diff options
Diffstat (limited to 'pkg')
| -rw-r--r-- | pkg/cpuid/cpuid.go | 203 | ||||
| -rw-r--r-- | pkg/cpuid/cpuid_test.go | 24 |
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)) |