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pkg/proc/native,pkg/proc/amd64util: xsave decoding cleanup (#3840)

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- move the cpuid querying code to pkg/proc/native/cpuid since
  pkg/proc/native is the only package entitled to calling it
- add a type to describe the xstate_bv bitmap instead of using
  hardcoded constants everywhere
- use xcr0 instead of xstate_bv for the offset heuristic like gdb does
This commit is contained in:
Alessandro Arzilli 2024-11-21 13:06:51 +01:00 committed by GitHub
parent f83958b923
commit e0c80c8612
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GPG Key ID: B5690EEEBB952194
7 changed files with 42 additions and 28 deletions
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34
pkg/proc/amd64util/xsave.go
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@ -18,6 +18,8 @@ type AMD64Xstate struct {
YmmSpace [256]byte
Avx512State bool // contains AVX512 state
ZmmSpace [512]byte
zmmHi256offset int
}
// AMD64PtraceFpRegs tracks user_fpregs_struct in /usr/include/x86_64-linux-gnu/sys/user.h
@ -72,15 +74,24 @@ func (xstate *AMD64Xstate) Decode() []proc.Register {
}
const (
_XSTATE_MAX_KNOWN_SIZE = 2969
_XSAVE_XMM_REGION_START = 160
_XSAVE_HEADER_START = 512
_XSAVE_HEADER_LEN = 64
_XSAVE_EXTENDED_REGION_START = 576
_XSAVE_SSE_REGION_LEN = 416
_I386_LINUX_XSAVE_XCR0_OFFSET = 464
)
// xstate_bv is a type representing the xcr0 and xstate_bv bitmaps as
// described in section 13.1 and 13.3 of the Intel® 64 and IA-32 Architectures
// Software Developer’s Manual, Volume 1
type xstate_bv uint64
func (s xstate_bv) hasAVX() bool { return s&(1<<2) != 0 }
func (s xstate_bv) hasZMM_Hi256() bool { return s&(1<<6) != 0 }
func (s xstate_bv) hasHi16_ZMM() bool { return s&(1<<7) != 0 } //lint:ignore U1000 future use
func (s xstate_bv) hasPKRU() bool { return s&(1<<9) != 0 }
// AMD64XstateRead reads a byte array containing an XSAVE area into regset.
// If readLegacy is true regset.PtraceFpRegs will be filled with the
// contents of the legacy region of the XSAVE area.
@ -97,17 +108,19 @@ func AMD64XstateRead(xstateargs []byte, readLegacy bool, regset *AMD64Xstate, xs
return err
}
}
xcr0 := xstate_bv(binary.LittleEndian.Uint64(xstateargs[_I386_LINUX_XSAVE_XCR0_OFFSET:][:8]))
xsaveheader := xstateargs[_XSAVE_HEADER_START : _XSAVE_HEADER_START+_XSAVE_HEADER_LEN]
xstate_bv := binary.LittleEndian.Uint64(xsaveheader[0:8])
xstate_bv := xstate_bv(binary.LittleEndian.Uint64(xsaveheader[0:8]))
xcomp_bv := binary.LittleEndian.Uint64(xsaveheader[8:16])
fmt.Printf("xcr0: %#x xstate_bv: %#x\n", xcr0, xstate_bv)
if xcomp_bv&(1<<63) != 0 {
// compact format not supported
return nil
}
if xstate_bv&(1<<2) == 0 {
// AVX state not present
if !xstate_bv.hasAVX() {
return nil
}
@ -115,15 +128,14 @@ func AMD64XstateRead(xstateargs []byte, readLegacy bool, regset *AMD64Xstate, xs
regset.AvxState = true
copy(regset.YmmSpace[:], avxstate[:len(regset.YmmSpace)])
if xstate_bv&(1<<6) == 0 {
// AVX512 state not present
if !xstate_bv.hasZMM_Hi256() {
return nil
}
if xstateZMMHi256Offset == 0 {
// Guess ZMM_Hi256 component offset
// ref: https://github.com/bminor/binutils-gdb/blob/df89bdf0baf106c3b0a9fae53e4e48607a7f3f87/gdb/i387-tdep.c#L916
if xstate_bv&(1<<9) != 0 && len(xstateargs) == 2440 {
if xcr0.hasPKRU() && len(xstateargs) == 2440 {
// AMD CPUs supporting PKRU
xstateZMMHi256Offset = 896
} else {
@ -132,11 +144,13 @@ func AMD64XstateRead(xstateargs []byte, readLegacy bool, regset *AMD64Xstate, xs
}
}
regset.zmmHi256offset = xstateZMMHi256Offset
avx512state := xstateargs[xstateZMMHi256Offset:]
regset.Avx512State = true
copy(regset.ZmmSpace[:], avx512state[:len(regset.ZmmSpace)])
// TODO(aarzilli): if xstate_bv&(1<<7) is set then xstateargs[1664:2688]
// TODO(aarzilli): if xstate_bv.hasHi16_ZMM() is set then xstateargs[1664:2688]
// contains ZMM16 through ZMM31, those aren't just the higher 256bits, it's
// the full register so each is 64 bytes (512bits)
@ -192,7 +206,7 @@ func (xstate *AMD64Xstate) SetXmmRegister(n int, value []byte) error {
// Copy bytes [32, 64) to Xsave area
zmmval := rest
zmmpos := AMD64XstateZMMHi256Offset() + (n * 32)
zmmpos := xstate.zmmHi256offset + (n * 32) //TODO: change this!!!
if zmmpos >= len(xstate.Xsave) {
return fmt.Errorf("could not set XMM%d: bytes 32..%d not in XSAVE area", n, 32+len(zmmval))
}

12
pkg/proc/amd64util/xsave_other.go
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@ -1,12 +0,0 @@
//go:build !amd64
package amd64util
func AMD64XstateMaxSize() int {
return _XSTATE_MAX_KNOWN_SIZE
}
func AMD64XstateZMMHi256Offset() int {
// AVX-512 not supported
return 0
}

8
pkg/proc/amd64util/xsave_amd64.go → pkg/proc/native/cpuid/xsave_x86.go
View File

@ -1,14 +1,20 @@
package amd64util
//go:build amd64 || 386
package cpuid
import (
"sync"
)
const _XSTATE_MAX_KNOWN_SIZE = 2969
var xstateMaxSize int
var loadXstateMaxSizeOnce sync.Once
func cpuid(axIn, cxIn uint32) (axOut, bxOut, cxOut, dxOut uint32)
// AMD64XstateMaxSize returns the maximum size of the xstate area.
func AMD64XstateMaxSize() int {
loadXstateMaxSizeOnce.Do(func() {
// See Intel 64 and IA-32 Architecture Software Developer's Manual, Vol. 1

3
pkg/proc/amd64util/xsave_amd64.s → pkg/proc/native/cpuid/xsave_x86.s
View File

@ -1,3 +1,5 @@
//go:build amd64 || 386
TEXT ·cpuid(SB),$0-24
MOVL axIn+0(FP), AX
MOVL cxIn+4(FP), CX
@ -7,3 +9,4 @@ TEXT ·cpuid(SB),$0-24
MOVL CX, cxOut+16(FP)
MOVL DX, dxOut+20(FP)
RET

3
pkg/proc/native/ptrace_freebsd_amd64.go
View File

@ -11,6 +11,7 @@ import (
"unsafe"
"github.com/go-delve/delve/pkg/proc/amd64util"
"github.com/go-delve/delve/pkg/proc/native/cpuid"
)
var (
@ -73,7 +74,7 @@ func ptraceGetRegset(id int) (*amd64util.AMD64Xstate, error) {
if err != nil {
return nil, err
}
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, amd64util.AMD64XstateZMMHi256Offset())
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, cpuid.AMD64XstateZMMHi256Offset())
return &regset, err
}

5
pkg/proc/native/ptrace_linux_386.go
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@ -8,6 +8,7 @@ import (
sys "golang.org/x/sys/unix"
"github.com/go-delve/delve/pkg/proc/amd64util"
"github.com/go-delve/delve/pkg/proc/native/cpuid"
)
// ptraceGetRegset returns floating point registers of the specified thread
@ -22,7 +23,7 @@ func ptraceGetRegset(tid int) (regset amd64util.AMD64Xstate, err error) {
err = nil
}
xstateargs := make([]byte, amd64util.AMD64XstateMaxSize())
xstateargs := make([]byte, cpuid.AMD64XstateMaxSize())
iov := sys.Iovec{Base: &xstateargs[0], Len: uint32(len(xstateargs))}
_, _, err = syscall.Syscall6(syscall.SYS_PTRACE, sys.PTRACE_GETREGSET, uintptr(tid), _NT_X86_XSTATE, uintptr(unsafe.Pointer(&iov)), 0, 0)
if err != syscall.Errno(0) {
@ -38,7 +39,7 @@ func ptraceGetRegset(tid int) (regset amd64util.AMD64Xstate, err error) {
}
regset.Xsave = xstateargs[:iov.Len]
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, amd64util.AMD64XstateZMMHi256Offset())
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, cpuid.AMD64XstateZMMHi256Offset())
return
}

5
pkg/proc/native/ptrace_linux_amd64.go
View File

@ -7,6 +7,7 @@ import (
sys "golang.org/x/sys/unix"
"github.com/go-delve/delve/pkg/proc/amd64util"
"github.com/go-delve/delve/pkg/proc/native/cpuid"
)
// ptraceGetRegset returns floating point registers of the specified thread
@ -21,7 +22,7 @@ func ptraceGetRegset(tid int) (regset amd64util.AMD64Xstate, err error) {
err = nil
}
xstateargs := make([]byte, amd64util.AMD64XstateMaxSize())
xstateargs := make([]byte, cpuid.AMD64XstateMaxSize())
iov := sys.Iovec{Base: &xstateargs[0], Len: uint64(len(xstateargs))}
_, _, err = syscall.Syscall6(syscall.SYS_PTRACE, sys.PTRACE_GETREGSET, uintptr(tid), _NT_X86_XSTATE, uintptr(unsafe.Pointer(&iov)), 0, 0)
if err != syscall.Errno(0) {
@ -37,6 +38,6 @@ func ptraceGetRegset(tid int) (regset amd64util.AMD64Xstate, err error) {
}
regset.Xsave = xstateargs[:iov.Len]
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, amd64util.AMD64XstateZMMHi256Offset())
err = amd64util.AMD64XstateRead(regset.Xsave, false, &regset, cpuid.AMD64XstateZMMHi256Offset())
return
}