Commit 0f92433b authored by Daniel Axtens's avatar Daniel Axtens Committed by Michael Ellerman
Browse files

powerpc/signal64: Rewrite rt_sigreturn() to minimise uaccess switches 



Add uaccess blocks and use the 'unsafe' versions of functions doing user
access where possible to reduce the number of times uaccess has to be
opened/closed.

Co-developed-by: default avatarChristopher M. Riedl <cmr@codefail.de>
Signed-off-by: default avatarDaniel Axtens <dja@axtens.net>
Signed-off-by: default avatarChristopher M. Riedl <cmr@codefail.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-10-cmr@codefail.de
parent 96d7a4e0

arch/powerpc/kernel/signal_64.c

+6 −4
Original line number Diff line number Diff line
@@ -822,11 +822,11 @@ SYSCALL_DEFINE0(rt_sigreturn) 
		 */

		current->thread.regs->msr &= ~MSR_TS_MASK;

		if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext)))

			return -EFAULT;

		if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) {

			user_read_access_end();

			goto badframe;

		}



		unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext,

					  badframe_block);



		user_read_access_end();

	}
@@ -836,6 +836,8 @@ SYSCALL_DEFINE0(rt_sigreturn) 
	set_thread_flag(TIF_RESTOREALL);

	return 0;



badframe_block:

	user_read_access_end();

badframe:

	signal_fault(current, regs, "rt_sigreturn", uc);