From 094cb1a9fbb6b2c9b6094cd6424139f70f8912cc Mon Sep 17 00:00:00 2001 From: Jubilee Young Date: Mon, 10 Jul 2023 01:45:31 -0700 Subject: [PATCH] Dynamically size sigaltstk in rustc rustc installs a signal stack that assumes that MINSIGSTKSZ is a constant, unchanging value. Newer hardware undermines that assumption greatly, with register files larger than MINSIGSTKZ. Properly handle this so that it is correct on all supported Linux versions with all CPUs. --- compiler/rustc_driver_impl/src/lib.rs | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs index 9352fe3147e..2e26ce111f0 100644 --- a/compiler/rustc_driver_impl/src/lib.rs +++ b/compiler/rustc_driver_impl/src/lib.rs @@ -1453,13 +1453,13 @@ extern "C" fn print_stack_trace(_: libc::c_int) { /// When an error signal (such as SIGABRT or SIGSEGV) is delivered to the /// process, print a stack trace and then exit. pub(super) fn install() { + use std::alloc::{alloc, Layout}; + unsafe { - const ALT_STACK_SIZE: usize = libc::MINSIGSTKSZ + 64 * 1024; + let alt_stack_size: usize = min_sigstack_size() + 64 * 1024; let mut alt_stack: libc::stack_t = std::mem::zeroed(); - alt_stack.ss_sp = - std::alloc::alloc(std::alloc::Layout::from_size_align(ALT_STACK_SIZE, 1).unwrap()) - as *mut libc::c_void; - alt_stack.ss_size = ALT_STACK_SIZE; + alt_stack.ss_sp = alloc(Layout::from_size_align(alt_stack_size, 1).unwrap()).cast(); + alt_stack.ss_size = alt_stack_size; libc::sigaltstack(&alt_stack, std::ptr::null_mut()); let mut sa: libc::sigaction = std::mem::zeroed(); @@ -1469,6 +1469,23 @@ pub(super) fn install() { libc::sigaction(libc::SIGSEGV, &sa, std::ptr::null_mut()); } } + + /// Modern kernels on modern hardware can have dynamic signal stack sizes. + #[cfg(any(target_os = "linux", target_os = "android"))] + fn min_sigstack_size() -> usize { + const AT_MINSIGSTKSZ: core::ffi::c_ulong = 51; + let dynamic_sigstksz = unsafe { libc::getauxval(AT_MINSIGSTKSZ) }; + // If getauxval couldn't find the entry, it returns 0, + // so take the higher of the "constant" and auxval. + // This transparently supports older kernels which don't provide AT_MINSIGSTKSZ + libc::MINSIGSTKSZ.max(dynamic_sigstksz as _) + } + + /// Not all OS support hardware where this is needed. + #[cfg(not(any(target_os = "linux", target_os = "android")))] + fn min_sigstack_size() -> usize { + libc::MINSIGSTKSZ + } } #[cfg(not(all(unix, any(target_env = "gnu", target_os = "macos"))))]