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 (64bit)
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-64bit.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 <sta...@vger.kernel.org> know about it.
>From foo@baz Fri Mar 29 16:04:51 CET 2019
From: Michael Ellerman <m...@ellerman.id.au>
Date: Fri, 29 Mar 2019 22:26:13 +1100
Subject: powerpc/fsl: Flush the branch predictor at each kernel entry (64bit)
To: sta...@vger.kernel.org, gre...@linuxfoundation.org
Cc: linuxppc-...@ozlabs.org, diana.crac...@nxp.com, msucha...@suse.de,
christophe.le...@c-s.fr
Message-ID: <20190329112620.14489-26-...@ellerman.id.au>
From: Diana Craciun <diana.crac...@nxp.com>
commit 10c5e83afd4a3f01712d97d3bb1ae34d5b74a185 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 <diana.crac...@nxp.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/powerpc/kernel/entry_64.S | 5 +++++
arch/powerpc/kernel/exceptions-64e.S | 26 +++++++++++++++++++++++++-
arch/powerpc/mm/tlb_low_64e.S | 7 +++++++
3 files changed, 37 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -80,6 +80,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
std r0,GPR0(r1)
std r10,GPR1(r1)
beq 2f /* if from kernel mode */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+START_BTB_FLUSH_SECTION
+ BTB_FLUSH(r10)
+END_BTB_FLUSH_SECTION
+#endif
ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
2: std r2,GPR2(r1)
std r3,GPR3(r1)
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -296,7 +296,8 @@ ret_from_mc_except:
andi. r10,r11,MSR_PR; /* save stack pointer */ \
beq 1f; /* branch around if supervisor */ \
ld r1,PACAKSAVE(r13); /* get kernel stack coming from usr */\
-1: cmpdi cr1,r1,0; /* check if SP makes sense */ \
+1: type##_BTB_FLUSH \
+ cmpdi cr1,r1,0; /* check if SP makes sense */ \
bge- cr1,exc_##n##_bad_stack;/* bad stack (TODO: out of line) */ \
mfspr r10,SPRN_##type##_SRR0; /* read SRR0 before touching stack */
@@ -328,6 +329,29 @@ ret_from_mc_except:
#define SPRN_MC_SRR0 SPRN_MCSRR0
#define SPRN_MC_SRR1 SPRN_MCSRR1
+#ifdef CONFIG_PPC_FSL_BOOK3E
+#define GEN_BTB_FLUSH \
+ START_BTB_FLUSH_SECTION \
+ beq 1f; \
+ BTB_FLUSH(r10) \
+ 1: \
+ END_BTB_FLUSH_SECTION
+
+#define CRIT_BTB_FLUSH \
+ START_BTB_FLUSH_SECTION \
+ BTB_FLUSH(r10) \
+ END_BTB_FLUSH_SECTION
+
+#define DBG_BTB_FLUSH CRIT_BTB_FLUSH
+#define MC_BTB_FLUSH CRIT_BTB_FLUSH
+#define GDBELL_BTB_FLUSH GEN_BTB_FLUSH
+#else
+#define GEN_BTB_FLUSH
+#define CRIT_BTB_FLUSH
+#define DBG_BTB_FLUSH
+#define GDBELL_BTB_FLUSH
+#endif
+
#define NORMAL_EXCEPTION_PROLOG(n, intnum, addition) \
EXCEPTION_PROLOG(n, intnum, GEN, addition##_GEN(n))
--- a/arch/powerpc/mm/tlb_low_64e.S
+++ b/arch/powerpc/mm/tlb_low_64e.S
@@ -70,6 +70,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
std r15,EX_TLB_R15(r12)
std r10,EX_TLB_CR(r12)
#ifdef CONFIG_PPC_FSL_BOOK3E
+START_BTB_FLUSH_SECTION
+ mfspr r11, SPRN_SRR1
+ andi. r10,r11,MSR_PR
+ beq 1f
+ BTB_FLUSH(r10)
+1:
+END_BTB_FLUSH_SECTION
std r7,EX_TLB_R7(r12)
#endif
TLB_MISS_PROLOG_STATS
Patches currently in stable-queue which might be from m...@ellerman.id.au 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
