25; +/// Key to access the CPU Hardware capabilities 2 bitfield. +pub(crate) const AT_HWCAP2: usize = 26; + +/// Cache HWCAP bitfields of the ELF Auxiliary Vector. +/// +/// If an entry cannot be read all the bits in the bitfield are set to zero. +/// This should be interpreted as all the features being disabled. +#[derive(Debug, Copy, Clone)] +pub(crate) struct AuxVec { + pub hwcap: usize, + pub hwcap2: usize, +} + +/// ELF Auxiliary Vector +/// +/// The auxiliary vector is a memory region in a running ELF program's stack +/// composed of (key: usize, value: usize) pairs. +/// +/// The keys used in the aux vector are platform dependent. For FreeBSD, they are +/// defined in [sys/elf_common.h][elf_common_h]. The hardware capabilities of a given +/// CPU can be queried with the `AT_HWCAP` and `AT_HWCAP2` keys. +/// +/// Note that run-time feature detection is not invoked for features that can +/// be detected at compile-time. +/// +/// [elf_common.h]: https://svnweb.freebsd.org/base/release/12.0.0/sys/sys/elf_common.h?revision=341707 +pub(crate) fn auxv() -> Result<AuxVec, ()> { + if let Ok(hwcap) = archauxv(AT_HWCAP) { + if let Ok(hwcap2) = archauxv(AT_HWCAP2) { + if hwcap != 0 && hwcap2 != 0 { + return Ok(AuxVec { hwcap, hwcap2 }); + } + } + } + Err(()) +} + +/// Tries to read the `key` from the auxiliary vector. +fn archauxv(key: usize) -> Result<usize, ()> { + use core::mem; + + #[derive(Copy, Clone)] + #[repr(C)] + pub struct Elf_Auxinfo { + pub a_type: usize, + pub a_un: unnamed, + } + #[derive(Copy, Clone)] + #[repr(C)] + pub union unnamed { + pub a_val: libc::c_long, + pub a_ptr: *mut libc::c_void, + pub a_fcn: Option<unsafe extern "C" fn() -> ()>, + } + + let mut auxv: [Elf_Auxinfo; 27] = [Elf_Auxinfo { + a_type: 0, + a_un: unnamed { a_val: 0 }, + }; 27]; + + let mut len: libc::c_uint = mem::size_of_val(&auxv) as libc::c_uint; + + unsafe { + let mut mib = [ + libc::CTL_KERN, + libc::KERN_PROC, + libc::KERN_PROC_AUXV, + libc::getpid(), + ]; + + let ret = libc::sysctl( + mib.as_mut_ptr(), + mib.len() as u32, + &mut auxv as *mut _ as *mut _, + &mut len as *mut _ as *mut _, + 0 as *mut libc::c_void, + 0, + ); + + if ret != -1 { + for i in 0..auxv.len() { + if auxv[i].a_type == key { + return Ok(auxv[i].a_un.a_val as usize); + } + } + } + } + return Ok(0); +} |