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Commit 4614b0bb authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Greg Kroah-Hartman
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x86/uaccess, signal: Fix AC=1 bloat 



[ Upstream commit 88e4718275c1bddca6f61f300688b4553dc8584b ]

Occasionally GCC is less agressive with inlining and the following is
observed:

  arch/x86/kernel/signal.o: warning: objtool: restore_sigcontext()+0x3cc: call to force_valid_ss.isra.5() with UACCESS enabled
  arch/x86/kernel/signal.o: warning: objtool: do_signal()+0x384: call to frame_uc_flags.isra.0() with UACCESS enabled

Cure this by moving this code out of the AC=1 region, since it really
isn't needed for the user access.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 1a3188d7

arch/x86/kernel/signal.c

+17 −12
Original line number Diff line number Diff line
@@ -132,16 +132,6 @@ static int restore_sigcontext(struct pt_regs *regs, 
		COPY_SEG_CPL3(cs);

		COPY_SEG_CPL3(ss);



#ifdef CONFIG_X86_64

		/*

		 * Fix up SS if needed for the benefit of old DOSEMU and

		 * CRIU.

		 */

		if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&

			     user_64bit_mode(regs)))

			force_valid_ss(regs);

#endif



		get_user_ex(tmpflags, &sc->flags);

		regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);

		regs->orig_ax = -1;		/* disable syscall checks */
@@ -150,6 +140,15 @@ static int restore_sigcontext(struct pt_regs *regs, 
		buf = (void __user *)buf_val;

	} get_user_catch(err);



#ifdef CONFIG_X86_64

	/*

	 * Fix up SS if needed for the benefit of old DOSEMU and

	 * CRIU.

	 */

	if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))

		force_valid_ss(regs);

#endif



	err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));



	force_iret();
@@ -461,6 +460,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
{

	struct rt_sigframe __user *frame;

	void __user *fp = NULL;

	unsigned long uc_flags;

	int err = 0;



	frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
@@ -473,9 +473,11 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
			return -EFAULT;

	}



	uc_flags = frame_uc_flags(regs);



	put_user_try {

		/* Create the ucontext.  */

		put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);

		put_user_ex(uc_flags, &frame->uc.uc_flags);

		put_user_ex(0, &frame->uc.uc_link);

		save_altstack_ex(&frame->uc.uc_stack, regs->sp);
@@ -541,6 +543,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig, 
{

#ifdef CONFIG_X86_X32_ABI

	struct rt_sigframe_x32 __user *frame;

	unsigned long uc_flags;

	void __user *restorer;

	int err = 0;

	void __user *fpstate = NULL;
@@ -555,9 +558,11 @@ static int x32_setup_rt_frame(struct ksignal *ksig, 
			return -EFAULT;

	}



	uc_flags = frame_uc_flags(regs);



	put_user_try {

		/* Create the ucontext.  */

		put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);

		put_user_ex(uc_flags, &frame->uc.uc_flags);

		put_user_ex(0, &frame->uc.uc_link);

		compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);

		put_user_ex(0, &frame->uc.uc__pad0);