bef326c6a5
The offset of state component i can be found via CPUID.(EAX=0DH,ECX=i):EBX. The ZMM_Hi256 is state component 6, so we use CPUID to enumerate the offset instead of hardcoding. For core dumps, we guess the ZMM_Hi256 offset based on xcr0 and the length of xsave region. The logic comes from binutils-gdb. Fixes #3827.
56 lines
1.5 KiB
Go
56 lines
1.5 KiB
Go
package amd64util
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import (
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"sync"
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)
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var xstateMaxSize int
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var loadXstateMaxSizeOnce sync.Once
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func cpuid(axIn, cxIn uint32) (axOut, bxOut, cxOut, dxOut uint32)
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func AMD64XstateMaxSize() int {
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loadXstateMaxSizeOnce.Do(func() {
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// See Intel 64 and IA-32 Architecture Software Developer's Manual, Vol. 1
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// chapter 13.2 and Vol. 2A CPUID instruction for a description of all the
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// magic constants.
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_, _, cx, _ := cpuid(0x01, 0x00)
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if cx&(1<<26) == 0 { // Vol. 2A, Table 3-10, XSAVE enabled bit check
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// XSAVE not supported by this processor
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xstateMaxSize = _XSTATE_MAX_KNOWN_SIZE
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return
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}
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_, _, cx, _ = cpuid(0x0d, 0x00) // processor extended state enumeration main leaf
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xstateMaxSize = int(cx)
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})
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return xstateMaxSize
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}
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var xstateZMMHi256Offset int
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var loadXstateZMMHi256OffsetOnce sync.Once
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// AMD64XstateZMMHi256Offset probes ZMM_Hi256 offset of the current CPU. Beware
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// that core dumps may be generated from a different CPU.
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func AMD64XstateZMMHi256Offset() int {
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loadXstateZMMHi256OffsetOnce.Do(func() {
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// See Intel 64 and IA-32 Architecture Software Developer's Manual, Vol. 1
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// chapter 13.2 and Vol. 2A CPUID instruction for a description of all the
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// magic constants.
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_, _, cx, _ := cpuid(0x01, 0x00)
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if cx&(1<<26) == 0 { // Vol. 2A, Table 3-10, XSAVE enabled bit check
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// XSAVE not supported by this processor
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xstateZMMHi256Offset = 0
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return
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}
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_, bx, _, _ := cpuid(0x0d, 0x06) // ZMM_Hi256 is component #6
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xstateZMMHi256Offset = int(bx)
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})
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return xstateZMMHi256Offset
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}
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