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| author |   Dan Williams <dan.j.williams@intel.com> | 2018-02-05 17:18:11 -0800 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-02-06 11:47:44 +0100 |
| commit | 3ac6d8c787b835b997eb23e43e09aa0895ef7d58 (patch) | |
| tree | e08f3c4bc1d80afd184a31f4836a759e014c16e3 /arch/x86/entry/calling.h | |
| parent | x86/entry/64: Clear extra registers beyond syscall arguments, to reduce speculation attack surface (diff) | |
| download | wireguard-linux-3ac6d8c787b835b997eb23e43e09aa0895ef7d58.tar.xz wireguard-linux-3ac6d8c787b835b997eb23e43e09aa0895ef7d58.zip | |
x86/entry/64: Clear registers for exceptions/interrupts, to reduce speculation attack surface
Clear the 'extra' registers on entering the 64-bit kernel for exceptions
and interrupts. The common registers are not cleared since they are
likely clobbered well before they can be exploited in a speculative
execution attack.
Originally-From: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/151787989146.7847.15749181712358213254.stgit@dwillia2-desk3.amr.corp.intel.com
[ Made small improvements to the changelog and the code comments. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/calling.h')
| -rw-r--r-- | arch/x86/entry/calling.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 3f48f695d5e6..f4b129d4af42 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -147,6 +147,25 @@ For 32-bit we have the following conventions - kernel is built with UNWIND_HINT_REGS offset=\offset .endm + /* + * Sanitize registers of values that a speculation attack + * might otherwise want to exploit. The lower registers are + * likely clobbered well before they could be put to use in + * a speculative execution gadget: + */ + .macro CLEAR_REGS_NOSPEC + xorl %ebp, %ebp + xorl %ebx, %ebx + xorq %r8, %r8 + xorq %r9, %r9 + xorq %r10, %r10 + xorq %r11, %r11 + xorq %r12, %r12 + xorq %r13, %r13 + xorq %r14, %r14 + xorq %r15, %r15 + .endm + .macro POP_EXTRA_REGS popq %r15 popq %r14 |