summaryrefslogtreecommitdiffhomepage
path: root/pkg/cpuid
diff options
context:
space:
mode:
Diffstat (limited to 'pkg/cpuid')
-rw-r--r--pkg/cpuid/cpuid.go203
-rw-r--r--pkg/cpuid/cpuid_test.go24
2 files changed, 178 insertions, 49 deletions
diff --git a/pkg/cpuid/cpuid.go b/pkg/cpuid/cpuid.go
index 3fabaf445..5d61dc2ff 100644
--- a/pkg/cpuid/cpuid.go
+++ b/pkg/cpuid/cpuid.go
@@ -418,6 +418,73 @@ var x86FeatureParseOnlyStrings = map[Feature]string{
X86FeaturePREFETCHWT1: "prefetchwt1",
}
+// intelCacheDescriptors describe the caches and TLBs on the system. They are
+// returned in the registers for eax=2. Intel only.
+type intelCacheDescriptor uint8
+
+// Valid cache/TLB descriptors. All descriptors can be found in Intel SDM Vol.
+// 2, Ch. 3.2, "CPUID", Table 3-12 "Encoding of CPUID Leaf 2 Descriptors".
+const (
+ intelNullDescriptor intelCacheDescriptor = 0
+ intelNoTLBDescriptor intelCacheDescriptor = 0xfe
+ intelNoCacheDescriptor intelCacheDescriptor = 0xff
+
+ // Most descriptors omitted for brevity as they are currently unused.
+)
+
+// CacheType describes the type of a cache, as returned in eax[4:0] for eax=4.
+type CacheType uint8
+
+const (
+ // cacheNull indicates that there are no more entries.
+ cacheNull CacheType = iota
+
+ // CacheData is a data cache.
+ CacheData
+
+ // CacheInstruction is an instruction cache.
+ CacheInstruction
+
+ // CacheUnified is a unified instruction and data cache.
+ CacheUnified
+)
+
+// Cache describes the parameters of a single cache on the system.
+//
+// +stateify savable
+type Cache struct {
+ // Level is the hierarchical level of this cache (L1, L2, etc).
+ Level uint32
+
+ // Type is the type of cache.
+ Type CacheType
+
+ // FullyAssociative indicates that entries may be placed in any block.
+ FullyAssociative bool
+
+ // Partitions is the number of physical partitions in the cache.
+ Partitions uint32
+
+ // Ways is the number of ways of associativity in the cache.
+ Ways uint32
+
+ // Sets is the number of sets in the cache.
+ Sets uint32
+
+ // InvalidateHierarchical indicates that WBINVD/INVD from threads
+ // sharing this cache acts upon lower level caches for threads sharing
+ // this cache.
+ InvalidateHierarchical bool
+
+ // Inclusive indicates that this cache is inclusive of lower cache
+ // levels.
+ Inclusive bool
+
+ // DirectMapped indicates that this cache is directly mapped from
+ // address, rather than using a hash function.
+ DirectMapped bool
+}
+
// Just a way to wrap cpuid function numbers.
type cpuidFunction uint32
@@ -494,7 +561,7 @@ func (f Feature) flagString(cpuinfoOnly bool) string {
return ""
}
-// FeatureSet is a set of Features for a cpu.
+// FeatureSet is a set of Features for a CPU.
//
// +stateify savable
type FeatureSet struct {
@@ -521,6 +588,15 @@ type FeatureSet struct {
// SteppingID is part of the processor signature.
SteppingID uint8
+
+ // Caches describes the caches on the CPU.
+ Caches []Cache
+
+ // CacheLine is the size of a cache line in bytes.
+ //
+ // All caches use the same line size. This is not enforced in the CPUID
+ // encoding, but is true on all known x86 processors.
+ CacheLine uint32
}
// FlagsString prints out supported CPU flags. If cpuinfoOnly is true, it is
@@ -557,22 +633,27 @@ func (fs FeatureSet) CPUInfo(cpu uint) string {
fmt.Fprintln(&b, "wp\t\t: yes")
fmt.Fprintf(&b, "flags\t\t: %s\n", fs.FlagsString(true))
fmt.Fprintf(&b, "bogomips\t: %.02f\n", cpuFreqMHz) // It's bogus anyway.
- fmt.Fprintf(&b, "clflush size\t: %d\n", 64)
- fmt.Fprintf(&b, "cache_alignment\t: %d\n", 64)
+ fmt.Fprintf(&b, "clflush size\t: %d\n", fs.CacheLine)
+ fmt.Fprintf(&b, "cache_alignment\t: %d\n", fs.CacheLine)
fmt.Fprintf(&b, "address sizes\t: %d bits physical, %d bits virtual\n", 46, 48)
fmt.Fprintln(&b, "power management:") // This is always here, but can be blank.
fmt.Fprintln(&b, "") // The /proc/cpuinfo file ends with an extra newline.
return b.String()
}
+const (
+ amdVendorID = "AuthenticAMD"
+ intelVendorID = "GenuineIntel"
+)
+
// AMD returns true if fs describes an AMD CPU.
func (fs *FeatureSet) AMD() bool {
- return fs.VendorID == "AuthenticAMD"
+ return fs.VendorID == amdVendorID
}
// Intel returns true if fs describes an Intel CPU.
func (fs *FeatureSet) Intel() bool {
- return fs.VendorID == "GenuineIntel"
+ return fs.VendorID == intelVendorID
}
// ErrIncompatible is returned by FeatureSet.HostCompatible if fs is not a
@@ -589,9 +670,18 @@ func (e ErrIncompatible) Error() string {
// CheckHostCompatible returns nil if fs is a subset of the host feature set.
func (fs *FeatureSet) CheckHostCompatible() error {
hfs := HostFeatureSet()
+
if diff := fs.Subtract(hfs); diff != nil {
return ErrIncompatible{fmt.Sprintf("CPU feature set %v incompatible with host feature set %v (missing: %v)", fs.FlagsString(false), hfs.FlagsString(false), diff)}
}
+
+ // The size of a cache line must match, as it is critical to correctly
+ // utilizing CLFLUSH. Other cache properties are allowed to change, as
+ // they are not important to correctness.
+ if fs.CacheLine != hfs.CacheLine {
+ return ErrIncompatible{fmt.Sprintf("CPU cache line size %d incompatible with host cache line size %d", fs.CacheLine, hfs.CacheLine)}
+ }
+
return nil
}
@@ -732,14 +822,6 @@ func (fs *FeatureSet) HasFeature(feature Feature) bool {
return fs.Set[feature]
}
-// IsSubset returns true if the FeatureSet is a subset of the FeatureSet passed in.
-// This is useful if you want to see if a FeatureSet is compatible with another
-// FeatureSet, since you can only run with a given FeatureSet if it's a subset of
-// the host's.
-func (fs *FeatureSet) IsSubset(other *FeatureSet) bool {
- return fs.Subtract(other) == nil
-}
-
// Subtract returns the features present in fs that are not present in other.
// If all features in fs are present in other, Subtract returns nil.
func (fs *FeatureSet) Subtract(other *FeatureSet) (diff map[Feature]bool) {
@@ -755,17 +837,6 @@ func (fs *FeatureSet) Subtract(other *FeatureSet) (diff map[Feature]bool) {
return
}
-// TakeFeatureIntersection will set the features in `fs` to the intersection of
-// the features in `fs` and `other` (effectively clearing any feature bits on
-// `fs` that are not also set in `other`).
-func (fs *FeatureSet) TakeFeatureIntersection(other *FeatureSet) {
- for f := range fs.Set {
- if !other.Set[f] {
- delete(fs.Set, f)
- }
- }
-}
-
// EmulateID emulates a cpuid instruction based on the feature set.
func (fs *FeatureSet) EmulateID(origAx, origCx uint32) (ax, bx, cx, dx uint32) {
switch cpuidFunction(origAx) {
@@ -773,9 +844,8 @@ func (fs *FeatureSet) EmulateID(origAx, origCx uint32) (ax, bx, cx, dx uint32) {
ax = uint32(xSaveInfo) // 0xd (xSaveInfo) is the highest function we support.
bx, dx, cx = fs.vendorIDRegs()
case featureInfo:
- // clflush line size (ebx bits[15:8]) hardcoded as 8. This
- // means cache lines of size 64 bytes.
- bx = 8 << 8
+ // CLFLUSH line size is encoded in quadwords. Other fields in bx unsupported.
+ bx = (fs.CacheLine / 8) << 8
cx = fs.blockMask(block(0))
dx = fs.blockMask(block(1))
ax = fs.signature()
@@ -789,10 +859,46 @@ func (fs *FeatureSet) EmulateID(origAx, origCx uint32) (ax, bx, cx, dx uint32) {
// will always return 01H. Software should ignore this value
// and not interpret it as an informational descriptor." - SDM
//
- // We do not support exposing cache information, but we do set
- // this fixed field because some language runtimes (dlang) get
- // confused by ax = 0 and will loop infinitely.
- ax = 1
+ // We only support reporting cache parameters via
+ // intelDeterministicCacheParams; report as much here.
+ //
+ // We do not support exposing TLB information at all.
+ ax = 1 | (uint32(intelNoCacheDescriptor) << 8)
+ case intelDeterministicCacheParams:
+ if !fs.Intel() {
+ // Reserved on non-Intel.
+ return 0, 0, 0, 0
+ }
+
+ // cx is the index of the cache to describe.
+ if int(origCx) >= len(fs.Caches) {
+ return uint32(cacheNull), 0, 0, 0
+ }
+ c := fs.Caches[origCx]
+
+ ax = uint32(c.Type)
+ ax |= c.Level << 5
+ ax |= 1 << 8 // Always claim the cache is "self-initializing".
+ if c.FullyAssociative {
+ ax |= 1 << 9
+ }
+ // Processor topology not supported.
+
+ bx = fs.CacheLine - 1
+ bx |= (c.Partitions - 1) << 12
+ bx |= (c.Ways - 1) << 22
+
+ cx = c.Sets - 1
+
+ if !c.InvalidateHierarchical {
+ dx |= 1
+ }
+ if c.Inclusive {
+ dx |= 1 << 1
+ }
+ if !c.DirectMapped {
+ dx |= 1 << 2
+ }
case xSaveInfo:
if !fs.UseXsave() {
return 0, 0, 0, 0
@@ -845,10 +951,41 @@ func HostFeatureSet() *FeatureSet {
vendorID := vendorIDFromRegs(bx, cx, dx)
// eax=1 gets basic features in ecx:edx.
- ax, _, cx, dx := HostID(1, 0)
+ ax, bx, cx, dx := HostID(1, 0)
featureBlock0 := cx
featureBlock1 := dx
ef, em, pt, f, m, sid := signatureSplit(ax)
+ cacheLine := 8 * (bx >> 8) & 0xff
+
+ // eax=4, ecx=i gets details about cache index i. Only supported on Intel.
+ var caches []Cache
+ if vendorID == intelVendorID {
+ // ecx selects the cache index until a null type is returned.
+ for i := uint32(0); ; i++ {
+ ax, bx, cx, dx := HostID(4, i)
+ t := CacheType(ax & 0xf)
+ if t == cacheNull {
+ break
+ }
+
+ lineSize := (bx & 0xfff) + 1
+ if lineSize != cacheLine {
+ panic(fmt.Sprintf("Mismatched cache line size: %d vs %d", lineSize, cacheLine))
+ }
+
+ caches = append(caches, Cache{
+ Type: t,
+ Level: (ax >> 5) & 0x7,
+ FullyAssociative: ((ax >> 9) & 1) == 1,
+ Partitions: ((bx >> 12) & 0x3ff) + 1,
+ Ways: ((bx >> 22) & 0x3ff) + 1,
+ Sets: cx + 1,
+ InvalidateHierarchical: (dx & 1) == 0,
+ Inclusive: ((dx >> 1) & 1) == 1,
+ DirectMapped: ((dx >> 2) & 1) == 0,
+ })
+ }
+ }
// eax=7, ecx=0 gets extended features in ecx:ebx.
_, bx, cx, _ = HostID(7, 0)
@@ -883,6 +1020,8 @@ func HostFeatureSet() *FeatureSet {
Family: f,
Model: m,
SteppingID: sid,
+ CacheLine: cacheLine,
+ Caches: caches,
}
}
diff --git a/pkg/cpuid/cpuid_test.go b/pkg/cpuid/cpuid_test.go
index 6ae14d2da..a707ebb55 100644
--- a/pkg/cpuid/cpuid_test.go
+++ b/pkg/cpuid/cpuid_test.go
@@ -57,24 +57,13 @@ var justFPUandPAE = &FeatureSet{
X86FeaturePAE: true,
}}
-func TestIsSubset(t *testing.T) {
- if !justFPU.IsSubset(justFPUandPAE) {
- t.Errorf("Got %v is not subset of %v, want IsSubset being true", justFPU, justFPUandPAE)
+func TestSubtract(t *testing.T) {
+ if diff := justFPU.Subtract(justFPUandPAE); diff != nil {
+ t.Errorf("Got %v is not subset of %v, want diff (%v) to be nil", justFPU, justFPUandPAE, diff)
}
- if justFPUandPAE.IsSubset(justFPU) {
- t.Errorf("Got %v is a subset of %v, want IsSubset being false", justFPU, justFPUandPAE)
- }
-}
-
-func TestTakeFeatureIntersection(t *testing.T) {
- testFeatures := HostFeatureSet()
- testFeatures.TakeFeatureIntersection(justFPU)
- if !testFeatures.IsSubset(justFPU) {
- t.Errorf("Got more features than expected after intersecting host features with justFPU: %v, want %v", testFeatures.Set, justFPU.Set)
- }
- if !testFeatures.HasFeature(X86FeatureFPU) {
- t.Errorf("Got no features in testFeatures after intersecting, want %v", X86FeatureFPU)
+ if justFPUandPAE.Subtract(justFPU) == nil {
+ t.Errorf("Got %v is a subset of %v, want diff to be nil", justFPU, justFPUandPAE)
}
}
@@ -83,7 +72,7 @@ func TestTakeFeatureIntersection(t *testing.T) {
// if HostFeatureSet gives back junk bits.
func TestHostFeatureSet(t *testing.T) {
hostFeatures := HostFeatureSet()
- if !justFPUandPAE.IsSubset(hostFeatures) {
+ if justFPUandPAE.Subtract(hostFeatures) != nil {
t.Errorf("Got invalid feature set %v from HostFeatureSet()", hostFeatures)
}
}
@@ -175,6 +164,7 @@ func TestEmulateIDBasicFeatures(t *testing.T) {
testFeatures := newEmptyFeatureSet()
testFeatures.Add(X86FeatureCLFSH)
testFeatures.Add(X86FeatureAVX)
+ testFeatures.CacheLine = 64
ax, bx, cx, dx := testFeatures.EmulateID(1, 0)
ECXAVXBit := uint32(1 << uint(X86FeatureAVX))
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 14:20:55 +0000