Subject: Patch "powerpc/fsl: Flush the branch predictor at each kernel entry (32 bit)" has been added to the 4.4-stable tree

From: <[email-masked]>
Date: Tue, 30 Apr 2019 12:40:30 +0200

This is a note to let you know that I've just added the patch titled

    powerpc/fsl: Flush the branch predictor at each kernel entry (32 bit)

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-32-bit.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email-masked]> know about it.

>From foo@baz Tue 30 Apr 2019 12:38:50 PM CEST
From: Diana Craciun <[email-masked]>
Date: Mon, 29 Apr 2019 18:49:04 +0300
Subject: powerpc/fsl: Flush the branch predictor at each kernel entry (32 bit)
To: [email-masked], [email-masked]
Cc: [email-masked], [email-masked], Diana Craciun <[email-masked]>
Message-ID: <[email-masked]>

From: Diana Craciun <[email-masked]>

commit 7fef436295bf6c05effe682c8797dfcb0deb112a upstream.

In order to protect against speculation attacks on
indirect branches, the branch predictor is flushed at
kernel entry to protect for the following situations:
- userspace process attacking another userspace process
- userspace process attacking the kernel
Basically when the privillege level change (i.e.the kernel
is entered), the branch predictor state is flushed.

Signed-off-by: Diana Craciun <[email-masked]>
Signed-off-by: Michael Ellerman <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 arch/powerpc/kernel/head_booke.h     |    6 ++++++
 arch/powerpc/kernel/head_fsl_booke.S |   15 +++++++++++++++
 2 files changed, 21 insertions(+)

--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -42,6 +42,9 @@
 	andi.	r11, r11, MSR_PR;	/* check whether user or kernel    */\
 	mr	r11, r1;						     \
 	beq	1f;							     \
+START_BTB_FLUSH_SECTION					\
+	BTB_FLUSH(r11)						\
+END_BTB_FLUSH_SECTION					\
 	/* if from user, start at top of this thread's kernel stack */       \
 	lwz	r11, THREAD_INFO-THREAD(r10);				     \
 	ALLOC_STACK_FRAME(r11, THREAD_SIZE);				     \
@@ -127,6 +130,9 @@
 	stw	r9,_CCR(r8);		/* save CR on stack		   */\
 	mfspr	r11,exc_level_srr1;	/* check whether user or kernel    */\
 	DO_KVM	BOOKE_INTERRUPT_##intno exc_level_srr1;		             \
+START_BTB_FLUSH_SECTION								\
+	BTB_FLUSH(r10)									\
+END_BTB_FLUSH_SECTION								\
 	andi.	r11,r11,MSR_PR;						     \
 	mfspr	r11,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
 	lwz	r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -451,6 +451,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
 	mfcr	r13
 	stw	r13, THREAD_NORMSAVE(3)(r10)
 	DO_KVM	BOOKE_INTERRUPT_DTLB_MISS SPRN_SRR1
+START_BTB_FLUSH_SECTION
+	mfspr r11, SPRN_SRR1
+	andi. r10,r11,MSR_PR
+	beq 1f
+	BTB_FLUSH(r10)
+1:
+END_BTB_FLUSH_SECTION
 	mfspr	r10, SPRN_DEAR		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the
@@ -545,6 +552,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
 	mfcr	r13
 	stw	r13, THREAD_NORMSAVE(3)(r10)
 	DO_KVM	BOOKE_INTERRUPT_ITLB_MISS SPRN_SRR1
+START_BTB_FLUSH_SECTION
+	mfspr r11, SPRN_SRR1
+	andi. r10,r11,MSR_PR
+	beq 1f
+	BTB_FLUSH(r10)
+1:
+END_BTB_FLUSH_SECTION
+
 	mfspr	r10, SPRN_SRR0		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the

Patches currently in stable-queue which might be from [email-masked] are

queue-4.4/powerpc-64s-add-support-for-a-store-forwarding-barrier-at-kernel-entry-exit.patch
queue-4.4/powerpc-fsl-emulate-sprn_bucsr-register.patch
queue-4.4/powerpc-64-make-stf-barrier-ppc_book3s_64-specific.patch
queue-4.4/powerpc-pseries-set-or-clear-security-feature-flags.patch
queue-4.4/powerpc-fsl-fix-spectre_v2-mitigations-reporting.patch
queue-4.4/powerpc-64s-patch-barrier_nospec-in-modules.patch
queue-4.4/powerpc-pseries-support-firmware-disable-of-rfi-flush.patch
queue-4.4/powerpc-rfi-flush-call-setup_rfi_flush-after-lpm-migration.patch
queue-4.4/powerpc-pseries-query-hypervisor-for-count-cache-flush-settings.patch
queue-4.4/powerpc-powernv-set-or-clear-security-feature-flags.patch
queue-4.4/powerpc-64s-add-support-for-software-count-cache-flush.patch
queue-4.4/powerpc64s-show-ori31-availability-in-spectre_v1-sysfs-file-not-v2.patch
queue-4.4/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-64bit.patch
queue-4.4/powerpc-fsl-update-spectre-v2-reporting.patch
queue-4.4/powerpc-64s-wire-up-cpu_show_spectre_v2.patch
queue-4.4/powerpc-64-make-meltdown-reporting-book3s-64-specific.patch
queue-4.4/powerpc-rfi-flush-make-it-possible-to-call-setup_rfi_flush-again.patch
queue-4.4/powerpc-64s-add-support-for-ori-barrier_nospec-patching.patch
queue-4.4/powerpc-use-barrier_nospec-in-copy_from_user.patch
queue-4.4/powerpc-64s-fix-section-mismatch-warnings-from-setup_rfi_flush.patch
queue-4.4/powerpc-fsl-sanitize-the-syscall-table-for-nxp-powerpc-32-bit-platforms.patch
queue-4.4/powerpc-avoid-code-patching-freed-init-sections.patch
queue-4.4/powerpc-fsl-add-macro-to-flush-the-branch-predictor.patch
queue-4.4/powerpc-xmon-add-rfi-flush-related-fields-to-paca-dump.patch
queue-4.4/powerpc-fsl-add-barrier_nospec-implementation-for-nxp-powerpc-book3e.patch
queue-4.4/powerpc-security-fix-spectre_v2-reporting.patch
queue-4.4/powerpc-add-security-feature-flags-for-spectre-meltdown.patch
queue-4.4/powerpc-powernv-use-the-security-flags-in-pnv_setup_rfi_flush.patch
queue-4.4/powerpc-64-disable-the-speculation-barrier-from-the-command-line.patch
queue-4.4/powerpc-fsl-fix-the-flush-of-branch-predictor.patch
queue-4.4/powerpc-pseries-use-the-security-flags-in-pseries_setup_rfi_flush.patch
queue-4.4/powerpc-64-add-config_ppc_barrier_nospec.patch
queue-4.4/powerpc-64s-move-cpu_show_meltdown.patch
queue-4.4/powerpc-fsl-enable-runtime-patching-if-nospectre_v2-boot-arg-is-used.patch
queue-4.4/powerpc-64-use-barrier_nospec-in-syscall-entry.patch
queue-4.4/powerpc-fsl-fixed-warning-orphan-section-__btb_flush_fixup.patch
queue-4.4/powerpc-fsl-add-nospectre_v2-command-line-argument.patch
queue-4.4/powerpc-64s-add-new-security-feature-flags-for-count-cache-flush.patch
queue-4.4/powerpc-fsl-add-infrastructure-to-fixup-branch-predictor-flush.patch
queue-4.4/powerpc-rfi-flush-differentiate-enabled-and-patched-flush-types.patch
queue-4.4/powerpc-64s-enhance-the-information-in-cpu_show_spectre_v1.patch
queue-4.4/powerpc-64-call-setup_barrier_nospec-from-setup_arch.patch
queue-4.4/powerpc-rfi-flush-always-enable-fallback-flush-on-pseries.patch
queue-4.4/powerpc-64s-improve-rfi-l1-d-cache-flush-fallback.patch
queue-4.4/powerpc-asm-add-a-patch_site-macro-helpers-for-patching-instructions.patch
queue-4.4/powerpc-pseries-add-new-h_get_cpu_characteristics-flags.patch
queue-4.4/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-32-bit.patch
queue-4.4/powerpc-64s-enable-barrier_nospec-based-on-firmware-settings.patch
queue-4.4/powerpc-powernv-support-firmware-disable-of-rfi-flush.patch
queue-4.4/powerpc-rfi-flush-move-the-logic-to-avoid-a-redo-into-the-debugfs-code.patch
queue-4.4/powerpc-fsl-flush-branch-predictor-when-entering-kvm.patch
queue-4.4/powerpc-powernv-query-firmware-for-count-cache-flush-settings.patch
queue-4.4/powerpc-64s-wire-up-cpu_show_spectre_v1.patch
queue-4.4/powerpc-64s-add-barrier_nospec.patch
queue-4.4/powerpc-64s-enhance-the-information-in-cpu_show_meltdown.patch
queue-4.4/powerpc-move-default-security-feature-flags.patch
queue-4.4/powerpc-pseries-fix-clearing-of-security-feature-flags.patch
queue-4.4/powerpc-pseries-restore-default-security-feature-flags-on-setup.patch