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Commit 51973a81 authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/64: Use barrier_nospec in syscall entry 



Our syscall entry is done in assembly so patch in an explicit
barrier_nospec.

Based on a patch by Michal Suchanek.

Signed-off-by: default avatarMichal Suchanek <msuchanek@suse.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent ddf35cf3

arch/powerpc/kernel/entry_64.S

+10 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <asm/context_tracking.h>

#include <asm/tm.h>

#include <asm/ppc-opcode.h>

#include <asm/barrier.h>

#include <asm/export.h>

#ifdef CONFIG_PPC_BOOK3S

#include <asm/exception-64s.h>
@@ -178,6 +179,15 @@ system_call: /* label this so stack traces look sane */ 
	clrldi	r8,r8,32

15:

	slwi	r0,r0,4



	barrier_nospec_asm

	/*

	 * Prevent the load of the handler below (based on the user-passed

	 * system call number) being speculatively executed until the test

	 * against NR_syscalls and branch to .Lsyscall_enosys above has

	 * committed.

	 */



	ldx	r12,r11,r0	/* Fetch system call handler [ptr] */

	mtctr   r12

	bctrl			/* Call handler */