Handle Data and Instruction exceptions caused by memory
protection-key.
The CPU will detect the key fault if the HPTE is already
programmed with the key.
However if the HPTE is not hashed, a key fault will not
be detected by the hardware. The software will detect
pkey violation in such a case.
Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/reg.h | 1 -
arch/powerpc/kernel/exceptions-64s.S | 2 +-
arch/powerpc/mm/fault.c | 22 ++++++++++++++++++++++
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index b779f3c..ffc9990 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -312,7 +312,6 @@
DSISR_BAD_EXT_CTRL)
#define DSISR_BAD_FAULT_64S (DSISR_BAD_FAULT_32S | \
DSISR_ATTR_CONFLICT | \
- DSISR_KEYFAULT | \
DSISR_UNSUPP_MMU | \
DSISR_PRTABLE_FAULT | \
DSISR_ICSWX_NO_CT | \
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e441b46..804e804 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1521,7 +1521,7 @@ USE_TEXT_SECTION()
.balign IFETCH_ALIGN_BYTES
do_hash_page:
#ifdef CONFIG_PPC_BOOK3S_64
- lis r0,(DSISR_BAD_FAULT_64S|DSISR_DABRMATCH)@h
+ lis r0,(DSISR_BAD_FAULT_64S | DSISR_DABRMATCH | DSISR_KEYFAULT)@h
ori r0,r0,DSISR_BAD_FAULT_64S@l
and. r0,r4,r0 /* weird error? */
bne- handle_page_fault /* if not, try to insert a HPTE */
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 4797d08..943a91e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -427,6 +427,11 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+ if (error_code & DSISR_KEYFAULT) {
+ _exception(SIGSEGV, regs, SEGV_PKUERR, address);
+ return 0;
+ }
+
/*
* We want to do this outside mmap_sem, because reading code around nip
* can result in fault, which will cause a deadlock when called with
@@ -498,6 +503,23 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
* the fault.
*/
fault = handle_mm_fault(vma, address, flags);
+
+#ifdef CONFIG_PPC_MEM_KEYS
+ /*
+ * if the HPTE is not hashed, hardware will not detect
+ * a key fault. Lets check if we failed because of a
+ * software detected key fault.
+ */
+ if (unlikely(fault & VM_FAULT_SIGSEGV) &&
+ !arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
+ is_exec, 0)) {
+ int pkey = vma_pkey(vma);
+
+ if (likely(pkey))
+ return __bad_area(regs, address, SEGV_PKUERR);
+ }
+#endif /* CONFIG_PPC_MEM_KEYS */
+
major |= fault & VM_FAULT_MAJOR;
/*
--
1.7.1
