diff options
Diffstat (limited to 'kpti-fix.patch')
| -rw-r--r-- | kpti-fix.patch | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/kpti-fix.patch b/kpti-fix.patch index 601940bb2..e01d3bd4b 100644 --- a/kpti-fix.patch +++ b/kpti-fix.patch @@ -54,3 +54,76 @@ index bce8aea..2da28ba 100644 -- cgit v1.1 +From fea692ec9308084475c0c93bf74bcb2a35f3d417 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Wed, 3 Jan 2018 19:52:04 +0100 +Subject: [PATCH] CONFIG_PAGE_TABLE_ISOLATION=y on x86_64 causes gcc to + segfault when building x86_32 binaries + +On Wed, 3 Jan 2018, Thomas Gleixner wrote: + +> On Wed, 3 Jan 2018, Lars Wendler wrote: +> > Am Wed, 3 Jan 2018 13:05:38 +0100 (CET) +> > schrieb Thomas Gleixner <tglx@linutronix.de>: +> > > Also can you please try Linus v4.15-rc6 with PTI enabled so we can see +> > > whether that's a backport issue or a general one? +> > +> > Same problem with 4.15-rc6. So I suppose that means it's a general +> > issue. +> +> Just a shot in the dark as I just decoded another issue on a AMD CPU. Can +> you please try the patch below? + +Ok. Found the real issue. This is a problem on AMD boxen. + +Fix below. + +Can Xen folks please have a look at that as well? + +Thanks, + + tglx + +8<------------------- + +arch/x86/entry/entry_64_compat.S | 13 ++++++------- + 1 file changed, 6 insertions(+), 7 deletions(-) +--- + arch/x86/entry/entry_64_compat.S | 13 ++++++------- + 1 file changed, 6 insertions(+), 7 deletions(-) + +diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S +index 40f17009ec20..4c4b9545b848 100644 +--- a/arch/x86/entry/entry_64_compat.S ++++ b/arch/x86/entry/entry_64_compat.S +@@ -190,8 +190,13 @@ ENTRY(entry_SYSCALL_compat) + /* Interrupts are off on entry. */ + swapgs + +- /* Stash user ESP and switch to the kernel stack. */ ++ /* Stash user ESP */ + movl %esp, %r8d ++ ++ /* Use %rsp as scratch reg. User ESP is stashed in r8 */ ++ SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp ++ ++ /* Switch to the kernel stack */ + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp + + /* Construct struct pt_regs on stack */ +@@ -219,12 +224,6 @@ GLOBAL(entry_SYSCALL_compat_after_hwframe) + pushq $0 /* pt_regs->r14 = 0 */ + pushq $0 /* pt_regs->r15 = 0 */ + +- /* +- * We just saved %rdi so it is safe to clobber. It is not +- * preserved during the C calls inside TRACE_IRQS_OFF anyway. +- */ +- SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi +- + /* + * User mode is traced as though IRQs are on, and SYSENTER + * turned them off. +-- +2.14.3 + |