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Sebastian Andrzej Siewior
39388e80f9
In commit72a671ced6("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels") the 32bit and 64bit path of the signal delivery code were merged. The 32bit version: int save_i387_xstate_ia32(void __user *buf) … if (cpu_has_xsave) return save_i387_xsave(fp); if (cpu_has_fxsr) return save_i387_fxsave(fp); The 64bit version: int save_i387_xstate(void __user *buf) … if (user_has_fpu()) { if (use_xsave()) err = xsave_user(buf); else err = fxsave_user(buf); if (unlikely(err)) { __clear_user(buf, xstate_size); return err; The merge: int save_xstate_sig(void __user *buf, void __user *buf_fx, int size) … if (user_has_fpu()) { /* Save the live register state to the user directly. */ if (save_user_xstate(buf_fx)) return -1; /* Update the thread's fxstate to save the fsave header. */ if (ia32_fxstate) fpu_fxsave(&tsk->thread.fpu); I don't think that we needed to save the FPU registers to ->thread.fpu because the registers were stored in buf_fx. Today the state will be restored from buf_fx after the signal was handled (I assume that this was also the case with lazy-FPU). Since commit66463db4fc("x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal()") it is ensured that the signal handler starts with clear/fresh set of FPU registers which means that the previous store is futile. Remove the copy_fxregs_to_kernel() call because task's FPU state is cleared later in handle_signal() via fpu__clear(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Dave Hansen <dave.hansen@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: kvm ML <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190403164156.19645-7-bigeasy@linutronix.de
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.