Subject: Patch "powerpc/fsl: Flush the branch predictor at each kernel entry (32 bit)" has been added to the 4.19-stable tree

From: <[email-masked]>
Date: Fri, 29 Mar 2019 16:07:54 +0100

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 4.19-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-4.19 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 Fri Mar 29 16:04:51 CET 2019
From: Michael Ellerman <[email-masked]>
Date: Fri, 29 Mar 2019 22:26:14 +1100
Subject: powerpc/fsl: Flush the branch predictor at each kernel entry (32 bit)
To: [email-masked], [email-masked]
Cc: [email-masked], [email-masked], [email-masked], [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
@@ -43,6 +43,9 @@
 	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);				     \
@@ -128,6 +131,9 @@
 	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
@@ -453,6 +453,13 @@ 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
@@ -547,6 +554,14 @@ 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-4.19/powerpc-fsl-emulate-sprn_bucsr-register.patch
queue-4.19/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-64bit.patch
queue-4.19/powerpc-fsl-update-spectre-v2-reporting.patch
queue-4.19/powerpc-fsl-add-macro-to-flush-the-branch-predictor.patch
queue-4.19/powerpc-security-fix-spectre_v2-reporting.patch
queue-4.19/powerpc-fsl-fix-the-flush-of-branch-predictor.patch
queue-4.19/powerpc-fsl-enable-runtime-patching-if-nospectre_v2-boot-arg-is-used.patch
queue-4.19/powerpc-fsl-fixed-warning-orphan-section-__btb_flush_fixup.patch
queue-4.19/powerpc-fsl-add-nospectre_v2-command-line-argument.patch
queue-4.19/powerpc-fsl-add-infrastructure-to-fixup-branch-predictor-flush.patch
queue-4.19/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-32-bit.patch
queue-4.19/powerpc-fsl-flush-branch-predictor-when-entering-kvm.patch