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authorAndy Lutomirski <luto@kernel.org>2019-05-14 13:24:39 -0700
committerIngo Molnar <mingo@kernel.org>2019-05-16 09:05:11 +0200
commit88640e1dcd089879530a49a8d212d1814678dfe7 (patch)
treeb3bfb6be2d0f41cef5c8d3b7797f55e70e510c61 /arch
parent00f5764dbb040188e5dce2cd9e648360886b045c (diff)
x86/speculation/mds: Revert CPU buffer clear on double fault exit
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/traps.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7de466eb960b..8b6d03e55d2f 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