Merge pull request #1934 from sayantn/fix-xsave

Fix xsave segfaults

Author: folkertdev

ci/docker/x86_64-unknown-linux-gnu/Dockerfile

@@ -14,5 +14,3 @@ RUN tar -xJf sde.tar.xz --strip-components=1 -C intel-sde
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="/intel-sde/sde64 \
             -cpuid-in /checkout/ci/docker/x86_64-unknown-linux-gnu/cpuid.def \
             -rtm-mode full -tsx --"
-# These tests fail with SDE as it doesn't support saving register data
-ENV STDARCH_TEST_SKIP_FUNCTION="xsave,xsaveopt,xsave64,xsaveopt64"

crates/core_arch/src/x86/xsave.rs

@@ -159,29 +159,39 @@ pub unsafe fn _xrstors(mem_addr: *const u8, rs_mask: u64) {
     xrstors(mem_addr, (rs_mask >> 32) as u32, rs_mask as u32);
 }
 
+#[cfg(test)]
+pub(crate) use tests::XsaveArea;
+
 #[cfg(test)]
 mod tests {
-    use std::{fmt, prelude::v1::*};
+    use std::boxed::Box;
 
     use crate::core_arch::x86::*;
     use stdarch_test::simd_test;
 
-    #[repr(align(64))]
     #[derive(Debug)]
-    struct XsaveArea {
-        // max size for 256-bit registers is 800 bytes:
-        // see https://software.intel.com/en-us/node/682996
-        // max size for 512-bit registers is 2560 bytes:
-        // FIXME: add source
-        data: [u8; 2560],
+    pub(crate) struct XsaveArea {
+        data: Box<[AlignedArray]>,
     }
 
+    #[repr(align(64))]
+    #[derive(Copy, Clone, Debug)]
+    struct AlignedArray([u8; 64]);
+
     impl XsaveArea {
-        fn new() -> XsaveArea {
-            XsaveArea { data: [0; 2560] }
+        #[target_feature(enable = "xsave")]
+        pub(crate) fn new() -> XsaveArea {
+            // `CPUID.(EAX=0DH,ECX=0):ECX` contains the size required to hold all supported xsave
+            // components. `EBX` contains the size required to hold all xsave components currently
+            // enabled in `XCR0`. We are using `ECX` to ensure enough space in all scenarios
+            let CpuidResult { ecx, .. } = unsafe { __cpuid(0x0d) };
+
+            XsaveArea {
+                data: vec![AlignedArray([0; 64]); ecx.div_ceil(64) as usize].into_boxed_slice(),
+            }
         }
-        fn ptr(&mut self) -> *mut u8 {
-            self.data.as_mut_ptr()
+        pub(crate) fn ptr(&mut self) -> *mut u8 {
+            self.data.as_mut_ptr().cast()
         }
     }
 

crates/core_arch/src/x86_64/xsave.rs

@@ -126,39 +126,20 @@ pub unsafe fn _xrstors64(mem_addr: *const u8, rs_mask: u64) {
 
 #[cfg(test)]
 mod tests {
-    use crate::core_arch::x86_64::xsave;
-    use std::fmt;
+    use crate::core_arch::x86::*;
+    use crate::core_arch::x86_64::*;
     use stdarch_test::simd_test;
 
-    #[repr(align(64))]
-    #[derive(Debug)]
-    struct XsaveArea {
-        // max size for 256-bit registers is 800 bytes:
-        // see https://software.intel.com/en-us/node/682996
-        // max size for 512-bit registers is 2560 bytes:
-        // FIXME: add source
-        data: [u8; 2560],
-    }
-
-    impl XsaveArea {
-        fn new() -> XsaveArea {
-            XsaveArea { data: [0; 2560] }
-        }
-        fn ptr(&mut self) -> *mut u8 {
-            self.data.as_mut_ptr()
-        }
-    }
-
     #[simd_test(enable = "xsave")]
     #[cfg_attr(miri, ignore)] // Register saving/restoring is not supported in Miri
     unsafe fn test_xsave64() {
         let m = 0xFFFFFFFFFFFFFFFF_u64; //< all registers
         let mut a = XsaveArea::new();
         let mut b = XsaveArea::new();
 
-        xsave::_xsave64(a.ptr(), m);
-        xsave::_xrstor64(a.ptr(), m);
-        xsave::_xsave64(b.ptr(), m);
+        _xsave64(a.ptr(), m);
+        _xrstor64(a.ptr(), m);
+        _xsave64(b.ptr(), m);
     }
 
     #[simd_test(enable = "xsave,xsaveopt")]
@@ -168,9 +149,9 @@ mod tests {
         let mut a = XsaveArea::new();
         let mut b = XsaveArea::new();
 
-        xsave::_xsaveopt64(a.ptr(), m);
-        xsave::_xrstor64(a.ptr(), m);
-        xsave::_xsaveopt64(b.ptr(), m);
+        _xsaveopt64(a.ptr(), m);
+        _xrstor64(a.ptr(), m);
+        _xsaveopt64(b.ptr(), m);
     }
 
     #[simd_test(enable = "xsave,xsavec")]
@@ -180,8 +161,8 @@ mod tests {
         let mut a = XsaveArea::new();
         let mut b = XsaveArea::new();
 
-        xsave::_xsavec64(a.ptr(), m);
-        xsave::_xrstor64(a.ptr(), m);
-        xsave::_xsavec64(b.ptr(), m);
+        _xsavec64(a.ptr(), m);
+        _xrstor64(a.ptr(), m);
+        _xsavec64(b.ptr(), m);
     }
 }