x86/fpu/signal: Remove the legacy alignment check

KAGA-KOKO · suryasaimadhu · commit 9ba589f9cdbd · 2021-06-23T20:01:55.000+02:00
Checking for the XSTATE buffer being 64-byte aligned, and if not, deciding just to restore the FXSR state is daft. If user space provides an unaligned math frame and has the extended state magic set in the FX software reserved bytes, then it really can keep the pieces. If the frame is unaligned and the FX software magic is not set, then fx_only is already set and the restore will use fxrstor. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210623121457.184149902@linutronix.de
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
@@ -306,9 +306,6 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 		}
 	}
 
-	if ((unsigned long)buf_fx % 64)
-		fx_only = 1;
-
 	if (!ia32_fxstate) {
 		/*
 		 * Attempt to restore the FPU registers directly from user

Original file line number	Diff line number	Diff line change
`@@ -306,9 +306,6 @@ static int __fpu_restore_sig(void __user buf, void __user buf_fx,`
`306`	`306`	`}`
`307`	`307`	`}`
`308`	`308`
`309`		`- if ((unsigned long)buf_fx % 64)`
`310`		`- fx_only = 1;`
`311`		`-`
`312`	`309`	`if (!ia32_fxstate) {`
`313`	`310`	`/*`
`314`	`311`	`* Attempt to restore the FPU registers directly from user`