netbird/gvisor
0
0
Fork 0
mirror of https://github.com/netbirdio/gvisor.git synced 2026-05-22 17:12:49 -07:00
Code Issues Packages Projects Releases Wiki Activity

cpuid: ExtendedStateSize returns the state size just for the enabled features

Browse Source 
It is impossible to enable any features from user-space, so
it is no reason to return the maximum size with all features enabled.

The kvm and systrap platforms uses ExtendedStateSize to generate fpu states
that are restored via rt_sigreturn, but the kernel rejects frames with
incorrect sizes.

PiperOrigin-RevId: 537333319
This commit is contained in:
Andrei Vagin
2023-06-02 09:39:06 -07:00
committed by gVisor bot
parent 2199d539ee
commit 4cc749881e
2 changed files with 11 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pkg/cpuid/cpuid_amd64.go
+10 -9
View File
@@ -360,22 +360,23 @@ func (fs FeatureSet) Intel() bool {
//
// If xSaveInfo isn't supported, cpuid will not fault but will
// return bogus values.
var maxXsaveSize = native(In{Eax: uint32(xSaveInfo)}).Ecx
var (
xsaveSize = native(In{Eax: uint32(xSaveInfo)}).Ebx
maxXsaveSize = native(In{Eax: uint32(xSaveInfo)}).Ecx
)
// ExtendedStateSize returns the number of bytes needed to save the "extended
// state" for this processor and the boundary it must be aligned to. Extended
// state includes floating point registers, and other cpu state that's not
// associated with the normal task context.
// state" for the enabled features and the boundary it must be aligned to.
// Extended state includes floating point registers, and other cpu state that's
// not associated with the normal task context.
//
// Note: We can save some space here with an optimization where we use a
// smaller chunk of memory depending on features that are actually enabled.
// Currently we just use the largest possible size for simplicity (which is
// about 2.5K worst case, with avx512).
// Note: the return value matches the size of signal FP state frames.
// Look at check_xstate_in_sigframe() in the kernel sources for more details.
//
//go:nosplit
func (fs FeatureSet) ExtendedStateSize() (size, align uint) {
if fs.UseXsave() {
return uint(maxXsaveSize), 64
return uint(xsaveSize), 64
}
// If we don't support xsave, we fall back to fxsave, which requires
pkg/cpuid/static_amd64.go
+1
View File
@@ -102,6 +102,7 @@ func (s Static) normalize() {
in := In{Eax: uint32(xSaveInfo)}
out := s[in]
out.Ecx = maxXsaveSize
out.Ebx = xsaveSize
s[in] = out
}
}