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

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>
This commit is contained in:
Diana Craciun 2018-12-12 16:03:06 +02:00 committed by Michael Ellerman
parent 10c5e83afd
commit 7fef436295
2 changed files with 21 additions and 0 deletions
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6
arch/powerpc/kernel/head_booke.h
View File

@ -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 */\

15
arch/powerpc/kernel/head_fsl_booke.S
View File

@ -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