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author | Andy Lutomirski <luto@kernel.org> | 2019-05-14 23:24:39 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-22 08:39:39 +0300 |
commit | dd5750d4ce2b86f96f54d721c313eb471f7a81a3 (patch) | |
tree | 193b00ac6b4bb7c53176cd632f37c205651d08fd /arch | |
parent | c48fddac8eca9d4d17ba5569a4d04838fcc81199 (diff) | |
download | linux-dd5750d4ce2b86f96f54d721c313eb471f7a81a3.tar.xz |
x86/speculation/mds: Revert CPU buffer clear on double fault exit
commit 88640e1dcd089879530a49a8d212d1814678dfe7 upstream.
The double fault ESPFIX path doesn't return to user mode at all --
it returns back to the kernel by simulating a #GP fault.
prepare_exit_to_usermode() will run on the way out of
general_protection before running user code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jon Masters <jcm@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 04dcbdb80578 ("x86/speculation/mds: Clear CPU buffers on exit to user")
Link: http://lkml.kernel.org/r/ac97612445c0a44ee10374f6ea79c222fe22a5c4.1557865329.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/traps.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 07c7bbe79e8b..d26f9e9c3d83 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -58,7 +58,6 @@ #include <asm/alternative.h> #include <asm/fpu/xstate.h> #include <asm/trace/mpx.h> -#include <asm/nospec-branch.h> #include <asm/mpx.h> #include <asm/vm86.h> #include <asm/umip.h> @@ -368,13 +367,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) regs->ip = (unsigned long)general_protection; regs->sp = (unsigned long)&gpregs->orig_ax; - /* - * This situation can be triggered by userspace via - * modify_ldt(2) and the return does not take the regular - * user space exit, so a CPU buffer clear is required when - * MDS mitigation is enabled. - */ - mds_user_clear_cpu_buffers(); return; } #endif |