===================================================================
@@ -155,7 +155,6 @@ static inline int copy_fpregs_to_sigfram
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
- struct fpu *fpu = ¤t->thread.fpu;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);
@@ -173,9 +172,6 @@ int copy_fpstate_to_sigframe(void __user
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
- /* Update the thread's fxstate to save the fsave header. */
- if (ia32_fxstate)
- copy_fxregs_to_kernel(fpu);
/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
In commit 72a671ced66db ("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 commit 66463db4fc560 ("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 copy_fxregs_to_kernel() because task's FPU state is cleared later in handle_signal() via fpu__clear(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- v1…v2: - reworte description. Replaced the "I don't know why it is like it is makes no sense buh" part with some pointer which might explain why copy_fxregs_to_kernel() ended there and since when it definitely is a nop. - removed `fpu' since it unused after that change. arch/x86/kernel/fpu/signal.c | 3 --- 1 file changed, 3 deletions(-)