This is a note to let you know that I've just added the patch titled
x86/retpoline/xen: Convert Xen hypercall indirect jumps
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From ea08816d5b185ab3d09e95e393f265af54560350 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw(a)amazon.co.uk>
Date: Thu, 11 Jan 2018 21:46:31 +0000
Subject: x86/retpoline/xen: Convert Xen hypercall indirect jumps
From: David Woodhouse <dwmw(a)amazon.co.uk>
commit ea08816d5b185ab3d09e95e393f265af54560350 upstream.
Convert indirect call in Xen hypercall to use non-speculative sequence,
when CONFIG_RETPOLINE is enabled.
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Acked-by: Arjan van de Ven <arjan(a)linux.intel.com>
Acked-by: Ingo Molnar <mingo(a)kernel.org>
Reviewed-by: Juergen Gross <jgross(a)suse.com>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Cc: Paul Turner <pjt(a)google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-10-git-send-email-dwmw@amazon.co…
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/include/asm/xen/hypercall.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -44,6 +44,7 @@
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/smap.h>
+#include <asm/nospec-branch.h>
#include <xen/interface/xen.h>
#include <xen/interface/sched.h>
@@ -216,9 +217,9 @@ privcmd_call(unsigned call,
__HYPERCALL_5ARG(a1, a2, a3, a4, a5);
stac();
- asm volatile("call *%[call]"
+ asm volatile(CALL_NOSPEC
: __HYPERCALL_5PARAM
- : [call] "a" (&hypercall_page[call])
+ : [thunk_target] "a" (&hypercall_page[call])
: __HYPERCALL_CLOBBER5);
clac();
Patches currently in stable-queue which might be from dwmw(a)amazon.co.uk are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch
This is a note to let you know that I've just added the patch titled
x86/retpoline: Remove compile time warning
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-remove-compile-time-warning.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From b8b9ce4b5aec8de9e23cabb0a26b78641f9ab1d6 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx(a)linutronix.de>
Date: Sun, 14 Jan 2018 22:13:29 +0100
Subject: x86/retpoline: Remove compile time warning
From: Thomas Gleixner <tglx(a)linutronix.de>
commit b8b9ce4b5aec8de9e23cabb0a26b78641f9ab1d6 upstream.
Remove the compile time warning when CONFIG_RETPOLINE=y and the compiler
does not have retpoline support. Linus rationale for this is:
It's wrong because it will just make people turn off RETPOLINE, and the
asm updates - and return stack clearing - that are independent of the
compiler are likely the most important parts because they are likely the
ones easiest to target.
And it's annoying because most people won't be able to do anything about
it. The number of people building their own compiler? Very small. So if
their distro hasn't got a compiler yet (and pretty much nobody does), the
warning is just annoying crap.
It is already properly reported as part of the sysfs interface. The
compile-time warning only encourages bad things.
Fixes: 76b043848fd2 ("x86/retpoline: Add initial retpoline support")
Requested-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Cc: David Woodhouse <dwmw(a)amazon.co.uk>
Cc: Peter Zijlstra (Intel) <peterz(a)infradead.org>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Link: https://lkml.kernel.org/r/CA+55aFzWgquv4i6Mab6bASqYXg3ErV3XDFEYf=GEcCDQg5uA…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/Makefile | 2 --
1 file changed, 2 deletions(-)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -187,8 +187,6 @@ ifdef CONFIG_RETPOLINE
RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
ifneq ($(RETPOLINE_CFLAGS),)
KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE
- else
- $(warning CONFIG_RETPOLINE=y, but not supported by the compiler. Toolchain update recommended.)
endif
endif
Patches currently in stable-queue which might be from tglx(a)linutronix.de are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-microcode-intel-extend-bdw-late-loading-with-a-revision-check.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/x86-asm-use-register-variable-to-get-stack-pointer-value.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/objtool-modules-discard-objtool-annotation-sections-for-modules.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/x86-documentation-add-pti-description.patch
queue-4.9/x86-acpi-handle-sci-interrupts-above-legacy-space-gracefully.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/selftests-x86-add-test_vsyscall.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-cpu-merge-bugs.c-and-bugs_64.c.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-acpi-reduce-code-duplication-in-mp_override_legacy_irq.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch
This is a note to let you know that I've just added the patch titled
x86/retpoline/ftrace: Convert ftrace assembler indirect jumps
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 9351803bd803cdbeb9b5a7850b7b6f464806e3db Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw(a)amazon.co.uk>
Date: Thu, 11 Jan 2018 21:46:29 +0000
Subject: x86/retpoline/ftrace: Convert ftrace assembler indirect jumps
From: David Woodhouse <dwmw(a)amazon.co.uk>
commit 9351803bd803cdbeb9b5a7850b7b6f464806e3db upstream.
Convert all indirect jumps in ftrace assembler code to use non-speculative
sequences when CONFIG_RETPOLINE is enabled.
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Acked-by: Arjan van de Ven <arjan(a)linux.intel.com>
Acked-by: Ingo Molnar <mingo(a)kernel.org>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Cc: Paul Turner <pjt(a)google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-8-git-send-email-dwmw@amazon.co.…
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/entry/entry_32.S | 5 +++--
arch/x86/kernel/mcount_64.S | 7 ++++---
2 files changed, 7 insertions(+), 5 deletions(-)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -985,7 +985,8 @@ trace:
movl 0x4(%ebp), %edx
subl $MCOUNT_INSN_SIZE, %eax
- call *ftrace_trace_function
+ movl ftrace_trace_function, %ecx
+ CALL_NOSPEC %ecx
popl %edx
popl %ecx
@@ -1021,7 +1022,7 @@ return_to_handler:
movl %eax, %ecx
popl %edx
popl %eax
- jmp *%ecx
+ JMP_NOSPEC %ecx
#endif
#ifdef CONFIG_TRACING
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -8,7 +8,7 @@
#include <asm/ptrace.h>
#include <asm/ftrace.h>
#include <asm/export.h>
-
+#include <asm/nospec-branch.h>
.code64
.section .entry.text, "ax"
@@ -290,8 +290,9 @@ trace:
* ip and parent ip are used and the list function is called when
* function tracing is enabled.
*/
- call *ftrace_trace_function
+ movq ftrace_trace_function, %r8
+ CALL_NOSPEC %r8
restore_mcount_regs
jmp fgraph_trace
@@ -334,5 +335,5 @@ GLOBAL(return_to_handler)
movq 8(%rsp), %rdx
movq (%rsp), %rax
addq $24, %rsp
- jmp *%rdi
+ JMP_NOSPEC %rdi
#endif
Patches currently in stable-queue which might be from dwmw(a)amazon.co.uk are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch
This is a note to let you know that I've just added the patch titled
x86/retpoline: Fill return stack buffer on vmexit
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 117cc7a908c83697b0b737d15ae1eb5943afe35b Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw(a)amazon.co.uk>
Date: Fri, 12 Jan 2018 11:11:27 +0000
Subject: x86/retpoline: Fill return stack buffer on vmexit
From: David Woodhouse <dwmw(a)amazon.co.uk>
commit 117cc7a908c83697b0b737d15ae1eb5943afe35b upstream.
In accordance with the Intel and AMD documentation, we need to overwrite
all entries in the RSB on exiting a guest, to prevent malicious branch
target predictions from affecting the host kernel. This is needed both
for retpoline and for IBRS.
[ak: numbers again for the RSB stuffing labels]
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Tested-by: Peter Zijlstra (Intel) <peterz(a)infradead.org>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Cc: Paul Turner <pjt(a)google.com>
Link: https://lkml.kernel.org/r/1515755487-8524-1-git-send-email-dwmw@amazon.co.uk
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/include/asm/nospec-branch.h | 78 ++++++++++++++++++++++++++++++++++-
arch/x86/kvm/svm.c | 4 +
arch/x86/kvm/vmx.c | 4 +
3 files changed, 85 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -7,6 +7,48 @@
#include <asm/alternative-asm.h>
#include <asm/cpufeatures.h>
+/*
+ * Fill the CPU return stack buffer.
+ *
+ * Each entry in the RSB, if used for a speculative 'ret', contains an
+ * infinite 'pause; jmp' loop to capture speculative execution.
+ *
+ * This is required in various cases for retpoline and IBRS-based
+ * mitigations for the Spectre variant 2 vulnerability. Sometimes to
+ * eliminate potentially bogus entries from the RSB, and sometimes
+ * purely to ensure that it doesn't get empty, which on some CPUs would
+ * allow predictions from other (unwanted!) sources to be used.
+ *
+ * We define a CPP macro such that it can be used from both .S files and
+ * inline assembly. It's possible to do a .macro and then include that
+ * from C via asm(".include <asm/nospec-branch.h>") but let's not go there.
+ */
+
+#define RSB_CLEAR_LOOPS 32 /* To forcibly overwrite all entries */
+#define RSB_FILL_LOOPS 16 /* To avoid underflow */
+
+/*
+ * Google experimented with loop-unrolling and this turned out to be
+ * the optimal version — two calls, each with their own speculation
+ * trap should their return address end up getting used, in a loop.
+ */
+#define __FILL_RETURN_BUFFER(reg, nr, sp) \
+ mov $(nr/2), reg; \
+771: \
+ call 772f; \
+773: /* speculation trap */ \
+ pause; \
+ jmp 773b; \
+772: \
+ call 774f; \
+775: /* speculation trap */ \
+ pause; \
+ jmp 775b; \
+774: \
+ dec reg; \
+ jnz 771b; \
+ add $(BITS_PER_LONG/8) * nr, sp;
+
#ifdef __ASSEMBLY__
/*
@@ -76,6 +118,20 @@
#endif
.endm
+ /*
+ * A simpler FILL_RETURN_BUFFER macro. Don't make people use the CPP
+ * monstrosity above, manually.
+ */
+.macro FILL_RETURN_BUFFER reg:req nr:req ftr:req
+#ifdef CONFIG_RETPOLINE
+ ANNOTATE_NOSPEC_ALTERNATIVE
+ ALTERNATIVE "jmp .Lskip_rsb_\@", \
+ __stringify(__FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP)) \
+ \ftr
+.Lskip_rsb_\@:
+#endif
+.endm
+
#else /* __ASSEMBLY__ */
#define ANNOTATE_NOSPEC_ALTERNATIVE \
@@ -119,7 +175,7 @@
X86_FEATURE_RETPOLINE)
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
-#else /* No retpoline */
+#else /* No retpoline for C / inline asm */
# define CALL_NOSPEC "call *%[thunk_target]\n"
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
#endif
@@ -134,5 +190,25 @@ enum spectre_v2_mitigation {
SPECTRE_V2_IBRS,
};
+/*
+ * On VMEXIT we must ensure that no RSB predictions learned in the guest
+ * can be followed in the host, by overwriting the RSB completely. Both
+ * retpoline and IBRS mitigations for Spectre v2 need this; only on future
+ * CPUs with IBRS_ATT *might* it be avoided.
+ */
+static inline void vmexit_fill_RSB(void)
+{
+#ifdef CONFIG_RETPOLINE
+ unsigned long loops = RSB_CLEAR_LOOPS / 2;
+
+ asm volatile (ANNOTATE_NOSPEC_ALTERNATIVE
+ ALTERNATIVE("jmp 910f",
+ __stringify(__FILL_RETURN_BUFFER(%0, RSB_CLEAR_LOOPS, %1)),
+ X86_FEATURE_RETPOLINE)
+ "910:"
+ : "=&r" (loops), ASM_CALL_CONSTRAINT
+ : "r" (loops) : "memory" );
+#endif
+}
#endif /* __ASSEMBLY__ */
#endif /* __NOSPEC_BRANCH_H__ */
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -44,6 +44,7 @@
#include <asm/debugreg.h>
#include <asm/kvm_para.h>
#include <asm/irq_remapping.h>
+#include <asm/nospec-branch.h>
#include <asm/virtext.h>
#include "trace.h"
@@ -4917,6 +4918,9 @@ static void svm_vcpu_run(struct kvm_vcpu
#endif
);
+ /* Eliminate branch target predictions from guest mode */
+ vmexit_fill_RSB();
+
#ifdef CONFIG_X86_64
wrmsrl(MSR_GS_BASE, svm->host.gs_base);
#else
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -48,6 +48,7 @@
#include <asm/kexec.h>
#include <asm/apic.h>
#include <asm/irq_remapping.h>
+#include <asm/nospec-branch.h>
#include "trace.h"
#include "pmu.h"
@@ -9026,6 +9027,9 @@ static void __noclone vmx_vcpu_run(struc
#endif
);
+ /* Eliminate branch target predictions from guest mode */
+ vmexit_fill_RSB();
+
/* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */
if (debugctlmsr)
update_debugctlmsr(debugctlmsr);
Patches currently in stable-queue which might be from dwmw(a)amazon.co.uk are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch
This is a note to let you know that I've just added the patch titled
x86/retpoline/entry: Convert entry assembler indirect jumps
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 2641f08bb7fc63a636a2b18173221d7040a3512e Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw(a)amazon.co.uk>
Date: Thu, 11 Jan 2018 21:46:28 +0000
Subject: x86/retpoline/entry: Convert entry assembler indirect jumps
From: David Woodhouse <dwmw(a)amazon.co.uk>
commit 2641f08bb7fc63a636a2b18173221d7040a3512e upstream.
Convert indirect jumps in core 32/64bit entry assembler code to use
non-speculative sequences when CONFIG_RETPOLINE is enabled.
Don't use CALL_NOSPEC in entry_SYSCALL_64_fastpath because the return
address after the 'call' instruction must be *precisely* at the
.Lentry_SYSCALL_64_after_fastpath label for stub_ptregs_64 to work,
and the use of alternatives will mess that up unless we play horrid
games to prepend with NOPs and make the variants the same length. It's
not worth it; in the case where we ALTERNATIVE out the retpoline, the
first instruction at __x86.indirect_thunk.rax is going to be a bare
jmp *%rax anyway.
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Acked-by: Ingo Molnar <mingo(a)kernel.org>
Acked-by: Arjan van de Ven <arjan(a)linux.intel.com>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Cc: Paul Turner <pjt(a)google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-7-git-send-email-dwmw@amazon.co.…
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/entry/entry_32.S | 5 +++--
arch/x86/entry/entry_64.S | 10 ++++++++--
2 files changed, 11 insertions(+), 4 deletions(-)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -45,6 +45,7 @@
#include <asm/asm.h>
#include <asm/smap.h>
#include <asm/export.h>
+#include <asm/nospec-branch.h>
.section .entry.text, "ax"
@@ -260,7 +261,7 @@ ENTRY(ret_from_fork)
/* kernel thread */
1: movl %edi, %eax
- call *%ebx
+ CALL_NOSPEC %ebx
/*
* A kernel thread is allowed to return here after successfully
* calling do_execve(). Exit to userspace to complete the execve()
@@ -1062,7 +1063,7 @@ error_code:
movl %ecx, %es
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
- call *%edi
+ CALL_NOSPEC %edi
jmp ret_from_exception
END(page_fault)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -37,6 +37,7 @@
#include <asm/pgtable_types.h>
#include <asm/export.h>
#include <asm/kaiser.h>
+#include <asm/nospec-branch.h>
#include <linux/err.h>
/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
@@ -208,7 +209,12 @@ entry_SYSCALL_64_fastpath:
* It might end up jumping to the slow path. If it jumps, RAX
* and all argument registers are clobbered.
*/
+#ifdef CONFIG_RETPOLINE
+ movq sys_call_table(, %rax, 8), %rax
+ call __x86_indirect_thunk_rax
+#else
call *sys_call_table(, %rax, 8)
+#endif
.Lentry_SYSCALL_64_after_fastpath_call:
movq %rax, RAX(%rsp)
@@ -380,7 +386,7 @@ ENTRY(stub_ptregs_64)
jmp entry_SYSCALL64_slow_path
1:
- jmp *%rax /* Called from C */
+ JMP_NOSPEC %rax /* Called from C */
END(stub_ptregs_64)
.macro ptregs_stub func
@@ -457,7 +463,7 @@ ENTRY(ret_from_fork)
1:
/* kernel thread */
movq %r12, %rdi
- call *%rbx
+ CALL_NOSPEC %rbx
/*
* A kernel thread is allowed to return here after successfully
* calling do_execve(). Exit to userspace to complete the execve()
Patches currently in stable-queue which might be from dwmw(a)amazon.co.uk are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch
This is a note to let you know that I've just added the patch titled
x86/retpoline/checksum32: Convert assembler indirect jumps
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From 5096732f6f695001fa2d6f1335a2680b37912c69 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw(a)amazon.co.uk>
Date: Thu, 11 Jan 2018 21:46:32 +0000
Subject: x86/retpoline/checksum32: Convert assembler indirect jumps
From: David Woodhouse <dwmw(a)amazon.co.uk>
commit 5096732f6f695001fa2d6f1335a2680b37912c69 upstream.
Convert all indirect jumps in 32bit checksum assembler code to use
non-speculative sequences when CONFIG_RETPOLINE is enabled.
Signed-off-by: David Woodhouse <dwmw(a)amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Acked-by: Arjan van de Ven <arjan(a)linux.intel.com>
Acked-by: Ingo Molnar <mingo(a)kernel.org>
Cc: gnomes(a)lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel(a)redhat.com>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe(a)redhat.com>
Cc: thomas.lendacky(a)amd.com
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Jiri Kosina <jikos(a)kernel.org>
Cc: Andy Lutomirski <luto(a)amacapital.net>
Cc: Dave Hansen <dave.hansen(a)intel.com>
Cc: Kees Cook <keescook(a)google.com>
Cc: Tim Chen <tim.c.chen(a)linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh(a)linux-foundation.org>
Cc: Paul Turner <pjt(a)google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-11-git-send-email-dwmw@amazon.co…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
arch/x86/lib/checksum_32.S | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -29,7 +29,8 @@
#include <asm/errno.h>
#include <asm/asm.h>
#include <asm/export.h>
-
+#include <asm/nospec-branch.h>
+
/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
@@ -156,7 +157,7 @@ ENTRY(csum_partial)
negl %ebx
lea 45f(%ebx,%ebx,2), %ebx
testl %esi, %esi
- jmp *%ebx
+ JMP_NOSPEC %ebx
# Handle 2-byte-aligned regions
20: addw (%esi), %ax
@@ -439,7 +440,7 @@ ENTRY(csum_partial_copy_generic)
andl $-32,%edx
lea 3f(%ebx,%ebx), %ebx
testl %esi, %esi
- jmp *%ebx
+ JMP_NOSPEC %ebx
1: addl $64,%esi
addl $64,%edi
SRC(movb -32(%edx),%bl) ; SRC(movb (%edx),%bl)
Patches currently in stable-queue which might be from dwmw(a)amazon.co.uk are
queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-cpufeatures-add-x86_bug_spectre_v.patch
queue-4.9/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/sysfs-cpu-fix-typos-in-vulnerability-documentation.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-cpu-implement-cpu-vulnerabilites-sysfs-functions.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/x86-cpu-factor-out-application-of-forced-cpu-caps.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.9/sysfs-cpu-add-vulnerability-folder.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-alternatives-fix-optimize_nops-checking.patch
queue-4.9/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch