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Message-Id: <20190415183712.229837735@linuxfoundation.org> Date: Mon, 15 Apr 2019 20:43:41 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Michal Suchanek <msuchanek@...e.de>, Michael Ellerman <mpe@...erman.id.au>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 4.9 17/76] powerpc/64: Use barrier_nospec in syscall entry commit 51973a815c6b46d7b23b68d6af371ad1c9d503ca upstream. Our syscall entry is done in assembly so patch in an explicit barrier_nospec. Based on a patch by Michal Suchanek. Signed-off-by: Michal Suchanek <msuchanek@...e.de> Signed-off-by: Michael Ellerman <mpe@...erman.id.au> Signed-off-by: Sasha Levin <sashal@...nel.org> --- arch/powerpc/kernel/entry_64.S | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index e24ae0fa80ed..11e390662384 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -38,6 +38,7 @@ #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> @@ -180,6 +181,15 @@ 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 */ -- 2.19.1
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