61 lines
2.1 KiB
Diff
61 lines
2.1 KiB
Diff
From c48697564de6da427f1e97a38192f4d456223942 Mon Sep 17 00:00:00 2001
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From: Andy Lutomirski <luto@kernel.org>
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Date: Thu, 2 Nov 2017 00:59:04 -0700
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Subject: [PATCH 092/232] x86/entry/64: Merge the fast and slow SYSRET paths
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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They did almost the same thing. Remove a bunch of pointless
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instructions (mostly hidden in macros) and reduce cognitive load by
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merging them.
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Signed-off-by: Andy Lutomirski <luto@kernel.org>
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Cc: Borislav Petkov <bpetkov@suse.de>
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Cc: Brian Gerst <brgerst@gmail.com>
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Cc: Dave Hansen <dave.hansen@intel.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Link: http://lkml.kernel.org/r/1204e20233fcab9130a1ba80b3b1879b5db3fc1f.1509609304.git.luto@kernel.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit a512210643da8082cb44181dba8b18e752bd68f0)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 7c4575d8bb2d01960ba9b9840fa22460e0179eca)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/entry/entry_64.S | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
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index 33a416c7df2d..87be1cd1fa88 100644
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--- a/arch/x86/entry/entry_64.S
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+++ b/arch/x86/entry/entry_64.S
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@@ -220,10 +220,9 @@ entry_SYSCALL_64_fastpath:
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TRACE_IRQS_ON /* user mode is traced as IRQs on */
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movq RIP(%rsp), %rcx
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movq EFLAGS(%rsp), %r11
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- RESTORE_C_REGS_EXCEPT_RCX_R11
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- movq RSP(%rsp), %rsp
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+ addq $6*8, %rsp /* skip extra regs -- they were preserved */
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UNWIND_HINT_EMPTY
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- USERGS_SYSRET64
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+ jmp .Lpop_c_regs_except_rcx_r11_and_sysret
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1:
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/*
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@@ -317,6 +316,7 @@ syscall_return_via_sysret:
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/* rcx and r11 are already restored (see code above) */
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UNWIND_HINT_EMPTY
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POP_EXTRA_REGS
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+.Lpop_c_regs_except_rcx_r11_and_sysret:
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popq %rsi /* skip r11 */
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popq %r10
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popq %r9
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--
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2.14.2
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