diff options
| author | Andy Lutomirski <luto@kernel.org> | 2019-05-14 13:24:39 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-09-23 21:12:07 +0100 |
| commit | 9dac3ede79734dd28714f0f514eb20a64d328b93 (patch) | |
| tree | 09c6fdadb58acd99ecb5334047051551efa5824e /arch | |
| parent | 77b37833667ba383f95e1a585f07608cb5647fa9 (diff) | |
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>
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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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 77a6f3b62786..57b24700c825 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -55,7 +55,6 @@ #include <asm/fixmap.h> #include <asm/mach_traps.h> #include <asm/alternative.h> -#include <asm/nospec-branch.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -260,13 +259,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) regs->ip = (unsigned long)general_protection; regs->sp = (unsigned long)&normal_regs->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 |