lkml.org 
[lkml]   [2017]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 31/43] x86/mm/kaiser: Map entry stack variable
Date
From: Dave Hansen <dave.hansen@linux.intel.com>

There are times where the kernel is entered but there is no
safe stack, like at SYSCALL entry. To obtain a safe stack, we
have to clobber %rsp and store the clobbered value in
'rsp_scratch'.

Map this to userspace to allow us to do this stack switch before
the CR3 switch.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at>
Cc: Moritz Lipp <moritz.lipp@iaik.tugraz.at>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Fellner <richard.fellner@student.tugraz.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20171123003459.C0FF167A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/process_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index bafe65b08697..9a0220aa2bf9 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -59,7 +59,7 @@
#include <asm/unistd_32_ia32.h>
#endif

-__visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
+__visible DEFINE_PER_CPU_USER_MAPPED(unsigned long, rsp_scratch);

/* Prints also some state that isn't saved in the pt_regs */
void __show_regs(struct pt_regs *regs, int all)
--
2.14.1
\
 
 \ /
  Last update: 2017-11-24 10:18    [W:0.226 / U:1.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site