Messages in this thread Patch in this message | | | From | Sebastian Andrzej Siewior <> | Subject | [RFC PATCH 09/10] x86/fpu: copy non-resident FPU state at fork time | Date | Wed, 12 Sep 2018 15:33:52 +0200 |
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From: Rik van Riel <riel@surriel.com>
If the FPU state is not loaded in registers at fork time, memcpy the fpstate from the parent task to the child task.
Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- arch/x86/kernel/fpu/core.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 2ea85b32421a0..8564086c217fc 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -210,11 +210,14 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu) * ( The function 'fails' in the FNSAVE case, which destroys * register contents so we have to copy them back. ) */ - if (!copy_fpregs_to_fpstate(dst_fpu)) { + __fpregs_changes_begin(); + if (test_thread_flag(TIF_LOAD_FPU)) { + memcpy(&src_fpu->state, &dst_fpu->state, fpu_kernel_xstate_size); + } else if (!copy_fpregs_to_fpstate(dst_fpu)) { memcpy(&src_fpu->state, &dst_fpu->state, fpu_kernel_xstate_size); copy_kernel_to_fpregs(&src_fpu->state); } - + __fpregs_changes_end(); trace_x86_fpu_copy_src(src_fpu); trace_x86_fpu_copy_dst(dst_fpu); -- 2.19.0
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