From: "Jan Beulich" <JBeulich@suse.com>
To: xen-devel <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Keir Fraser <keir@xen.org>, Feng Wu <feng.wu@intel.com>
Subject: [PATCH v3 3/4] x86: use optimal NOPs to fill the SMEP/SMAP placeholders
Date: Thu, 17 Mar 2016 02:03:50 -0600 [thread overview]
Message-ID: <56EA72F602000078000DD933@prv-mh.provo.novell.com> (raw)
In-Reply-To: <56EA6FDF02000078000DD8FB@prv-mh.provo.novell.com>
[-- Attachment #1: Type: text/plain, Size: 2875 bytes --]
Alternatives patching code picks the most suitable NOPs for the
running system, so simply use it to replace the pre-populated ones.
Use an arbitrary, always available feature to key off from, but
hide this behind the new X86_FEATURE_ALWAYS.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Re-base.
v2: Introduce and use X86_FEATURE_ALWAYS.
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -175,12 +175,7 @@ compat_bad_hypercall:
ENTRY(compat_restore_all_guest)
ASSERT_INTERRUPTS_DISABLED
.Lcr4_orig:
- ASM_NOP8 /* testb $3,UREGS_cs(%rsp) */
- ASM_NOP2 /* jpe .Lcr4_alt_end */
- ASM_NOP8 /* mov CPUINFO_cr4...(%rsp), %rax */
- ASM_NOP6 /* and $..., %rax */
- ASM_NOP8 /* mov %rax, CPUINFO_cr4...(%rsp) */
- ASM_NOP3 /* mov %rax, %cr4 */
+ .skip (.Lcr4_alt_end - .Lcr4_alt) - (. - .Lcr4_orig), 0x90
.Lcr4_orig_end:
.pushsection .altinstr_replacement, "ax"
.Lcr4_alt:
@@ -192,6 +187,7 @@ ENTRY(compat_restore_all_guest)
mov %rax, %cr4
.Lcr4_alt_end:
.section .altinstructions, "a"
+ altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_ALWAYS, 12, 0
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMEP, \
(.Lcr4_orig_end - .Lcr4_orig), \
(.Lcr4_alt_end - .Lcr4_alt)
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -204,6 +204,7 @@ void ret_from_intr(void);
662: __ASM_##op; \
.popsection; \
.pushsection .altinstructions, "a"; \
+ altinstruction_entry 661b, 661b, X86_FEATURE_ALWAYS, 3, 0; \
altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3; \
.popsection
@@ -215,6 +216,7 @@ void ret_from_intr(void);
.pushsection .altinstr_replacement, "ax"; \
668: call cr4_pv32_restore; \
.section .altinstructions, "a"; \
+ altinstruction_entry 667b, 667b, X86_FEATURE_ALWAYS, 5, 0; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMEP, 5, 5; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMAP, 5, 5; \
.popsection
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -162,6 +162,9 @@
#define cpufeat_bit(idx) ((idx) % 32)
#define cpufeat_mask(idx) (_AC(1, U) << cpufeat_bit(idx))
+/* An alias of a feature we know is always going to be present. */
+#define X86_FEATURE_ALWAYS X86_FEATURE_LM
+
#if !defined(__ASSEMBLY__) && !defined(X86_FEATURES_ONLY)
#include <xen/bitops.h>
[-- Attachment #2: x86-SMEP-SMAP-NOPs.patch --]
[-- Type: text/plain, Size: 2929 bytes --]
x86: use optimal NOPs to fill the SMEP/SMAP placeholders
Alternatives patching code picks the most suitable NOPs for the
running system, so simply use it to replace the pre-populated ones.
Use an arbitrary, always available feature to key off from, but
hide this behind the new X86_FEATURE_ALWAYS.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Re-base.
v2: Introduce and use X86_FEATURE_ALWAYS.
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -175,12 +175,7 @@ compat_bad_hypercall:
ENTRY(compat_restore_all_guest)
ASSERT_INTERRUPTS_DISABLED
.Lcr4_orig:
- ASM_NOP8 /* testb $3,UREGS_cs(%rsp) */
- ASM_NOP2 /* jpe .Lcr4_alt_end */
- ASM_NOP8 /* mov CPUINFO_cr4...(%rsp), %rax */
- ASM_NOP6 /* and $..., %rax */
- ASM_NOP8 /* mov %rax, CPUINFO_cr4...(%rsp) */
- ASM_NOP3 /* mov %rax, %cr4 */
+ .skip (.Lcr4_alt_end - .Lcr4_alt) - (. - .Lcr4_orig), 0x90
.Lcr4_orig_end:
.pushsection .altinstr_replacement, "ax"
.Lcr4_alt:
@@ -192,6 +187,7 @@ ENTRY(compat_restore_all_guest)
mov %rax, %cr4
.Lcr4_alt_end:
.section .altinstructions, "a"
+ altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_ALWAYS, 12, 0
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMEP, \
(.Lcr4_orig_end - .Lcr4_orig), \
(.Lcr4_alt_end - .Lcr4_alt)
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -204,6 +204,7 @@ void ret_from_intr(void);
662: __ASM_##op; \
.popsection; \
.pushsection .altinstructions, "a"; \
+ altinstruction_entry 661b, 661b, X86_FEATURE_ALWAYS, 3, 0; \
altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3; \
.popsection
@@ -215,6 +216,7 @@ void ret_from_intr(void);
.pushsection .altinstr_replacement, "ax"; \
668: call cr4_pv32_restore; \
.section .altinstructions, "a"; \
+ altinstruction_entry 667b, 667b, X86_FEATURE_ALWAYS, 5, 0; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMEP, 5, 5; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMAP, 5, 5; \
.popsection
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -162,6 +162,9 @@
#define cpufeat_bit(idx) ((idx) % 32)
#define cpufeat_mask(idx) (_AC(1, U) << cpufeat_bit(idx))
+/* An alias of a feature we know is always going to be present. */
+#define X86_FEATURE_ALWAYS X86_FEATURE_LM
+
#if !defined(__ASSEMBLY__) && !defined(X86_FEATURES_ONLY)
#include <xen/bitops.h>
[-- Attachment #3: Type: text/plain, Size: 126 bytes --]
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-03-17 8:03 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-04 11:08 [PATCH 0/4] x86: accommodate 32-bit PV guests with SMAP/SMEP handling Jan Beulich
2016-03-04 11:27 ` [PATCH 1/4] x86/alternatives: correct near branch check Jan Beulich
2016-03-07 15:43 ` Andrew Cooper
2016-03-07 15:56 ` Jan Beulich
2016-03-07 16:11 ` Andrew Cooper
2016-03-07 16:21 ` Jan Beulich
2016-03-08 17:33 ` Andrew Cooper
2016-03-04 11:27 ` [PATCH 2/4] x86: suppress SMAP and SMEP while running 32-bit PV guest code Jan Beulich
2016-03-07 16:59 ` Andrew Cooper
2016-03-08 7:57 ` Jan Beulich
2016-03-09 8:09 ` Wu, Feng
2016-03-09 14:09 ` Jan Beulich
2016-03-09 11:19 ` Andrew Cooper
2016-03-09 14:28 ` Jan Beulich
2016-03-09 8:09 ` Wu, Feng
2016-03-09 10:45 ` Andrew Cooper
2016-03-09 12:27 ` Wu, Feng
2016-03-09 12:33 ` Andrew Cooper
2016-03-09 12:36 ` Jan Beulich
2016-03-09 12:54 ` Wu, Feng
2016-03-09 13:35 ` Wu, Feng
2016-03-09 13:42 ` Andrew Cooper
2016-03-09 14:03 ` Jan Beulich
2016-03-09 14:07 ` Jan Beulich
2016-03-04 11:28 ` [PATCH 3/4] x86: use optimal NOPs to fill the SMAP/SMEP placeholders Jan Beulich
2016-03-07 17:43 ` Andrew Cooper
2016-03-08 8:02 ` Jan Beulich
2016-03-04 11:29 ` [PATCH 4/4] x86: use 32-bit loads for 32-bit PV guest state reload Jan Beulich
2016-03-07 17:45 ` Andrew Cooper
2016-03-10 9:44 ` [PATCH v2 0/3] x86: accommodate 32-bit PV guests with SMEP/SMAP handling Jan Beulich
2016-03-10 9:53 ` [PATCH v2 1/3] x86: suppress SMEP and SMAP while running 32-bit PV guest code Jan Beulich
2016-05-13 15:48 ` Andrew Cooper
2016-03-10 9:54 ` [PATCH v2 2/3] x86: use optimal NOPs to fill the SMEP/SMAP placeholders Jan Beulich
2016-05-13 15:49 ` Andrew Cooper
2016-03-10 9:55 ` [PATCH v2 3/3] x86: use 32-bit loads for 32-bit PV guest state reload Jan Beulich
[not found] ` <56E9A0DB02000078000DD54C@prv-mh.provo.novell.com>
2016-03-17 7:50 ` [PATCH v3 0/4] x86: accommodate 32-bit PV guests with SMEP/SMAP handling Jan Beulich
2016-03-17 8:02 ` [PATCH v3 1/4] x86: move cached CR4 value to struct cpu_info Jan Beulich
2016-03-17 16:20 ` Andrew Cooper
2016-03-17 8:03 ` [PATCH v3 2/4] x86: suppress SMEP and SMAP while running 32-bit PV guest code Jan Beulich
2016-03-25 18:01 ` Konrad Rzeszutek Wilk
2016-03-29 6:55 ` Jan Beulich
2016-05-13 15:58 ` Andrew Cooper
2016-03-17 8:03 ` Jan Beulich [this message]
2016-05-13 15:57 ` [PATCH v3 3/4] x86: use optimal NOPs to fill the SMEP/SMAP placeholders Andrew Cooper
2016-05-13 16:06 ` Jan Beulich
2016-05-13 16:09 ` Andrew Cooper
2016-03-17 8:04 ` [PATCH v3 4/4] x86: use 32-bit loads for 32-bit PV guest state reload Jan Beulich
2016-03-25 18:02 ` Konrad Rzeszutek Wilk
2016-03-17 16:14 ` [PATCH v3 5/4] x86: reduce code size of struct cpu_info member accesses Jan Beulich
2016-03-25 18:47 ` Konrad Rzeszutek Wilk
2016-03-29 6:59 ` Jan Beulich
2016-03-30 14:28 ` Konrad Rzeszutek Wilk
2016-03-30 14:42 ` Jan Beulich
2016-05-13 16:11 ` Andrew Cooper
2016-05-03 13:58 ` Ping: [PATCH v3 2/4] x86: suppress SMEP and SMAP while running 32-bit PV guest code Jan Beulich
2016-05-03 14:10 ` Andrew Cooper
2016-05-03 14:25 ` Jan Beulich
2016-05-04 10:03 ` Andrew Cooper
2016-05-04 13:35 ` Jan Beulich
2016-05-04 3:07 ` Wu, Feng
2016-05-13 15:21 ` Wei Liu
2016-05-13 15:30 ` Jan Beulich
2016-05-13 15:33 ` Wei Liu
2016-05-13 17:02 ` [PATCH v3 0/4] x86: accommodate 32-bit PV guests with SMEP/SMAP handling Wei Liu
2016-05-13 17:21 ` Andrew Cooper
2016-06-21 6:19 ` Wu, Feng
2016-06-21 7:17 ` Jan Beulich
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=56EA72F602000078000DD933@prv-mh.provo.novell.com \
--to=jbeulich@suse.com \
--cc=andrew.cooper3@citrix.com \
--cc=feng.wu@intel.com \
--cc=keir@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).