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authorDiana Craciun <diana.craciun@nxp.com>2018-12-12 16:03:05 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2018-12-20 22:59:03 +1100
commit10c5e83afd4a3f01712d97d3bb1ae34d5b74a185 (patch)
tree19f032a9630407a6b0d0bbfe13c44cb4573f57f1
parentf633a8ad636efb5d4bba1a047d4a0f1ef719aa06 (diff)
powerpc/fsl: Flush the branch predictor at each kernel entry (64bit)
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.craciun@nxp.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
-rw-r--r--arch/powerpc/kernel/entry_64.S5
-rw-r--r--arch/powerpc/kernel/exceptions-64e.S26
-rw-r--r--arch/powerpc/mm/tlb_low_64e.S7
3 files changed, 37 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 7b1693adff2a..7c2032e83ce7 100644
--- 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)
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 6d6e144a28ce..afb638778f44 100644
--- 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))
diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S
index 7fd20c52a8ec..9ed90064f542 100644
--- 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