copy_user_to_xstate

Name:Convert from a ptrace or sigreturn standard-format user-space buffer to* kernel XSAVES format and copy to the target thread. This is called from* xstateregs_set(), as well as potentially from the sigreturn() and* rt_sigreturn() system calls.

Proto:int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)

Type:int

Parameter:

Type	Parameter	Name
struct xregs_state *	xsave
const void __user *	ubuf

1197

offset = offsetof(structxregs_state, header)

1198

size = size of hdr

1200

If __copy_from_user( & hdr, ubuf + offset, size) Then Return -EFAULT

1203

If Validate an xstate header supplied by userspace (ptrace or sigreturn) Then Return -EINVAL

1206

When i < XFEATURE_MAX cycle

1207

mask = 1 << i

1209

If xfeatures & mask Then

1210

dst = Given an xstate feature nr, calculate where in the xsave* buffer the state is. Callers should ensure that the buffer* is valid.

1212

offset = xstate_offsets[i]

1213

size = xstate_sizes[i]

1215

If __copy_from_user(dst, ubuf + offset, size) Then Return -EFAULT

1220

If Weird legacy quirk: SSE and YMM states store information in the* MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP* area is marked as unused in the xfeatures header, we need to copy* MXCSR and MXCSR_FLAGS if either SSE or YMM are in use. Then

1221

offset = offsetof(structfxregs_state, mxcsr)

1222

size = Copy both mxcsr & mxcsr_flags with a single u64 memcpy:

1223

If __copy_from_user( & MXCSR Register State , ubuf + offset, size) Then Return -EFAULT

1231

xfeatures &= Supervisor features

1236

xfeatures |= xfeatures

1238

Return 0

**Caller**
Name	Describe
__fpu__restore_sig

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