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| Started by | Ricardo Neri <ricardo.neri-calderon@linux.intel.com> |
|---|---|
| First post | 2016-12-24 02:40 +0100 |
| Last post | 2016-12-27 23:40 +0100 |
| Articles | 3 — 2 participants |
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[v2 6/7] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-12-24 02:40 +0100
Re: [v2 6/7] x86/traps: Fixup general protection faults caused by UMIP Andy Lutomirski <luto@amacapital.net> - 2016-12-24 03:20 +0100
Re: [v2 6/7] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-12-27 23:40 +0100
| From | Ricardo Neri <ricardo.neri-calderon@linux.intel.com> |
|---|---|
| Date | 2016-12-24 02:40 +0100 |
| Subject | [v2 6/7] x86/traps: Fixup general protection faults caused by UMIP |
| Message-ID | <sRJtv-6WG-11@gated-at.bofh.it> |
If the User-Mode Instruction Prevention CPU feature is available and
enabled, a general protection fault will be issued if the instructions
sgdt, sldt, sidt, str or smsw are executed from user-mode context
(CPL > 0). If the fault was caused by any of the instructions protected
by UMIP, fixup_umip_exceptino will emulate dummy results for these
instructions.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Liang Z. Li <liang.z.li@intel.com>
Cc: Alexandre Julliard <julliard@winehq.org>
Cc: Stas Sergeev <stsp@list.ru>
Cc: x86@kernel.org
Cc: linux-msdos@vger.kernel.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
---
arch/x86/kernel/traps.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bf0c6d0..5044fb3 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -64,6 +64,7 @@
#include <asm/trace/mpx.h>
#include <asm/mpx.h>
#include <asm/vm86.h>
+#include <asm/umip.h>
#ifdef CONFIG_X86_64
#include <asm/x86_init.h>
@@ -491,6 +492,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
cond_local_irq_enable(regs);
+ if (user_mode(regs) && !fixup_umip_exception(regs))
+ return;
+
if (v8086_mode(regs)) {
local_irq_enable();
handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
--
2.9.3
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| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Date | 2016-12-24 03:20 +0100 |
| Message-ID | <sRK6e-7Lj-5@gated-at.bofh.it> |
| In reply to | #1547001 |
On Fri, Dec 23, 2016 at 5:37 PM, Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote: > If the User-Mode Instruction Prevention CPU feature is available and > enabled, a general protection fault will be issued if the instructions > sgdt, sldt, sidt, str or smsw are executed from user-mode context > (CPL > 0). If the fault was caused by any of the instructions protected > by UMIP, fixup_umip_exceptino will emulate dummy results for these > instructions. > > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Borislav Petkov <bp@suse.de> > Cc: Brian Gerst <brgerst@gmail.com> > Cc: Chen Yucong <slaoub@gmail.com> > Cc: Chris Metcalf <cmetcalf@mellanox.com> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Fenghua Yu <fenghua.yu@intel.com> > Cc: Huang Rui <ray.huang@amd.com> > Cc: Jiri Slaby <jslaby@suse.cz> > Cc: Jonathan Corbet <corbet@lwn.net> > Cc: Michael S. Tsirkin <mst@redhat.com> > Cc: Paul Gortmaker <paul.gortmaker@windriver.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> > Cc: Shuah Khan <shuah@kernel.org> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Tony Luck <tony.luck@intel.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Liang Z. Li <liang.z.li@intel.com> > Cc: Alexandre Julliard <julliard@winehq.org> > Cc: Stas Sergeev <stsp@list.ru> > Cc: x86@kernel.org > Cc: linux-msdos@vger.kernel.org > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > --- > arch/x86/kernel/traps.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index bf0c6d0..5044fb3 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -64,6 +64,7 @@ > #include <asm/trace/mpx.h> > #include <asm/mpx.h> > #include <asm/vm86.h> > +#include <asm/umip.h> > > #ifdef CONFIG_X86_64 > #include <asm/x86_init.h> > @@ -491,6 +492,9 @@ do_general_protection(struct pt_regs *regs, long error_code) > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > cond_local_irq_enable(regs); > > + if (user_mode(regs) && !fixup_umip_exception(regs)) > + return; > + I would do fixup_umip_exception(regs) == 0 to make it more obvious what's going on. Also, since you're allowing this in v8086 mode, I think this should have an explicit test in tools/testing/selftests/x86/entry_from_vm86.c. I *think* it will work fine, but the pt_regs handling in vm86 mode is quite scary and has been rewritten recently.
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| From | Ricardo Neri <ricardo.neri-calderon@linux.intel.com> |
|---|---|
| Date | 2016-12-27 23:40 +0100 |
| Subject | Re: [v2 6/7] x86/traps: Fixup general protection faults caused by UMIP |
| Message-ID | <sT8zw-83k-21@gated-at.bofh.it> |
| In reply to | #1547011 |
On Fri, 2016-12-23 at 18:11 -0800, Andy Lutomirski wrote: > On Fri, Dec 23, 2016 at 5:37 PM, Ricardo Neri > <ricardo.neri-calderon@linux.intel.com> wrote: > > If the User-Mode Instruction Prevention CPU feature is available and > > enabled, a general protection fault will be issued if the instructions > > sgdt, sldt, sidt, str or smsw are executed from user-mode context > > (CPL > 0). If the fault was caused by any of the instructions protected > > by UMIP, fixup_umip_exceptino will emulate dummy results for these > > instructions. > > > > Cc: Andy Lutomirski <luto@kernel.org> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: H. Peter Anvin <hpa@zytor.com> > > Cc: Borislav Petkov <bp@suse.de> > > Cc: Brian Gerst <brgerst@gmail.com> > > Cc: Chen Yucong <slaoub@gmail.com> > > Cc: Chris Metcalf <cmetcalf@mellanox.com> > > Cc: Dave Hansen <dave.hansen@linux.intel.com> > > Cc: Fenghua Yu <fenghua.yu@intel.com> > > Cc: Huang Rui <ray.huang@amd.com> > > Cc: Jiri Slaby <jslaby@suse.cz> > > Cc: Jonathan Corbet <corbet@lwn.net> > > Cc: Michael S. Tsirkin <mst@redhat.com> > > Cc: Paul Gortmaker <paul.gortmaker@windriver.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> > > Cc: Shuah Khan <shuah@kernel.org> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Tony Luck <tony.luck@intel.com> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Cc: Liang Z. Li <liang.z.li@intel.com> > > Cc: Alexandre Julliard <julliard@winehq.org> > > Cc: Stas Sergeev <stsp@list.ru> > > Cc: x86@kernel.org > > Cc: linux-msdos@vger.kernel.org > > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > > --- > > arch/x86/kernel/traps.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > > index bf0c6d0..5044fb3 100644 > > --- a/arch/x86/kernel/traps.c > > +++ b/arch/x86/kernel/traps.c > > @@ -64,6 +64,7 @@ > > #include <asm/trace/mpx.h> > > #include <asm/mpx.h> > > #include <asm/vm86.h> > > +#include <asm/umip.h> > > > > #ifdef CONFIG_X86_64 > > #include <asm/x86_init.h> > > @@ -491,6 +492,9 @@ do_general_protection(struct pt_regs *regs, long error_code) > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > > cond_local_irq_enable(regs); > > > > + if (user_mode(regs) && !fixup_umip_exception(regs)) > > + return; > > + > > I would do fixup_umip_exception(regs) == 0 to make it more obvious > what's going on. Sure. I will make this change. > > Also, since you're allowing this in v8086 mode, I think this should > have an explicit test in > tools/testing/selftests/x86/entry_from_vm86.c. I *think* it will work > fine, but the pt_regs handling in vm86 mode is quite scary and has > been rewritten recently. I will include a test for this. Thanks and BR, Ricardo
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