Thread (11 messages) 11 messages, 2 authors, 2016-11-11

Re: [PATCH 2/3] Detect instruction fetch denied and report

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From: Aneesh Kumar K.V <hidden>
Date: 2016-11-08 16:17:08

Balbir Singh [off-list ref] writes:
quoted hunk ↗ jump to hunk
ISA 3 allows for prevention of instruction fetch and execution
of user mode pages. If such an error occurs, SRR1 bit 35
reports the error. We catch and report the error in do_page_fault()

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/mm/fault.c | 4 ++++
 1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index d0b137d..835fd03 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -404,6 +404,10 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 		    (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
 		     !(vma->vm_flags & (VM_READ | VM_WRITE))))
 			goto bad_area;
+
+		if (radix_enabled() && (regs->msr & SRR1_ISI_N_OR_G))
+			goto bad_area;
+
Can we also do this check early, ie, before down_read(mmap_sem)

-aneesh
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